[PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Derrick Stolee via GitGitGadget]

This RFC explores a new git config-batch builtin that allows tools to
interact with Git's config data with multiple queries using a single
process. This is an orthogonal alternative to the effort to create a stable,
linkable config API. Both approaches have different strengths.

My main motivation is the performance of git-credential-manager on Windows
platforms as it can call git config get dozens of times. At 150-200ms per
execution, that adds up significantly, leading to multiple seconds just to
load a credential that already exists. I believe that there are other
benefits to having this interface available, but I can't recall any
specifics at the moment.

This RFC adds git config-batch with a protocol over stdin/stdout for
executing multiple config queries. The implementation has a limited set of
potential queries, but also creates a model for compatibility for tools to
automatically adapt to different Git versions.

I'm submitting this as an RFC before I've polished all of the details
because I want to make sure I'm going down a good direction. Please focus
feedback in these questions:

 * Is this a worthwhile feature to add to Git?
 * Is this a reasonable protocol for stdin/stdout?
 * How can we structure the code to make it easier to contribute new
   commands in the future?
 * This seems like a place where parallel contributions can be made once the
   baseline is implemented. Is there interest in further contributions to
   expand the commands?

This RFC adds the following commands over stdin:

 1. help lists the available commands, giving the caller an understanding of
    what is available in this Git version.
 2. get loads a value for a given key within a certain scope, with optional
    value patterns.
 3. set assigns a key-value pair in a given scope.
 4. unset removes a key-value pair in a given scope with optional value
    patterns.

Each command has an associated version, in case we need to expand or alter
the functionality in the future. This includes the potential to deprecate
and remove certain versions that we no longer want to support, such as
replacing set version 1 with a version 2 and making version 1 no longer
available. I do hope that we will mostly be able to move with new command
names, such as a set-all command including the options for git config set
--all ... instead of increasing the version of the set command.

There is a -z option that changes the command interface to use
NUL-terminated strings. Two NULs specify a command boundary, which promotes
compatibility with a caller that sends an unknown command. However, this
means that we cannot specify an empty string as a token within a command
unless we add more data. This format uses <N>:<string> to provide the
integer <N> which specifies the length of <string>. This is a little
cumbersome, but the format is intended for tools, not humans.

I have a test integration with git-credential-manager available [1] for
testing. This includes a model for interacting with git config-batch in a
compatible way that will respond to certain features not being available:

 1. If git config-batch fails immediately, then all queries are handled by
    git config.
 2. If git config-batch starts without failure, then the first query is for
    the help command.
 3. As queries come to the config system, the query is checked against the
    available commands advertised by git config-batch. If the appropriate
    command is available, then the query is made in that process. If not,
    then the query uses the existing git config command.

One thing that I think would be valuable to include is a reload command that
signals that the git config-batch process should reload the configset into
memory due to config manipulations in other processes, especially while git
config-batch doesn't have all capabilities from git config. I'll include
that in the first version for review, if this RFC leads to positive support.

[1] https://github.com/git-ecosystem/git-credential-manager/pull/2245

I have a few concerns with this implementation that I'd like to improve
before submitting a version for full review. I list them here so you can see
the flaws that I already see, but also so you can add to this list:

 * We need a reload command (as mentioned above).
 * The tests need to include a submodule and submodule-level config.
 * When specifying the local scope to the get command, the matched value
   does not include worktree or submodule config in the same way that git
   config get --local <key> would.
 * The token-parsing API in this helper is still too complicated to use. I
   should create parsing tooling similar to the parse-opts API so each
   command could specify its use of positional values and optional
   arguments.
 * The use of arg:<arg> to specify an optional argument creates the
   inability to submit a value that starts with arg:. Consider alternative
   ways to specify arguments or to specify that the remaining data in the
   command (including spaces) is a final positional argument.
 * In general, I found myself implementing behavior based on the deprecated
   forms of git config that use the --get or --unset style arguments instead
   of git config (set|unset|get) subcommands. It's worth making sure that
   any references to equivalent git config commands use the new modes.
 * I need to add an --[no-]includes option as a command-line argument that
   signals whether include sections should be followed. I don't believe this
   should be specified on a per-command basis, but I'm open to suggestions.
 * I have an early draft of a technical document detailing the plan for this
   builtin. It has some lists of intended future commands that have not been
   implemented. This would also be a good place to document any parsing APIs
   built to help contributors adding to this builtin.

Thanks, -Stolee

Derrick Stolee (11):
  config-batch: basic boilerplate of new builtin
  config-batch: create parse loop and unknown command
  config-batch: implement get v1
  config-batch: create 'help' command
  config-batch: add NUL-terminated I/O format
  docs: add design doc for config-batch
  config: extract location structs from builtin
  config-batch: pass prefix through commands
  config-batch: add 'set' v1 command
  t1312: create read/write test
  config-batch: add unset v1 command

 .gitignore                                |   1 +
 Documentation/git-config-batch.adoc       | 214 ++++++
 Documentation/meson.build                 |   1 +
 Documentation/technical/config-batch.adoc |  70 ++
 Makefile                                  |   1 +
 builtin.h                                 |   7 +
 builtin/config-batch.c                    | 772 ++++++++++++++++++++++
 builtin/config.c                          | 117 +---
 command-list.txt                          |   1 +
 config.c                                  | 116 ++++
 config.h                                  |  26 +
 git.c                                     |   1 +
 meson.build                               |   1 +
 t/meson.build                             |   1 +
 t/t1312-config-batch.sh                   | 372 +++++++++++
 15 files changed, 1592 insertions(+), 109 deletions(-)
 create mode 100644 Documentation/git-config-batch.adoc
 create mode 100644 Documentation/technical/config-batch.adoc
 create mode 100644 builtin/config-batch.c
 create mode 100755 t/t1312-config-batch.sh


base-commit: 83a69f19359e6d9bc980563caca38b2b5729808c
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2033%2Fderrickstolee%2Fbatched-config-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2033/derrickstolee/batched-config-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2033
-- 
gitgitgadget

[PATCH 01/11] config-batch: basic boilerplate of new builtin

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

Later changes will document, implement, and test this new builtin. For now,
this serves as the latest example of the minimum boilerplate to introduce a
new builtin.

Recently, we updated the comment in builtin.h about how to create a new
builtin, but failed to mention the required change to meson.build files for
some CI builds to pass. Fix that oversight.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 .gitignore                          |  1 +
 Documentation/git-config-batch.adoc | 24 +++++++++++++++++++++++
 Documentation/meson.build           |  1 +
 Makefile                            |  1 +
 builtin.h                           |  7 +++++++
 builtin/config-batch.c              | 30 +++++++++++++++++++++++++++++
 command-list.txt                    |  1 +
 git.c                               |  1 +
 meson.build                         |  1 +
 t/meson.build                       |  1 +
 t/t1312-config-batch.sh             | 12 ++++++++++++
 11 files changed, 80 insertions(+)
 create mode 100644 Documentation/git-config-batch.adoc
 create mode 100644 builtin/config-batch.c
 create mode 100755 t/t1312-config-batch.sh

diff --git a/.gitignore b/.gitignore
index 78a45cb5be..42640b5e24 100644
--- a/.gitignore
+++ b/.gitignore
@@ -44,6 +44,7 @@
 /git-commit-graph
 /git-commit-tree
 /git-config
+/git-config-batch
 /git-count-objects
 /git-credential
 /git-credential-cache
diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
new file mode 100644
index 0000000000..dfa0bd83e2
--- /dev/null
+++ b/Documentation/git-config-batch.adoc
@@ -0,0 +1,24 @@
+git-config-batch(1)
+===================
+
+NAME
+----
+git-config-batch - Get and set options using machine-parseable interface
+
+
+SYNOPSIS
+--------
+[verse]
+'git config-batch' <options>
+
+DESCRIPTION
+-----------
+TODO
+
+SEE ALSO
+--------
+linkgit:git-config[1]
+
+GIT
+---
+Part of the linkgit:git[1] suite
diff --git a/Documentation/meson.build b/Documentation/meson.build
index f02dbc20cb..f5ad117921 100644
--- a/Documentation/meson.build
+++ b/Documentation/meson.build
@@ -29,6 +29,7 @@ manpages = {
   'git-commit-tree.adoc' : 1,
   'git-commit.adoc' : 1,
   'git-config.adoc' : 1,
+  'git-config-batch.adoc' : 1,
   'git-count-objects.adoc' : 1,
   'git-credential-cache--daemon.adoc' : 1,
   'git-credential-cache.adoc' : 1,
diff --git a/Makefile b/Makefile
index 8aa489f3b6..aa3868e513 100644
--- a/Makefile
+++ b/Makefile
@@ -1390,6 +1390,7 @@ BUILTIN_OBJS += builtin/commit-graph.o
 BUILTIN_OBJS += builtin/commit-tree.o
 BUILTIN_OBJS += builtin/commit.o
 BUILTIN_OBJS += builtin/config.o
+BUILTIN_OBJS += builtin/config-batch.o
 BUILTIN_OBJS += builtin/count-objects.o
 BUILTIN_OBJS += builtin/credential-cache--daemon.o
 BUILTIN_OBJS += builtin/credential-cache.o
diff --git a/builtin.h b/builtin.h
index e5e16ecaa6..5f5a19635e 100644
--- a/builtin.h
+++ b/builtin.h
@@ -68,12 +68,18 @@
  *
  * . Add `builtin/foo.o` to `BUILTIN_OBJS` in `Makefile`.
  *
+ * . Add 'builtin/foo.c' to the 'builtin_sources' array in 'meson.build'.
+ *
  * Additionally, if `foo` is a new command, there are 4 more things to do:
  *
  * . Add tests to `t/` directory.
  *
+ * . Add the test script to 'integration_tests' in  't/meson.build'.
+ *
  * . Write documentation in `Documentation/git-foo.adoc`.
  *
+ * . Add 'git-foo.adoc' to the manpages list in 'Documentation/meson.build'.
+ *
  * . Add an entry for `git-foo` to `command-list.txt`.
  *
  * . Add an entry for `/git-foo` to `.gitignore`.
@@ -167,6 +173,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix, struct repositor
 int cmd_commit_graph(int argc, const char **argv, const char *prefix, struct repository *repo);
 int cmd_commit_tree(int argc, const char **argv, const char *prefix, struct repository *repo);
 int cmd_config(int argc, const char **argv, const char *prefix, struct repository *repo);
+int cmd_config_batch(int argc, const char **argv, const char *prefix, struct repository *repo);
 int cmd_count_objects(int argc, const char **argv, const char *prefix, struct repository *repo);
 int cmd_credential(int argc, const char **argv, const char *prefix, struct repository *repo);
 int cmd_credential_cache(int argc, const char **argv, const char *prefix, struct repository *repo);
diff --git a/builtin/config-batch.c b/builtin/config-batch.c
new file mode 100644
index 0000000000..ea4f408ecb
--- /dev/null
+++ b/builtin/config-batch.c
@@ -0,0 +1,30 @@
+#define USE_THE_REPOSITORY_VARIABLE
+#include "builtin.h"
+#include "config.h"
+#include "environment.h"
+#include "parse-options.h"
+
+static const char *const builtin_config_batch_usage[] = {
+	N_("git config-batch <options>"),
+	NULL
+};
+
+int cmd_config_batch(int argc,
+		     const char **argv,
+		     const char *prefix,
+		     struct repository *repo)
+{
+	struct option options[] = {
+		OPT_END(),
+	};
+
+	show_usage_with_options_if_asked(argc, argv,
+					 builtin_config_batch_usage, options);
+
+	argc = parse_options(argc, argv, prefix, options, builtin_config_batch_usage,
+			     0);
+
+	repo_config(repo, git_default_config, NULL);
+
+	return 0;
+}
diff --git a/command-list.txt b/command-list.txt
index accd3d0c4b..57c7c7458d 100644
--- a/command-list.txt
+++ b/command-list.txt
@@ -83,6 +83,7 @@ git-commit                              mainporcelain           history
 git-commit-graph                        plumbingmanipulators
 git-commit-tree                         plumbingmanipulators
 git-config                              ancillarymanipulators           complete
+git-config-batch                        plumbinginterrogators
 git-count-objects                       ancillaryinterrogators
 git-credential                          purehelpers
 git-credential-cache                    purehelpers
diff --git a/git.c b/git.c
index c5fad56813..6b55a867dd 100644
--- a/git.c
+++ b/git.c
@@ -557,6 +557,7 @@ static struct cmd_struct commands[] = {
 	{ "commit-graph", cmd_commit_graph, RUN_SETUP },
 	{ "commit-tree", cmd_commit_tree, RUN_SETUP },
 	{ "config", cmd_config, RUN_SETUP_GENTLY | DELAY_PAGER_CONFIG },
+	{ "config-batch", cmd_config_batch, RUN_SETUP_GENTLY },
 	{ "count-objects", cmd_count_objects, RUN_SETUP },
 	{ "credential", cmd_credential, RUN_SETUP_GENTLY | NO_PARSEOPT },
 	{ "credential-cache", cmd_credential_cache },
diff --git a/meson.build b/meson.build
index dd52efd1c8..040bc32c2d 100644
--- a/meson.build
+++ b/meson.build
@@ -582,6 +582,7 @@ builtin_sources = [
   'builtin/commit-tree.c',
   'builtin/commit.c',
   'builtin/config.c',
+  'builtin/config-batch.c',
   'builtin/count-objects.c',
   'builtin/credential-cache--daemon.c',
   'builtin/credential-cache.c',
diff --git a/t/meson.build b/t/meson.build
index 459c52a489..0e9f1826f8 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -186,6 +186,7 @@ integration_tests = [
   't1309-early-config.sh',
   't1310-config-default.sh',
   't1311-config-optional.sh',
+  't1312-config-batch.sh',
   't1350-config-hooks-path.sh',
   't1400-update-ref.sh',
   't1401-symbolic-ref.sh',
diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
new file mode 100755
index 0000000000..f59ba4a0f3
--- /dev/null
+++ b/t/t1312-config-batch.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+test_description='Test git config-batch'
+
+. ./test-lib.sh
+
+test_expect_success 'help text' '
+	test_must_fail git config-batch -h >out &&
+	grep usage out
+'
+
+test_done
-- 
gitgitgadget

[PATCH 02/11] config-batch: create parse loop and unknown command

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

As we build new features in the config-batch command, we define the
plaintext protocol with line-by-line output and responses. To think to the
future, we make sure that the protocol has a clear way to respond to an
unknown command or an unknown version of that command.

As some commands will allow the final argument to contain spaces or even be
able to parse "\ " as a non-split token, we only provide the remaining line
as data.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 Documentation/git-config-batch.adoc |  23 ++++-
 builtin/config-batch.c              | 133 +++++++++++++++++++++++++++-
 t/t1312-config-batch.sh             |  19 +++-
 3 files changed, 170 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
index dfa0bd83e2..9ca04b0c1e 100644
--- a/Documentation/git-config-batch.adoc
+++ b/Documentation/git-config-batch.adoc
@@ -13,7 +13,28 @@ SYNOPSIS
 
 DESCRIPTION
 -----------
-TODO
+Tools frequently need to change their behavior based on values stored in
+Git's configuration files. These files may have complicated conditions
+for including extra files, so it is difficult to produce an independent
+parser. To avoid executing multiple processes to discover or modify
+multiple configuration values, the `git config-batch` command allows a
+single process to handle multiple requests using a machine-parseable
+interface across `stdin` and `stdout`.
+
+PROTOCOL
+--------
+By default, the protocol uses line feeds (`LF`) to signal the end of a
+command over `stdin` or a response over `stdout`.
+
+The protocol will be extended in the future, and consumers should be
+resilient to older Git versions not understanding the latest command
+set. Thus, if the Git version includes the `git config-batch` builtin
+but doesn't understand an input command, it will return a single line
+response:
+
+```
+unknown_command LF
+```
 
 SEE ALSO
 --------
diff --git a/builtin/config-batch.c b/builtin/config-batch.c
index ea4f408ecb..dffedb8ca2 100644
--- a/builtin/config-batch.c
+++ b/builtin/config-batch.c
@@ -3,17 +3,144 @@
 #include "config.h"
 #include "environment.h"
 #include "parse-options.h"
+#include "strbuf.h"
+#include "string-list.h"
 
 static const char *const builtin_config_batch_usage[] = {
 	N_("git config-batch <options>"),
 	NULL
 };
 
+#define UNKNOWN_COMMAND "unknown_command"
+
+static int emit_response(const char *response, ...)
+{
+	va_list params;
+	const char *token;
+
+	printf("%s", response);
+
+	va_start(params, response);
+	while ((token = va_arg(params, const char *)))
+		printf(" %s", token);
+	va_end(params);
+
+	printf("\n");
+	fflush(stdout);
+	return 0;
+}
+
+/**
+ * A function pointer type for defining a command. The function is
+ * responsible for handling different versions of the command name.
+ *
+ * Provides the remaining 'data' for the command, to be parsed by
+ * the function as needed according to its parsing rules.
+ *
+ * These functions should only return a negative value if they result
+ * in such a catastrophic failure that the process should end.
+ *
+ * Return 0 on success.
+ */
+typedef int (*command_fn)(struct repository *repo,
+			  char *data, size_t data_len);
+
+static int unknown_command(struct repository *repo UNUSED,
+			  char *data UNUSED, size_t data_len UNUSED)
+{
+	return emit_response(UNKNOWN_COMMAND, NULL);
+}
+
+struct command {
+	const char *name;
+	command_fn fn;
+	int version;
+};
+
+static struct command commands[] = {
+	/* unknown_command must be last. */
+	{
+		.name = "",
+		.fn   = unknown_command,
+	},
+};
+
+#define COMMAND_COUNT ((size_t)(sizeof(commands) / sizeof(*commands)))
+
+/**
+ * Process a single line from stdin and process the command.
+ *
+ * Returns 0 on successful processing of command, including the
+ * unknown_command output.
+ *
+ * Returns 1 on natural exit due to exist signal of empty line.
+ *
+ * Returns negative value on other catastrophic error.
+ */
+static int process_command(struct repository *repo)
+{
+	static struct strbuf line = STRBUF_INIT;
+	struct string_list tokens = STRING_LIST_INIT_NODUP;
+	const char *command;
+	int version;
+	char *data = NULL;
+	size_t data_len = 0;
+	int res = 0;
+
+	strbuf_getline(&line, stdin);
+
+	if (!line.len)
+		return 1;
+
+	/* Parse out the first two tokens, command and version. */
+	string_list_split_in_place(&tokens, line.buf, " ", 2);
+
+	if (tokens.nr < 2) {
+		res = error(_("expected at least 2 tokens, got %"PRIu32),
+			    (uint32_t)tokens.nr);
+		goto cleanup;
+	}
+
+	command = tokens.items[0].string;
+
+	if (!git_parse_int(tokens.items[1].string, &version)) {
+		res = error(_("unable to parse '%s' to integer"),
+			    tokens.items[1].string);
+		goto cleanup;
+	}
+
+	if (tokens.nr >= 3) {
+		data = tokens.items[2].string;
+		data_len = strlen(tokens.items[2].string);
+	}
+
+	for (size_t i = 0; i < COMMAND_COUNT; i++) {
+		/*
+		 * Run the ith command if we have hit the unknown
+		 * command or if the name and version match.
+		 */
+		if (!commands[i].name[0] ||
+		    (!strcmp(command, commands[i].name) &&
+		     commands[i].version == version)) {
+			res = commands[i].fn(repo, data, data_len);
+			goto cleanup;
+		}
+	}
+
+	BUG(_("scanned to end of command list, including 'unknown_command'"));
+
+cleanup:
+	strbuf_reset(&line);
+	string_list_clear(&tokens, 0);
+	return res;
+}
+
 int cmd_config_batch(int argc,
 		     const char **argv,
 		     const char *prefix,
 		     struct repository *repo)
 {
+	int res = 0;
 	struct option options[] = {
 		OPT_END(),
 	};
@@ -26,5 +153,9 @@ int cmd_config_batch(int argc,
 
 	repo_config(repo, git_default_config, NULL);
 
-	return 0;
+	while (!(res = process_command(repo)));
+
+	if (res == 1)
+		return 0;
+	die(_("an unrecoverable error occurred during command execution"));
 }
diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
index f59ba4a0f3..f60ef35e38 100755
--- a/t/t1312-config-batch.sh
+++ b/t/t1312-config-batch.sh
@@ -4,9 +4,22 @@ test_description='Test git config-batch'
 
 . ./test-lib.sh
 
-test_expect_success 'help text' '
-	test_must_fail git config-batch -h >out &&
-	grep usage out
+test_expect_success 'no commands' '
+	echo | git config-batch >out &&
+	test_must_be_empty out
+'
+
+test_expect_success 'unknown_command' '
+	echo unknown_command >expect &&
+	echo "bogus 1 line of tokens" >in &&
+	git config-batch >out <in &&
+	test_cmp expect out
+'
+
+test_expect_success 'failed to parse version' '
+	echo "bogus BAD_VERSION line of tokens" >in &&
+	test_must_fail git config-batch 2>err <in &&
+	test_grep BAD_VERSION err
 '
 
 test_done
-- 
gitgitgadget

[PATCH 03/11] config-batch: implement get v1

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

The 'get' command for the 'git config-batch' builtin is the first command
and is currently at version 1. It returns at most one value, the same as
'git config --get <key>' with optional value-based filtering.

The documentation and tests detail the specifics of how to format requests
of this format and how to parse the results.

Future versions could consider multi-valued responses or regex-based key
matching.

For the sake of incremental exploration of the potential in the 'git
config-batch' command, this is the only implementation being presented in
the first patch series.

Future extensions could include a '-z' parameter that uses NUL bytes in the
command and output format to allow for spaces or newlines in the input or
newlines in the output.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 Documentation/git-config-batch.adoc |  53 +++++-
 builtin/config-batch.c              | 251 +++++++++++++++++++++++++++-
 config.h                            |   3 +
 t/t1312-config-batch.sh             | 101 +++++++++++
 4 files changed, 405 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
index 9ca04b0c1e..31dd42f481 100644
--- a/Documentation/git-config-batch.adoc
+++ b/Documentation/git-config-batch.adoc
@@ -32,9 +32,58 @@ set. Thus, if the Git version includes the `git config-batch` builtin
 but doesn't understand an input command, it will return a single line
 response:
 
-```
+------------
 unknown_command LF
-```
+------------
+
+These are the commands that are currently understood:
+
+`get` version 1::
+	The `get` command searches the config key-value pairs within a
+	given `<scope>` for values that match the fixed `<key>` and
+	filters the resulting value based on an optional `<value-filter>`.
+	This can either be a regex or a fixed value. The command format
+	is one of the following formats:
++
+------------
+get 1 <scope> <key>
+get 1 <scope> <key> arg:regex <value-pattern>
+get 1 <scope> <key> arg:fixed-value <value>
+------------
++
+The `<scope>` value can be one of `inherited`, `system`, `global`,
+`local`, `worktree`, `submodule`, or `command`. If `inherited`, then all
+config key-value pairs will be considered regardless of scope. Otherwise,
+only the given scope will be considered.
++
+If no optional arguments are given, then the value will not be filtered
+by any pattern matching. If `arg:regex` is specified, then the rest of
+the line is considered a single string, `<value-pattern>`, and is
+interpreted as a regular expression for matching against stored values,
+similar to specifying a value to `get config --get <key> "<value-pattern>"`.
+If `arg:fixed-value` is specified, then the rest of the line is
+considered a single string, `<value>`, and is checked for an exact
+match against the key-value pairs, simmilar to `git config --get <key>
+--fixed-value "<value>"`.
++
+At mmost one key-value pair is returned, that being the last key-value
+pair in the standard config order by scope and sequence within each scope.
++
+If a key-value pair is found, then the following output is given:
++
+------------
+get 1 found <key> <scope> <value>
+------------
++
+If no matching key-value pair is found, then the following output is
+given:
++
+------------
+get 1 missing <key> [<value-pattern>|<value>]
+------------
++
+where `<value-pattern>` or `<value>` is only supplied if provided in
+the command.
 
 SEE ALSO
 --------
diff --git a/builtin/config-batch.c b/builtin/config-batch.c
index dffedb8ca2..5782004080 100644
--- a/builtin/config-batch.c
+++ b/builtin/config-batch.c
@@ -12,6 +12,8 @@ static const char *const builtin_config_batch_usage[] = {
 };
 
 #define UNKNOWN_COMMAND "unknown_command"
+#define GET_COMMAND "get"
+#define COMMAND_PARSE_ERROR "command_parse_error"
 
 static int emit_response(const char *response, ...)
 {
@@ -30,6 +32,11 @@ static int emit_response(const char *response, ...)
 	return 0;
 }
 
+static int command_parse_error(const char *command)
+{
+	return emit_response(COMMAND_PARSE_ERROR, command, NULL);
+}
+
 /**
  * A function pointer type for defining a command. The function is
  * responsible for handling different versions of the command name.
@@ -46,11 +53,248 @@ typedef int (*command_fn)(struct repository *repo,
 			  char *data, size_t data_len);
 
 static int unknown_command(struct repository *repo UNUSED,
-			  char *data UNUSED, size_t data_len UNUSED)
+			   char *data UNUSED, size_t data_len UNUSED)
 {
 	return emit_response(UNKNOWN_COMMAND, NULL);
 }
 
+static size_t parse_whitespace_token(char **data, size_t *data_len,
+				     char **token, int *err UNUSED)
+{
+	size_t i = 0;
+
+	*token = *data;
+
+	while (i < *data_len && (*data)[i] && (*data)[i] != ' ')
+		i++;
+
+	if (i >= *data_len) {
+		*data_len = 0;
+		*data = NULL;
+		return i;
+	}
+
+	(*data)[i] = 0;
+	*data_len = (*data_len) - (i + 1);
+	*data = *data + (i + 1);
+	return i;
+}
+
+/**
+ * Given the remaining data line and its size, attempt to extract
+ * a token. When the token delimiter is determined, the data
+ * string is mutated to insert a NUL byte at the end of the token.
+ * The data pointer is mutated to point at the next character (or
+ * set to NULL if that exceeds the string length). The data_len
+ * value is mutated to subtract the length of the discovered
+ * token.
+ *
+ * The returned value is the length of the token that was
+ * discovered.
+ *
+ * 'err' is ignored for now, but will be filled in in a future
+ * change.
+ */
+static size_t parse_token(char **data, size_t *data_len,
+			  char **token, int *err)
+{
+	if (!*data_len)
+		return 0;
+
+	return parse_whitespace_token(data, data_len, token, err);
+}
+
+enum value_match_mode {
+	MATCH_ALL,
+	MATCH_EXACT,
+	MATCH_REGEX,
+};
+
+struct get_command_1_data {
+	/* parameters */
+	char *key;
+	enum config_scope scope;
+	enum value_match_mode mode;
+
+	/* optional parameters */
+	char *value;
+	regex_t *value_pattern;
+
+	/* data along the way, for single values. */
+	char *found;
+	enum config_scope found_scope;
+};
+
+static int get_command_1_cb(const char *key, const char *value,
+			    const struct config_context *context,
+			    void *data)
+{
+	struct get_command_1_data *d = data;
+
+	if (strcasecmp(key, d->key))
+		return 0;
+
+	if (d->scope != CONFIG_SCOPE_UNKNOWN &&
+	    d->scope != context->kvi->scope)
+		return 0;
+
+	switch (d->mode) {
+	case MATCH_EXACT:
+		if (strcasecmp(value, d->value))
+			return 0;
+		break;
+
+	case MATCH_REGEX:
+		if (regexec(d->value_pattern, value, 0, NULL, 0))
+			return 0;
+		break;
+
+	default:
+		break;
+	}
+
+	free(d->found);
+	d->found = xstrdup(value);
+	d->found_scope = context->kvi->scope;
+	return 0;
+}
+
+static const char *scope_str(enum config_scope scope)
+{
+	switch (scope) {
+	case CONFIG_SCOPE_UNKNOWN:
+		return "unknown";
+
+	case CONFIG_SCOPE_SYSTEM:
+		return "system";
+
+	case CONFIG_SCOPE_GLOBAL:
+		return "global";
+
+	case CONFIG_SCOPE_LOCAL:
+		return "local";
+
+	case CONFIG_SCOPE_WORKTREE:
+		return "worktree";
+
+	case CONFIG_SCOPE_SUBMODULE:
+		return "submodule";
+
+	case CONFIG_SCOPE_COMMAND:
+		return "command";
+
+	default:
+		BUG("invalid config scope");
+	}
+}
+
+static int parse_scope(const char *str, enum config_scope *scope)
+{
+	if (!strcmp(str, "inherited")) {
+		*scope = CONFIG_SCOPE_UNKNOWN;
+		return 0;
+	}
+
+	for (enum config_scope s = 0; s < CONFIG_SCOPE__NR; s++) {
+		if (!strcmp(str, scope_str(s))) {
+			*scope = s;
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+/**
+ * 'get' command, version 1.
+ *
+ * Positional arguments should be of the form:
+ *
+ * [0] scope ("system", "global", "local", "worktree", "command", "submodule", or "inherited")
+ * [1] config key
+ * [2*] multi-mode ("regex", "fixed-value")
+ * [3*] value regex OR value string
+ *
+ * [N*] indicates optional parameters that are not needed.
+ */
+static int get_command_1(struct repository *repo,
+			 char *data,
+			 size_t data_len)
+{
+	struct get_command_1_data gc_data = {
+		.found = NULL,
+		.mode = MATCH_ALL,
+	};
+	int res = 0, err = 0;
+	char *token;
+	size_t token_len;
+
+	if (!parse_token(&data, &data_len, &token, &err) || err)
+		goto parse_error;
+
+	if (parse_scope(token, &gc_data.scope))
+		goto parse_error;
+
+	if (!parse_token(&data, &data_len, &gc_data.key, &err) || err)
+		goto parse_error;
+
+	token_len = parse_token(&data, &data_len, &token, &err);
+	if (err)
+		goto parse_error;
+
+	if (token_len && !strncmp(token, "arg:", 4)) {
+		if (!strcmp(token + 4, "regex"))
+			gc_data.mode = MATCH_REGEX;
+		else if (!strcmp(token + 4, "fixed-value"))
+			gc_data.mode = MATCH_EXACT;
+		else
+			goto parse_error; /* unknown arg. */
+
+		/* Use the remaining data as the value string. */
+		gc_data.value = data;
+
+		if (gc_data.mode == MATCH_REGEX) {
+			CALLOC_ARRAY(gc_data.value_pattern, 1);
+			if (regcomp(gc_data.value_pattern, gc_data.value,
+				    REG_EXTENDED)) {
+				FREE_AND_NULL(gc_data.value_pattern);
+				goto parse_error;
+			}
+		}
+	} else if (token_len) {
+		/*
+		 * If we have remaining tokens not starting in "arg:",
+		 * then we don't understand them.
+		 */
+		goto parse_error;
+	}
+
+	repo_config(repo, get_command_1_cb, &gc_data);
+
+	if (gc_data.found)
+		res = emit_response(GET_COMMAND, "1", "found", gc_data.key,
+				    scope_str(gc_data.found_scope),
+				    gc_data.found,
+				    NULL);
+	else
+		res = emit_response(GET_COMMAND, "1", "missing", gc_data.key,
+				    gc_data.value, NULL);
+
+	goto cleanup;
+
+
+parse_error:
+	res = command_parse_error(GET_COMMAND);
+
+cleanup:
+	if (gc_data.value_pattern) {
+		regfree(gc_data.value_pattern);
+		free(gc_data.value_pattern);
+	}
+	free(gc_data.found);
+	return res;
+}
+
 struct command {
 	const char *name;
 	command_fn fn;
@@ -58,6 +302,11 @@ struct command {
 };
 
 static struct command commands[] = {
+	{
+		.name = GET_COMMAND,
+		.fn = get_command_1,
+		.version = 1,
+	},
 	/* unknown_command must be last. */
 	{
 		.name = "",
diff --git a/config.h b/config.h
index ba426a960a..966a228f0e 100644
--- a/config.h
+++ b/config.h
@@ -44,6 +44,9 @@ enum config_scope {
 	CONFIG_SCOPE_WORKTREE,
 	CONFIG_SCOPE_COMMAND,
 	CONFIG_SCOPE_SUBMODULE,
+
+	/* Must be last */
+	CONFIG_SCOPE__NR
 };
 const char *config_scope_name(enum config_scope scope);
 
diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
index f60ef35e38..e638b54d13 100755
--- a/t/t1312-config-batch.sh
+++ b/t/t1312-config-batch.sh
@@ -16,10 +16,111 @@ test_expect_success 'unknown_command' '
 	test_cmp expect out
 '
 
+test_expect_success 'completely broken input' '
+	echo "not_even_two_tokens" >in &&
+	test_must_fail git config-batch 2>err <in &&
+	test_grep "expected at least 2 tokens" err &&
+	test_grep "an unrecoverable error occurred during command execution" err
+'
+
 test_expect_success 'failed to parse version' '
 	echo "bogus BAD_VERSION line of tokens" >in &&
 	test_must_fail git config-batch 2>err <in &&
 	test_grep BAD_VERSION err
 '
 
+test_expect_success 'get inherited config' '
+	test_when_finished git config --unset test.key &&
+
+	git config test.key "test value with spaces" &&
+
+	echo "get 1 inherited test.key" >in &&
+	echo "get 1 found test.key local test value with spaces" >expect &&
+	git config-batch >out <in &&
+	test_cmp expect out &&
+
+	echo "get 1 global test.key" >in &&
+	echo "get 1 missing test.key" >expect &&
+	git config-batch >out <in &&
+	test_cmp expect out
+'
+
+test_expect_success 'set up worktree' '
+	test_commit A &&
+	git config extensions.worktreeconfig true &&
+	git worktree add --detach worktree
+'
+
+test_expect_success 'get config with arg:regex' '
+	test_when_finished git config --unset-all test.key &&
+	GIT_CONFIG_SYSTEM=system-config-file &&
+	GIT_CONFIG_NOSYSTEM=0 &&
+	GIT_CONFIG_GLOBAL=global-config-file &&
+	export GIT_CONFIG_SYSTEM &&
+	export GIT_CONFIG_NOSYSTEM &&
+	export GIT_CONFIG_GLOBAL &&
+
+	git config --system test.key on1e &&
+	git config --global test.key t2wo &&
+	git config test.key "thre3e space" &&
+	git config --worktree test.key 4four &&
+
+	cat >in <<-\EOF &&
+	get 1 inherited test.key arg:regex .*1.*
+	get 1 inherited test.key arg:regex [a-z]2.*
+	get 1 inherited test.key arg:regex .*3e s.*
+	get 1 inherited test.key arg:regex 4.*
+	get 1 inherited test.key arg:regex .*5.*
+	get 1 inherited test.key arg:regex .*6.*
+	EOF
+
+	cat >expect <<-\EOF &&
+	get 1 found test.key system on1e
+	get 1 found test.key global t2wo
+	get 1 found test.key local thre3e space
+	get 1 found test.key worktree 4four
+	get 1 found test.key command five5
+	get 1 missing test.key .*6.*
+	EOF
+
+	git -c test.key=five5 config-batch >out <in &&
+	test_cmp expect out
+'
+
+test_expect_success 'get config with arg:fixed-value' '
+	test_when_finished git config --unset-all test.key &&
+	GIT_CONFIG_SYSTEM=system-config-file &&
+	GIT_CONFIG_NOSYSTEM=0 &&
+	GIT_CONFIG_GLOBAL=global-config-file &&
+	export GIT_CONFIG_SYSTEM &&
+	export GIT_CONFIG_NOSYSTEM &&
+	export GIT_CONFIG_GLOBAL &&
+
+	git config --system test.key one &&
+	git config --global test.key two &&
+	git config test.key "three space" &&
+	git config --worktree test.key four &&
+
+	cat >in <<-\EOF &&
+	get 1 inherited test.key arg:fixed-value one
+	get 1 inherited test.key arg:fixed-value two
+	get 1 inherited test.key arg:fixed-value three space
+	get 1 inherited test.key arg:fixed-value four
+	get 1 inherited test.key arg:fixed-value five
+	get 1 inherited test.key arg:fixed-value six
+	EOF
+
+	cat >expect <<-\EOF &&
+	get 1 found test.key system one
+	get 1 found test.key global two
+	get 1 found test.key local three space
+	get 1 found test.key worktree four
+	get 1 found test.key command five
+	get 1 missing test.key six
+	EOF
+
+	git -c test.key=five config-batch >out <in &&
+	test_cmp expect out
+'
+
 test_done
-- 
gitgitgadget

[PATCH 04/11] config-batch: create 'help' command

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

Tools that use the 'git config-batch' tool will want to know which commands
are available in the current Git version. Having a 'help' command assists
greatly to give a clear set of available commands and their versions.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 Documentation/git-config-batch.adoc | 17 +++++++++++++++
 builtin/config-batch.c              | 32 +++++++++++++++++++++++++++++
 t/t1312-config-batch.sh             | 13 ++++++++++++
 3 files changed, 62 insertions(+)

diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
index 31dd42f481..1fff68a13c 100644
--- a/Documentation/git-config-batch.adoc
+++ b/Documentation/git-config-batch.adoc
@@ -38,6 +38,23 @@ unknown_command LF
 
 These are the commands that are currently understood:
 
+`help` version 1::
+	The `help` command lists the currently-available commands in
+	this version of Git. The output is multi-line, but the first
+	line provides the count of possible commands via `help count <N>`.
+	The next `<N>` lines are of the form `help <command> <version>`
+	to state that this Git version supports that `<command>` at
+	version `<version>`. Note that the same command may have multiple
+	available versions.
++
+Here is the currentl output of the help text at the latest version:
++
+------------
+help 1 count 2
+help 1 help 1
+help 1 get 1
+------------
+
 `get` version 1::
 	The `get` command searches the config key-value pairs within a
 	given `<scope>` for values that match the fixed `<key>` and
diff --git a/builtin/config-batch.c b/builtin/config-batch.c
index 5782004080..1c19e4889f 100644
--- a/builtin/config-batch.c
+++ b/builtin/config-batch.c
@@ -12,6 +12,7 @@ static const char *const builtin_config_batch_usage[] = {
 };
 
 #define UNKNOWN_COMMAND "unknown_command"
+#define HELP_COMMAND "help"
 #define GET_COMMAND "get"
 #define COMMAND_PARSE_ERROR "command_parse_error"
 
@@ -104,6 +105,9 @@ static size_t parse_token(char **data, size_t *data_len,
 	return parse_whitespace_token(data, data_len, token, err);
 }
 
+static int help_command_1(struct repository *repo,
+			  char *data, size_t data_len);
+
 enum value_match_mode {
 	MATCH_ALL,
 	MATCH_EXACT,
@@ -302,6 +306,11 @@ struct command {
 };
 
 static struct command commands[] = {
+	{
+		.name = HELP_COMMAND,
+		.fn = help_command_1,
+		.version = 1,
+	},
 	{
 		.name = GET_COMMAND,
 		.fn = get_command_1,
@@ -316,6 +325,29 @@ static struct command commands[] = {
 
 #define COMMAND_COUNT ((size_t)(sizeof(commands) / sizeof(*commands)))
 
+static int help_command_1(struct repository *repo UNUSED,
+			  char *data UNUSED, size_t data_len UNUSED)
+{
+	struct strbuf fmt_str = STRBUF_INIT;
+
+	strbuf_addf(&fmt_str, "%"PRIu32, (uint32_t)(COMMAND_COUNT - 1));
+	emit_response(HELP_COMMAND, "1", "count", fmt_str.buf, NULL);
+	strbuf_reset(&fmt_str);
+
+	for (size_t i = 0; i < COMMAND_COUNT; i++) {
+		/* Halt at unknown command. */
+		if (!commands[i].name[0])
+			break;
+
+		strbuf_addf(&fmt_str, "%d", commands[i].version);
+		emit_response(HELP_COMMAND, "1", commands[i].name, fmt_str.buf, NULL);
+		strbuf_reset(&fmt_str);
+	}
+
+	strbuf_release(&fmt_str);
+	return 0;
+}
+
 /**
  * Process a single line from stdin and process the command.
  *
diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
index e638b54d13..6b550a0e76 100755
--- a/t/t1312-config-batch.sh
+++ b/t/t1312-config-batch.sh
@@ -23,6 +23,19 @@ test_expect_success 'completely broken input' '
 	test_grep "an unrecoverable error occurred during command execution" err
 '
 
+test_expect_success 'help command' '
+	echo "help 1" >in &&
+
+	cat >expect <<-\EOF &&
+	help 1 count 2
+	help 1 help 1
+	help 1 get 1
+	EOF
+
+	git config-batch >out <in &&
+	test_cmp expect out
+'
+
 test_expect_success 'failed to parse version' '
 	echo "bogus BAD_VERSION line of tokens" >in &&
 	test_must_fail git config-batch 2>err <in &&
-- 
gitgitgadget

[PATCH 05/11] config-batch: add NUL-terminated I/O format

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

When using automated tools, it is critical to allow for input/output formats
that include special characters such as spaces and newlines. While the
existing protocol for 'git config-batch' is human-readable and has some
capacity for some spaces in certain positions, it is not available for
spaces in the config key or newlines in the config values.

