[PATCH v6 5/6] fast-import: add option command

[Sverre Rabbelier <srabbelier@gmail.com>]

This allows the frontend to specify any of the supported options as
long as no non-option command has been given. This way the
user does not have to include any frontend-specific options, but
instead she can rely on the frontend to tell fast-import what it
needs.

Also factor out parsing of argv and have it execute when we reach the
first non-option command, or after all commands have been read and
no non-option command has been encountered.

Signed-off-by: Sverre Rabbelier <srabbelier@gmail.com>
---

  Main difference with v5 is that the syntax is now 'option git ...'
  as per a discussion with the other fast-import devs. Other options,
  e.g. 'option hg' are ignored. Also fixed the docs to say that
  feature commands are allowed before git option commands.

 Documentation/git-fast-import.txt |   24 ++++++++++++
 fast-import.c                     |   75 +++++++++++++++++++++++++++++++------
 2 files changed, 87 insertions(+), 12 deletions(-)

diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index 1e293f2..f1c94b4 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -307,6 +307,11 @@ and control the current import process.  More detailed discussion
 	Require that fast-import supports the specified feature, or
 	abort if it does not.
 
+`option`::
+    Specify any of the options listed under OPTIONS to change
+    fast-import's behavior to suit the frontend's needs. This command
+    is optional and is not needed to perform an import.
+
 `commit`
 ~~~~~~~~
 Create or update a branch with a new commit, recording one logical
@@ -829,6 +834,25 @@ it does not.
 The <feature> part of the command may be any string matching
 [a-zA-Z-] and should be understood by a version of fast-import.
 
+`option`
+~~~~~~~~
+Processes the specified option so that git fast-import behaves in a
+way that suits the frontend's needs.
+Note that options specified by the frontend are overridden by any
+options the user may specify to git fast-import itself.
+
+....
+    'option' SP <option> LF
+....
+
+The `<option>` part of the command may contain any of the options
+listed in the OPTIONS section, without the leading '--' and is
+treated in the same way.
+
+Option commands must be the first commands on the input (not counting
+feature commands), to give an option command after any non-option
+command is an error.
+
 Crash Reports
 -------------
 If fast-import is supplied invalid input it will terminate with a
diff --git a/fast-import.c b/fast-import.c
index 9bf06a4..bad93dc 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -292,6 +292,8 @@ static unsigned long branch_load_count;
 static int failure;
 static FILE *pack_edges;
 static unsigned int show_stats = 1;
+static int global_argc;
+static const char **global_argv;
 
 /* Memory pools */
 static size_t mem_pool_alloc = 2*1024*1024 - sizeof(struct mem_pool);
@@ -349,6 +351,10 @@ static struct recent_command *rc_free;
 static unsigned int cmd_save = 100;
 static uintmax_t next_mark;
 static struct strbuf new_data = STRBUF_INIT;
+static int options_enabled;
+static int seen_non_option_command;
+
+static void parse_argv(void);
 
 static void write_branch_report(FILE *rpt, struct branch *b)
 {
@@ -1700,6 +1706,12 @@ static int read_next_command(void)
 			if (stdin_eof)
 				return EOF;
 
+			if (!seen_non_option_command
+				&& prefixcmp(command_buf.buf, "feature ")
+				&& prefixcmp(command_buf.buf, "option ")) {
+				parse_argv();
+			}
+
 			rc = rc_free;
 			if (rc)
 				rc_free = rc->next;
@@ -2456,11 +2468,31 @@ static void parse_feature(void)
 
 	if (!prefixcmp(feature, "date-format=")) {
 		option_date_format(feature + 12);
+	} else if (!strcmp("git-options", feature)) {
+		options_enabled = 1;
 	} else {
 		die("This version of fast-import does not support feature %s.", feature);
 	}
 }
 
+static void parse_option(void)
+{
+	char* option = command_buf.buf + 11;
+
+	if (!options_enabled)
+		die("Got option command '%s' before options feature'", option);
+
+	if (seen_non_option_command)
+		die("Got option command '%s' after non-option command", option);
+
+	parse_one_option(option);
+}
+
+static void parse_nongit_option(void)
+{
+  // do nothing
+}
+
 static int git_pack_config(const char *k, const char *v, void *cb)
 {
 	if (!strcmp(k, "pack.depth")) {
@@ -2485,6 +2517,26 @@ static int git_pack_config(const char *k, const char *v, void *cb)
 static const char fast_import_usage[] =
 "git fast-import [--date-format=f] [--max-pack-size=n] [--depth=n] [--active-branches=n] [--export-marks=marks.file]";
 
+static void parse_argv(void)
+{
+	unsigned int i;
+
+	for (i = 1; i < global_argc; i++) {
+		const char *a = global_argv[i];
+
+		if (*a != '-' || !strcmp(a, "--"))
+			break;
+
+		parse_one_option(a + 2);
+	}
+	if (i != global_argc)
+		usage(fast_import_usage);
+
+	seen_non_option_command = 1;
+	if (input_file)
+		read_marks();
+}
+
 int main(int argc, const char **argv)
 {
 	unsigned int i;
@@ -2503,18 +2555,8 @@ int main(int argc, const char **argv)
 	avail_tree_table = xcalloc(avail_tree_table_sz, sizeof(struct avail_tree_content*));
 	marks = pool_calloc(1, sizeof(struct mark_set));
 
-	for (i = 1; i < argc; i++) {
-		const char *a = argv[i];
-
-		if (*a != '-' || !strcmp(a, "--"))
-			break;
-
-		parse_one_option(a + 2);
-	}
-	if (i != argc)
-		usage(fast_import_usage);
-	if (input_file)
-		read_marks();
+	global_argc = argc;
+	global_argv = argv;
 
 	rc_free = pool_alloc(cmd_save * sizeof(*rc_free));
 	for (i = 0; i < (cmd_save - 1); i++)
@@ -2539,9 +2581,18 @@ int main(int argc, const char **argv)
 			parse_progress();
 		else if (!prefixcmp(command_buf.buf, "feature "))
 			parse_feature();
+		else if (!prefixcmp(command_buf.buf, "option git "))
+			parse_option();
+    else if (!prefixcmp(command_buf.buf, "option "))
+      parse_nongit_option();
 		else
 			die("Unsupported command: %s", command_buf.buf);
 	}
+
+	// argv hasn't been parsed yet, do so
+	if (!seen_non_option_command)
+		parse_argv();
+
 	end_packfile();
 
 	dump_branches();
-- 
1.6.4.16.g72c66.dirty