upload-pack: add a trigger for post-upload-pack hook

After upload-pack successfully finishes its operation, post-upload-pack
hook can be called for logging purposes.

The hook is passed various pieces of information, one per line, from its
standard input.  Currently the following items can be fed to the hook, but
more types of information may be added in the future:

    want SHA-1::
        40-byte hexadecimal object name the client asked to include in the
        resulting pack.  Can occur one or more times in the input.

    have SHA-1::
        40-byte hexadecimal object name the client asked to exclude from
        the resulting pack, claiming to have them already.  Can occur zero
        or more times in the input.

    time float::
        Number of seconds spent for creating the packfile.

    size decimal::
        Size of the resulting packfile in bytes.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-upload-pack.txt

@@ -20,6 +20,8 @@ The UI for the protocol is on the 'git-fetch-pack' side, and the
 program pair is meant to be used to pull updates from a remote
 repository.  For push operations, see 'git-send-pack'.
 
+After finishing the operation successfully, `post-upload-pack`
+hook is called (see linkgit:githooks[5]).
 
 OPTIONS
 -------

Documentation/githooks.txt

@@ -307,6 +307,31 @@ Both standard output and standard error output are forwarded to
 'git-send-pack' on the other end, so you can simply `echo` messages
 for the user.
 
+post-upload-pack
+----------------
+
+After upload-pack successfully finishes its operation, this hook is called
+for logging purposes.
+
+The hook is passed various pieces of information, one per line, from its
+standard input.  Currently the following items can be fed to the hook, but
+more types of information may be added in the future:
+
+want SHA-1::
+    40-byte hexadecimal object name the client asked to include in the
+    resulting pack.  Can occur one or more times in the input.
+
+have SHA-1::
+    40-byte hexadecimal object name the client asked to exclude from
+    the resulting pack, claiming to have them already.  Can occur zero
+    or more times in the input.
+
+time float::
+    Number of seconds spent for creating the packfile.
+
+size decimal::
+    Size of the resulting packfile in bytes.
+
 pre-auto-gc
 -----------
 

t/t5501-post-upload-pack.sh

@@ -0,0 +1,49 @@
+#!/bin/sh
+
+test_description='post upload-hook'
+
+. ./test-lib.sh
+
+LOGFILE=".git/post-upload-pack-log"
+
+test_expect_success setup '
+	test_commit A &&
+	test_commit B &&
+	git reset --hard A &&
+	test_commit C &&
+	git branch prev B &&
+	mkdir -p .git/hooks &&
+	{
+		echo "#!$SHELL_PATH" &&
+		echo "cat >post-upload-pack-log"
+	} >".git/hooks/post-upload-pack" &&
+	chmod +x .git/hooks/post-upload-pack
+'
+
+test_expect_success initial '
+	rm -fr sub &&
+	git init sub &&
+	(
+		cd sub &&
+		git fetch --no-tags .. prev
+	) &&
+	want=$(sed -n "s/^want //p" "$LOGFILE") &&
+	test "$want" = "$(git rev-parse --verify B)" &&
+	! grep "^have " "$LOGFILE"
+'
+
+test_expect_success second '
+	rm -fr sub &&
+	git init sub &&
+	(
+		cd sub &&
+		git fetch --no-tags .. prev:refs/remotes/prev &&
+		git fetch --no-tags .. master
+	) &&
+	want=$(sed -n "s/^want //p" "$LOGFILE") &&
+	test "$want" = "$(git rev-parse --verify C)" &&
+	have=$(sed -n "s/^have //p" "$LOGFILE") &&
+	test "$have" = "$(git rev-parse --verify B)"
+'
+
+test_done

upload-pack.c

@@ -141,19 +141,75 @@ static int do_rev_list(int fd, void *create_full_pack)
 	return 0;
 }
 
+static int feed_msg_to_hook(int fd, const char *fmt, ...)
+{
+	int cnt;
+	char buf[1024];
+	va_list params;
+
+	va_start(params, fmt);
+	cnt = vsprintf(buf, fmt, params);
+	va_end(params);
+	return write_in_full(fd, buf, cnt) != cnt;
+}
+
+static int feed_obj_to_hook(const char *label, struct object_array *oa, int i, int fd)
+{
+	return feed_msg_to_hook(fd, "%s %s\n", label,
+				sha1_to_hex(oa->objects[i].item->sha1));
+}
+
+static int run_post_upload_pack_hook(size_t total, struct timeval *tv)
+{
+	const char *argv[2];
+	struct child_process proc;
+	int err, i;
+
+	argv[0] = "hooks/post-upload-pack";
+	argv[1] = NULL;
+
+	if (access(argv[0], X_OK) < 0)
+		return 0;
+
+	memset(&proc, 0, sizeof(proc));
+	proc.argv = argv;
+	proc.in = -1;
+	proc.stdout_to_stderr = 1;
+	err = start_command(&proc);
+	if (err)
+		return err;
+	for (i = 0; !err && i < want_obj.nr; i++)
+		err |= feed_obj_to_hook("want", &want_obj, i, proc.in);
+	for (i = 0; !err && i < have_obj.nr; i++)
+		err |= feed_obj_to_hook("have", &have_obj, i, proc.in);
+	if (!err)
+		err |= feed_msg_to_hook(proc.in, "time %ld.%06ld\n",
+					(long)tv->tv_sec, (long)tv->tv_usec);
+	if (!err)
+		err |= feed_msg_to_hook(proc.in, "size %ld\n", (long)total);
+	if (close(proc.in))
+		err = 1;
+	if (finish_command(&proc))
+		err = 1;
+	return err;
+}
+
 static void create_pack_file(void)
 {
+	struct timeval start_tv, tv;
 	struct async rev_list;
 	struct child_process pack_objects;
 	int create_full_pack = (nr_our_refs == want_obj.nr && !have_obj.nr);
 	char data[8193], progress[128];
 	char abort_msg[] = "aborting due to possible repository "
 		"corruption on the remote side.";
 	int buffered = -1;
-	ssize_t sz;
+	ssize_t sz, total_sz;
 	const char *argv[10];
 	int arg = 0;
 
+	gettimeofday(&start_tv, NULL);
+	total_sz = 0;
 	if (shallow_nr) {
 		rev_list.proc = do_rev_list;
 		rev_list.data = 0;
@@ -262,7 +318,7 @@ static void create_pack_file(void)
 			sz = xread(pack_objects.out, cp,
 				  sizeof(data) - outsz);
 			if (0 < sz)
-					;
+				total_sz += sz;
 			else if (sz == 0) {
 				close(pack_objects.out);
 				pack_objects.out = -1;
@@ -314,6 +370,16 @@ static void create_pack_file(void)
 	}
 	if (use_sideband)
 		packet_flush(1);
+
+	gettimeofday(&tv, NULL);
+	tv.tv_sec -= start_tv.tv_sec;
+	if (tv.tv_usec < start_tv.tv_usec) {
+		tv.tv_sec--;
+		tv.tv_usec += 1000000;
+	}
+	tv.tv_usec -= start_tv.tv_usec;
+	if (run_post_upload_pack_hook(total_sz, &tv))
+		warning("post-upload-hook failed");
 	return;
 
  fail: