move run_commit_hook() to libgit and use it there

This function was declared in commit.h but was implemented in
builtin/commit.c so was not part of libgit. Move it to libgit so we can
use it in the sequencer. This simplifies the implementation of
run_prepare_commit_msg_hook() and will be used in the next commit.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -1443,28 +1443,6 @@ static int git_commit_config(const char *k, const char *v, void *cb)
 	return git_status_config(k, v, s);
 }
 
-int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...)
-{
-	struct argv_array hook_env = ARGV_ARRAY_INIT;
-	va_list args;
-	int ret;
-
-	argv_array_pushf(&hook_env, "GIT_INDEX_FILE=%s", index_file);
-
-	/*
-	 * Let the hook know that no editor will be launched.
-	 */
-	if (!editor_is_used)
-		argv_array_push(&hook_env, "GIT_EDITOR=:");
-
-	va_start(args, name);
-	ret = run_hook_ve(hook_env.argv,name, args);
-	va_end(args);
-	argv_array_clear(&hook_env);
-
-	return ret;
-}
-
 int cmd_commit(int argc, const char **argv, const char *prefix)
 {
 	const char *argv_gc_auto[] = {"gc", "--auto", NULL};

commit.c

@@ -19,6 +19,7 @@
 #include "advice.h"
 #include "refs.h"
 #include "commit-reach.h"
+#include "run-command.h"
 
 static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
 
@@ -1581,3 +1582,26 @@ size_t ignore_non_trailer(const char *buf, size_t len)
 	}
 	return boc ? len - boc : len - cutoff;
 }
+
+int run_commit_hook(int editor_is_used, const char *index_file,
+		    const char *name, ...)
+{
+	struct argv_array hook_env = ARGV_ARRAY_INIT;
+	va_list args;
+	int ret;
+
+	argv_array_pushf(&hook_env, "GIT_INDEX_FILE=%s", index_file);
+
+	/*
+	 * Let the hook know that no editor will be launched.
+	 */
+	if (!editor_is_used)
+		argv_array_push(&hook_env, "GIT_EDITOR=:");
+
+	va_start(args, name);
+	ret = run_hook_ve(hook_env.argv,name, args);
+	va_end(args);
+	argv_array_clear(&hook_env);
+
+	return ret;
+}

sequencer.c

@@ -1127,25 +1127,22 @@ static int run_prepare_commit_msg_hook(struct repository *r,
 				       struct strbuf *msg,
 				       const char *commit)
 {
-	struct argv_array hook_env = ARGV_ARRAY_INIT;
-	int ret;
-	const char *name;
+	int ret = 0;
+	const char *name, *arg1 = NULL, *arg2 = NULL;
 
 	name = git_path_commit_editmsg();
 	if (write_message(msg->buf, msg->len, name, 0))
 		return -1;
 
-	argv_array_pushf(&hook_env, "GIT_INDEX_FILE=%s", r->index_file);
-	argv_array_push(&hook_env, "GIT_EDITOR=:");
-	if (commit)
-		ret = run_hook_le(hook_env.argv, "prepare-commit-msg", name,
-				  "commit", commit, NULL);
-	else
-		ret = run_hook_le(hook_env.argv, "prepare-commit-msg", name,
-				  "message", NULL);
-	if (ret)
+	if (commit) {
+		arg1 = "commit";
+		arg2 = commit;
+	} else {
+		arg1 = "message";
+	}
+	if (run_commit_hook(0, r->index_file, "prepare-commit-msg", name,
+			    arg1, arg2, NULL))
 		ret = error(_("'prepare-commit-msg' hook failed"));
-	argv_array_clear(&hook_env);
 
 	return ret;
 }