Add the '-z' option to signal the use of NUL-terminated strings. To
understand where commands end regardless of potential future formats, use
two NUL bytes in a row to terminate a command. To allow for empty string
values, each token is provided in a <length>:<value> format, making "0:"
the empty string value.

Update the existing 'help' and 'get' commands to match this format. Create
helper methods that make it easy to parse and print in both formats
simultaneously.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 Documentation/git-config-batch.adoc |  57 ++++++++-
 builtin/config-batch.c              | 188 +++++++++++++++++++++++++---
 t/t1312-config-batch.sh             |  69 ++++++++++
 3 files changed, 293 insertions(+), 21 deletions(-)

diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
index 1fff68a13c..3c9a3bb763 100644
--- a/Documentation/git-config-batch.adoc
+++ b/Documentation/git-config-batch.adoc
@@ -21,6 +21,15 @@ multiple configuration values, the `git config-batch` command allows a
 single process to handle multiple requests using a machine-parseable
 interface across `stdin` and `stdout`.
 
+OPTIONS
+-------
+
+`-z`::
+	If specified, then use the NUL-terminated input and output
+	format instead of the space and newline format. This format is
+	useful when the strings involved may include spaces or newlines.
+	See PROTOCOL for more details.
+
 PROTOCOL
 --------
 By default, the protocol uses line feeds (`LF`) to signal the end of a
@@ -41,13 +50,13 @@ These are the commands that are currently understood:
 `help` version 1::
 	The `help` command lists the currently-available commands in
 	this version of Git. The output is multi-line, but the first
-	line provides the count of possible commands via `help count <N>`.
-	The next `<N>` lines are of the form `help <command> <version>`
+	line provides the count of possible commands via `help 1 count <N>`.
+	The next `<N>` lines are of the form `help 1 <command> <version>`
 	to state that this Git version supports that `<command>` at
 	version `<version>`. Note that the same command may have multiple
 	available versions.
 +
-Here is the currentl output of the help text at the latest version:
+Here is the current output of the help text at the latest version:
 +
 ------------
 help 1 count 2
@@ -102,6 +111,48 @@ get 1 missing <key> [<value-pattern>|<value>]
 where `<value-pattern>` or `<value>` is only supplied if provided in
 the command.
 
+NUL-Terminated Format
+~~~~~~~~~~~~~~~~~~~~~
+
+When `-z` is given, the protocol changes in some structural ways.
+
+First, each command is terminated with two NUL bytes, providing a clear
+boundary between commands regardless of future possibilities of new
+command formats.
+
+Second, any time that a space _would_ be used to partition tokens in a
+command, a NUL byte is used instead. Further, each token is prefixed
+with `<N>:` where `<N>` is a decimal representation of the length of
+the string between the `:` and the next NUL byte. Any disagreement in
+these lengths is treated as a parsing error. This use of a length does
+imply that "`0:`" is the representation of an empty string, if relevant.
+
+The decimal representation must have at most five numerals, thus the
+maximum length of a string token can have 99999 characters.
+
+For example, the `get` command, version 1, could have any of the
+following forms:
+
+------------
+3:get NUL 1:1 NUL 5:local NUL 14:key.with space NUL NUL
+3:get NUL 1:1 NUL 9:inherit NUL 8:test.key NUL 9:arg:regex NUL 6:.*\ .* NUL NUL
+3:get NUL 1:1 NUL 6:global NUL 8:test.key NUL 15:arg:fixed-value NUL 3:a b NUL NUL
+------------
+
+The output is modified similarly, such as the following output examples,
+as if the input has a parse error, a valid `help` command, a `get`
+command that had a match, and a `get` command that did not match.
+
+------------
+15:unknown_command NUL NUL
+4:help NUL 1:1 NUL 5:count NUL 1:2 NUL NUL
+4:help NUL 1:1 NUL 4:help NUL 1:1 NUL NUL
+4:help NUL 1:1 NUL 3:get NUL 1:1 NUL NUL
+3:get NUL 1:1 NUL 5:found NUL 8:test.key NUL 5:value NUL NUL
+3:get NUL 1:1 NUL 7:missing NUL 8:test.key NUL NUL
+------------
+
+
 SEE ALSO
 --------
 linkgit:git-config[1]
diff --git a/builtin/config-batch.c b/builtin/config-batch.c
index 1c19e4889f..2c48c4ea37 100644
--- a/builtin/config-batch.c
+++ b/builtin/config-batch.c
@@ -11,24 +11,40 @@ static const char *const builtin_config_batch_usage[] = {
 	NULL
 };
 
+static int zformat = 0;
+
 #define UNKNOWN_COMMAND "unknown_command"
 #define HELP_COMMAND "help"
 #define GET_COMMAND "get"
 #define COMMAND_PARSE_ERROR "command_parse_error"
 
+static void print_word(const char *word, int start)
+{
+	if (zformat) {
+		printf("%"PRIu32":%s", (uint32_t)strlen(word), word);
+		fputc(0, stdout);
+	} else if (start)
+		printf("%s", word);
+	else
+		printf(" %s", word);
+}
+
 static int emit_response(const char *response, ...)
 {
 	va_list params;
 	const char *token;
 
-	printf("%s", response);
+	print_word(response, 1);
 
 	va_start(params, response);
 	while ((token = va_arg(params, const char *)))
-		printf(" %s", token);
+		print_word(token, 0);
 	va_end(params);
 
-	printf("\n");
+	if (zformat)
+		fputc(0, stdout);
+	else
+		printf("\n");
 	fflush(stdout);
 	return 0;
 }
@@ -59,6 +75,52 @@ static int unknown_command(struct repository *repo UNUSED,
 	return emit_response(UNKNOWN_COMMAND, NULL);
 }
 
+/*
+ * Parse the next token using the NUL-byte format.
+ */
+static size_t parse_ztoken(char **data, size_t *data_len,
+			   char **token, int *err)
+{
+	size_t i = 0, token_len;
+
+	while (i < *data_len && (*data)[i] != ':') {
+		if ((*data)[i] < '0' || (*data)[i] > '9') {
+			goto parse_error;
+		}
+		i++;
+	}
+
+	if (i >= *data_len || (*data)[i] != ':' || i > 5)
+		goto parse_error;
+
+	(*data)[i] = 0;
+	token_len = atoi(*data);
+
+	if (token_len + i + 1 >= *data_len)
+		goto parse_error;
+
+	*token = *data + i + 1;
+	*data_len = *data_len - (i + 1);
+
+	/* check for early NULs. */
+	for (i = 0; i < token_len; i++) {
+		if (!(*token)[i])
+			goto parse_error;
+	}
+	/* check for matching NUL. */
+	if ((*token)[token_len])
+		goto parse_error;
+
+	*data = *token + token_len + 1;
+	*data_len = *data_len - (token_len + 1);
+	return token_len;
+
+parse_error:
+	*err = 1;
+	*token = NULL;
+	return 0;
+}
+
 static size_t parse_whitespace_token(char **data, size_t *data_len,
 				     char **token, int *err UNUSED)
 {
@@ -93,15 +155,23 @@ static size_t parse_whitespace_token(char **data, size_t *data_len,
  * The returned value is the length of the token that was
  * discovered.
  *
- * 'err' is ignored for now, but will be filled in in a future
- * change.
+ * The 'token' pointer is used to set the start of the token.
+ * In the whitespace format, this is always the input value of
+ * 'data' but in the NUL-terminated format this follows an "<N>:"
+ * prefix.
+ *
+ * In the case of the NUL-terminated format, a bad parse of the
+ * decimal length or a mismatch of the decimal length and the
+ * length of the following NUL-terminated string will result in
+ * the value pointed at by 'err' to be set to 1.
  */
 static size_t parse_token(char **data, size_t *data_len,
 			  char **token, int *err)
 {
 	if (!*data_len)
 		return 0;
-
+	if (zformat)
+		return parse_ztoken(data, data_len, token, err);
 	return parse_whitespace_token(data, data_len, token, err);
 }
 
@@ -255,7 +325,13 @@ static int get_command_1(struct repository *repo,
 			goto parse_error; /* unknown arg. */
 
 		/* Use the remaining data as the value string. */
-		gc_data.value = data;
+		if (!zformat)
+			gc_data.value = data;
+		else {
+			parse_token(&data, &data_len, &gc_data.value, &err);
+			if (err)
+				goto parse_error;
+		}
 
 		if (gc_data.mode == MATCH_REGEX) {
 			CALLOC_ARRAY(gc_data.value_pattern, 1);
@@ -348,17 +424,74 @@ static int help_command_1(struct repository *repo UNUSED,
 	return 0;
 }
 
-/**
- * Process a single line from stdin and process the command.
- *
- * Returns 0 on successful processing of command, including the
- * unknown_command output.
- *
- * Returns 1 on natural exit due to exist signal of empty line.
- *
- * Returns negative value on other catastrophic error.
- */
-static int process_command(struct repository *repo)
+static int process_command_nul(struct repository *repo)
+{
+	static struct strbuf line = STRBUF_INIT;
+	char *data, *command, *versionstr;
+	size_t data_len, token_len;
+	int res = 0, err = 0, version = 0, getc;
+	char c;
+
+	/* If we start with EOF it's not an error. */
+	getc = fgetc(stdin);
+	if (getc == EOF)
+		return 1;
+
+	do {
+		c = (char)getc;
+		strbuf_addch(&line, c);
+
+		if (!c && line.len > 1 && !line.buf[line.len - 2])
+			break;
+
+		getc = fgetc(stdin);
+
+		/* It's an error if we reach EOF while parsing a command. */
+		if (getc == EOF)
+			goto parse_error;
+	} while (1);
+
+	data = line.buf;
+	data_len = line.len - 1;
+
+	token_len = parse_ztoken(&data, &data_len, &command, &err);
+	if (!token_len || err)
+		goto parse_error;
+
+	token_len = parse_ztoken(&data, &data_len, &versionstr, &err);
+	if (!token_len || err)
+		goto parse_error;
+
+	if (!git_parse_int(versionstr, &version)) {
+		res = error(_("unable to parse '%s' to integer"),
+			    versionstr);
+		goto parse_error;
+	}
+
+	for (size_t i = 0; i < COMMAND_COUNT; i++) {
+		/*
+		 * Run the ith command if we have hit the unknown
+		 * command or if the name and version match.
+		 */
+		if (!commands[i].name[0] ||
+		    (!strcmp(command, commands[i].name) &&
+		     commands[i].version == version)) {
+			res = commands[i].fn(repo, data, data_len);
+			goto cleanup;
+		}
+	}
+
+	BUG(_("scanned to end of command list, including 'unknown_command'"));
+
+parse_error:
+	res = unknown_command(repo, NULL, 0);
+
+cleanup:
+	strbuf_release(&line);
+	return res;
+}
+
+static int process_command_whitespace(struct repository *repo)
 {
 	static struct strbuf line = STRBUF_INIT;
 	struct string_list tokens = STRING_LIST_INIT_NODUP;
@@ -416,6 +549,23 @@ cleanup:
 	return res;
 }
 
+/**
+ * Process a single line from stdin and process the command.
+ *
+ * Returns 0 on successful processing of command, including the
+ * unknown_command output.
+ *
+ * Returns 1 on natural exit due to exist signal of empty line.
+ *
+ * Returns negative value on other catastrophic error.
+ */
+static int process_command(struct repository *repo)
+{
+	if (zformat)
+		return process_command_nul(repo);
+	return process_command_whitespace(repo);
+}
+
 int cmd_config_batch(int argc,
 		     const char **argv,
 		     const char *prefix,
@@ -423,6 +573,8 @@ int cmd_config_batch(int argc,
 {
 	int res = 0;
 	struct option options[] = {
+		OPT_BOOL('z', NULL, &zformat,
+			 N_("stdin and stdout is NUL-terminated")),
 		OPT_END(),
 	};
 
diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
index 6b550a0e76..f7a74ddc2c 100755
--- a/t/t1312-config-batch.sh
+++ b/t/t1312-config-batch.sh
@@ -4,6 +4,26 @@ test_description='Test git config-batch'
 
 . ./test-lib.sh
 
+# usage: test_zformat <command> <args> <in >out
+#
+# Let 'in' be a z-format input but with " NUL " between tokens in
+# a single command and " NUL NUL" trailing each line.
+#
+# The values in 'out' will be space- and newline-delimited where
+# NUL-bytes would normally be output.
+test_zformat () {
+	sed -e "s/\ NUL\ /!/g" >nullin1 &&
+	sed -e "s/NUL//g" <nullin1 >nullin2 &&
+
+	tr "!" "\0" <nullin2 >nullin3 &&
+	tr "\n" "\0" <nullin3 >zin &&
+
+	$* <zin >zout &&
+
+	tr "\0" " " <zout >outspace &&
+	sed "s/\ \ /\n/g" <outspace
+}
+
 test_expect_success 'no commands' '
 	echo | git config-batch >out &&
 	test_must_be_empty out
@@ -36,6 +56,23 @@ test_expect_success 'help command' '
 	test_cmp expect out
 '
 
+test_expect_success 'help -z' '
+	cat >in <<-\EOF &&
+	4:help NUL 1:1 NUL NUL
+	5:bogus NUL 2:10 NUL NUL
+	EOF
+
+	cat >expect <<-\EOF &&
+	4:help 1:1 5:count 1:2
+	4:help 1:1 4:help 1:1
+	4:help 1:1 3:get 1:1
+	15:unknown_command
+	EOF
+
+	test_zformat git config-batch -z >out <in &&
+	test_cmp expect out
+'
+
 test_expect_success 'failed to parse version' '
 	echo "bogus BAD_VERSION line of tokens" >in &&
 	test_must_fail git config-batch 2>err <in &&
@@ -136,4 +173,36 @@ test_expect_success 'get config with arg:fixed-value' '
 	test_cmp expect out
 '
 
+test_expect_success 'get config with -z' '
+	test_when_finished git config --unset-all test.key &&
+	GIT_CONFIG_SYSTEM=system-config-file &&
+	GIT_CONFIG_NOSYSTEM=0 &&
+	GIT_CONFIG_GLOBAL=global-config-file &&
+	export GIT_CONFIG_SYSTEM &&
+	export GIT_CONFIG_NOSYSTEM &&
+	export GIT_CONFIG_GLOBAL &&
+
+	git config --system test.key on1e &&
+	git config --global test.key t2wo &&
+	git config test.key "thre3e space" &&
+	git config --worktree test.key 4four &&
+
+	cat >in <<-\EOF &&
+	3:get NUL 1:1 NUL 9:inherited NUL 8:test.key NUL NUL
+	3:get NUL 1:1 NUL 6:global NUL 8:test.key NUL 9:arg:regex NUL 3:2.* NUL NUL
+	3:get NUL 1:1 NUL 5:local NUL 8:test.key NUL 15:arg:fixed-value NUL 12:thre3e space NUL NUL
+	3:get NUL 1:1 NUL 9:inherited NUL 11:key.missing NUL NUL
+	EOF
+
+	cat >expect <<-\EOF &&
+	3:get 1:1 5:found 8:test.key 8:worktree 5:4four
+	3:get 1:1 5:found 8:test.key 6:global 4:t2wo
+	3:get 1:1 5:found 8:test.key 5:local 12:thre3e space
+	3:get 1:1 7:missing 11:key.missing
+	EOF
+
+	test_zformat git config-batch -z >out <in &&
+	test_cmp expect out
+'
+
 test_done
-- 
gitgitgadget

[PATCH 06/11] docs: add design doc for config-batch

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

This document will be a place that tracks the future directions of the
'git config-batch' builtin. We plan to remove items as they are
implemented in new commands and documented in the builtin documentation.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 Documentation/technical/config-batch.adoc | 70 +++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/technical/config-batch.adoc

diff --git a/Documentation/technical/config-batch.adoc b/Documentation/technical/config-batch.adoc
new file mode 100644
index 0000000000..dbd614ad4f
--- /dev/null
+++ b/Documentation/technical/config-batch.adoc
@@ -0,0 +1,70 @@
+Git Config-Batch Design Notes
+=============================
+
+The `git config-batch` builtin has a robust protocol for parsing multiple
+commands over `stdin` and providing structured output over `stdout`. The
+intended use is for scripts or third-party software to interact with the
+config settings of a repository multiple times within the same Git process.
+The protocol is built with versioning that allows the consumer to know when
+a certain command is available and to fall back to single-use `git config`
+processes if the installed Git version does not have the latest commands
+at the required versions.
+
+Recommended interaction pattern
+-------------------------------
+
+This section provides a guide for ideal interaction with the `git
+config-batch` command and its protocol.
+
+For maximum compatibility, do not attempt parsing the output of `git
+version` to determine which commands are available. Instead, first check
+if the `git config-batch` command succeeds and does not die immediately
+due to the builtin being unavailable. Then, use the v1 of the `help`
+command to get a list of available commands and versions. Use this list to
+determine if your capabilities are available or should be replaced with an
+appropriate `git config` single-use process.
+
+Further, all automated tooling would be better off using the
+NUL-terminated format instead of the whitespace-delimited format, in case
+config keys contain spaces or config values contain newlines. The
+whitespace-delimited version is available for simpler integration and
+human inspection.
+
+Current commands
+----------------
+
+See the documentation in linkgit::config-batch[1] for the latest set of
+available commands and their protocols.
+
+Future commands
+---------------
+
+The following modes of `git config` are not currently available as commands
+in `git config-batch`, but are planned for future integration:
+
+`git config list [--<scope>]`::
+	Getting all values, regardless of config key, would require a
+	multi-valued output similar to the `help` command. This tool will
+	likely assume advanced options such as `--show-origin`.
+
+`git config set [--<scope>] <key> <value>`::
+	It will be desirable to set a config key at a given scope as a
+	single value, replacing the current value at that scope, if it
+	exists and is a single value. A `set` command could satisfy this
+	purpose.
+
+`git config set --all [<value-pattern>|--fixed-value=<fixedvalue>] <key> <value>`::
+	When replacing multiple values, it may be necessary to have a different
+	output describing the places those values were set, so it may need to
+	be implemented via a `set-all` command to differentiate from a `set`
+	command.
+
+`git config unset <key>`::
+
+`git config unset --all [<value-pattern>|--fixed-value=<fixedvalue>] <key>`::
+
+`git config get --all --rexexp <key-pattern> [<value-options>]`::
+
+`--replace-all` option::
+
+`--type=<type>` option::
-- 
gitgitgadget

[PATCH 07/11] config: extract location structs from builtin

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

Before reusing these concepts in builtin/config-batch.c, extract the
config_location_options struct from builtin/config.c to config.h with
implementation in config.c.

