hook: add -z option to "git hook list"

Add a NUL-terminate mode to git hook list, just in case hooks are
configured with weird characters like newlines in their names.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: 10ne1

Documentation/git-hook.adoc

@@ -9,7 +9,7 @@ SYNOPSIS
 --------
 [verse]
 'git hook' run [--ignore-missing] [--to-stdin=<path>] <hook-name> [-- <hook-args>]
-'git hook' list <hook-name>
+'git hook' list [-z] <hook-name>
 
 DESCRIPTION
 -----------
@@ -113,9 +113,10 @@ Any positional arguments to the hook should be passed after a
 mandatory `--` (or `--end-of-options`, see linkgit:gitcli[7]). See
 linkgit:githooks[5] for arguments hooks might expect (if any).
 
-list::
+list [-z]::
 	Print a list of hooks which will be run on `<hook-name>` event. If no
 	hooks are configured for that event, print a warning and return 1.
+	Use `-z` to terminate output lines with NUL instead of newlines.
 
 OPTIONS
 -------
@@ -130,6 +131,9 @@ OPTIONS
 	tools that want to do a blind one-shot run of a hook that may
 	or may not be present.
 
+-z::
+	Terminate "list" output lines with NUL instead of newlines.
+
 WRAPPERS
 --------
 

builtin/hook.c

@@ -11,7 +11,7 @@
 #define BUILTIN_HOOK_RUN_USAGE \
 	N_("git hook run [--ignore-missing] [--to-stdin=<path>] <hook-name> [-- <hook-args>]")
 #define BUILTIN_HOOK_LIST_USAGE \
-	N_("git hook list <hook-name>")
+	N_("git hook list [-z] <hook-name>")
 
 static const char * const builtin_hook_usage[] = {
 	BUILTIN_HOOK_RUN_USAGE,
@@ -34,9 +34,12 @@ static int list(int argc, const char **argv, const char *prefix,
 	struct string_list *head;
 	struct string_list_item *item;
 	const char *hookname = NULL;
+	int line_terminator = '\n';
 	int ret = 0;
 
 	struct option list_options[] = {
+		OPT_SET_INT('z', NULL, &line_terminator,
+			    N_("use NUL as line terminator"), '\0'),
 		OPT_END(),
 	};
 
@@ -66,10 +69,10 @@ static int list(int argc, const char **argv, const char *prefix,
 
 		switch (h->kind) {
 		case HOOK_TRADITIONAL:
-			printf("%s\n", _("hook from hookdir"));
+			printf("%s%c", _("hook from hookdir"), line_terminator);
 			break;
 		case HOOK_CONFIGURED:
-			printf("%s\n", h->u.configured.friendly_name);
+			printf("%s%c", h->u.configured.friendly_name, line_terminator);
 			break;
 		default:
 			BUG("unknown hook kind");

t/t1800-hook.sh

@@ -61,6 +61,19 @@ test_expect_success 'git hook list: configured hook' '
 	test_cmp expect actual
 '
 
+test_expect_success 'git hook list: -z shows NUL-terminated output' '
+	test_hook test-hook <<-EOF &&
+	echo Test hook
+	EOF
+	test_config hook.myhook.command "echo Hello" &&
+	test_config hook.myhook.event test-hook --add &&
+
+	printf "myhookQhook from hookdirQ" >expect &&
+	git hook list -z test-hook >actual.raw &&
+	nul_to_q <actual.raw >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'git hook run: nonexistent hook' '
 	cat >stderr.expect <<-\EOF &&
 	error: cannot find a hook named test-hook