Merge branch 'ab/hook-api-with-stdin'

Extend the run-hooks API to allow feeding data from the standard
input when running the hook script(s).

* ab/hook-api-with-stdin:
  hook: support a --to-stdin=<path> option
  sequencer: use the new hook API for the simpler "post-rewrite" call
  hook API: support passing stdin to hooks, convert am's 'post-rewrite'
  run-command: allow stdin for run_processes_parallel
  run-command.c: remove dead assignment in while-loop

8 files changed, 54 insertions, 36 deletions

diff --git a/Documentation/git-hook.txt b/Documentation/git-hook.txt
index 77c3a8ad90..3407f3c2c0 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 [--ignore-missing] <hook-name> [-- <hook-args>]
+'git hook' run [--ignore-missing] [--to-stdin=<path>] <hook-name> [-- <hook-args>]
 
 DESCRIPTION
 -----------
@@ -31,6 +31,11 @@ linkgit:githooks[5] for arguments hooks might expect (if any).
 OPTIONS
 -------
 
+--to-stdin::
+	For "run"; Specify a file which will be streamed into the
+	hook's stdin. The hook will receive the entire file from
+	beginning to EOF.
+
 --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
diff --git a/builtin/am.c b/builtin/am.c
index 8b3dcb66f0..e0848ddadf 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -495,24 +495,12 @@ static int run_applypatch_msg_hook(struct am_state *state)
  */
 static int run_post_rewrite_hook(const struct am_state *state)
 {
-	struct child_process cp = CHILD_PROCESS_INIT;
-	const char *hook = find_hook("post-rewrite");
-	int ret;
-
-	if (!hook)
-		return 0;
+	struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT;
 
-	strvec_push(&cp.args, hook);
-	strvec_push(&cp.args, "rebase");
+	strvec_push(&opt.args, "rebase");
+	opt.path_to_stdin = am_path(state, "rewritten");
 
-	cp.in = xopen(am_path(state, "rewritten"), O_RDONLY);
-	cp.stdout_to_stderr = 1;
-	cp.trace2_hook_name = "post-rewrite";
-
-	ret = run_command(&cp);
-
-	close(cp.in);
-	return ret;
+	return run_hooks_opt("post-rewrite", &opt);
 }
 
 /**
diff --git a/builtin/hook.c b/builtin/hook.c
index b6530d189a..f95b7965c5 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 [--ignore-missing] <hook-name> [-- <hook-args>]")
+	N_("git hook run [--ignore-missing] [--to-stdin=<path>] <hook-name> [-- <hook-args>]")
 
 static const char * const builtin_hook_usage[] = {
 	BUILTIN_HOOK_RUN_USAGE,
@@ -28,6 +28,8 @@ static int run(int argc, const char **argv, const char *prefix)
 	struct option run_options[] = {
 		OPT_BOOL(0, "ignore-missing", &ignore_missing,
 			 N_("silently ignore missing requested <hook-name>")),
+		OPT_STRING(0, "to-stdin", &opt.path_to_stdin, N_("path"),
+			   N_("file to read into hooks' stdin")),
 		OPT_END(),
 	};
 	int ret;
diff --git a/hook.c b/hook.c
index a4fa1031f2..1a84831863 100644
--- a/hook.c
+++ b/hook.c
@@ -55,6 +55,11 @@ static int pick_next_hook(struct child_process *cp,
 
 	cp->no_stdin = 1;
 	strvec_pushv(&cp->env, hook_cb->options->env.v);
+	/* reopen the file for stdin; run_command closes it. */
+	if (hook_cb->options->path_to_stdin) {
+		cp->no_stdin = 0;
+		cp->in = xopen(hook_cb->options->path_to_stdin, O_RDONLY);
+	}
 	cp->stdout_to_stderr = 1;
 	cp->trace2_hook_name = hook_cb->hook_name;
 	cp->dir = hook_cb->options->dir;
diff --git a/hook.h b/hook.h
index 4258b13da0..19ab9a5806 100644
--- a/hook.h
+++ b/hook.h
@@ -30,6 +30,11 @@ struct run_hooks_opt
 	 * was invoked.
 	 */
 	int *invoked_hook;
+
+	/**
+	 * Path to file which should be piped to stdin for each hook.
+	 */
+	const char *path_to_stdin;
 };
 