The only modification in this conversion is the use of a repository
parameter instead of the_repository.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 builtin/config.c | 117 ++++-------------------------------------------
 config.c         |  89 +++++++++++++++++++++++++++++++++++
 config.h         |  20 ++++++++
 3 files changed, 117 insertions(+), 109 deletions(-)

diff --git a/builtin/config.c b/builtin/config.c
index 288ebdfdaa..d129b1204d 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -71,20 +71,6 @@ static const char *const builtin_config_edit_usage[] = {
 	OPT_STRING('f', "file", &opts.source.file, N_("file"), N_("use given config file")), \
 	OPT_STRING(0, "blob", &opts.source.blob, N_("blob-id"), N_("read config from given blob object"))
 
-struct config_location_options {
-	struct git_config_source source;
-	struct config_options options;
-	char *file_to_free;
-	int use_global_config;
-	int use_system_config;
-	int use_local_config;
-	int use_worktree_config;
-	int respect_includes_opt;
-};
-#define CONFIG_LOCATION_OPTIONS_INIT { \
-	.respect_includes_opt = -1, \
-}
-
 #define CONFIG_TYPE_OPTIONS(type) \
 	OPT_GROUP(N_("Type")), \
 	OPT_CALLBACK('t', "type", &type, N_("type"), N_("value is given this type"), option_parse_type), \
@@ -772,93 +758,6 @@ static char *default_user_config(void)
 	return strbuf_detach(&buf, NULL);
 }
 
-static void location_options_init(struct config_location_options *opts,
-				  const char *prefix)
-{
-	if (!opts->source.file)
-		opts->source.file = opts->file_to_free =
-			xstrdup_or_null(getenv(CONFIG_ENVIRONMENT));
-
-	if (opts->use_global_config + opts->use_system_config +
-	    opts->use_local_config + opts->use_worktree_config +
-	    !!opts->source.file + !!opts->source.blob > 1) {
-		error(_("only one config file at a time"));
-		exit(129);
-	}
-
-	if (!startup_info->have_repository) {
-		if (opts->use_local_config)
-			die(_("--local can only be used inside a git repository"));
-		if (opts->source.blob)
-			die(_("--blob can only be used inside a git repository"));
-		if (opts->use_worktree_config)
-			die(_("--worktree can only be used inside a git repository"));
-	}
-
-	if (opts->source.file &&
-			!strcmp(opts->source.file, "-")) {
-		opts->source.file = NULL;
-		opts->source.use_stdin = 1;
-		opts->source.scope = CONFIG_SCOPE_COMMAND;
-	}
-
-	if (opts->use_global_config) {
-		opts->source.file = opts->file_to_free = git_global_config();
-		if (!opts->source.file)
-			/*
-			 * It is unknown if HOME/.gitconfig exists, so
-			 * we do not know if we should write to XDG
-			 * location; error out even if XDG_CONFIG_HOME
-			 * is set and points at a sane location.
-			 */
-			die(_("$HOME not set"));
-		opts->source.scope = CONFIG_SCOPE_GLOBAL;
-	} else if (opts->use_system_config) {
-		opts->source.file = opts->file_to_free = git_system_config();
-		opts->source.scope = CONFIG_SCOPE_SYSTEM;
-	} else if (opts->use_local_config) {
-		opts->source.file = opts->file_to_free = repo_git_path(the_repository, "config");
-		opts->source.scope = CONFIG_SCOPE_LOCAL;
-	} else if (opts->use_worktree_config) {
-		struct worktree **worktrees = get_worktrees();
-		if (the_repository->repository_format_worktree_config)
-			opts->source.file = opts->file_to_free =
-				repo_git_path(the_repository, "config.worktree");
-		else if (worktrees[0] && worktrees[1])
-			die(_("--worktree cannot be used with multiple "
-			      "working trees unless the config\n"
-			      "extension worktreeConfig is enabled. "
-			      "Please read \"CONFIGURATION FILE\"\n"
-			      "section in \"git help worktree\" for details"));
-		else
-			opts->source.file = opts->file_to_free =
-				repo_git_path(the_repository, "config");
-		opts->source.scope = CONFIG_SCOPE_LOCAL;
-		free_worktrees(worktrees);
-	} else if (opts->source.file) {
-		if (!is_absolute_path(opts->source.file) && prefix)
-			opts->source.file = opts->file_to_free =
-				prefix_filename(prefix, opts->source.file);
-		opts->source.scope = CONFIG_SCOPE_COMMAND;
-	} else if (opts->source.blob) {
-		opts->source.scope = CONFIG_SCOPE_COMMAND;
-	}
-
-	if (opts->respect_includes_opt == -1)
-		opts->options.respect_includes = !opts->source.file;
-	else
-		opts->options.respect_includes = opts->respect_includes_opt;
-	if (startup_info->have_repository) {
-		opts->options.commondir = repo_get_common_dir(the_repository);
-		opts->options.git_dir = repo_get_git_dir(the_repository);
-	}
-}
-
-static void location_options_release(struct config_location_options *opts)
-{
-	free(opts->file_to_free);
-}
-
 static void display_options_init(struct config_display_options *opts)
 {
 	if (opts->end_nul) {
@@ -885,7 +784,7 @@ static int cmd_config_list(int argc, const char **argv, const char *prefix,
 	argc = parse_options(argc, argv, prefix, opts, builtin_config_list_usage, 0);
 	check_argc(argc, 0, 0);
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	display_options_init(&display_opts);
 
 	setup_auto_pager("config", 1);
@@ -944,7 +843,7 @@ static int cmd_config_get(int argc, const char **argv, const char *prefix,
 		    value_pattern))
 		die(_("--url= cannot be used with --all, --regexp or --value"));
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	display_options_init(&display_opts);
 
 	if (display_opts.type != TYPE_COLOR)
@@ -998,7 +897,7 @@ static int cmd_config_set(int argc, const char **argv, const char *prefix,
 
 	comment = git_config_prepare_comment_string(comment_arg);
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	check_write(&location_opts.source);
 
 	value = normalize_value(argv[0], argv[1], type, &default_kvi);
@@ -1044,7 +943,7 @@ static int cmd_config_unset(int argc, const char **argv, const char *prefix,
 	if ((flags & CONFIG_FLAGS_FIXED_VALUE) && !value_pattern)
 		die(_("--fixed-value only applies with 'value-pattern'"));
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	check_write(&location_opts.source);
 
 	if ((flags & CONFIG_FLAGS_MULTI_REPLACE) || value_pattern)
@@ -1073,7 +972,7 @@ static int cmd_config_rename_section(int argc, const char **argv, const char *pr
 			     PARSE_OPT_STOP_AT_NON_OPTION);
 	check_argc(argc, 2, 2);
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	check_write(&location_opts.source);
 
 	ret = repo_config_rename_section_in_file(the_repository, location_opts.source.file,
@@ -1103,7 +1002,7 @@ static int cmd_config_remove_section(int argc, const char **argv, const char *pr
 			     PARSE_OPT_STOP_AT_NON_OPTION);
 	check_argc(argc, 1, 1);
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	check_write(&location_opts.source);
 
 	ret = repo_config_rename_section_in_file(the_repository, location_opts.source.file,
@@ -1163,7 +1062,7 @@ static int cmd_config_edit(int argc, const char **argv, const char *prefix,
 	argc = parse_options(argc, argv, prefix, opts, builtin_config_edit_usage, 0);
 	check_argc(argc, 0, 0);
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	check_write(&location_opts.source);
 
 	ret = show_editor(&location_opts);
@@ -1231,7 +1130,7 @@ static int cmd_config_actions(int argc, const char **argv, const char *prefix)
 			     builtin_config_usage,
 			     PARSE_OPT_STOP_AT_NON_OPTION);
 
-	location_options_init(&location_opts, prefix);
+	location_options_init(the_repository, &location_opts, prefix);
 	display_options_init(&display_opts);
 
 	if ((actions & (ACTION_GET_COLOR|ACTION_GET_COLORBOOL)) && display_opts.type) {
diff --git a/config.c b/config.c
index 7f6d53b473..9f1a7b45cf 100644
--- a/config.c
+++ b/config.c
@@ -35,6 +35,7 @@
 #include "strvec.h"
 #include "trace2.h"
 #include "wildmatch.h"
+#include "worktree.h"
 #include "write-or-die.h"
 
 struct config_source {
@@ -3592,3 +3593,91 @@ int lookup_config(const char **mapping, int nr_mapping, const char *var)
 	}
 	return -1;
 }
+
+void location_options_init(struct repository *repo,
+			   struct config_location_options *opts,
+			   const char *prefix)
+{
+	if (!opts->source.file)
+		opts->source.file = opts->file_to_free =
+			xstrdup_or_null(getenv(CONFIG_ENVIRONMENT));
+
+	if (opts->use_global_config + opts->use_system_config +
+	    opts->use_local_config + opts->use_worktree_config +
+	    !!opts->source.file + !!opts->source.blob > 1) {
+		error(_("only one config file at a time"));
+		exit(129);
+	}
+
+	if (!startup_info->have_repository) {
+		if (opts->use_local_config)
+			die(_("--local can only be used inside a git repository"));
+		if (opts->source.blob)
+			die(_("--blob can only be used inside a git repository"));
+		if (opts->use_worktree_config)
+			die(_("--worktree can only be used inside a git repository"));
+	}
+
+	if (opts->source.file &&
+			!strcmp(opts->source.file, "-")) {
+		opts->source.file = NULL;
+		opts->source.use_stdin = 1;
+		opts->source.scope = CONFIG_SCOPE_COMMAND;
+	}
+
+	if (opts->use_global_config) {
+		opts->source.file = opts->file_to_free = git_global_config();
+		if (!opts->source.file)
+			/*
+			 * It is unknown if HOME/.gitconfig exists, so
+			 * we do not know if we should write to XDG
+			 * location; error out even if XDG_CONFIG_HOME
+			 * is set and points at a sane location.
+			 */
+			die(_("$HOME not set"));
+		opts->source.scope = CONFIG_SCOPE_GLOBAL;
+	} else if (opts->use_system_config) {
+		opts->source.file = opts->file_to_free = git_system_config();
+		opts->source.scope = CONFIG_SCOPE_SYSTEM;
+	} else if (opts->use_local_config) {
+		opts->source.file = opts->file_to_free = repo_git_path(repo, "config");
+		opts->source.scope = CONFIG_SCOPE_LOCAL;
+	} else if (opts->use_worktree_config) {
+		struct worktree **worktrees = get_worktrees();
+		if (repo->repository_format_worktree_config)
+			opts->source.file = opts->file_to_free =
+				repo_git_path(repo, "config.worktree");
+		else if (worktrees[0] && worktrees[1])
+			die(_("--worktree cannot be used with multiple "
+			      "working trees unless the config\n"
+			      "extension worktreeConfig is enabled. "
+			      "Please read \"CONFIGURATION FILE\"\n"
+			      "section in \"git help worktree\" for details"));
+		else
+			opts->source.file = opts->file_to_free =
+				repo_git_path(repo, "config");
+		opts->source.scope = CONFIG_SCOPE_LOCAL;
+		free_worktrees(worktrees);
+	} else if (opts->source.file) {
+		if (!is_absolute_path(opts->source.file) && prefix)
+			opts->source.file = opts->file_to_free =
+				prefix_filename(prefix, opts->source.file);
+		opts->source.scope = CONFIG_SCOPE_COMMAND;
+	} else if (opts->source.blob) {
+		opts->source.scope = CONFIG_SCOPE_COMMAND;
+	}
+
+	if (opts->respect_includes_opt == -1)
+		opts->options.respect_includes = !opts->source.file;
+	else
+		opts->options.respect_includes = opts->respect_includes_opt;
+	if (startup_info->have_repository) {
+		opts->options.commondir = repo_get_common_dir(repo);
+		opts->options.git_dir = repo_get_git_dir(repo);
+	}
+}
+
+void location_options_release(struct config_location_options *opts)
+{
+	free(opts->file_to_free);
+}
diff --git a/config.h b/config.h
index 966a228f0e..6663964977 100644
--- a/config.h
+++ b/config.h
@@ -166,6 +166,26 @@ struct config_context {
 typedef int (*config_fn_t)(const char *, const char *,
 			   const struct config_context *, void *);
 
+struct config_location_options {
+	struct git_config_source source;
+	struct config_options options;
+	char *file_to_free;
+	int use_global_config;
+	int use_system_config;
+	int use_local_config;
+	int use_worktree_config;
+	int respect_includes_opt;
+};
+#define CONFIG_LOCATION_OPTIONS_INIT { \
+	.respect_includes_opt = -1, \
+}
+
+void location_options_init(struct repository *repo,
+			   struct config_location_options *opts,
+			   const char *prefix);
+
+void location_options_release(struct config_location_options *opts);
+
 /**
  * Read a specific file in git-config format.
  * This function takes the same callback and data parameters as `repo_config`.
-- 
gitgitgadget

[PATCH 08/11] config-batch: pass prefix through commands

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

The 'help' and 'get' commands of 'git config-batch' have not needed the
prefix parameter from the builtin entrance point, but an upcoming
command will need it in order to identify the location of the
appropriate config file. Pass it through the appropriate functions and
function pointers.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 builtin/config-batch.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/builtin/config-batch.c b/builtin/config-batch.c
index 2c48c4ea37..9829b16c6f 100644
--- a/builtin/config-batch.c
+++ b/builtin/config-batch.c
@@ -67,9 +67,11 @@ static int command_parse_error(const char *command)
  * Return 0 on success.
  */
 typedef int (*command_fn)(struct repository *repo,
+			  const char *prefix,
 			  char *data, size_t data_len);
 
 static int unknown_command(struct repository *repo UNUSED,
+			   const char *prefix UNUSED,
 			   char *data UNUSED, size_t data_len UNUSED)
 {
 	return emit_response(UNKNOWN_COMMAND, NULL);
@@ -176,6 +178,7 @@ static size_t parse_token(char **data, size_t *data_len,
 }
 
 static int help_command_1(struct repository *repo,
+			  const char *prefix UNUSED,
 			  char *data, size_t data_len);
 
 enum value_match_mode {
@@ -292,6 +295,7 @@ static int parse_scope(const char *str, enum config_scope *scope)
  * [N*] indicates optional parameters that are not needed.
  */
 static int get_command_1(struct repository *repo,
+			 const char *prefix UNUSED,
 			 char *data,
 			 size_t data_len)
 {
@@ -402,6 +406,7 @@ static struct command commands[] = {
 #define COMMAND_COUNT ((size_t)(sizeof(commands) / sizeof(*commands)))
 
 static int help_command_1(struct repository *repo UNUSED,
+			  const char *prefix UNUSED,
 			  char *data UNUSED, size_t data_len UNUSED)
 {
 	struct strbuf fmt_str = STRBUF_INIT;
@@ -424,7 +429,8 @@ static int help_command_1(struct repository *repo UNUSED,
 	return 0;
 }
 
-static int process_command_nul(struct repository *repo)
+static int process_command_nul(struct repository *repo,
+			       const char *prefix)
 {
 	static struct strbuf line = STRBUF_INIT;
 	char *data, *command, *versionstr;
@@ -476,7 +482,7 @@ static int process_command_nul(struct repository *repo)
 		if (!commands[i].name[0] ||
 		    (!strcmp(command, commands[i].name) &&
 		     commands[i].version == version)) {
-			res = commands[i].fn(repo, data, data_len);
+			res = commands[i].fn(repo, prefix, data, data_len);
 			goto cleanup;
 		}
 	}
@@ -484,14 +490,15 @@ static int process_command_nul(struct repository *repo)
 	BUG(_("scanned to end of command list, including 'unknown_command'"));
 
 parse_error:
-	res = unknown_command(repo, NULL, 0);
+	res = unknown_command(repo, prefix, NULL, 0);
 
 cleanup:
 	strbuf_release(&line);
 	return res;
 }
 
-static int process_command_whitespace(struct repository *repo)
+static int process_command_whitespace(struct repository *repo,
+				      const char *prefix)
 {
 	static struct strbuf line = STRBUF_INIT;
 	struct string_list tokens = STRING_LIST_INIT_NODUP;
@@ -536,7 +543,7 @@ static int process_command_whitespace(struct repository *repo)
 		if (!commands[i].name[0] ||
 		    (!strcmp(command, commands[i].name) &&
 		     commands[i].version == version)) {
-			res = commands[i].fn(repo, data, data_len);
+			res = commands[i].fn(repo, prefix, data, data_len);
 			goto cleanup;
 		}
 	}
@@ -559,11 +566,12 @@ cleanup:
  *
  * Returns negative value on other catastrophic error.
  */
-static int process_command(struct repository *repo)
+static int process_command(struct repository *repo,
+			   const char *prefix)
 {
 	if (zformat)
-		return process_command_nul(repo);
-	return process_command_whitespace(repo);
+		return process_command_nul(repo, prefix);
+	return process_command_whitespace(repo, prefix);
 }
 
 int cmd_config_batch(int argc,
@@ -586,7 +594,7 @@ int cmd_config_batch(int argc,
 
 	repo_config(repo, git_default_config, NULL);
 
-	while (!(res = process_command(repo)));
+	while (!(res = process_command(repo, prefix)));
 
 	if (res == 1)
 		return 0;
-- 
gitgitgadget

[PATCH 09/11] config-batch: add 'set' v1 command

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

This new command is intended for single-value assignments to a specific
chosen scope. More complicated versions of the 'git config set' command
will be incorporated into future commands.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 Documentation/git-config-batch.adoc | 24 ++++++++
 builtin/config-batch.c              | 71 ++++++++++++++++++++++
 config.c                            | 27 +++++++++
 config.h                            |  3 +
 t/t1312-config-batch.sh             | 94 ++++++++++++++++++++++++++++-
 5 files changed, 217 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
index 3c9a3bb763..feec85c4ef 100644
--- a/Documentation/git-config-batch.adoc
+++ b/Documentation/git-config-batch.adoc
@@ -111,6 +111,30 @@ get 1 missing <key> [<value-pattern>|<value>]
 where `<value-pattern>` or `<value>` is only supplied if provided in
 the command.
 
