[PATCH 07/13] git hook run: add an --ignore-missing flag

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

For certain one-shot hooks we'd like to optimistically run them, and
not complain if they don't exist. This will be used by send-email in a
subsequent commit.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-hook.txt | 10 +++++++++-
 builtin/hook.c             | 10 ++++++++--
 t/t1800-hook.sh            |  5 +++++
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-hook.txt b/Documentation/git-hook.txt
index 660d6a992a0..097fb9de63b 100644
--- a/Documentation/git-hook.txt
+++ b/Documentation/git-hook.txt
@@ -8,7 +8,7 @@ git-hook - run git hooks
 SYNOPSIS
 --------
 [verse]
-'git hook' run <hook-name> [-- <hook-args>]
+'git hook' run [--ignore-missing] <hook-name> [-- <hook-args>]
 
 DESCRIPTION
 -----------
@@ -29,6 +29,14 @@ optional `--` (or `--end-of-options`, see linkgit:gitcli[7]). The
 arguments (if any) differ by hook name, see linkgit:githooks[5] for
 what those are.
 
+OPTIONS
+-------
+
+--ignore-missing::
+	Ignore any missing hook by quietly returning zero. Used for
+	tools that want to do a blind one-shot run of a hook that may
+	or may not be present.
+
 SEE ALSO
 --------
 linkgit:githooks[5]
diff --git a/builtin/hook.c b/builtin/hook.c
index 012a2973b38..e6b01a7f5c6 100644
--- a/builtin/hook.c
+++ b/builtin/hook.c
@@ -7,7 +7,7 @@
 #include "strvec.h"
 
 #define BUILTIN_HOOK_RUN_USAGE \
-	N_("git hook run <hook-name> [-- <hook-args>]")
+	N_("git hook run [--ignore-missing] <hook-name> [-- <hook-args>]")
 
 static const char * const builtin_hook_usage[] = {
 	BUILTIN_HOOK_RUN_USAGE,
@@ -23,9 +23,12 @@ static int run(int argc, const char **argv, const char *prefix)
 {
 	int i;
 	struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT;
+	int ignore_missing = 0;
 	const char *hook_name;
 	const char *hook_path;
 	struct option run_options[] = {
+		OPT_BOOL(0, "ignore-missing", &ignore_missing,
+			 N_("silently ignore missing requested <hook-name>")),
 		OPT_END(),
 	};
 	int ret;
@@ -55,9 +58,12 @@ static int run(int argc, const char **argv, const char *prefix)
 	/*
 	 * We are not using a plain run_hooks() because we'd like to
 	 * detect missing hooks. Let's find it ourselves and call
-	 * run_hooks() instead.
+	 * run_hooks() instead...
 	 */
 	hook_name = argv[0];
+	if (ignore_missing)
+		/* ... act like a plain run_hooks() under --ignore-missing */
+		return run_hooks_oneshot(hook_name, &opt);
 	hook_path = find_hook(hook_name);
 	if (!hook_path) {
 		error("cannot find a hook named %s", hook_name);
diff --git a/t/t1800-hook.sh b/t/t1800-hook.sh
index 3aea1b105f0..29718aa9913 100755
--- a/t/t1800-hook.sh
+++ b/t/t1800-hook.sh
@@ -21,6 +21,11 @@ test_expect_success 'git hook run: nonexistent hook' '
 	test_cmp stderr.expect stderr.actual
 '
 
+test_expect_success 'git hook run: nonexistent hook with --ignore-missing' '
+	git hook run --ignore-missing does-not-exist 2>stderr.actual &&
+	test_must_be_empty stderr.actual
+'
+
 test_expect_success 'git hook run: basic' '
 	write_script .git/hooks/test-hook <<-EOF &&
 	echo Test hook
-- 
2.33.0.1567.g7b23ce7ed9e