[PATCH v3 1/3] config: add git_config_append_parameter()

["Thomas Bachem via GitGitGadget" <gitgitgadget@gmail.com>]

From: Thomas Bachem <mail@thomasbachem.com>

"git -c key=value" passes its settings on to the git commands it
spawns through the environment variable GIT_CONFIG_PARAMETERS. The
value is a space separated list of 'key'='value' pairs with both
sides single quoted, which git_config_from_parameters() reads back in
the child. The only place we write such an entry is
git_config_push_split_parameter(), and it writes straight into our
own environment.

Split the formatting out into git_config_append_parameter(), which
appends one entry to a strbuf, so that we can build such a value for
a child's environment without repeating the quoting. The sequencer
will use it in a later commit to pass settings to the commands it
spawns.

Assisted-by: Claude Fable 5.1
Signed-off-by: Thomas Bachem <mail@thomasbachem.com>
---
 config.c | 20 +++++++++++++-------
 config.h | 13 +++++++++++++
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/config.c b/config.c
index d9019e7e6c..e0bb29b53d 100644
--- a/config.c
+++ b/config.c
@@ -450,18 +450,24 @@ static int git_config_include(const char *var, const char *value,
 	return ret;
 }
 
+void git_config_append_parameter(struct strbuf *env, const char *key,
+				 const char *value)
+{
+	if (env->len)
+		strbuf_addch(env, ' ');
+	sq_quote_buf(env, key);
+	strbuf_addch(env, '=');
+	if (value)
+		sq_quote_buf(env, value);
+}
+
 static void git_config_push_split_parameter(const char *key, const char *value)
 {
 	struct strbuf env = STRBUF_INIT;
 	const char *old = getenv(CONFIG_DATA_ENVIRONMENT);
-	if (old && *old) {
+	if (old && *old)
 		strbuf_addstr(&env, old);
-		strbuf_addch(&env, ' ');
-	}
-	sq_quote_buf(&env, key);
-	strbuf_addch(&env, '=');
-	if (value)
-		sq_quote_buf(&env, value);
+	git_config_append_parameter(&env, key, value);
 	setenv(CONFIG_DATA_ENVIRONMENT, env.buf, 1);
 	strbuf_release(&env);
 }
diff --git a/config.h b/config.h
index b66dd08007..838d1509a9 100644
--- a/config.h
+++ b/config.h
@@ -22,6 +22,7 @@
  */
 
 struct object_id;
+struct strbuf;
 
 /* git_config_parse_key() returns these negated: */
 #define CONFIG_INVALID_KEY 1
@@ -186,6 +187,18 @@ int git_config_from_blob_oid(config_fn_t fn, const char *name,
 			     enum config_scope scope);
 void git_config_push_parameter(const char *text);
 void git_config_push_env(const char *spec);
+
+/*
+ * Append a "-c key=value" setting to a GIT_CONFIG_PARAMETERS value in
+ * `env`. The variable carries such settings from a git process to the
+ * git commands it spawns, as a space separated list of 'key'='value'
+ * pairs with both sides single quoted, which git_config_from_parameters()
+ * reads back. A NULL `value` appends 'key'= with nothing after the equals
+ * sign, which stands for a boolean true, like "-c key" on the command
+ * line.
+ */
+void git_config_append_parameter(struct strbuf *env, const char *key,
+				 const char *value);
 int git_config_from_parameters(config_fn_t fn, void *data);
 
 /*
-- 
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