+`set` version 1::
+	The `set` command writes a single key-value pair to a config
+	file. It specifies which file by a `<scope>` parameter from
+	among `system`, `global`, `local`, and `worktree`. The `<key>`
+	is the next positional argument. The remaining data in the line
+	is provided as the `<value>` to assign the config.
++
+------------
+set 1 <scope> <key> <value>
+------------
++
+These uses will match the behavior of `git config --set --<scope> <key>
+<value>`. Note that replacing all values with the `--all` option or
+matching specific value patterns are not supported by this command.
++
+The response of these commands will include a `success` message if the
+value is written as expected or `failed` if an unexpected failure
+occurs:
++
+------------
+set 1 success <scope> <key> <value>
+set 1 failed <scope> <key> <value>
+------------
+
 NUL-Terminated Format
 ~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/builtin/config-batch.c b/builtin/config-batch.c
index 9829b16c6f..373b0cad47 100644
--- a/builtin/config-batch.c
+++ b/builtin/config-batch.c
@@ -16,6 +16,7 @@ static int zformat = 0;
 #define UNKNOWN_COMMAND "unknown_command"
 #define HELP_COMMAND "help"
 #define GET_COMMAND "get"
+#define SET_COMMAND "set"
 #define COMMAND_PARSE_ERROR "command_parse_error"
 
 static void print_word(const char *word, int start)
@@ -379,6 +380,71 @@ cleanup:
 	return res;
 }
 
+
+/**
+ * 'set' command, version 1.
+ *
+ * Positional arguments should be of the form:
+ *
+ * [0] scope ("system", "global", "local", or "worktree")
+ * [1] config key
+ * [2] config value
+ */
+static int set_command_1(struct repository *repo,
+			 const char *prefix,
+			 char *data,
+			 size_t data_len)
+{
+	int res = 0, err = 0;
+	enum config_scope scope = CONFIG_SCOPE_UNKNOWN;
+	char *token = NULL, *key = NULL, *value = NULL;
+	struct config_location_options locopts = CONFIG_LOCATION_OPTIONS_INIT;
+
+	if (!parse_token(&data, &data_len, &token, &err) || err)
+		goto parse_error;
+
+	if (parse_scope(token, &scope) ||
+	    scope == CONFIG_SCOPE_UNKNOWN ||
+	    scope == CONFIG_SCOPE_SUBMODULE ||
+	    scope == CONFIG_SCOPE_COMMAND)
+		goto parse_error;
+
+	if (!parse_token(&data, &data_len, &key, &err) || err)
+		goto parse_error;
+
+	/* Use the remaining data as the value string. */
+	if (!zformat)
+		value = data;
+	else {
+		parse_token(&data, &data_len, &value, &err);
+		if (err)
+			goto parse_error;
+	}
+
+	if (location_options_set_scope(&locopts, scope))
+		goto parse_error;
+	location_options_init(repo, &locopts, prefix);
+
+	res = repo_config_set_in_file_gently(repo, locopts.source.file,
+					     key, NULL, value);
+
+	if (res)
+		res = emit_response(SET_COMMAND, "1", "failure",
+				    scope_str(scope), key, value, NULL);
+	else
+		res = emit_response(SET_COMMAND, "1", "success",
+				    scope_str(scope), key, value, NULL);
+
+	goto cleanup;
+
+parse_error:
+	res = command_parse_error(SET_COMMAND);
+
+cleanup:
+	location_options_release(&locopts);
+	return res;
+}
+
 struct command {
 	const char *name;
 	command_fn fn;
@@ -396,6 +462,11 @@ static struct command commands[] = {
 		.fn = get_command_1,
 		.version = 1,
 	},
+	{
+		.name = SET_COMMAND,
+		.fn = set_command_1,
+		.version = 1,
+	},
 	/* unknown_command must be last. */
 	{
 		.name = "",
diff --git a/config.c b/config.c
index 9f1a7b45cf..fa72234750 100644
--- a/config.c
+++ b/config.c
@@ -3594,6 +3594,33 @@ int lookup_config(const char **mapping, int nr_mapping, const char *var)
 	return -1;
 }
 
+int location_options_set_scope(struct config_location_options *opts,
+			       enum config_scope scope)
+{
+	switch (scope) {
+	case CONFIG_SCOPE_SYSTEM:
+		opts->use_system_config = 1;
+		break;
+
+	case CONFIG_SCOPE_GLOBAL:
+		opts->use_global_config = 1;
+		break;
+
+	case CONFIG_SCOPE_LOCAL:
+		opts->use_local_config = 1;
+		break;
+
+	case CONFIG_SCOPE_WORKTREE:
+		opts->use_worktree_config = 1;
+		break;
+
+	default:
+		return -1;
+	}
+
+	return 0;
+}
+
 void location_options_init(struct repository *repo,
 			   struct config_location_options *opts,
 			   const char *prefix)
diff --git a/config.h b/config.h
index 6663964977..f6432c1ec2 100644
--- a/config.h
+++ b/config.h
@@ -180,6 +180,9 @@ struct config_location_options {
 	.respect_includes_opt = -1, \
 }
 
+int location_options_set_scope(struct config_location_options *opts,
+			       enum config_scope scope);
+
 void location_options_init(struct repository *repo,
 			   struct config_location_options *opts,
 			   const char *prefix);
diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
index f7a74ddc2c..40f6f90ef2 100755
--- a/t/t1312-config-batch.sh
+++ b/t/t1312-config-batch.sh
@@ -47,9 +47,10 @@ test_expect_success 'help command' '
 	echo "help 1" >in &&
 
 	cat >expect <<-\EOF &&
-	help 1 count 2
+	help 1 count 3
 	help 1 help 1
 	help 1 get 1
+	help 1 set 1
 	EOF
 
 	git config-batch >out <in &&
@@ -63,9 +64,10 @@ test_expect_success 'help -z' '
 	EOF
 
 	cat >expect <<-\EOF &&
-	4:help 1:1 5:count 1:2
+	4:help 1:1 5:count 1:3
 	4:help 1:1 4:help 1:1
 	4:help 1:1 3:get 1:1
+	4:help 1:1 3:set 1:1
 	15:unknown_command
 	EOF
 
@@ -205,4 +207,92 @@ test_expect_success 'get config with -z' '
 	test_cmp expect out
 '
 
+test_expect_success 'set config by scope' '
+	test_when_finished git config remove-section test.set &&
+	GIT_CONFIG_SYSTEM=system-config-file &&
+	GIT_CONFIG_NOSYSTEM=0 &&
+	GIT_CONFIG_GLOBAL=global-config-file &&
+	export GIT_CONFIG_SYSTEM &&
+	export GIT_CONFIG_NOSYSTEM &&
+	export GIT_CONFIG_GLOBAL &&
+
+	cat >in <<-\EOF &&
+	set 1 system test.set.system system
+	set 1 global test.set.global global
+	set 1 local test.set.local local with spaces
+	set 1 worktree test.set.worktree worktree
+	set 1 submodule test.set.submodule submodule
+	set 1 command test.set.command command
+	set 1 inherited test.set.inherited inherited
+	EOF
+
+	cat >expect <<-\EOF &&
+	set 1 success system test.set.system system
+	set 1 success global test.set.global global
+	set 1 success local test.set.local local with spaces
+	set 1 success worktree test.set.worktree worktree
+	command_parse_error set
+	command_parse_error set
+	command_parse_error set
+	EOF
+
+	git config-batch <in >out 2>err &&
+
+	test_must_be_empty err &&
+	test_cmp expect out &&
+
+	cat >expect-values <<-EOF &&
+	file:system-config-file	system
+	file:global-config-file	global
+	file:.git/config	local with spaces
+	file:.git/config.worktree	worktree
+	EOF
+
+	git config get --show-origin --regexp --all test.set.* >values &&
+	test_cmp expect-values values
+'
+
+test_expect_success 'set config by scope with -z' '
+	test_when_finished git config remove-section test.set &&
+	GIT_CONFIG_SYSTEM=system-config-file &&
+	GIT_CONFIG_NOSYSTEM=0 &&
+	GIT_CONFIG_GLOBAL=global-config-file &&
+	export GIT_CONFIG_SYSTEM &&
+	export GIT_CONFIG_NOSYSTEM &&
+	export GIT_CONFIG_GLOBAL &&
+
+	cat >in <<-\EOF &&
+	3:set NUL 1:1 NUL 6:system NUL 15:test.set.system NUL 6:system NUL NUL
+	3:set NUL 1:1 NUL 6:global NUL 15:test.set.global NUL 6:global NUL NUL
+	3:set NUL 1:1 NUL 5:local NUL 14:test.set.local NUL 17:local with spaces NUL NUL
+	3:set NUL 1:1 NUL 8:worktree NUL 17:test.set.worktree NUL 8:worktree NUL NUL
+	3:set NUL 1:1 NUL 9:submodule NUL 18:test.set.submodule NUL 9:submodule NUL NUL
+	3:set NUL 1:1 NUL 7:command NUL 16:test.set.command NUL 7:command NUL NUL
+	3:set NUL 1:1 NUL 9:inherited NUL 18:test.set.inherited NUL 9:inherited NUL NUL
+	EOF
+
+	cat >expect <<-\EOF &&
+	3:set 1:1 7:success 6:system 15:test.set.system 6:system
+	3:set 1:1 7:success 6:global 15:test.set.global 6:global
+	3:set 1:1 7:success 5:local 14:test.set.local 17:local with spaces
+	3:set 1:1 7:success 8:worktree 17:test.set.worktree 8:worktree
+	19:command_parse_error 3:set
+	19:command_parse_error 3:set
+	19:command_parse_error 3:set
+	EOF
+
+	test_zformat git config-batch -z >out <in &&
+	test_cmp expect out &&
+
+	cat >expect-values <<-EOF &&
+	file:system-config-file	system
+	file:global-config-file	global
+	file:.git/config	local with spaces
+	file:.git/config.worktree	worktree
+	EOF
+
+	git config get --show-origin --regexp --all test.set.* >values &&
+	test_cmp expect-values values
+'
+
 test_done
-- 
gitgitgadget

[PATCH 10/11] t1312: create read/write test

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

This new test will be extended in the future to ensure that multiple
commands that execute in order update the configuration state enough to
reflect new written values as we read them in later commands.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 t/t1312-config-batch.sh | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
index 40f6f90ef2..11380f4247 100755
--- a/t/t1312-config-batch.sh
+++ b/t/t1312-config-batch.sh
@@ -295,4 +295,31 @@ test_expect_success 'set config by scope with -z' '
 	test_cmp expect-values values
 '
 
+test_expect_success 'read/write interactions in sequence' '
+	test_when_finished git config remove-section test.rw &&
+
+	cat >in <<-\EOF &&
+	get 1 local test.rw.missing
+	set 1 local test.rw.found found
+	get 1 local test.rw.found
+	set 1 local test.rw.found updated
+	get 1 local test.rw.found
+	EOF
+
+	cat >expect <<-\EOF &&
+	get 1 missing test.rw.missing
+	set 1 success local test.rw.found found
+	get 1 found test.rw.found local found
+	set 1 success local test.rw.found updated
+	get 1 found test.rw.found local updated
+	EOF
+
+	git config-batch <in >out 2>err &&
+
+	test_must_be_empty err &&
+	test_cmp expect out &&
+
+	test_cmp_config updated test.rw.found
+'
+
 test_done
-- 
gitgitgadget

[PATCH 11/11] config-batch: add unset v1 command

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <stolee@gmail.com>

Add a new 'unset' command with version 1 that mimics 'git config
--unset' with optional regex pattern or '--fixed-value' arguments.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
---
 Documentation/git-config-batch.adoc | 28 ++++++++
 builtin/config-batch.c              | 99 +++++++++++++++++++++++++++++
 t/t1312-config-batch.sh             | 61 ++++++++++++++++--
 3 files changed, 181 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
index feec85c4ef..bdfd872d65 100644
--- a/Documentation/git-config-batch.adoc
+++ b/Documentation/git-config-batch.adoc
@@ -135,6 +135,34 @@ set 1 success <scope> <key> <value>
 set 1 failed <scope> <key> <value>
 ------------
 
+`unset` version 1::
+	The `unset` command removes a single value from a config file.
+	It specifies which file by a `<scope>` parameter from among
+	`system`, `global`, `local`, and `worktree`. The `<key>` is the
+	next positional argument. There could be two additional
+	arguments used to match specific config values, where the first
+	is either `arg:regex` or `arg:fixed-value` to specify the type
+	of match.
++
+------------
+unset 1 <scope> <key>
+unset 1 <scope> <key> arg:regex <value-pattern>
+unset 1 <scope> <key> arg:fixed-value <value>
+------------
++
+These uses will match the behavior of `git config --unset --<scope> <key>`
+with the additional arguments of `<value-pattern>` if `arg:regex` is
+given or `--fixed-value <value>` if `arg:fixed-value` is given.
++
+The response of these commands will include a `success` message
+if matched values are found and removed as expected or `failed` if an
+unexpected failure occurs:
++
+------------
+unset 1 success <scope> <key>
+unset 1 failed <scope> <key>
+------------
+
 NUL-Terminated Format
 ~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/builtin/config-batch.c b/builtin/config-batch.c
index 373b0cad47..25a942ba61 100644
--- a/builtin/config-batch.c
+++ b/builtin/config-batch.c
@@ -17,6 +17,7 @@ static int zformat = 0;
 #define HELP_COMMAND "help"
 #define GET_COMMAND "get"
 #define SET_COMMAND "set"
+#define UNSET_COMMAND "unset"
 #define COMMAND_PARSE_ERROR "command_parse_error"
 
 static void print_word(const char *word, int start)
@@ -445,6 +446,99 @@ cleanup:
 	return res;
 }
 
+/**
+ * 'unset' command, version 1.
+ *
+ * Positional arguments should be of the form:
+ *
+ * [0] scope ("system", "global", "local", or "worktree")
+ * [1] config key
+ * [2] config value
+ * [3*] match ("regex", "fixed-value")
+ * [4*] value regex OR value string
+ *
+ * [N*] indicates optional parameters that are not needed.
+ */
+static int unset_command_1(struct repository *repo,
+			 const char *prefix,
+			 char *data,
+			 size_t data_len)
+{
+	int res = 0, err = 0, flags = 0;
+	enum config_scope scope = CONFIG_SCOPE_UNKNOWN;
+	char *token = NULL, *key = NULL, *value_pattern = NULL;
+	size_t token_len;
+	struct config_location_options locopts = CONFIG_LOCATION_OPTIONS_INIT;
+
+	if (!parse_token(&data, &data_len, &token, &err) || err)
+		goto parse_error;
+
+	if (parse_scope(token, &scope) ||
+	    scope == CONFIG_SCOPE_UNKNOWN ||
+	    scope == CONFIG_SCOPE_SUBMODULE ||
+	    scope == CONFIG_SCOPE_COMMAND)
+		goto parse_error;
+
+	if (!parse_token(&data, &data_len, &key, &err) || err)
+		goto parse_error;
+
+	token_len = parse_token(&data, &data_len, &token, &err);
+	if (err)
+		goto parse_error;
+
+	if (token_len && !strncmp(token, "arg:", 4)) {
+		if (!strcmp(token + 4, "fixed-value"))
+			flags |= CONFIG_FLAGS_FIXED_VALUE;
+		/* no special logic for arg:regex. */
+		else if (strcmp(token + 4, "regex"))
+			goto parse_error; /* unknown arg. */
+
+		/* Use the remaining data as the value string. */
+		if (!zformat)
+			value_pattern = data;
+		else {
+			parse_token(&data, &data_len, &value_pattern, &err);
+			if (err)
+				goto parse_error;
+		}
+	} else if (token_len) {
+		/*
+		 * If we have remaining tokens not starting in "arg:",
+		 * then we don't understand them.
+		 */
+		goto parse_error;
+	}
+
+	if (location_options_set_scope(&locopts, scope))
+		goto parse_error;
+	location_options_init(repo, &locopts, prefix);
+
+	res = repo_config_set_multivar_in_file_gently(
+			repo,
+			locopts.source.file,
+			key,
+			/* value */ NULL,
+			value_pattern,
+			/* comment */ NULL,
+			flags);
+
+	if (res)
+		res = emit_response(UNSET_COMMAND, "1", "failure",
+				    scope_str(scope), key, NULL);
+	else
+		res = emit_response(UNSET_COMMAND, "1", "success",
+				    scope_str(scope), key, NULL);
+
+	goto cleanup;
+
+parse_error:
+	res = command_parse_error(UNSET_COMMAND);
+
+cleanup:
+	location_options_release(&locopts);
+	return res;
+}
+
 struct command {
 	const char *name;
 	command_fn fn;
@@ -467,6 +561,11 @@ static struct command commands[] = {
 		.fn = set_command_1,
 		.version = 1,
 	},
+	{
+		.name = UNSET_COMMAND,
+		.fn = unset_command_1,
+		.version = 1,
+	},
 	/* unknown_command must be last. */
 	{
 		.name = "",
diff --git a/t/t1312-config-batch.sh b/t/t1312-config-batch.sh
index 11380f4247..3bddbc0de3 100755
--- a/t/t1312-config-batch.sh
+++ b/t/t1312-config-batch.sh
@@ -47,10 +47,11 @@ test_expect_success 'help command' '
 	echo "help 1" >in &&
 
 	cat >expect <<-\EOF &&
-	help 1 count 3
+	help 1 count 4
 	help 1 help 1
 	help 1 get 1
 	help 1 set 1
+	help 1 unset 1
 	EOF
 
 	git config-batch >out <in &&
@@ -64,10 +65,11 @@ test_expect_success 'help -z' '
 	EOF
 
 	cat >expect <<-\EOF &&
-	4:help 1:1 5:count 1:3
+	4:help 1:1 5:count 1:4
 	4:help 1:1 4:help 1:1
 	4:help 1:1 3:get 1:1
 	4:help 1:1 3:set 1:1
+	4:help 1:1 5:unset 1:1
 	15:unknown_command
 	EOF
 
@@ -295,15 +297,60 @@ test_expect_success 'set config by scope with -z' '
 	test_cmp expect-values values
 '
 
-test_expect_success 'read/write interactions in sequence' '
-	test_when_finished git config remove-section test.rw &&
+test_expect_success 'unset config by scope and filter' '
+	GIT_CONFIG_SYSTEM=system-config-file &&
+	GIT_CONFIG_NOSYSTEM=0 &&
+	GIT_CONFIG_GLOBAL=global-config-file &&
+	export GIT_CONFIG_SYSTEM &&
+	export GIT_CONFIG_NOSYSTEM &&
+	export GIT_CONFIG_GLOBAL &&
+
+	cat >in <<-\EOF &&
+	set 1 system test.unset.key system
+	set 1 global test.unset.key global
+	set 1 local test.unset.key local with spaces
+	set 1 worktree test.unset.key worktree
+	unset 1 system test.unset.key
+	unset 1 global test.unset.key arg:regex g.*
+	unset 1 local test.unset.key arg:fixed-value local with spaces
+	unset 1 worktree test.unset.key arg:fixed-value submodule
+	unset 1 worktree test.unset.key arg:regex l.*
+	EOF
+
+	cat >expect <<-\EOF &&
+	set 1 success system test.unset.key system
+	set 1 success global test.unset.key global
+	set 1 success local test.unset.key local with spaces
+	set 1 success worktree test.unset.key worktree
+	unset 1 success system test.unset.key
+	unset 1 success global test.unset.key
+	unset 1 success local test.unset.key
+	unset 1 failure worktree test.unset.key
+	unset 1 failure worktree test.unset.key
+	EOF
+
+	git config-batch <in >out 2>err &&
 
+	test_must_be_empty err &&
+	test_cmp expect out &&
+
+	cat >expect-values <<-EOF &&
+	file:.git/config.worktree	worktree
+	EOF
+
+	git config get --show-origin --regexp --all test.unset.key >values &&
+	test_cmp expect-values values
+'
+
+test_expect_success 'read/write interactions in sequence' '
 	cat >in <<-\EOF &&
 	get 1 local test.rw.missing
 	set 1 local test.rw.found found
 	get 1 local test.rw.found
 	set 1 local test.rw.found updated
 	get 1 local test.rw.found
+	unset 1 local test.rw.found arg:fixed-value updated
+	get 1 local test.rw.found
 	EOF
 
 	cat >expect <<-\EOF &&
@@ -312,14 +359,14 @@ test_expect_success 'read/write interactions in sequence' '
 	get 1 found test.rw.found local found
 	set 1 success local test.rw.found updated
 	get 1 found test.rw.found local updated
+	unset 1 success local test.rw.found
+	get 1 missing test.rw.found
 	EOF
 
 	git config-batch <in >out 2>err &&
 
 	test_must_be_empty err &&
-	test_cmp expect out &&
-
-	test_cmp_config updated test.rw.found
+	test_cmp expect out
 '
 
 test_done
-- 
gitgitgadget

Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Junio C Hamano]

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

> This RFC explores a new git config-batch builtin that allows tools to
> interact with Git's config data with multiple queries using a single
> process. This is an orthogonal alternative to the effort to create a stable,
> linkable config API. Both approaches have different strengths.

