diff options
author | Daniel Duvall <dan@mutual.io> | 2020-10-31 05:39:02 +0300 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2020-10-31 07:18:10 +0300 |
commit | fb3d1a083f776f02caa514cad8b232d8b974641f (patch) | |
tree | 70bef9495daacaa1cf359f9fc1492c90de539d9d | |
parent | e2850a27a95c6f5b141dd88398b1702d2e524a81 (diff) |
upload-pack: allow stateless client EOF just prior to haves
During stateless packfile negotiation where a depth is given, stateless
RPC clients (e.g. git-remote-curl) will send multiple upload-pack
requests with the first containing only the
wants/shallows/deepens/filters and the subsequent containing haves/done.
When upload-pack handles such requests, entering get_common_commits
without checking whether the client has hung up can result in unexpected
EOF during the negotiation loop and a die() with message "fatal: the
remote end hung up unexpectedly".
Real world effects include:
- A client speaking to git-http-backend via a server that doesn't check
the exit codes of CGIs (e.g. mod_cgi) doesn't know and doesn't care
about the fatal. It continues to process the response body as normal.
- A client speaking to a server that does check the exit code and
returns an errant HTTP status as a result will fail with the message
"error: RPC failed; HTTP 500 curl 22 The requested URL returned error:
500."
- Admins running servers that surface the failure must workaround it by
patching code that handles execution of git-http-backend to ignore exit
codes or take other heuristic approaches.
- Admins may have to deal with "hung up unexpectedly" log spam related
to the failures even in cases where the exit code isn't surfaced as an
HTTP server-side error status.
To avoid these EOF related fatals, have upload-pack gently peek for an
EOF between the sending of shallow/unshallow lines (followed by flush)
and the reading of client haves. If the client has hung up at this
point, exit normally.
Signed-off-by: Daniel Duvall <dan@mutual.io>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rwxr-xr-x | t/t5530-upload-pack-error.sh | 17 | ||||
-rw-r--r-- | upload-pack.c | 13 |
2 files changed, 29 insertions, 1 deletions
diff --git a/t/t5530-upload-pack-error.sh b/t/t5530-upload-pack-error.sh index 205a2631e7..9dd2d2457a 100755 --- a/t/t5530-upload-pack-error.sh +++ b/t/t5530-upload-pack-error.sh @@ -88,6 +88,23 @@ test_expect_success 'upload-pack fails due to error in pack-objects enumeration' grep "pack-objects died" output.err ' +test_expect_success 'upload-pack tolerates EOF just after stateless client wants' ' + test_commit initial && + head=$(git rev-parse HEAD) && + + { + packetize "want $head" && + packetize "shallow $head" && + packetize "deepen 1" && + printf "0000" + } >request && + + printf "0000" >expect && + + git upload-pack --stateless-rpc . <request >actual && + test_cmp expect actual +' + test_expect_success 'create empty repository' ' mkdir foo && diff --git a/upload-pack.c b/upload-pack.c index 3b858eb457..5dc8e1f844 100644 --- a/upload-pack.c +++ b/upload-pack.c @@ -1344,7 +1344,18 @@ void upload_pack(struct upload_pack_options *options) PACKET_READ_DIE_ON_ERR_PACKET); receive_needs(&data, &reader); - if (data.want_obj.nr) { + + /* + * An EOF at this exact point in negotiation should be + * acceptable from stateless clients as they will consume the + * shallow list before doing subsequent rpc with haves/etc. + */ + if (data.stateless_rpc) + reader.options |= PACKET_READ_GENTLE_ON_EOF; + + if (data.want_obj.nr && + packet_reader_peek(&reader) != PACKET_READ_EOF) { + reader.options &= ~PACKET_READ_GENTLE_ON_EOF; get_common_commits(&data, &reader); create_pack_file(&data, NULL); } |