[PATCH 13/17] hook: allow specifying working directory for hooks

[Emily Shaffer <emilyshaffer@google.com>]

Hooks like "post-checkout" require that hooks have a different working
directory than the initial process. Pipe that directly through to struct
child_process.

Because we can just run 'git -C <some-dir> hook run ...' it shouldn't be
necessary to pipe this option through the frontend. In fact, this
reduces the possibility of users running hooks which affect some part of
the filesystem outside of the repo in question.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
---

Notes:
    Needed later for "post-checkout" conversion.

 hook.c | 1 +
 hook.h | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/hook.c b/hook.c
index edea54f95c..f0c052d847 100644
--- a/hook.c
+++ b/hook.c
@@ -271,6 +271,7 @@ static int pick_next_hook(struct child_process *cp,
 	cp->env = hook_cb->options->env.v;
 	cp->stdout_to_stderr = 1;
 	cp->trace2_hook_name = hook->command.buf;
+	cp->dir = hook_cb->options->dir;
 
 	/* reopen the file for stdin; run_command closes it. */
 	if (hook_cb->options->path_to_stdin) {
diff --git a/hook.h b/hook.h
index f54568afe3..4aae8e2dbb 100644
--- a/hook.h
+++ b/hook.h
@@ -60,6 +60,9 @@ struct run_hooks_opt
 
 	/* Number of threads to parallelize across */
 	int jobs;
+
+	/* Path to initial working directory for subprocess */
+	const char *dir;
 };
 
 /*
@@ -77,6 +80,7 @@ struct hook_cb_data {
 	.args = STRVEC_INIT, 			\
 	.path_to_stdin = NULL,			\
 	.jobs = 1,				\
+	.dir = NULL,				\
 	.run_hookdir = configured_hookdir_opt()	\
 }
 
@@ -85,6 +89,7 @@ struct hook_cb_data {
 	.args = STRVEC_INIT, 			\
 	.path_to_stdin = NULL,			\
 	.jobs = configured_hook_jobs(),		\
+	.dir = NULL,				\
 	.run_hookdir = configured_hookdir_opt()	\
 }
 
-- 
2.28.0.rc0.142.g3c755180ce-goog