Just a few random thoughts before diving into the patches.

> My main motivation is the performance of git-credential-manager on Windows
> platforms as it can call git config get dozens of times. At 150-200ms per
> execution, that adds up significantly, leading to multiple seconds just to
> load a credential that already exists. I believe that there are other
> benefits to having this interface available, but I can't recall any
> specifics at the moment.

So this would be "credential-manager gets started, and instead of
having to spawn 'git config' many times, spawn a single instance of
'git config --batch' and talk with it".  Would it be beneficial to
further think about a long-running 'git config --server' that can be
contacted by a credential-manager (or other processes) whose lifetime
is totally independent, possibly over local transport mechanisms
like named pipes, or is it a key to keep the mechanism and design
simple to limit the number of customer this service supports to only
one at a time and we would prefer to keep it that way?

> One thing that I think would be valuable to include is a reload command that
> signals that the git config-batch process should reload the configset into
> memory due to config manipulations in other processes, especially while git
> config-batch doesn't have all capabilities from git config. I'll include
> that in the first version for review, if this RFC leads to positive support.

Can "git config --batch" write/modify configuration, and if so, when
does it make its modification available to the outside world?  Would
we have a "flush" command, or it would pretty much be immediate?

Can we do without an explicit "reload" command by noticing when
the configuration files are updated and automatically reload?

I am trying to figure out how more than one "git config --batch"
processes can coordinate with each other with minimum overhead.  It
is not a goal to have multiple such processes, but it would be a
goal to support multiple clients each of which would benefit from
having access to the configuration data service (which is why I
brought up a single and shared long-running daemon as a possible
alternative earlier).

Re: [PATCH 01/11] config-batch: basic boilerplate of new builtin

[Junio C Hamano]

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Derrick Stolee <stolee@gmail.com>
>
> Later changes will document, implement, and test this new builtin. For now,
> this serves as the latest example of the minimum boilerplate to introduce a
> new builtin.
>
> Recently, we updated the comment in builtin.h about how to create a new
> builtin, but failed to mention the required change to meson.build files for
> some CI builds to pass. Fix that oversight.
>
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---

We have had a bad reputation for having too many commands; would it
be better to present it as a new mode of existing "git config"
command at the end-user level, I wonder?

Also after reading patches for a few early steps, I do not quite see
"batch"-ness in this protocol; it is strictly "a single request is
met with a single response".

Re: [PATCH 02/11] config-batch: create parse loop and unknown command

[Junio C Hamano]

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

> +static struct command commands[] = {
> +	/* unknown_command must be last. */
> +	{
> +		.name = "",
> +		.fn   = unknown_command,
> +	},
> +};

A useful trick is to deliberately omit the trailing comma after the
element that MUST be last.  You did that for the __NR enum element
in a later step.

> +#define COMMAND_COUNT ((size_t)(sizeof(commands) / sizeof(*commands)))

Isn't this ARRAY_SIZE(commands)?


> +	while (!(res = process_command(repo)));

Please write an empty statement on its own line, i.e.

	while (!(res = process_command(repo)))
		;

Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[brian m. carlson]

[-- Attachment #1: Type: text/plain, Size: 1748 bytes --]

On 2026-02-04 at 14:19:52, Derrick Stolee via GitGitGadget wrote:
> This RFC explores a new git config-batch builtin that allows tools to
> interact with Git's config data with multiple queries using a single
> process. This is an orthogonal alternative to the effort to create a stable,
> linkable config API. Both approaches have different strengths.
> 
> My main motivation is the performance of git-credential-manager on Windows
> platforms as it can call git config get dozens of times. At 150-200ms per
> execution, that adds up significantly, leading to multiple seconds just to
> load a credential that already exists. I believe that there are other
> benefits to having this interface available, but I can't recall any
> specifics at the moment.
> 
> This RFC adds git config-batch with a protocol over stdin/stdout for
> executing multiple config queries. The implementation has a limited set of
> potential queries, but also creates a model for compatibility for tools to
> automatically adapt to different Git versions.
> 
> I'm submitting this as an RFC before I've polished all of the details
> because I want to make sure I'm going down a good direction. Please focus
> feedback in these questions:
> 
>  * Is this a worthwhile feature to add to Git?

Git LFS has the same needs, but I believe it can use `git config -l -z`
to do that and parse the config options itself.  If this is just config
fetching, I'm not sure of the additional utility that such a feature
would add.  If that interface _almost_ meets your needs, could we add
functionality there instead of a new interface?

If you need to set many keys, I'm curious as to why that is.
-- 
brian m. carlson (they/them)
Toronto, Ontario, CA

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 262 bytes --]

Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Derrick Stolee]

On 2/4/2026 7:04 PM, brian m. carlson wrote:
> On 2026-02-04 at 14:19:52, Derrick Stolee via GitGitGadget wrote:
>> This RFC explores a new git config-batch builtin that allows tools to
>> interact with Git's config data with multiple queries using a single
>> process. This is an orthogonal alternative to the effort to create a stable,
>> linkable config API. Both approaches have different strengths.
>>
>> My main motivation is the performance of git-credential-manager on Windows
>> platforms as it can call git config get dozens of times. At 150-200ms per
>> execution, that adds up significantly, leading to multiple seconds just to
>> load a credential that already exists. I believe that there are other
>> benefits to having this interface available, but I can't recall any
>> specifics at the moment.

>>  * Is this a worthwhile feature to add to Git?
> 
> Git LFS has the same needs, but I believe it can use `git config -l -z`
> to do that and parse the config options itself.  If this is just config
> fetching, I'm not sure of the additional utility that such a feature
> would add.  If that interface _almost_ meets your needs, could we add
> functionality there instead of a new interface?

This is a good suggestion to look into as a potentially-easier solution.

There may be some work required on the consumer to interpret multiple
values and the right inheritance rules. This is relatively minor
compared to attempting a full parser with complicated 'includeIf'
logic.
 > If you need to set many keys, I'm curious as to why that is.

I know that the credential manager does more than just query the config,
but also sets and unsets config. The full interface is here [1]. However,
the performance-critical parts may not require mutating configuration
values, and hence such a 

[1] https://github.com/git-ecosystem/git-credential-manager/blob/main/src/shared/Core/GitConfiguration.cs#L31

Thanks for the pointer to git-lfs as a similar use case. I see that it
has a way to get the full list of config values [2] with '-l' (but not
'-z'). It also has methods for getting values on a per-key (or even
per-file) basis. I have not tracked the uses of config code into its
consumers to know how often one is used over the other.

[2] https://github.com/git-lfs/git-lfs/blob/bb65882304a655ffa8abf2be6922e53ff18af5a5/git/config.go#L208

Thanks,
-Stolee

Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Derrick Stolee]

On 2/4/2026 6:04 PM, Junio C Hamano wrote:
> "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> This RFC explores a new git config-batch builtin that allows tools to
>> interact with Git's config data with multiple queries using a single
>> process. This is an orthogonal alternative to the effort to create a stable,
>> linkable config API. Both approaches have different strengths.
> 
> Just a few random thoughts before diving into the patches.
> 
>> My main motivation is the performance of git-credential-manager on Windows
>> platforms as it can call git config get dozens of times. At 150-200ms per
>> execution, that adds up significantly, leading to multiple seconds just to
>> load a credential that already exists. I believe that there are other
>> benefits to having this interface available, but I can't recall any
>> specifics at the moment.
> 
> So this would be "credential-manager gets started, and instead of
> having to spawn 'git config' many times, spawn a single instance of
> 'git config --batch' and talk with it".  Would it be beneficial to
> further think about a long-running 'git config --server' that can be
> contacted by a credential-manager (or other processes) whose lifetime
> is totally independent, possibly over local transport mechanisms
> like named pipes, or is it a key to keep the mechanism and design
> simple to limit the number of customer this service supports to only
> one at a time and we would prefer to keep it that way?

I could imagine a world where we have this approach, similar to the
fsmonitor server. I should do more research and refresh my memory on that
I/O model, if only to potentially reuse some of the parsing logic.

But this would be an interesting potential direction, saving the process
start-up time entirely.

The one big difficulty that I see is that the config will need to be
refreshed proactively by the server, potentially by watching the config
files themselves (including any files included along the way) and also any
changes to repo state, such as the current branch. Any repo state that
could impact the 'includeIf' logic would need to be checked carefully. 

>> One thing that I think would be valuable to include is a reload command that
>> signals that the git config-batch process should reload the configset into
>> memory due to config manipulations in other processes, especially while git
>> config-batch doesn't have all capabilities from git config. I'll include
>> that in the first version for review, if this RFC leads to positive support.
> 
> Can "git config --batch" write/modify configuration, and if so, when
> does it make its modification available to the outside world?  Would
> we have a "flush" command, or it would pretty much be immediate?

The 'set' command in this series calls methods that reach into
repo_config_set_multivar_in_file_gently() which updates the config file as
part of that call, including using the .lock file technique to avoid
concurrent writes. Looking closely, it appears we do the right thing by
parsing the existing file so we only update the new values while allowing
any concurrent writes to the file to be respected, even if they disagree
with our current view of the config.

Such assignments also update our in-memory view _of those keys_ but it may
be a good time to automatically refresh the entire set of config values.

> Can we do without an explicit "reload" command by noticing when
> the configuration files are updated and automatically reload?

This would be an interesting approach, especially for the server concept.

> I am trying to figure out how more than one "git config --batch"
> processes can coordinate with each other with minimum overhead.  It
> is not a goal to have multiple such processes, but it would be a
> goal to support multiple clients each of which would benefit from
> having access to the configuration data service (which is why I
> brought up a single and shared long-running daemon as a possible
> alternative earlier).

You're right to bring up these concerns. While 'git config-batch' is
intended to be relatively short-lived, users could build tools that keep
it alive for a long time. Thus, it is important to consider these
automatically-refreshing scenarios. And if we are automatically
refreshing, then should we instead consider a client/server model?

I have some things to explore at the highest levels. I will likely start
by exploring brian's 'git config -l -z' suggestion to see if that solves
the short-term need. But I will consider these other ideas to see where
they lead in terms of complexity and potential applications.

Thanks,
-Stolee

Re: [PATCH 01/11] config-batch: basic boilerplate of new builtin

[Derrick Stolee]

On 2/4/2026 6:23 PM, Junio C Hamano wrote:
> "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> From: Derrick Stolee <stolee@gmail.com>
>>
>> Later changes will document, implement, and test this new builtin. For now,
>> this serves as the latest example of the minimum boilerplate to introduce a
>> new builtin.
>>
>> Recently, we updated the comment in builtin.h about how to create a new
>> builtin, but failed to mention the required change to meson.build files for
>> some CI builds to pass. Fix that oversight.
>>
>> Signed-off-by: Derrick Stolee <stolee@gmail.com>
>> ---
> 
> We have had a bad reputation for having too many commands; would it
> be better to present it as a new mode of existing "git config"
> command at the end-user level, I wonder?

Interesting thought. I think we also have a bad reputation of commands
that are overloaded with too many purposes.

In this case, though, I do think that the modern 'git config <subcommand>'
model presents some clear boundaries for how the command should behave
with the 'batch' (or 'server') subcommand. Grouping all config-related
operations in the same builtin may be ideal. 

> Also after reading patches for a few early steps, I do not quite see
> "batch"-ness in this protocol; it is strictly "a single request is
> met with a single response".

The batch-ness is that multiple requests can eventually go to the same
process. The client could collect multiple commands in a batch and send
them all without processing the responses one-by-one. This is how it works
in the tests: a single input file is prepared and all responses are
scanned after-the-fact.

The back-and-forth mechanism is how the git-credential-manager tool would
use it, because it dynamically explores certain config keys. For example:
it checks the deepest possible URL for a specific key then peels away the
last segment of the URL to see if there is a directory-prefix match in a
key. (This is the main reason that there are so many requests in this
application.)

I believe this is similar to how 'git cat-file --batch' or 'git cat-file
--batch-check' work, which was my inspiration for this word. If we regret
those names, then I'm happy to move towards a better name.

Thanks,
-Stolee

Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Phillip Wood]

Hi Stolee

On 04/02/2026 14:19, Derrick Stolee via GitGitGadget wrote:
> This RFC explores a new git config-batch builtin that allows tools to
> interact with Git's config data with multiple queries using a single
> process. This is an orthogonal alternative to the effort to create a stable,
> linkable config API. Both approaches have different strengths.
> 
> My main motivation is the performance of git-credential-manager on Windows
> platforms as it can call git config get dozens of times. At 150-200ms per
> execution, that adds up significantly, leading to multiple seconds just to
> load a credential that already exists. I believe that there are other
> benefits to having this interface available, but I can't recall any
> specifics at the moment.

It would be helpful to explain what the advantage of this new command is 
over using "git config --list -z" or "git config --get-regex 
'^(some|section|names)\.' -z". I've found those to be effective in 
programs that read several config keys. Elsewhere brian has mentioned 
that git-lfs does something similar and I believe git-filter-repo uses 
"git config --list -z" as well.

One potential advantage would be if this command supported specifying 
the type of the value. When using "git config --list" it is a pain to 
have to normalize boolean values and parse color descriptions into 
terminal escape codes.

Being able to set multiple keys at once would also be an advantage if 
there is a convincing use case for it.

> This RFC adds git config-batch with a protocol over stdin/stdout for
> executing multiple config queries. The implementation has a limited set of
> potential queries, but also creates a model for compatibility for tools to
> automatically adapt to different Git versions.
> 
> I'm submitting this as an RFC before I've polished all of the details
> because I want to make sure I'm going down a good direction. Please focus
> feedback in these questions:
> 
>   * Is this a worthwhile feature to add to Git?

Possibly, if there are clear benefits over "git config --list". I'm not 
sure it needs to be a separate command though - I agree with Junio that 
it would be more discoverable if this was a subcommand of "git config"

>   * Is this a reasonable protocol for stdin/stdout?

The protocol sounds quite complicated with capability queries and 
versioning. At the same time it looks like the line oriented version 
does not support keys that contain spaces, values that contain newlines 
or retrieving settings from a file whose path contains a newline. I 
think it might be better to have a single protocol variant based using 
NUL delimiters like "git merge-tree --stdin" and "git diff-pairs". Those 
commands use a simple NUL terminated protocol without the need to 
specify the length of the input.

> Each command has an associated version, in case we need to expand or alter
> the functionality in the future. This includes the potential to deprecate
> and remove certain versions that we no longer want to support, such as
> replacing set version 1 with a version 2 and making version 1 no longer
> available. I do hope that we will mostly be able to move with new command
> names, such as a set-all command including the options for git config set
> --all ... instead of increasing the version of the set command.

It's good that you're thinking about future functionality but I wonder 
if we really need to specify the version on a per command basis rather 
than as a command line option or simply adding commands like "get-v2".

> There is a -z option that changes the command interface to use
> NUL-terminated strings. Two NULs specify a command boundary, which promotes
> compatibility with a caller that sends an unknown command.

That also allows optional fields such as the file to read the config 
from or the value to match to be NUL delimited while making the end of a 
record unambiguous.

> However, this
> means that we cannot specify an empty string as a token within a command
> unless we add more data. 

Is there a need to do that? Can we require key=value pairs or possibly a 
fixed number of positional parameters if there is a chance the value 
will be empty?

> This format uses <N>:<string> to provide the
> integer <N> which specifies the length of <string>. This is a little
> cumbersome, but the format is intended for tools, not humans.

It does seem cumbersome. I can see that it might be helpful to have the 
length of the complete query and response to avoid deadlocks when 
reading and writing but I'm not sure requiring the length of each field 
is helpful.

> I have a test integration with git-credential-manager available [1] for
> testing. This includes a model for interacting with git config-batch in a
> compatible way that will respond to certain features not being available:
> 
>   1. If git config-batch fails immediately, then all queries are handled by
>      git config.
>   2. If git config-batch starts without failure, then the first query is for
>      the help command.
>   3. As queries come to the config system, the query is checked against the
>      available commands advertised by git config-batch. If the appropriate
>      command is available, then the query is made in that process. If not,
>      then the query uses the existing git config command.

This seems like quite a lot of effort just to check a few config settings.

> I have a few concerns with this implementation that I'd like to improve
> before submitting a version for full review. I list them here so you can see
> the flaws that I already see, but also so you can add to this list:
> 
>   * The use of arg:<arg> to specify an optional argument creates the
>     inability to submit a value that starts with arg:. Consider alternative
>     ways to specify arguments or to specify that the remaining data in the
>     command (including spaces) is a final positional argument.

The protocol should be unambiguous. Requiring key=value pairs for all 
fields would be one way to achieve that

	set key=my.key scope=global value-regex=my-regex value=new-value

or we could force all optional fields to come first and count the number 
of fields to figure out whether any optional fields have been passed

	set value-regex=my-regex global my.key new-value

(I've used spaces above to delimit fields but we'd want to use NUL in 
the protocol)

Thanks

Phillip

>   * In general, I found myself implementing behavior based on the deprecated
>     forms of git config that use the --get or --unset style arguments instead
>     of git config (set|unset|get) subcommands. It's worth making sure that
>     any references to equivalent git config commands use the new modes.
>   * I need to add an --[no-]includes option as a command-line argument that
>     signals whether include sections should be followed. I don't believe this
>     should be specified on a per-command basis, but I'm open to suggestions.
>   * I have an early draft of a technical document detailing the plan for this
>     builtin. It has some lists of intended future commands that have not been
>     implemented. This would also be a good place to document any parsing APIs
>     built to help contributors adding to this builtin.
> 
> Thanks, -Stolee
> 
> Derrick Stolee (11):
>    config-batch: basic boilerplate of new builtin
>    config-batch: create parse loop and unknown command
>    config-batch: implement get v1
>    config-batch: create 'help' command
>    config-batch: add NUL-terminated I/O format
>    docs: add design doc for config-batch
>    config: extract location structs from builtin
>    config-batch: pass prefix through commands
>    config-batch: add 'set' v1 command
>    t1312: create read/write test
>    config-batch: add unset v1 command
> 
>   .gitignore                                |   1 +
>   Documentation/git-config-batch.adoc       | 214 ++++++
>   Documentation/meson.build                 |   1 +
>   Documentation/technical/config-batch.adoc |  70 ++
>   Makefile                                  |   1 +
>   builtin.h                                 |   7 +
>   builtin/config-batch.c                    | 772 ++++++++++++++++++++++
>   builtin/config.c                          | 117 +---
>   command-list.txt                          |   1 +
>   config.c                                  | 116 ++++
>   config.h                                  |  26 +
>   git.c                                     |   1 +
>   meson.build                               |   1 +
>   t/meson.build                             |   1 +
>   t/t1312-config-batch.sh                   | 372 +++++++++++
>   15 files changed, 1592 insertions(+), 109 deletions(-)
>   create mode 100644 Documentation/git-config-batch.adoc
>   create mode 100644 Documentation/technical/config-batch.adoc
>   create mode 100644 builtin/config-batch.c
>   create mode 100755 t/t1312-config-batch.sh
> 
> 
> base-commit: 83a69f19359e6d9bc980563caca38b2b5729808c
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2033%2Fderrickstolee%2Fbatched-config-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2033/derrickstolee/batched-config-v1
> Pull-Request: https://github.com/gitgitgadget/git/pull/2033

Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:
> This RFC explores a new git config-batch builtin that allows tools to
> interact with Git's config data with multiple queries using a single
> process. This is an orthogonal alternative to the effort to create a stable,
> linkable config API. Both approaches have different strengths.
>[snip]

This sounds incredibly useful. Thanks!

Re: [PATCH 09/11] config-batch: add 'set' v1 command

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:
>[snip]
> +git-config-batch(1)
> +===================
> +
> +NAME
> +----
> +git-config-batch - Get and set options using machine-parseable
> interface
> +
> +
> +SYNOPSIS
> +--------
> +[verse]

There’s work lead by Jean-Noël Avila to use `[synopsis]` instead of
`[verse]`.[1] Would it make sense to start off with that?

† 1: E.g. acffc5e9 (doc: convert git-remote to synopsis style, 2025-12-20)

> +'git config-batch' <options>
> +
> +DESCRIPTION
> +-----------
>[snip]

Re: [PATCH 01/11] config-batch: basic boilerplate of new builtin

[Kristoffer Haugsbakk]

On Thu, Feb 5, 2026, at 15:17, Derrick Stolee wrote:
>>>[snip]
>>
>> We have had a bad reputation for having too many commands; would it
>> be better to present it as a new mode of existing "git config"
>> command at the end-user level, I wonder?
>
> Interesting thought. I think we also have a bad reputation of commands
> that are overloaded with too many purposes.

I had a response to that in my head...

> In this case, though, I do think that the modern 'git config <subcommand>'
> model presents some clear boundaries for how the command should behave
> with the 'batch' (or 'server') subcommand. Grouping all config-related
> operations in the same builtin may be ideal.

Which turned out to be exactly about a subcommand. :)

I find the modern subcommand model very easy to navigate. And with much
less downsides compared to having dozens of options for one command (or: one
particular subcommand to git(1)).

>
>> Also after reading patches for a few early steps, I do not quite see
>> "batch"-ness in this protocol; it is strictly "a single request is
>> met with a single response".
>
> The batch-ness is that multiple requests can eventually go to the same
> process. The client could collect multiple commands in a batch and send
> them all without processing the responses one-by-one. This is how it works
> in the tests: a single input file is prepared and all responses are
> scanned after-the-fact.

As a user that makes sense given the existing `--batch` and
`--stdin` options.

> The back-and-forth mechanism is how the git-credential-manager tool would
> use it, because it dynamically explores certain config keys. For example:
> it checks the deepest possible URL for a specific key then peels away the
> last segment of the URL to see if there is a directory-prefix match in a
> key. (This is the main reason that there are so many requests in this
> application.)
>
> I believe this is similar to how 'git cat-file --batch' or 'git cat-file
> --batch-check' work, which was my inspiration for this word. If we regret
> those names, then I'm happy to move towards a better name.
>
> Thanks,
> -Stolee

Re: [PATCH 01/11] config-batch: basic boilerplate of new builtin

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:
>[snip]
> +git-config-batch(1)
> +===================
> +
> +NAME
> +----
> +git-config-batch - Get and set options using machine-parseable
> interface
> +
> +
> +SYNOPSIS
> +--------
> +[verse]

There’s work lead by Jean-Noël Avila to use `[synopsis]` instead of
`[verse]`.[1] Would it make sense to start off with that?

† 1: E.g. acffc5e9 (doc: convert git-remote to synopsis style, 2025-12-20)

> +'git config-batch' <options>
> +
> +DESCRIPTION
> +-----------
>[snip]

Re: [PATCH 02/11] config-batch: create parse loop and unknown command

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:
>[snip]
>  DESCRIPTION
>  -----------
> -TODO
> +Tools frequently need to change their behavior based on values stored in
> +Git's configuration files. These files may have complicated conditions
> +for including extra files, so it is difficult to produce an independent
> +parser. To avoid executing multiple processes to discover or modify
> +multiple configuration values, the `git config-batch` command allows a
> +single process to handle multiple requests using a machine-parseable
> +interface across `stdin` and `stdout`.

I really like that the doc itself motivates the command. Many man pages
on git(1) just tells you what it does as if you would already know why
you need it.

> +
>[snip]

Re: [PATCH 11/11] config-batch: add unset v1 command

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:20, Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <stolee@gmail.com>
>
> Add a new 'unset' command with version 1 that mimics 'git config
> --unset' with optional regex pattern or '--fixed-value' arguments.

`git config --unset` is deprecated in favor of `git config unset`.

>
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  Documentation/git-config-batch.adoc | 28 ++++++++
>  builtin/config-batch.c              | 99 +++++++++++++++++++++++++++++
>  t/t1312-config-batch.sh             | 61 ++++++++++++++++--
>  3 files changed, 181 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/git-config-batch.adoc
> b/Documentation/git-config-batch.adoc
> index feec85c4ef..bdfd872d65 100644
> --- a/Documentation/git-config-batch.adoc
> +++ b/Documentation/git-config-batch.adoc
> @@ -135,6 +135,34 @@ set 1 success <scope> <key> <value>
>  set 1 failed <scope> <key> <value>
>  ------------
>
> +`unset` version 1::
> +	The `unset` command removes a single value from a config file.
> +	It specifies which file by a `<scope>` parameter from among
> +	`system`, `global`, `local`, and `worktree`. The `<key>` is the
> +	next positional argument. There could be two additional
> +	arguments used to match specific config values, where the first
> +	is either `arg:regex` or `arg:fixed-value` to specify the type
> +	of match.
> ++
> +------------
> +unset 1 <scope> <key>
> +unset 1 <scope> <key> arg:regex <value-pattern>
> +unset 1 <scope> <key> arg:fixed-value <value>
> +------------
> ++
> +These uses will match the behavior of `git config --unset --<scope> <key>`

Same as above.

> +with the additional arguments of `<value-pattern>` if `arg:regex` is
> +given or `--fixed-value <value>` if `arg:fixed-value` is given.
> ++
> +The response of these commands will include a `success` message
> +if matched values are found and removed as expected or `failed` if an
> +unexpected failure occurs:
> ++
> +------------
> +unset 1 success <scope> <key>
> +unset 1 failed <scope> <key>
> +------------
> +
>  NUL-Terminated Format
>  ~~~~~~~~~~~~~~~~~~~~~
>
> diff --git a/builtin/config-batch.c b/builtin/config-batch.c
> index 373b0cad47..25a942ba61 100644
> --- a/builtin/config-batch.c
> +++ b/builtin/config-batch.c
> @@ -17,6 +17,7 @@ static int zformat = 0;
>  #define HELP_COMMAND "help"
>  #define GET_COMMAND "get"
>  #define SET_COMMAND "set"
> +#define UNSET_COMMAND "unset"
>  #define COMMAND_PARSE_ERROR "command_parse_error"
>
>  static void print_word(const char *word, int start)
> @@ -445,6 +446,99 @@ cleanup:
>  	return res;
>  }
>
> +/**
> + * 'unset' command, version 1.
> + *
> + * Positional arguments should be of the form:
> + *
> + * [0] scope ("system", "global", "local", or "worktree")
> + * [1] config key
> + * [2] config value
> + * [3*] match ("regex", "fixed-value")
> + * [4*] value regex OR value string
> + *
> + * [N*] indicates optional parameters that are not needed.
> + */
> +static int unset_command_1(struct repository *repo,
> +			 const char *prefix,
> +			 char *data,
> +			 size_t data_len)
> +{
> +	int res = 0, err = 0, flags = 0;
> +	enum config_scope scope = CONFIG_SCOPE_UNKNOWN;
> +	char *token = NULL, *key = NULL, *value_pattern = NULL;
> +	size_t token_len;
> +	struct config_location_options locopts = CONFIG_LOCATION_OPTIONS_INIT;
> +
> +	if (!parse_token(&data, &data_len, &token, &err) || err)
> +		goto parse_error;
> +
> +	if (parse_scope(token, &scope) ||
> +	    scope == CONFIG_SCOPE_UNKNOWN ||
> +	    scope == CONFIG_SCOPE_SUBMODULE ||
> +	    scope == CONFIG_SCOPE_COMMAND)
> +		goto parse_error;

I think this should get braces since it has many lines? Or maybe
multi-line conditionals are excempt.

> +
> +	if (!parse_token(&data, &data_len, &key, &err) || err)
> +		goto parse_error;
>[snip]

Re: [PATCH 06/11] docs: add design doc for config-batch

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:
>[snip]
> +Current commands
> +----------------
> +
> +See the documentation in linkgit::config-batch[1] for the latest set of

s/linkgit::config-batch[1]/linkgit:git-config-batch[1]/

> +available commands and their protocols.
> +
> +Future commands
> +---------------
> +
> +The following modes of `git config` are not currently available as
> commands
> +in `git config-batch`, but are planned for future integration:
> +
> +`git config list [--<scope>]`::
> +	Getting all values, regardless of config key, would require a
> +	multi-valued output similar to the `help` command. This tool will
> +	likely assume advanced options such as `--show-origin`.

What does it mean to assume options?

> +
> +`git config set [--<scope>] <key> <value>`::
> +	It will be desirable to set a config key at a given scope as a
> +	single value, replacing the current value at that scope, if it
> +	exists and is a single value. A `set` command could satisfy this
> +	purpose.
> +
> +`git config set --all [<value-pattern>|--fixed-value=<fixedvalue>]
> <key> <value>`::
> +	When replacing multiple values, it may be necessary to have a
> different
> +	output describing the places those values were set, so it may need to
> +	be implemented via a `set-all` command to differentiate from a `set`
> +	command.
> +
> +`git config unset <key>`::
> +
> +`git config unset --all [<value-pattern>|--fixed-value=<fixedvalue>]
> <key>`::
> +
> +`git config get --all --rexexp <key-pattern> [<value-options>]`::
> +
> +`--replace-all` option::
> +
> +`--type=<type>` option::
> --
> gitgitgadget

Re: [PATCH 05/11] config-batch: add NUL-terminated I/O format

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <stolee@gmail.com>
>[snip]
> +OPTIONS
> +-------
> +
> +`-z`::
> +	If specified, then use the NUL-terminated input and output

It seems to me that using the imperative mood for options might be
preferred now. Like:

    Use NUL-terminated input and output...

See: https://lore.kernel.org/git/bcd6fcd1190fe21c667b5253a4a33b833e658609.1769462744.git.gitgitgadget@gmail.com/

>[snip]
> -	line provides the count of possible commands via `help count <N>`.
> -	The next `<N>` lines are of the form `help <command> <version>`
> +	line provides the count of possible commands via `help 1 count <N>`.
> +	The next `<N>` lines are of the form `help 1 <command> <version>`
>  	to state that this Git version supports that `<command>` at
>  	version `<version>`. Note that the same command may have multiple
>  	available versions.
>  +
> -Here is the currentl output of the help text at the latest version:
> +Here is the current output of the help text at the latest version:

Innocent intra-series typofix.

>  +
>  ------------
>  help 1 count 2
> @@ -102,6 +111,48 @@ get 1 missing <key> [<value-pattern>|<value>]
>  where `<value-pattern>` or `<value>` is only supplied if provided in
>  the command.
>
> +NUL-Terminated Format
> +~~~~~~~~~~~~~~~~~~~~~
> +
> +When `-z` is given, the protocol changes in some structural ways.

It might flow better with “Option `-z` changes the protocol...” ?

I don’t know how usual it is to say “Option <x>”.

>[snip]
> +static void print_word(const char *word, int start)
> +{
> +	if (zformat) {
> +		printf("%"PRIu32":%s", (uint32_t)strlen(word), word);
> +		fputc(0, stdout);
> +	} else if (start)

All of the arms should get braces here.

> +		printf("%s", word);
> +	else
> +		printf(" %s", word);
> +}
> +
>[snip]

Re: [PATCH 09/11] config-batch: add 'set' v1 command

[Kristoffer Haugsbakk]

On Thu, Feb 5, 2026, at 18:21, Kristoffer Haugsbakk wrote:
> On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:
>>[snip]
>> +git-config-batch(1)
>> +===================
>> +
>> +NAME
>> +----
>> +git-config-batch - Get and set options using machine-parseable
>> interface
>> +
>> +
>> +SYNOPSIS
>> +--------
>> +[verse]
>
> There’s work lead by Jean-Noël Avila to use `[synopsis]` instead of
> `[verse]`.[1] Would it make sense to start off with that?
>
> † 1: E.g. acffc5e9 (doc: convert git-remote to synopsis style, 2025-12-20)
>
>> +'git config-batch' <options>
>> +
>> +DESCRIPTION
>> +-----------
>>[snip]

(sorry for replying to the wrong email)

Re: [PATCH 09/11] config-batch: add 'set' v1 command

[Kristoffer Haugsbakk]

On Wed, Feb 4, 2026, at 15:20, Derrick Stolee via GitGitGadget wrote:
>[snip]
> +`set` version 1::
> +	The `set` command writes a single key-value pair to a config
> +	file. It specifies which file by a `<scope>` parameter from
> +	among `system`, `global`, `local`, and `worktree`. The `<key>`
> +	is the next positional argument. The remaining data in the line
> +	is provided as the `<value>` to assign the config.
> ++
> +------------
> +set 1 <scope> <key> <value>
> +------------
> ++
> +These uses will match the behavior of `git config --set --<scope> <key>

`--set` doesn’t exist. I think you meant `set`.

>[snip]
> +int location_options_set_scope(struct config_location_options *opts,
> +			       enum config_scope scope)
> +{
> +	switch (scope) {
> +	case CONFIG_SCOPE_SYSTEM:
> +		opts->use_system_config = 1;
> +		break;
> +
> +	case CONFIG_SCOPE_GLOBAL:
> +		opts->use_global_config = 1;
> +		break;
> +
> +	case CONFIG_SCOPE_LOCAL:
> +		opts->use_local_config = 1;
> +		break;
> +
> +	case CONFIG_SCOPE_WORKTREE:
> +		opts->use_worktree_config = 1;
> +		break;
> +
> +	default:
> +		return -1;
> +	}

Is there support for a user-provided file? (`git config --file=...`)

> +
> +	return 0;
> +}
> +
>[snip]

Re: [PATCH 01/11] config-batch: basic boilerplate of new builtin

[Jean-Noël Avila]

Le 04/02/2026 à 15:19, Derrick Stolee via GitGitGadget a écrit :
> From: Derrick Stolee <stolee@gmail.com>
> 
> Later changes will document, implement, and test this new builtin. For now,
> this serves as the latest example of the minimum boilerplate to introduce a
> new builtin.
> 
> Recently, we updated the comment in builtin.h about how to create a new
> builtin, but failed to mention the required change to meson.build files for
> some CI builds to pass. Fix that oversight.
> 
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  .gitignore                          |  1 +
>  Documentation/git-config-batch.adoc | 24 +++++++++++++++++++++++
>  Documentation/meson.build           |  1 +
>  Makefile                            |  1 +
>  builtin.h                           |  7 +++++++
>  builtin/config-batch.c              | 30 +++++++++++++++++++++++++++++
>  command-list.txt                    |  1 +
>  git.c                               |  1 +
>  meson.build                         |  1 +
>  t/meson.build                       |  1 +
>  t/t1312-config-batch.sh             | 12 ++++++++++++
>  11 files changed, 80 insertions(+)
>  create mode 100644 Documentation/git-config-batch.adoc
>  create mode 100644 builtin/config-batch.c
>  create mode 100755 t/t1312-config-batch.sh
> 
> diff --git a/.gitignore b/.gitignore
> index 78a45cb5be..42640b5e24 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -44,6 +44,7 @@
>  /git-commit-graph
>  /git-commit-tree
>  /git-config
> +/git-config-batch
>  /git-count-objects
>  /git-credential
>  /git-credential-cache
> diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
> new file mode 100644
> index 0000000000..dfa0bd83e2
> --- /dev/null
> +++ b/Documentation/git-config-batch.adoc
> @@ -0,0 +1,24 @@
> +git-config-batch(1)
> +===================
> +
> +NAME
> +----
> +git-config-batch - Get and set options using machine-parseable interface
> +
> +
> +SYNOPSIS
> +--------
> +[verse]
> +'git config-batch' <options>

For this new manual page, please use the synopsis style:

[synopsis]
git config-batch <options>

Thanks

Re: [PATCH 02/11] config-batch: create parse loop and unknown command

[Jean-Noël Avila]

Le 04/02/2026 à 15:19, Derrick Stolee via GitGitGadget a écrit :
> From: Derrick Stolee <stolee@gmail.com>
> 
> As we build new features in the config-batch command, we define the
> plaintext protocol with line-by-line output and responses. To think to the
> future, we make sure that the protocol has a clear way to respond to an
> unknown command or an unknown version of that command.
> 
> As some commands will allow the final argument to contain spaces or even be
> able to parse "\ " as a non-split token, we only provide the remaining line
> as data.
> 
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  Documentation/git-config-batch.adoc |  23 ++++-
>  builtin/config-batch.c              | 133 +++++++++++++++++++++++++++-
>  t/t1312-config-batch.sh             |  19 +++-
>  3 files changed, 170 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
> index dfa0bd83e2..9ca04b0c1e 100644
> --- a/Documentation/git-config-batch.adoc
> +++ b/Documentation/git-config-batch.adoc
> @@ -13,7 +13,28 @@ SYNOPSIS
>  
>  DESCRIPTION
>  -----------
> -TODO
> +Tools frequently need to change their behavior based on values stored in
> +Git's configuration files. These files may have complicated conditions
> +for including extra files, so it is difficult to produce an independent
> +parser. To avoid executing multiple processes to discover or modify
> +multiple configuration values, the `git config-batch` command allows a
> +single process to handle multiple requests using a machine-parseable
> +interface across `stdin` and `stdout`.
> +
> +PROTOCOL
> +--------
> +By default, the protocol uses line feeds (`LF`) to signal the end of a

Characters are typefaced as placeholders: _LF_

> +command over `stdin` or a response over `stdout`.
> +
> +The protocol will be extended in the future, and consumers should be
> +resilient to older Git versions not understanding the latest command
> +set. Thus, if the Git version includes the `git config-batch` builtin
> +but doesn't understand an input command, it will return a single line
> +response:
> +
> +```
> +unknown_command LF> +```
>  
This is Markdown. For Asciidoc, use code block:

----
unknown_command LF
----

Re: [PATCH 03/11] config-batch: implement get v1

[Jean-Noël Avila]

Le 04/02/2026 à 15:19, Derrick Stolee via GitGitGadget a écrit :
> From: Derrick Stolee <stolee@gmail.com>
> 
> The 'get' command for the 'git config-batch' builtin is the first command
> and is currently at version 1. It returns at most one value, the same as
> 'git config --get <key>' with optional value-based filtering.
> 
> The documentation and tests detail the specifics of how to format requests
> of this format and how to parse the results.
> 
> Future versions could consider multi-valued responses or regex-based key
> matching.
> 
> For the sake of incremental exploration of the potential in the 'git
> config-batch' command, this is the only implementation being presented in
> the first patch series.
> 
> Future extensions could include a '-z' parameter that uses NUL bytes in the
> command and output format to allow for spaces or newlines in the input or
> newlines in the output.
> 
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  Documentation/git-config-batch.adoc |  53 +++++-
>  builtin/config-batch.c              | 251 +++++++++++++++++++++++++++-
>  config.h                            |   3 +
>  t/t1312-config-batch.sh             | 101 +++++++++++
>  4 files changed, 405 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
> index 9ca04b0c1e..31dd42f481 100644
> --- a/Documentation/git-config-batch.adoc
> +++ b/Documentation/git-config-batch.adoc
> @@ -32,9 +32,58 @@ set. Thus, if the Git version includes the `git config-batch` builtin
>  but doesn't understand an input command, it will return a single line
>  response:
>  
> -```
> +------------
>  unknown_command LF
> -```
> +------------
> +

OK, the change to Asciidoc code block is done here. Would it be possible
to push it up at the introduction of these lines?

