Subject: [PATCH v7 08/17] hook: add 'run' subcommand

From: Emily Shaffer <[email-masked]>
Date: Mon, 21 Dec 2020 16:02:11 -0800

In order to enable hooks to be run as an external process, by a
standalone Git command, or by tools which wrap Git, provide an external
means to run all configured hook commands for a given hook event.

For now, the hook commands will run in config order, in series. As
alternate ordering or parallelism is supported in the future, we should
add knobs to use those to the command line as well.

As with the legacy hook implementation, all stdout generated by hook
commands is redirected to stderr. Piping from stdin is not yet
supported.

Legacy hooks (those present in $GITDIR/hooks) are run at the end of the
execution list. For now, there is no way to disable them.

Users may wish to provide hook commands like 'git config
hook.pre-commit.command "~/linter.sh --pre-commit"'. To enable this,
config-defined hooks are run in a shell. (Since hooks in $GITDIR/hooks
can't be specified with included arguments or paths which need expansion
like this, they are run without a shell instead.)

Signed-off-by: Emily Shaffer <[email-masked]>
---

Notes:
    Since v4, updated the docs, and did less local application of single
    quotes. In order for hookdir hooks to run successfully with a space in
    the path, though, they must not be run with 'sh -c'. So we can treat the
    hookdir hooks specially, and warn users via doc about special
    considerations for configured hooks with spaces in their path.

 Documentation/git-hook.txt    |  31 +++++++++-
 builtin/hook.c                |  48 ++++++++++++++-
 hook.c                        | 112 ++++++++++++++++++++++++++++++++++
 hook.h                        |  32 ++++++++++
 t/t1360-config-based-hooks.sh |  65 +++++++++++++++++++-
 5 files changed, 281 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-hook.txt b/Documentation/git-hook.txt
index f19875ed68..18a817d832 100644
--- a/Documentation/git-hook.txt
+++ b/Documentation/git-hook.txt
@@ -9,11 +9,12 @@ SYNOPSIS
 --------
 [verse]
 'git hook' list <hook-name>
+'git hook' run [(-e|--env)=<var>...] [(-a|--arg)=<arg>...] <hook-name>
 
 DESCRIPTION
 -----------
-You can list configured hooks with this command. Later, you will be able to run,
-add, and modify hooks with this command.
+You can list and run configured hooks with this command. Later, you will be able
+to add and modify hooks with this command.
 
 This command parses the default configuration files for sections `hook` and
 `hookcmd`. `hook` is used to describe the commands which will be run during a
@@ -64,6 +65,32 @@ in the order they should be run, and print the config scope where the relevant
 `hook.<hook-name>.command` was specified, not the `hookcmd` (if applicable).
 This output is human-readable and the format is subject to change over time.
 
+run [(-e|--env)=<var>...] [(-a|--arg)=<arg>...] `<hook-name>`::
+
+Runs hooks configured for `<hook-name>`, in the same order displayed by `git
+hook list`. Hooks configured this way are run prepended with `sh -c`, so paths
+containing special characters or spaces should be wrapped in single quotes:
+`command = '/my/path with spaces/script.sh' some args`.
+
+OPTIONS
+-------
+--run-hookdir::
+	Overrides the hook.runHookDir config. Must be 'yes', 'warn',
+	'interactive', or 'no'. Specifies how to handle hooks located in the Git
+	hook directory (core.hooksPath).
+
+-a::
+--arg::
+	Only valid for `run`.
++
+Specify arguments to pass to every hook that is run.
+
+-e::
+--env::
+	Only valid for `run`.
++
+Specify environment variables to set for every hook that is run.
+
 CONFIGURATION
 -------------
 include::config/hook.txt[]
diff --git a/builtin/hook.c b/builtin/hook.c
index d087e6f5b0..07ba00e07a 100644
--- a/builtin/hook.c
+++ b/builtin/hook.c
@@ -5,9 +5,11 @@
 #include "hook.h"
 #include "parse-options.h"
 #include "strbuf.h"
+#include "strvec.h"
 
 static const char * const builtin_hook_usage[] = {
 	N_("git hook list <hookname>"),
+	N_("git hook run [(-e|--env)=<var>...] [(-a|--arg)=<arg>...] <hookname>"),
 	NULL
 };
 
@@ -84,6 +86,46 @@ static int list(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
+static int run(int argc, const char **argv, const char *prefix)
+{
+	struct strbuf hookname = STRBUF_INIT;
+	struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT;
+	int rc = 0;
+
+	struct option run_options[] = {
+		OPT_STRVEC('e', "env", &opt.env, N_("var"),
+			   N_("environment variables for hook to use")),
+		OPT_STRVEC('a', "arg", &opt.args, N_("args"),
+			   N_("argument to pass to hook")),
+		OPT_END(),
+	};
+
+	/*
+	 * While it makes sense to list hooks out-of-repo, it doesn't make sense
+	 * to execute them. Hooks usually want to look at repository artifacts.
+	 */
+	if (!have_git_dir())
+		usage_msg_opt(_("You must be in a Git repo to execute hooks."),
+			      builtin_hook_usage, run_options);
+
+	argc = parse_options(argc, argv, prefix, run_options,
+			     builtin_hook_usage, 0);
+
+	if (argc < 1)
+		usage_msg_opt(_("You must specify a hook event to run."),
+			      builtin_hook_usage, run_options);
+
+	strbuf_addstr(&hookname, argv[0]);
+	opt.run_hookdir = should_run_hookdir;
+
+	rc = run_hooks(hookname.buf, &opt);
+
+	strbuf_release(&hookname);
+	run_hooks_opt_clear(&opt);
+
+	return rc;
+}
+
 int cmd_hook(int argc, const char **argv, const char *prefix)
 {
 	const char *run_hookdir = NULL;
@@ -95,10 +137,10 @@ int cmd_hook(int argc, const char **argv, const char *prefix)
 	};
 
 	argc = parse_options(argc, argv, prefix, builtin_hook_options,
-			     builtin_hook_usage, 0);
+			     builtin_hook_usage, PARSE_OPT_KEEP_UNKNOWN);
 
 	/* after the parse, we should have "<command> <hookname> <args...>" */
-	if (argc < 1)
+	if (argc < 2)
 		usage_with_options(builtin_hook_usage, builtin_hook_options);
 
 	git_config(git_default_config, NULL);
@@ -122,6 +164,8 @@ int cmd_hook(int argc, const char **argv, const char *prefix)
 
 	if (!strcmp(argv[0], "list"))
 		return list(argc, argv, prefix);
+	if (!strcmp(argv[0], "run"))
+		return run(argc, argv, prefix);
 
 	usage_with_options(builtin_hook_usage, builtin_hook_options);
 }
diff --git a/hook.c b/hook.c
index d262503725..5836bbb739 100644
--- a/hook.c
+++ b/hook.c
@@ -3,6 +3,7 @@
 #include "hook.h"
 #include "config.h"
 #include "run-command.h"
+#include "prompt.h"
 
 void free_hook(struct hook *ptr)
 {
@@ -135,6 +136,56 @@ enum hookdir_opt configured_hookdir_opt(void)
 	return HOOKDIR_UNKNOWN;
 }
 
