http: permit unlinking partial packs on Windows
On Windows, an open file must permit FILE_SHARE_DELETE before another process can unlink it. MinGW's non-append O_RDWR open enables that sharing mode only for an existing file; adding O_CREAT falls back to _wopen(), which cannot set it. First try opening the partial pack without O_CREAT. If it does not exist, create it exclusively, close that descriptor, and retry through the existing-file path. A racing creator retries after EEXIST. This ensures that every retained descriptor permits another downloader to unlink the staging path. Add an unlink-while-indexing test that does not require FIFOs and can therefore run on MinGW. Signed-off-by: Ted Nyman <tnyman@openai.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ted Nyman committed
Jul 26, 2026 at 17:28 UTC
e92a518a741ead85634c43f871e7e095bcf66f1f
2 files changed
+37
-1
http.c
+16
-1
index 4965e89248..a530995363 100644
--- a/http.c
+++ b/http.c
@@ -2746,7 +2746,22 @@ struct http_pack_request *new_direct_http_pack_request(
odb_pack_name(the_repository, &preq->tmpfile, packed_git_hash, "pack");
strbuf_addstr(&preq->tmpfile, ".temp");
- fd = open(preq->tmpfile.buf, O_RDWR | O_CREAT, 0666);
+ /*
+ * MinGW's non-append O_RDWR open grants FILE_SHARE_DELETE only for an
+ * existing file; reopen a newly created file so others may unlink it.
+ */
+ for (;;) {
+ fd = open(preq->tmpfile.buf, O_RDWR);
+ if (fd >= 0 || errno != ENOENT)
+ break;
+ fd = open(preq->tmpfile.buf, O_RDWR | O_CREAT | O_EXCL, 0666);
+ if (fd >= 0) {
+ close(fd);
+ continue;
+ }
+ if (errno != EEXIST)
+ break;
+ }
if (fd < 0) {
error_errno("unable to open local file %s for pack",
preq->tmpfile.buf);
t/t5550-http-fetch-dumb.sh
+21
index 76cfcb8006..1660baa0d1 100755
--- a/t/t5550-http-fetch-dumb.sh
+++ b/t/t5550-http-fetch-dumb.sh
@@ -328,6 +328,27 @@ test_expect_success 'http-fetch --packfile resumes a partial download' '
git -C packfileclient-resume cat-file -e "$HASH"
'
+test_expect_success 'http-fetch --packfile permits unlink while indexing' '
+ git init packfileclient-unlink &&
+ p=$(cd "$HTTPD_DOCUMENT_ROOT_PATH"/repo_pack.git &&
+ ls objects/pack/pack-*.pack) &&
+ tmpfile="packfileclient-unlink/.git/objects/pack/pack-$ARBITRARY.pack.temp" &&
+ write_script git-unlink-index-pack <<-\EOF &&
+ test -f "$GIT_TEST_PACK_TEMP" || exit 1
+ rm "$GIT_TEST_PACK_TEMP" || exit 1
+ exec git index-pack "$@"
+ EOF
+ test_when_finished "rm -f git-unlink-index-pack" &&
+ PATH="$TRASH_DIRECTORY:$PATH" \
+ GIT_TEST_PACK_TEMP="$TRASH_DIRECTORY/$tmpfile" \
+ git -C packfileclient-unlink http-fetch --packfile="$ARBITRARY" \
+ --index-pack-arg=unlink-index-pack \
+ --index-pack-arg=--stdin --index-pack-arg=--keep \
+ "$HTTPD_URL/dumb/repo_pack.git/$p" >out &&
+ test_path_is_missing "$tmpfile" &&
+ git -C packfileclient-unlink cat-file -e "$HASH"
+'
+
test_expect_success PERL,PIPE 'concurrent http-fetch --packfile cannot corrupt an overlapping download' '
git init packfileclient-overlap &&
blob=$(test-tool genrandom pack-overlap 2m |