Merge branch 'mh/write-refs-sooner-2.4' into maint

Multi-ref transaction support we merged a few releases ago
unnecessarily kept many file descriptors open, risking to fail with
resource exhaustion.  This is for 2.4.x track.

* mh/write-refs-sooner-2.4:
  ref_transaction_commit(): fix atomicity and avoid fd exhaustion
  ref_transaction_commit(): remove the local flags variable
  ref_transaction_commit(): inline call to write_ref_sha1()
  rename_ref(): inline calls to write_ref_sha1() from this function
  commit_ref_update(): new function, extracted from write_ref_sha1()
  write_ref_to_lockfile(): new function, extracted from write_ref_sha1()
  t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE
  update-ref: test handling large transactions properly
  ref_transaction_commit(): fix atomicity and avoid fd exhaustion
  ref_transaction_commit(): remove the local flags variable
  ref_transaction_commit(): inline call to write_ref_sha1()
  rename_ref(): inline calls to write_ref_sha1() from this function
  commit_ref_update(): new function, extracted from write_ref_sha1()
  write_ref_to_lockfile(): new function, extracted from write_ref_sha1()
  t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE
  update-ref: test handling large transactions properly

2 files changed, 30 insertions, 2 deletions

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 86fa46856c..ba89f4c009 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -1065,4 +1065,32 @@ test_expect_success 'stdin -z delete refs works with packed and loose refs' '
 	test_must_fail git rev-parse --verify -q $c
 '
 
+run_with_limited_open_files () {
+	(ulimit -n 32 && "$@")
+}
+
+test_lazy_prereq ULIMIT_FILE_DESCRIPTORS 'run_with_limited_open_files true'
+
+test_expect_success ULIMIT_FILE_DESCRIPTORS 'large transaction creating branches does not burst open file limit' '
+(
+	for i in $(test_seq 33)
+	do
+		echo "create refs/heads/$i HEAD"
+	done >large_input &&
+	run_with_limited_open_files git update-ref --stdin <large_input &&
+	git rev-parse --verify -q refs/heads/33
+)
+'
+
+test_expect_success ULIMIT_FILE_DESCRIPTORS 'large transaction deleting branches does not burst open file limit' '
+(
+	for i in $(test_seq 33)
+	do
+		echo "delete refs/heads/$i HEAD"
+	done >large_input &&
+	run_with_limited_open_files git update-ref --stdin <large_input &&
+	test_must_fail git rev-parse --verify -q refs/heads/33
+)
+'
+
 test_done
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index fa207f3b8c..d1ff5c94f2 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -1491,10 +1491,10 @@ run_with_limited_stack () {
 	(ulimit -s 128 && "$@")
 }
 
-test_lazy_prereq ULIMIT 'run_with_limited_stack true'
+test_lazy_prereq ULIMIT_STACK_SIZE 'run_with_limited_stack true'
 
 # we require ulimit, this excludes Windows
-test_expect_success ULIMIT '--contains works in a deep repo' '
+test_expect_success ULIMIT_STACK_SIZE '--contains works in a deep repo' '
 	>expect &&
 	i=1 &&
 	while test $i -lt 8000