Subject: [PATCH v2] receive-pack: purge temporary data if no command is ready to run

From: Chen BoJun <[email-masked]>
Date: Sat, 29 Jan 2022 14:35:38 +0800

From: Chen Bojun <[email-masked]>

When pushing a hidden ref, e.g.:

    $ git push origin HEAD:refs/hidden/foo

"receive-pack" will reject our request with an error message like this:

    ! [remote rejected] HEAD -> refs/hidden/foo (deny updating a hidden ref)

The remote side ("git-receive-pack") will not create the hidden ref as
expected, but the pack file sent by "git-send-pack" is left inside the
remote repository. I.e. the quarantine directory is not purged as it
should be.

Add a checkpoint before calling "tmp_objdir_migrate()" and after calling
the "pre-receive" hook to purge that temporary data in the quarantine
area when there is no command ready to run.

The reason we do not add the checkpoint before the "pre-receive" hook,
but after it, is that the "pre-receive" hook is called with a switch-off
"skip_broken" flag, and all commands, even broken ones, should be fed
by calling "feed_receive_hook()".

Add a new test case in t5516 as well.

Helped-by: Jiang Xin <[email-masked]>
Helped-by: Teng Long <[email-masked]>
Signed-off-by: Chen Bojun <[email-masked]>
---
 builtin/receive-pack.c | 9 +++++++++
 t/t5516-fetch-push.sh  | 8 ++++++++
 2 files changed, 17 insertions(+)

diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 9f4a0b816c..a0b193ab3f 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -1971,6 +1971,15 @@ static void execute_commands(struct command *commands,
 		return;
 	}
 
+	/*
+	 * If there is no command ready to run, should return directly to destroy
+	 * temporary data in the quarantine area.
+	 */
+	for (cmd = commands; cmd && cmd->error_string; cmd = cmd->next)
+		; /* nothing */
+	if (!cmd)
+		return;
+
 	/*
 	 * Now we'll start writing out refs, which means the objects need
 	 * to be in their final positions so that other processes can see them.
diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index 2f04cf9a1c..da70c45857 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -1809,4 +1809,12 @@ test_expect_success 'refuse fetch to current branch of bare repository worktree'
 	git -C bare.git fetch -u .. HEAD:wt
 '
 
+test_expect_success 'refuse to push a hidden ref, and make sure do not pollute the repository' '
+	mk_empty testrepo &&
+	git -C testrepo config receive.hiderefs refs/hidden &&
+	git -C testrepo config receive.unpackLimit 1 &&
+	test_must_fail git push testrepo HEAD:refs/hidden/foo &&
+	test_dir_is_empty testrepo/.git/objects/pack
+'
+
 test_done
-- 
2.32.0 (Apple Git-132)