From e5256c82e569694c64adbbe4c1bef12bbba94f30 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Fri, 7 Aug 2020 09:05:58 +0200 Subject: [PATCH] refs: fix interleaving hook calls with reference-transaction hook In order to not repeatedly search for the reference-transaction hook in case it's getting called multiple times, we use a caching mechanism to only call `find_hook()` once. What was missed though is that the return value of `find_hook()` actually comes from a static strbuf, which means it will get overwritten when calling `find_hook()` again. As a result, we may call the wrong hook with parameters of the reference-transaction hook. This scenario was spotted in the wild when executing a git-push(1) with multiple references, where there are interleaving calls to both the update and the reference-transaction hook. While initial calls to the reference-transaction hook work as expected, it will stop working after the next invocation of the update hook. The result is that we now start calling the update hook with parameters and stdin of the reference-transaction hook. This commit fixes the issue by storing a copy of `find_hook()`'s return value in the cache. Signed-off-by: Junio C Hamano --- refs.c | 2 +- t/t1416-ref-transaction-hooks.sh | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+), 1 deletion(-) diff --git a/refs.c b/refs.c index f05295f503..836d49b958 100644 --- a/refs.c +++ b/refs.c @@ -2001,7 +2001,7 @@ static int run_transaction_hook(struct ref_transaction *transaction, if (hook == &hook_not_found) return ret; if (!hook) - hook = find_hook("reference-transaction"); + hook = xstrdup_or_null(find_hook("reference-transaction")); if (!hook) { hook = &hook_not_found; return ret; diff --git a/t/t1416-ref-transaction-hooks.sh b/t/t1416-ref-transaction-hooks.sh index da58d867a5..d4d19194bf 100755 --- a/t/t1416-ref-transaction-hooks.sh +++ b/t/t1416-ref-transaction-hooks.sh @@ -106,4 +106,30 @@ test_expect_success 'hook gets all queued updates in aborted state' ' test_cmp expect actual ' +test_expect_success 'interleaving hook calls succeed' ' + test_when_finished "rm -r target-repo.git" && + + git init --bare target-repo.git && + + write_script target-repo.git/hooks/reference-transaction <<-\EOF && + echo $0 "$@" >>actual + EOF + + write_script target-repo.git/hooks/update <<-\EOF && + echo $0 "$@" >>actual + EOF + + cat >expect <<-EOF && + hooks/update refs/tags/PRE 0000000000000000000000000000000000000000 63ac8e7bcdb882293465435909f54a96de17d4f7 + hooks/reference-transaction prepared + hooks/reference-transaction committed + hooks/update refs/tags/POST 0000000000000000000000000000000000000000 99d53161c3a0a903b6561b9f6c0c665b3a476401 + hooks/reference-transaction prepared + hooks/reference-transaction committed + EOF + + git push ./target-repo.git PRE POST && + test_cmp expect target-repo.git/actual +' + test_done