Merge branch 'jk/http-backend-deadlock' into maint

Communication between the HTTP server and http_backend process can
lead to a dead-lock when relaying a large ref negotiation request.
Diagnose the situation better, and mitigate it by reading such a
request first into core (to a reasonable limit).

* jk/http-backend-deadlock:
  http-backend: spool ref negotiation requests to buffer
  t5551: factor out tag creation
  http-backend: fix die recursion with custom handler

1 files changed, 36 insertions, 13 deletions

diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh
index 2b29311901..58207d8825 100755
--- a/t/t5551-http-fetch-smart.sh
+++ b/t/t5551-http-fetch-smart.sh
@@ -218,27 +218,35 @@ test_expect_success 'transfer.hiderefs works over smart-http' '
 	git -C hidden.git rev-parse --verify b
 '
 
-test_expect_success 'create 2,000 tags in the repo' '
-	(
-	cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
-	for i in $(test_seq 2000)
+# create an arbitrary number of tags, numbered from tag-$1 to tag-$2
+create_tags () {
+	rm -f marks &&
+	for i in $(test_seq "$1" "$2")
 	do
-		echo "commit refs/heads/too-many-refs"
-		echo "mark :$i"
-		echo "committer git <git@example.com> $i +0000"
-		echo "data 0"
-		echo "M 644 inline bla.txt"
-		echo "data 4"
-		echo "bla"
+		# don't use here-doc, because it requires a process
+		# per loop iteration
+		echo "commit refs/heads/too-many-refs-$1" &&
+		echo "mark :$i" &&
+		echo "committer git <git@example.com> $i +0000" &&
+		echo "data 0" &&
+		echo "M 644 inline bla.txt" &&
+		echo "data 4" &&
+		echo "bla" &&
 		# make every commit dangling by always
 		# rewinding the branch after each commit
-		echo "reset refs/heads/too-many-refs"
-		echo "from :1"
+		echo "reset refs/heads/too-many-refs-$1" &&
+		echo "from :$1"
 	done | git fast-import --export-marks=marks &&
 
 	# now assign tags to all the dangling commits we created above
 	tag=$(perl -e "print \"bla\" x 30") &&
 	sed -e "s|^:\([^ ]*\) \(.*\)$|\2 refs/tags/$tag-\1|" <marks >>packed-refs
+}
+
+test_expect_success 'create 2,000 tags in the repo' '
+	(
+		cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+		create_tags 1 2000
 	)
 '
 
@@ -259,5 +267,20 @@ test_expect_success 'large fetch-pack requests can be split across POSTs' '
 	test_line_count = 2 posts
 '
 
+test_expect_success EXPENSIVE 'http can handle enormous ref negotiation' '
+	(
+		cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+		create_tags 2001 50000
+	) &&
+	git -C too-many-refs fetch -q --tags &&
+	(
+		cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+		create_tags 50001 100000
+	) &&
+	git -C too-many-refs fetch -q --tags &&
+	git -C too-many-refs for-each-ref refs/tags >tags &&
+	test_line_count = 100000 tags
+'
+
 stop_httpd
 test_done