+static int should_include_hookdir(const char *path, enum hookdir_opt cfg)
+{
+	struct strbuf prompt = STRBUF_INIT;
+	/*
+	 * If the path doesn't exist, don't bother adding the empty hook and
+	 * don't bother checking the config or prompting the user.
+	 */
+	if (!path)
+		return 0;
+
+	switch (cfg)
+	{
+		case HOOKDIR_NO:
+			return 0;
+		case HOOKDIR_UNKNOWN:
+			fprintf(stderr,
+				_("Unrecognized value for 'hook.runHookDir'. "
+				  "Is there a typo? "));
+			/* FALLTHROUGH */
+		case HOOKDIR_WARN:
+			fprintf(stderr, _("Running legacy hook at '%s'\n"),
+				path);
+			return 1;
+		case HOOKDIR_INTERACTIVE:
+			do {
+				/*
+				 * TRANSLATORS: Make sure to include [Y] and [n]
+				 * in your translation. Only English input is
+				 * accepted. Default option is "yes".
+				 */
+				fprintf(stderr, _("Run '%s'? [Yn] "), path);
+				git_read_line_interactively(&prompt);
+				strbuf_tolower(&prompt);
+				if (starts_with(prompt.buf, "n")) {
+					strbuf_release(&prompt);
+					return 0;
+				} else if (starts_with(prompt.buf, "y")) {
+					strbuf_release(&prompt);
+					return 1;
+				}
+				/* otherwise, we didn't understand the input */
+			} while (prompt.len); /* an empty reply means "Yes" */
+			strbuf_release(&prompt);
+			return 1;
+		case HOOKDIR_YES:
+		default:
+			return 1;
+	}
+}
+
 struct list_head* hook_list(const struct strbuf* hookname)
 {
 	struct strbuf hook_key = STRBUF_INIT;
@@ -166,3 +217,64 @@ struct list_head* hook_list(const struct strbuf* hookname)
 	strbuf_release(&hook_key);
 	return hook_head;
 }
+
+void run_hooks_opt_init(struct run_hooks_opt *o)
+{
+	strvec_init(&o->env);
+	strvec_init(&o->args);
+	o->run_hookdir = configured_hookdir_opt();
+}
+
+void run_hooks_opt_clear(struct run_hooks_opt *o)
+{
+	strvec_clear(&o->env);
+	strvec_clear(&o->args);
+}
+
+int run_hooks(const char *hookname, struct run_hooks_opt *options)
+{
+	struct strbuf hookname_str = STRBUF_INIT;
+	struct list_head *to_run, *pos = NULL, *tmp = NULL;
+	int rc = 0;
+
+	if (!options)
+		BUG("a struct run_hooks_opt must be provided to run_hooks");
+
+	strbuf_addstr(&hookname_str, hookname);
+
+	to_run = hook_list(&hookname_str);
+
+	list_for_each_safe(pos, tmp, to_run) {
+		struct child_process hook_proc = CHILD_PROCESS_INIT;
+		struct hook *hook = list_entry(pos, struct hook, list);
+
+		hook_proc.env = options->env.v;
+		hook_proc.no_stdin = 1;
+		hook_proc.stdout_to_stderr = 1;
+		hook_proc.trace2_hook_name = hook->command.buf;
+		hook_proc.use_shell = 1;
+
+		if (hook->from_hookdir) {
+		    if (!should_include_hookdir(hook->command.buf, options->run_hookdir))
+			continue;
+		    /*
+		     * Commands from the config could be oneliners, but we know
+		     * for certain that hookdir commands are not.
+		     */
+		    hook_proc.use_shell = 0;
+		}
+
+		/* add command */
+		strvec_push(&hook_proc.args, hook->command.buf);
+
+		/*
+		 * add passed-in argv, without expanding - let the user get back
+		 * exactly what they put in
+		 */
+		strvec_pushv(&hook_proc.args, options->args.v);
+
+		rc |= run_command(&hook_proc);
+	}
+
+	return rc;
+}
diff --git a/hook.h b/hook.h
index ccdf6272f2..259662968f 100644
--- a/hook.h
+++ b/hook.h
@@ -1,6 +1,7 @@
 #include "config.h"
 #include "list.h"
 #include "strbuf.h"
+#include "strvec.h"
 
 struct hook
 {
@@ -36,6 +37,37 @@ enum hookdir_opt
  */
 enum hookdir_opt configured_hookdir_opt(void);
 
