[PATCH 1/3] run_builtin(): save "-h" detection result for later use

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

When run_builtin() sees "-h" as the first argument, it assumes:

 - this is the call for help usage
 - the real git command will only print help usage then exit

So it skips all setup in this case.  Unfortunately, some commands do
other things before calling parse_options(), which is often where the
help usage is printed.  Some of those things may try to access the
repository, which has yet to be set up.

Make real commands aware of this fast path so that they can handle it
properly (i.e., print help usage then exit immediately) if they need
to do more initialization than git_config().

git_config() is a bit of a special case: it is perfectly legitimate to
use it without access to a valid repository. In the future, we should
make git_config() aware of the repository search status so that it can
skip reading $GIT_DIR/config if no repository is found.
---
 cache.h |    1 +
 git.c   |    8 ++++----
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/cache.h b/cache.h
index 33decd9..43763c1 100644
--- a/cache.h
+++ b/cache.h
@@ -1117,6 +1117,7 @@ const char *split_cmdline_strerror(int cmdline_errno);
 /* git.c */
 struct startup_info {
 	int have_repository;
+	int help; /* print help and exit, except git_config(), repo must not be touched */
 };
 extern struct startup_info *startup_info;
 
diff --git a/git.c b/git.c
index 50a1401..5962cdd 100644
--- a/git.c
+++ b/git.c
@@ -246,13 +246,13 @@ struct cmd_struct {
 
 static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 {
-	int status, help;
+	int status;
 	struct stat st;
 	const char *prefix;
 
 	prefix = NULL;
-	help = argc == 2 && !strcmp(argv[1], "-h");
-	if (!help) {
+	startup_info->help = argc == 2 && !strcmp(argv[1], "-h");
+	if (!startup_info->help) {
 		if (p->option & RUN_SETUP)
 			prefix = setup_git_directory();
 		if (p->option & RUN_SETUP_GENTLY) {
@@ -267,7 +267,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 	}
 	commit_pager_choice();
 
-	if (!help && p->option & NEED_WORK_TREE)
+	if (!startup_info->help && p->option & NEED_WORK_TREE)
 		setup_work_tree();
 
 	trace_argv_printf(argv, "trace: built-in: git");
-- 
1.7.0.2.445.gcbdb3