> +These are the commands that are currently understood:
> +
> +`get` version 1::
> +	The `get` command searches the config key-value pairs within a
> +	given `<scope>` for values that match the fixed `<key>` and

The rendering of these is correct due to the synopsis formatter, but we
usually prefer to use the direct formatting for placeholders: _<scope>_,
_<key>_,…

> +	filters the resulting value based on an optional `<value-filter>`.
> +	This can either be a regex or a fixed value. The command format
> +	is one of the following formats:
> ++
> +------------
> +get 1 <scope> <key>
> +get 1 <scope> <key> arg:regex <value-pattern>
> +get 1 <scope> <key> arg:fixed-value <value>
> +------------
> ++

If you are using synopsis style in the block, with the upcoming change
of synopsis style block[1], you can format it:

[synopsis]
------------
get 1 <scope> <key>
get 1 <scope> <key> arg:regex <value-pattern>
get 1 <scope> <key> arg:fixed-value <value>
------------

> +The `<scope>` value can be one of `inherited`, `system`, `global`,
> +`local`, `worktree`, `submodule`, or `command`. If `inherited`, then all
> +config key-value pairs will be considered regardless of scope. Otherwise,
> +only the given scope will be considered.
> ++
> +If no optional arguments are given, then the value will not be filtered
> +by any pattern matching. If `arg:regex` is specified, then the rest of
> +the line is considered a single string, `<value-pattern>`, and is
> +interpreted as a regular expression for matching against stored values,
> +similar to specifying a value to `get config --get <key> "<value-pattern>"`.
> +If `arg:fixed-value` is specified, then the rest of the line is
> +considered a single string, `<value>`, and is checked for an exact
> +match against the key-value pairs, simmilar to `git config --get <key>

similar

> +--fixed-value "<value>"`.
> ++

Here I would use a sub definition list for each matching type, instead
of long running description paragraph.

optional arguments can be specified:

no optional arguments;;
the value will not be filteredby any pattern matching.
`arg:regex <value-pattern>`;;
`<value-pattern>` is interpreted as a regular expression for matching
against stored values, similar to specifying a value to `get config
--get <key> "<value-pattern>"`.
`arg:fixed-value <value>`;;
`<value>` is checked for an exact match against the key-value pairs,
similar to `git config --get <key>`.

> +At mmost one key-value pair is returned, that being the last key-value

At most

> +pair in the standard config order by scope and sequence within each scope.
> ++
> +If a key-value pair is found, then the following output is given:
> ++
> +------------
> +get 1 found <key> <scope> <value>
> +------------
> ++
> +If no matching key-value pair is found, then the following output is
> +given:
> ++
> +------------
> +get 1 missing <key> [<value-pattern>|<value>]
> +------------
> ++

Please also apply synopsis block style.

> +where `<value-pattern>` or `<value>` is only supplied if provided in
> +the command.
>  
>  SEE ALSO
>  --------

[1]:
https://lore.kernel.org/git/6a2b94e720862fa07fe9463ebf7f7beaa9a1ccd4.1770351146.git.gitgitgadget@gmail.com/T/#u

Re: [PATCH 04/11] config-batch: create 'help' command

[Jean-Noël Avila]

Le 04/02/2026 à 15:19, Derrick Stolee via GitGitGadget a écrit :
> From: Derrick Stolee <stolee@gmail.com>
> 
> Tools that use the 'git config-batch' tool will want to know which commands
> are available in the current Git version. Having a 'help' command assists
> greatly to give a clear set of available commands and their versions.
> 
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  Documentation/git-config-batch.adoc | 17 +++++++++++++++
>  builtin/config-batch.c              | 32 +++++++++++++++++++++++++++++
>  t/t1312-config-batch.sh             | 13 ++++++++++++
>  3 files changed, 62 insertions(+)
> 
> diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
> index 31dd42f481..1fff68a13c 100644
> --- a/Documentation/git-config-batch.adoc
> +++ b/Documentation/git-config-batch.adoc
> @@ -38,6 +38,23 @@ unknown_command LF
>  
>  These are the commands that are currently understood:
>  
> +`help` version 1::
> +	The `help` command lists the currently-available commands in

The boilerplat text "The `help` command" is not very useful to the
reader. The new usage is to directly state the command in imperative mood:

List the currently...

> +	this version of Git. The output is multi-line, but the first
> +	line provides the count of possible commands via `help count <N>`.
> +	The next `<N>` lines are of the form `help <command> <version>`
> +	to state that this Git version supports that `<command>` at
> +	version `<version>`. Note that the same command may have multiple
> +	available versions.

Placeholder punning to keep a consistency between the command and its
description. Good!

> ++
> +Here is the currentl output of the help text at the latest version:

current

It may not be wise to talk about the "latest version". If the manpages
and the git command are out of sync (the user compiles her own git
version, but does not update the man pages), this may be confusing.

Is this specification of version critical to the understanding?


> ++
> +------------
> +help 1 count 2
> +help 1 help 1
> +help 1 get 1
> +------------
> +
>  `get` version 1::
>  	The `get` command searches the config key-value pairs within a
>  	given `<scope>` for values that match the fixed `<key>` and

Re: [PATCH 05/11] config-batch: add NUL-terminated I/O format

[Jean-Noël Avila]

Le 04/02/2026 à 15:19, Derrick Stolee via GitGitGadget a écrit :
> From: Derrick Stolee <stolee@gmail.com>
> 
> When using automated tools, it is critical to allow for input/output formats
> that include special characters such as spaces and newlines. While the
> existing protocol for 'git config-batch' is human-readable and has some
> capacity for some spaces in certain positions, it is not available for
> spaces in the config key or newlines in the config values.
> 
> Add the '-z' option to signal the use of NUL-terminated strings. To
> understand where commands end regardless of potential future formats, use
> two NUL bytes in a row to terminate a command. To allow for empty string
> values, each token is provided in a <length>:<value> format, making "0:"
> the empty string value.
> 
> Update the existing 'help' and 'get' commands to match this format. Create
> helper methods that make it easy to parse and print in both formats
> simultaneously.
> 
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  Documentation/git-config-batch.adoc |  57 ++++++++-
>  builtin/config-batch.c              | 188 +++++++++++++++++++++++++---
>  t/t1312-config-batch.sh             |  69 ++++++++++
>  3 files changed, 293 insertions(+), 21 deletions(-)
> 
> diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
> index 1fff68a13c..3c9a3bb763 100644
> --- a/Documentation/git-config-batch.adoc
> +++ b/Documentation/git-config-batch.adoc
> @@ -21,6 +21,15 @@ multiple configuration values, the `git config-batch` command allows a
>  single process to handle multiple requests using a machine-parseable
>  interface across `stdin` and `stdout`.
>  
> +OPTIONS
> +-------
> +
> +`-z`::
> +	If specified, then use the NUL-terminated input and output

This boilerplate preliminary does not convey information, it is simpler
to just jump to the action performed by the option:

Use the _NUL_-terminated input and output…

> +	format instead of the space and newline format. This format is
> +	useful when the strings involved may include spaces or newlines.
> +	See PROTOCOL for more details.
> +
>  PROTOCOL
>  --------
>  By default, the protocol uses line feeds (`LF`) to signal the end of a
> @@ -41,13 +50,13 @@ These are the commands that are currently understood:
>  `help` version 1::
>  	The `help` command lists the currently-available commands in
>  	this version of Git. The output is multi-line, but the first
> -	line provides the count of possible commands via `help count <N>`.
> -	The next `<N>` lines are of the form `help <command> <version>`
> +	line provides the count of possible commands via `help 1 count <N>`.
> +	The next `<N>` lines are of the form `help 1 <command> <version>`
>  	to state that this Git version supports that `<command>` at
>  	version `<version>`. Note that the same command may have multiple
>  	available versions.
>  +
> -Here is the currentl output of the help text at the latest version:
> +Here is the current output of the help text at the latest version:

OK, the typo was fixed here.

>  +
>  ------------
>  help 1 count 2
> @@ -102,6 +111,48 @@ get 1 missing <key> [<value-pattern>|<value>]
>  where `<value-pattern>` or `<value>` is only supplied if provided in
>  the command.
>  
> +NUL-Terminated Format
> +~~~~~~~~~~~~~~~~~~~~~
> +
> +When `-z` is given, the protocol changes in some structural ways.
> +
> +First, each command is terminated with two NUL bytes, providing a clear
> +boundary between commands regardless of future possibilities of new
> +command formats.
> +
> +Second, any time that a space _would_ be used to partition tokens in a
> +command, a NUL byte is used instead. Further, each token is prefixed
> +with `<N>:` where `<N>` is a decimal representation of the length of
> +the string between the `:` and the next NUL byte. Any disagreement in
> +these lengths is treated as a parsing error. This use of a length does

I thought this length encoding was used to allow _NUL_ in the config
values. But here it is considered a parse error.

> +imply that "`0:`" is the representation of an empty string, if relevant.
> +
> +The decimal representation must have at most five numerals, thus the
> +maximum length of a string token can have 99999 characters.
> +
> +For example, the `get` command, version 1, could have any of the
> +following forms:
> +
> +------------
> +3:get NUL 1:1 NUL 5:local NUL 14:key.with space NUL NUL
> +3:get NUL 1:1 NUL 9:inherit NUL 8:test.key NUL 9:arg:regex NUL 6:.*\ .* NUL NUL
> +3:get NUL 1:1 NUL 6:global NUL 8:test.key NUL 15:arg:fixed-value NUL 3:a b NUL NUL
> +------------
> +
> +The output is modified similarly, such as the following output examples,
> +as if the input has a parse error, a valid `help` command, a `get`
> +command that had a match, and a `get` command that did not match.
> +
> +------------
> +15:unknown_command NUL NUL
> +4:help NUL 1:1 NUL 5:count NUL 1:2 NUL NUL
> +4:help NUL 1:1 NUL 4:help NUL 1:1 NUL NUL
> +4:help NUL 1:1 NUL 3:get NUL 1:1 NUL NUL
> +3:get NUL 1:1 NUL 5:found NUL 8:test.key NUL 5:value NUL NUL
> +3:get NUL 1:1 NUL 7:missing NUL 8:test.key NUL NUL
> +------------
> +
> +
>  SEE ALSO
>  --------
>  linkgit:git-config[1]

Re: [PATCH 09/11] config-batch: add 'set' v1 command

[Jean-Noël Avila]

Le 04/02/2026 à 15:20, Derrick Stolee via GitGitGadget a écrit :
> From: Derrick Stolee <stolee@gmail.com>
> 
> This new command is intended for single-value assignments to a specific
> chosen scope. More complicated versions of the 'git config set' command
> will be incorporated into future commands.
> 
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  Documentation/git-config-batch.adoc | 24 ++++++++
>  builtin/config-batch.c              | 71 ++++++++++++++++++++++
>  config.c                            | 27 +++++++++
>  config.h                            |  3 +
>  t/t1312-config-batch.sh             | 94 ++++++++++++++++++++++++++++-
>  5 files changed, 217 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
> index 3c9a3bb763..feec85c4ef 100644
> --- a/Documentation/git-config-batch.adoc
> +++ b/Documentation/git-config-batch.adoc
> @@ -111,6 +111,30 @@ get 1 missing <key> [<value-pattern>|<value>]
>  where `<value-pattern>` or `<value>` is only supplied if provided in
>  the command.
>  
> +`set` version 1::
> +	The `set` command writes a single key-value pair to a config

Please use direct imperative form.

> +	file. It specifies which file by a `<scope>` parameter from
> +	among `system`, `global`, `local`, and `worktree`. The `<key>`
> +	is the next positional argument. The remaining data in the line
> +	is provided as the `<value>` to assign the config.
> ++
> +------------
> +set 1 <scope> <key> <value>
> +------------
> ++
> +These uses will match the behavior of `git config --set --<scope> <key>

This "--<scope>" form is new in the synopsis grammar. Would we just cite
all alternatives or use a "normal" placeholder _<scope>_ ?

> +<value>`. Note that replacing all values with the `--all` option or
> +matching specific value patterns are not supported by this command.
> ++
> +The response of these commands will include a `success` message if the
> +value is written as expected or `failed` if an unexpected failure
> +occurs:
> ++
> +------------
> +set 1 success <scope> <key> <value>
> +set 1 failed <scope> <key> <value>
> +------------
> +

Please use synopsis style block for these too.

>  NUL-Terminated Format
>  ~~~~~~~~~~~~~~~~~~~~~
>  

Re: [PATCH 04/11] config-batch: create 'help' command

[Derrick Stolee]

On 2/5/2026 11:49 PM, Jean-Noël Avila wrote:
> Le 04/02/2026 à 15:19, Derrick Stolee via GitGitGadget a écrit :

>> ++
>> +Here is the currentl output of the help text at the latest version:
> It may not be wise to talk about the "latest version". If the manpages
> and the git command are out of sync (the user compiles her own git
> version, but does not update the man pages), this may be confusing.
> 
> Is this specification of version critical to the understanding?

It's important to talk about how to build tools that work against
versions that don't match the current documentation.

If you build something against v2.58.0 and we deprecate them in
v2.59.0 and delete them in v3.0.0, then the tool should know that
the command isn't available (and maybe it was replaced with a v2).

The same holds for someone who builds against v3.0.0 but their
tool is run against v2.58.0 and the feature they want to use isn't
available (or not at the same version).

Thanks,
-Stolee

Re: [PATCH 06/11] docs: add design doc for config-batch

[Derrick Stolee]

On 2/5/2026 12:38 PM, Kristoffer Haugsbakk wrote:
> On Wed, Feb 4, 2026, at 15:19, Derrick Stolee via GitGitGadget wrote:

>> +`git config list [--<scope>]`::
>> +	Getting all values, regardless of config key, would require a
>> +	multi-valued output similar to the `help` command. This tool will
>> +	likely assume advanced options such as `--show-origin`.
> 
> What does it mean to assume options?

I mean that since we expect to have the output parsed by tools, then
we will probably want the maximum amount of information by default.
Maybe --show-origin isn't as helpful as --show-scope.
 
Thanks,
-Stolee

Re: [PATCH 09/11] config-batch: add 'set' v1 command

[Derrick Stolee]

On 2/5/2026 2:01 PM, Kristoffer Haugsbakk wrote:
> On Wed, Feb 4, 2026, at 15:20, Derrick Stolee via GitGitGadget wrote:
>> [snip]
>> +`set` version 1::
>> +	The `set` command writes a single key-value pair to a config
>> +	file. It specifies which file by a `<scope>` parameter from
>> +	among `system`, `global`, `local`, and `worktree`. The `<key>`
>> +	is the next positional argument. The remaining data in the line
>> +	is provided as the `<value>` to assign the config.
>> ++
>> +------------
>> +set 1 <scope> <key> <value>
>> +------------
>> ++
>> +These uses will match the behavior of `git config --set --<scope> <key>
> 
> `--set` doesn’t exist. I think you meant `set`.

You're right. Also `git config --<scope> <key>` is the older mode. I'm
not always catching myself using the old format. Or inventing a mixed-up
one that never existed!

> Is there support for a user-provided file? (`git config --file=...`)

Not at the moment. It's worth thinking about what that interface would
be within this query model.

My initial feeling is that we wouldn't want to accept arbitrary filenames
on a per-command basis, but instead would want to provide an alternate
file in the command-line arguments as a replacement for the local config.

Thanks,
-Stolee

Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Derrick Stolee]

On 2/5/2026 8:52 AM, Derrick Stolee wrote:
> On 2/4/2026 7:04 PM, brian m. carlson wrote:
>> On 2026-02-04 at 14:19:52, Derrick Stolee via GitGitGadget wrote:

>>>  * Is this a worthwhile feature to add to Git?
>>
>> Git LFS has the same needs, but I believe it can use `git config -l -z`
>> to do that and parse the config options itself.  If this is just config
>> fetching, I'm not sure of the additional utility that such a feature
>> would add.  If that interface _almost_ meets your needs, could we add
>> functionality there instead of a new interface?
> 
> This is a good suggestion to look into as a potentially-easier solution.
After digging into this, I realized that GCM uses Git's --type=<X>
option, which doesn't work with 'git config list'!

Please see a new RFC [1] that adds that feature, though it is a
"breaking" change from previous behavior.

[1] https://lore.kernel.org/git/pull.2044.git.1770698579.gitgitgadget@gmail.com/

There's still some awkwardness in my GCM prototype, as it can
require three commands to query all the types (no type, path, and
book) that are needed. I found that the slowest queries are using
the path type, but only because they are the most frequent ones.

This awkwardness does make me think both of these things:

1. I can get performance boosts to GCM faster by the RFC in [1].

2. Using 'git config list' isn't sufficient to minimize multiple
   processes.

For now, I'll put _this_ RFC down for a little while to pursue
those easier gains. I'll come back again and consider all of the
big-picture considerations, including:

* Make this a subcommand of 'git config'.

* Make this a server that can serve multiple client processes.

* Ensure that all "complicated" options are accounted for.

Thanks,
-Stolee