[PATCH 13/17] receive-pack: convert 'update' hook to hook.h

[Emily Shaffer <emilyshaffer@google.com>]

By using hook.h to invoke the 'update' hook, now hooks can be specified
in the config in addition to the hookdir.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
---
 Documentation/githooks.txt       |  2 +
 builtin/receive-pack.c           | 65 +++++++++++++++++++++-----------
 t/t1416-ref-transaction-hooks.sh |  4 +-
 3 files changed, 48 insertions(+), 23 deletions(-)

diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index 3a35500132..2b3a74f249 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -359,6 +359,8 @@ The default 'update' hook, when enabled--and with
 `hooks.allowunannotated` config option unset or set to false--prevents
 unannotated tags to be pushed.
 
+Hooks executed during 'update' are run in parallel by default.
+
 [[proc-receive]]
 proc-receive
 ~~~~~~~~~~~~
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index d64a3076be..cd79ad6bdc 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -930,33 +930,56 @@ static int run_receive_hook(struct command *commands,
 	return status;
 }
 
-static int run_update_hook(struct command *cmd)
+static void hook_output_to_sideband(struct strbuf *output, void *cb_data)
 {
-	const char *argv[5];
-	struct child_process proc = CHILD_PROCESS_INIT;
-	int code;
+	int keepalive_active = 0;
 
-	argv[0] = find_hook("update");
-	if (!argv[0])
-		return 0;
+	if (keepalive_in_sec <= 0)
+		use_keepalive = KEEPALIVE_NEVER;
+	if (use_keepalive == KEEPALIVE_ALWAYS)
+		keepalive_active = 1;
 
-	argv[1] = cmd->ref_name;
-	argv[2] = oid_to_hex(&cmd->old_oid);
-	argv[3] = oid_to_hex(&cmd->new_oid);
-	argv[4] = NULL;
+	/* send a keepalive if there is no data to write */
+	if (keepalive_active && !output->len) {
+		static const char buf[] = "0005\1";
+		write_or_die(1, buf, sizeof(buf) - 1);
+		return;
+	}
 
-	proc.no_stdin = 1;
-	proc.stdout_to_stderr = 1;
-	proc.err = use_sideband ? -1 : 0;
-	proc.argv = argv;
-	proc.trace2_hook_name = "update";
+	if (use_keepalive == KEEPALIVE_AFTER_NUL && !keepalive_active) {
+		const char *first_null = memchr(output->buf, '\0', output->len);
+		if (first_null) {
+			/* The null bit is excluded. */
+			size_t before_null = first_null - output->buf;
+			size_t after_null = output->len - (before_null + 1);
+			keepalive_active = 1;
+			send_sideband(1, 2, output->buf, before_null, use_sideband);
+			send_sideband(1, 2, first_null + 1, after_null, use_sideband);
+
+			return;
+		}
+	}
+
+	send_sideband(1, 2, output->buf, output->len, use_sideband);
+}
+
+static int run_update_hook(struct command *cmd)
+{
+	struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT_ASYNC;
+	int code;
+
+	strvec_pushl(&opt.args,
+		     cmd->ref_name,
+		     oid_to_hex(&cmd->old_oid),
+		     oid_to_hex(&cmd->new_oid),
+		     NULL);
 
-	code = start_command(&proc);
-	if (code)
-		return code;
 	if (use_sideband)
-		copy_to_sideband(proc.err, -1, NULL);
-	return finish_command(&proc);
+		opt.consume_sideband = hook_output_to_sideband;
+
+	code = run_hooks("update", &opt);
+	run_hooks_opt_clear(&opt);
+	return code;
 }
 
 static struct command *find_command_by_refname(struct command *list,
diff --git a/t/t1416-ref-transaction-hooks.sh b/t/t1416-ref-transaction-hooks.sh
index 17f11f5cb0..28359f6099 100755
--- a/t/t1416-ref-transaction-hooks.sh
+++ b/t/t1416-ref-transaction-hooks.sh
@@ -121,10 +121,10 @@ test_expect_success 'interleaving hook calls succeed' '
 	EOF
 
 	cat >expect <<-EOF &&
-		hooks/update refs/tags/PRE $ZERO_OID $PRE_OID
+		$(pwd)/target-repo.git/hooks/update refs/tags/PRE $ZERO_OID $PRE_OID
 		$(pwd)/target-repo.git/hooks/reference-transaction prepared
 		$(pwd)/target-repo.git/hooks/reference-transaction committed
-		hooks/update refs/tags/POST $ZERO_OID $POST_OID
+		$(pwd)/target-repo.git/hooks/update refs/tags/POST $ZERO_OID $POST_OID
 		$(pwd)/target-repo.git/hooks/reference-transaction prepared
 		$(pwd)/target-repo.git/hooks/reference-transaction committed
 	EOF
-- 
2.28.0.rc0.142.g3c755180ce-goog