 #define RUN_HOOKS_OPT_INIT { \
diff --git a/run-command.c b/run-command.c
index 50cc011654..6bd16acb06 100644
--- a/run-command.c
+++ b/run-command.c
@@ -1586,6 +1586,14 @@ static int pp_start_one(struct parallel_processes *pp,
 	if (i == opts->processes)
 		BUG("bookkeeping is hard");
 
+	/*
+	 * By default, do not inherit stdin from the parent process - otherwise,
+	 * all children would share stdin! Users may overwrite this to provide
+	 * something to the child's stdin by having their 'get_next_task'
+	 * callback assign 0 to .no_stdin and an appropriate integer to .in.
+	 */
+	pp->children[i].process.no_stdin = 1;
+
 	code = opts->get_next_task(&pp->children[i].process,
 				   opts->ungroup ? NULL : &pp->children[i].err,
 				   opts->data,
@@ -1601,7 +1609,6 @@ static int pp_start_one(struct parallel_processes *pp,
 		pp->children[i].process.err = -1;
 		pp->children[i].process.stdout_to_stderr = 1;
 	}
-	pp->children[i].process.no_stdin = 1;
 
 	if (start_command(&pp->children[i].process)) {
 		if (opts->start_failure)
@@ -1632,9 +1639,7 @@ static void pp_buffer_stderr(struct parallel_processes *pp,
 			     const struct run_process_parallel_opts *opts,
 			     int output_timeout)
 {
-	int i;
-
-	while ((i = poll(pp->pfd, opts->processes, output_timeout) < 0)) {
+	while (poll(pp->pfd, opts->processes, output_timeout) < 0) {
 		if (errno == EINTR)
 			continue;
 		pp_cleanup(pp, opts);
diff --git a/sequencer.c b/sequencer.c
index fb23f734ad..65a34f9676 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4844,8 +4844,7 @@ cleanup_head_ref:
 		if (!stat(rebase_path_rewritten_list(), &st) &&
 				st.st_size > 0) {
 			struct child_process child = CHILD_PROCESS_INIT;
-			const char *post_rewrite_hook =
-				find_hook("post-rewrite");
+			struct run_hooks_opt hook_opt = RUN_HOOKS_OPT_INIT;
 
 			child.in = open(rebase_path_rewritten_list(), O_RDONLY);
 			child.git_cmd = 1;
@@ -4855,18 +4854,9 @@ cleanup_head_ref:
 			/* we don't care if this copying failed */
 			run_command(&child);
 
-			if (post_rewrite_hook) {
-				struct child_process hook = CHILD_PROCESS_INIT;
-
-				hook.in = open(rebase_path_rewritten_list(),
-					O_RDONLY);
-				hook.stdout_to_stderr = 1;
-				hook.trace2_hook_name = "post-rewrite";
-				strvec_push(&hook.args, post_rewrite_hook);
-				strvec_push(&hook.args, "rebase");
-				/* we don't care if this hook failed */
-				run_command(&hook);
-			}
+			hook_opt.path_to_stdin = rebase_path_rewritten_list();
+			strvec_push(&hook_opt.args, "rebase");
+			run_hooks_opt("post-rewrite", &hook_opt);
 		}
 		apply_autostash(rebase_path_autostash());
 
diff --git a/t/t1800-hook.sh b/t/t1800-hook.sh
index 2ef3579fa7..3506f627b6 100755
--- a/t/t1800-hook.sh
+++ b/t/t1800-hook.sh
@@ -177,4 +177,22 @@ test_expect_success 'git hook run a hook with a bad shebang' '
 	test_cmp expect actual
 '
 
+test_expect_success 'stdin to hooks' '
+	write_script .git/hooks/test-hook <<-\EOF &&
+	echo BEGIN stdin
+	cat
+	echo END stdin
+	EOF
+
+	cat >expect <<-EOF &&
+	BEGIN stdin
+	hello
+	END stdin
+	EOF
+
+	echo hello >input &&
+	git hook run --to-stdin=input test-hook 2>actual &&
+	test_cmp expect actual
+'
+
 test_done