Subject: [PATCH 6/6] hook: teach --porcelain mode

From: Emily Shaffer <[email-masked]>
Date: Mon, 9 Dec 2019 18:33:35 -0800

It might be desirable - for a user script, or a scripted Git command -
to run the appropriate set of hooks from outside of the compiled Git
binary. So, teach --porcelain in a way that enables the following:

  git hook --list --porcelain pre-commit | xargs -I% sh "%"

Signed-off-by: Emily Shaffer <[email-masked]>
---
 Documentation/git-hook.txt    |  5 ++++-
 builtin/hook.c                | 19 +++++++++++++------
 t/t1360-config-based-hooks.sh | 12 ++++++++++++
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-hook.txt b/Documentation/git-hook.txt
index b4a992d43f..34276f5bce 100644
--- a/Documentation/git-hook.txt
+++ b/Documentation/git-hook.txt
@@ -8,7 +8,7 @@ git-hook - Manage configured hooks
 SYNOPSIS
 --------
 [verse]
-'git hook' -l | --list <hook-name>
+'git hook' -l | --list [--porcelain] <hook-name>
 
 DESCRIPTION
 -----------
@@ -45,6 +45,9 @@ OPTIONS
 	in the order they should be run. Output of this command follows the
 	format '<order number> <origin config> <hook command>'.
 
+--porcelain::
+	Print in a machine-readable format suitable for scripting.
+
 GIT
 ---
 Part of the linkgit:git[1] suite
diff --git a/builtin/hook.c b/builtin/hook.c
index 8261302b27..b76dd3ad8f 100644
--- a/builtin/hook.c
+++ b/builtin/hook.c
@@ -16,7 +16,7 @@ enum hook_command {
 	HOOK_LIST,
 };
 
-static int print_hook_list(const struct strbuf *hookname)
+static int print_hook_list(const struct strbuf *hookname, int porcelain)
 {
 	struct list_head *head, *pos;
 	struct hook *item;
@@ -25,10 +25,14 @@ static int print_hook_list(const struct strbuf *hookname)
 
 	list_for_each(pos, head) {
 		item = list_entry(pos, struct hook, list);
-		if (item)
-			printf("%.3d\t%s\t%s\n", item->order,
-			       config_scope_to_string(item->origin),
-			       item->command.buf);
+		if (item) {
+			if (porcelain)
+				printf("%s\n", item->command.buf);
+			else
+				printf("%.3d\t%s\t%s\n", item->order,
+				       config_scope_to_string(item->origin),
+				       item->command.buf);
+		}
 	}
 
 	return 0;
@@ -38,11 +42,14 @@ int cmd_hook(int argc, const char **argv, const char *prefix)
 {
 	enum hook_command command = 0;
 	struct strbuf hookname = STRBUF_INIT;
+	int porcelain = 0;
 
 	struct option builtin_hook_options[] = {
 		OPT_CMDMODE('l', "list", &command,
 			    N_("list scripts which will be run for <hookname>"),
 			    HOOK_LIST),
+		OPT_BOOL(0, "porcelain", &porcelain,
+			 N_("display in machine parseable format")),
 		OPT_END(),
 	};
 
@@ -59,7 +66,7 @@ int cmd_hook(int argc, const char **argv, const char *prefix)
 
 	switch(command) {
 		case HOOK_LIST:
-			return print_hook_list(&hookname);
+			return print_hook_list(&hookname, porcelain);
 			break;
 		default:
 			usage_msg_opt("no command given.", builtin_hook_usage,
diff --git a/t/t1360-config-based-hooks.sh b/t/t1360-config-based-hooks.sh
index 66e70ae222..6f16ea1dd8 100755
--- a/t/t1360-config-based-hooks.sh
+++ b/t/t1360-config-based-hooks.sh
@@ -33,6 +33,18 @@ test_expect_success 'git hook --list orders by order number' '
 	test_cmp expected actual
 '
 
+test_expect_success 'git hook --list --porcelain' '
+	cat >expected <<-\EOF &&
+	/path/def
+	/path/ghi
+	/path/rst
+	/path/uvw
+	EOF
+
+	git hook --list --porcelain pre-commit >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'order number collisions resolved in config order' '
 	cat >expected <<-\EOF &&
 	010	global	/path/def
-- 
2.24.0.393.g34dc348eaf-goog