+struct run_hooks_opt
+{
+	/* Environment vars to be set for each hook */
+	struct strvec env;
+
+	/* Args to be passed to each hook */
+	struct strvec args;
+
+	/*
+	 * How should the hookdir be handled?
+	 * Leave the RUN_HOOKS_OPT_INIT default in most cases; this only needs
+	 * to be overridden if the user can override it at the command line.
+	 */
+	enum hookdir_opt run_hookdir;
+};
+
+#define RUN_HOOKS_OPT_INIT  {   		\
+	.env = STRVEC_INIT, 				\
+	.args = STRVEC_INIT, 			\
+	.run_hookdir = configured_hookdir_opt()	\
+}
+
+void run_hooks_opt_init(struct run_hooks_opt *o);
+void run_hooks_opt_clear(struct run_hooks_opt *o);
+
+/*
+ * Runs all hooks associated to the 'hookname' event in order. Each hook will be
+ * passed 'env' and 'args'.
+ */
+int run_hooks(const char *hookname, struct run_hooks_opt *options);
+
 /* Free memory associated with a 'struct hook' */
 void free_hook(struct hook *ptr);
 /* Empties the list at 'head', calling 'free_hook()' on each entry */
diff --git a/t/t1360-config-based-hooks.sh b/t/t1360-config-based-hooks.sh
index ebd3bc623f..5b3003d59b 100755
--- a/t/t1360-config-based-hooks.sh
+++ b/t/t1360-config-based-hooks.sh
@@ -115,7 +115,10 @@ test_expect_success 'hook.runHookDir = no is respected by list' '
 
 	git hook list pre-commit >actual &&
 	# the hookdir annotation is translated
-	test_i18ncmp expected actual
+	test_i18ncmp expected actual &&
+
+	git hook run pre-commit 2>actual &&
+	test_must_be_empty actual
 '
 
 test_expect_success 'hook.runHookDir = warn is respected by list' '
@@ -129,6 +132,14 @@ test_expect_success 'hook.runHookDir = warn is respected by list' '
 
 	git hook list pre-commit >actual &&
 	# the hookdir annotation is translated
+	test_i18ncmp expected actual &&
+
+	cat >expected <<-EOF &&
+	Running legacy hook at '\''$(pwd)/.git/hooks/pre-commit'\''
+	"Legacy Hook"
+	EOF
+
+	git hook run pre-commit 2>actual &&
 	test_i18ncmp expected actual
 '
 
@@ -156,7 +167,7 @@ test_expect_success 'git hook list removes skipped inlined hook' '
 	test_cmp expected actual
 '
 
-test_expect_success 'hook.runHookDir = interactive is respected by list' '
+test_expect_success 'hook.runHookDir = interactive is respected by list and run' '
 	setup_hookdir &&
 
 	test_config hook.runHookDir "interactive" &&
@@ -167,7 +178,55 @@ test_expect_success 'hook.runHookDir = interactive is respected by list' '
 
 	git hook list pre-commit >actual &&
 	# the hookdir annotation is translated
-	test_i18ncmp expected actual
+	test_i18ncmp expected actual &&
+
+	test_write_lines n | git hook run pre-commit 2>actual &&
+	! grep "Legacy Hook" actual &&
+
+	test_write_lines y | git hook run pre-commit 2>actual &&
+	grep "Legacy Hook" actual
+'
+
+test_expect_success 'inline hook definitions execute oneliners' '
+	test_config hook.pre-commit.command "echo \"Hello World\"" &&
+
+	echo "Hello World" >expected &&
+
+	# hooks are run with stdout_to_stderr = 1
+	git hook run pre-commit 2>actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'inline hook definitions resolve paths' '
+	write_script sample-hook.sh <<-EOF &&
+	echo \"Sample Hook\"
+	EOF
+
+	test_when_finished "rm sample-hook.sh" &&
+
+	test_config hook.pre-commit.command "\"$(pwd)/sample-hook.sh\"" &&
+
+	echo \"Sample Hook\" >expected &&
+
+	# hooks are run with stdout_to_stderr = 1
+	git hook run pre-commit 2>actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'hookdir hook included in git hook run' '
+	setup_hookdir &&
+
+	echo \"Legacy Hook\" >expected &&
+
+	# hooks are run with stdout_to_stderr = 1
+	git hook run pre-commit 2>actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'out-of-repo runs excluded' '
+	setup_hooks &&
+
+	nongit test_must_fail git hook run pre-commit
 '
 
 test_done
-- 
2.28.0.rc0.142.g3c755180ce-goog