[PATCH 1/4] hooks: Add function to check if a hook exists

[Aaron Schrab <aaron@schrab.com>]

Create find_hook() function to determine if a given hook exists and is
executable.  If it is the path to the script will be returned, otherwise
NULL is returned.

This is in support for an upcoming run_hook_argv() function which will
expect the full path to the hook script as the first element in the
argv_array.  This also makes it simple for places that can use a hook to
check if a hook exists before doing, possibly lengthy, setup work which
would be pointless if no such hook is present.

The returned value is left as a static value from get_pathname() rather
than a duplicate because it is anticipated that the return value will
either be used as a boolean, or immediately added to an argv_array list
which would result in it being duplicated at that point.

Signed-off-by: Aaron Schrab <aaron@schrab.com>
---
 run-command.c |   15 +++++++++++++--
 run-command.h |    1 +
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/run-command.c b/run-command.c
index 3b982e4..49c8fa0 100644
--- a/run-command.c
+++ b/run-command.c
@@ -735,6 +735,15 @@ int finish_async(struct async *async)
 #endif
 }
 
+char *find_hook(const char *name)
+{
+	char *path = git_path("hooks/%s", name);
+	if (access(path, X_OK) < 0)
+		path = NULL;
+
+	return path;
+}
+
 int run_hook(const char *index_file, const char *name, ...)
 {
 	struct child_process hook;
@@ -744,11 +753,13 @@ int run_hook(const char *index_file, const char *name, ...)
 	va_list args;
 	int ret;
 
-	if (access(git_path("hooks/%s", name), X_OK) < 0)
+	p = find_hook(name);
+	if (!p)
 		return 0;
 
+	argv_array_push(&argv, p);
+
 	va_start(args, name);
-	argv_array_push(&argv, git_path("hooks/%s", name));
 	while ((p = va_arg(args, const char *)))
 		argv_array_push(&argv, p);
 	va_end(args);
diff --git a/run-command.h b/run-command.h
index 850c638..221ce33 100644
--- a/run-command.h
+++ b/run-command.h
@@ -45,6 +45,7 @@ int start_command(struct child_process *);
 int finish_command(struct child_process *);
 int run_command(struct child_process *);
 
+extern char *find_hook(const char *name);
 extern int run_hook(const char *index_file, const char *name, ...);
 
 #define RUN_COMMAND_NO_STDIN 1
-- 
1.7.10.4