Let 'git <command> -h' show usage without a git dir

There is no need for "git <command> -h" to depend on being inside
a repository.

Reported by Gerfried Fuchs through http://bugs.debian.org/462557

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-log.c

@@ -50,6 +50,12 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 	if (default_date_mode)
 		rev->date_mode = parse_date_format(default_date_mode);
 
+	/*
+	 * Check for -h before setup_revisions(), or "git log -h" will
+	 * fail when run without a git directory.
+	 */
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage(builtin_log_usage);
 	argc = setup_revisions(argc, argv, rev, "HEAD");
 
 	if (rev->diffopt.pickaxe || rev->diffopt.filter)

builtin-mv.c

@@ -64,15 +64,15 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config, NULL);
 
-	newfd = hold_locked_index(&lock_file, 1);
-	if (read_cache() < 0)
-		die("index file corrupt");
-
 	argc = parse_options(argc, argv, prefix, builtin_mv_options,
 			     builtin_mv_usage, 0);
 	if (--argc < 1)
 		usage_with_options(builtin_mv_usage, builtin_mv_options);
 
+	newfd = hold_locked_index(&lock_file, 1);
+	if (read_cache() < 0)
+		die("index file corrupt");
+
 	source = copy_pathspec(prefix, argv, argc, 0);
 	modes = xcalloc(argc, sizeof(enum update_mode));
 	dest_path = copy_pathspec(prefix, argv + argc, 1, 0);

builtin-read-tree.c

@@ -108,11 +108,11 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 
 	git_config(git_default_config, NULL);
 
-	newfd = hold_locked_index(&lock_file, 1);
-
 	argc = parse_options(argc, argv, unused_prefix, read_tree_options,
 			     read_tree_usage, 0);
 
+	newfd = hold_locked_index(&lock_file, 1);
+
 	prefix_set = opts.prefix ? 1 : 0;
 	if (1 < opts.merge + opts.reset + prefix_set)
 		die("Which one? -m, --reset, or --prefix?");

builtin-reflog.c

@@ -698,6 +698,9 @@ static const char reflog_usage[] =
 
 int cmd_reflog(int argc, const char **argv, const char *prefix)
 {
+	if (argc > 1 && !strcmp(argv[1], "-h"))
+		usage(reflog_usage);
+
 	/* With no command, we default to showing it. */
 	if (argc < 2 || *argv[1] == '-')
 		return cmd_log_reflog(argc, argv, prefix);

builtin-rerere.c

@@ -106,6 +106,9 @@ int cmd_rerere(int argc, const char **argv, const char *prefix)
 	if (argc < 2)
 		return rerere();
 
+	if (!strcmp(argv[1], "-h"))
+		usage(git_rerere_usage);
+
 	fd = setup_rerere(&merge_rr);
 	if (fd < 0)
 		return 0;

git.c

@@ -229,11 +229,13 @@ struct cmd_struct {
 
 static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 {
-	int status;
+	int status, help;
 	struct stat st;
 	const char *prefix;
 
 	prefix = NULL;
+	help = argc == 2 && !strcmp(argv[1], "-h");
+	if (!help) {
 		if (p->option & RUN_SETUP)
 			prefix = setup_git_directory();
 
@@ -241,9 +243,10 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 			use_pager = check_pager_config(p->cmd);
 		if (use_pager == -1 && p->option & USE_PAGER)
 			use_pager = 1;
+	}
 	commit_pager_choice();
 
-	if (p->option & NEED_WORK_TREE)
+	if (!help && p->option & NEED_WORK_TREE)
 		setup_work_tree();
 
 	trace_argv_printf(argv, "trace: built-in: git");

index-pack.c

@@ -882,6 +882,9 @@ int main(int argc, char **argv)
 
 	git_extract_argv0_path(argv[0]);
 
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage(index_pack_usage);
+
 	/*
 	 * We wish to read the repository's config file if any, and
 	 * for that it is necessary to call setup_git_directory_gently().

pack-redundant.c

@@ -603,6 +603,9 @@ int main(int argc, char **argv)
 
 	git_extract_argv0_path(argv[0]);
 
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage(pack_redundant_usage);
+
 	setup_git_directory();
 
 	for (i = 1; i < argc; i++) {