Re: [PATCH] fetch-pack: make unexpected peek result non-fatal
- From
Junio C Hamano <gitster@pobox.com>
- Date
- May 16, 2022, 16:10 UTC
- Message-ID
- <xmqqr14t4fwf.fsf@gitster.g>
- In-Reply-To
- <20220516110221.3490982-1-jonathantanmy@google.com>
Jonathan Tan <jonathantanmy@google.com> writes:
Show 17 quoted lines
> When a Git server responds to a fetch request, it may send optional > sections before the packfile section. To handle this, the Git client > calls packet_reader_peek() (see process_section_header()) in order to > see what's next without consuming the line. > > However, as implemented, Git errors out whenever what's peeked is not an > ordinary line. This is not only unexpected (here, we only need to know > whether the upcoming line is the section header we want) but causes > errors to include the name of a section header that is irrelevant to the > cause of the error. For example, at $DAYJOB, we have seen "fatal: error > reading section header 'shallow-info'" error messages when none of the > repositories involved are shallow. > > Therefore, fix this so that the peek returns 1 if the upcoming line is > the wanted section header and nothing else. Because of this change, > reader->line may now be NULL later in the function, so update the error > message printing code accordingly.
[not a suggestion to change anything; just making sure I got the above correct]
We used to die unless READ_NORMAL was returned, so the code after packet_reader_peek() can rely on reader->line to be populated. Now that code must handle cases where an earlier _peek() gave something other than READ_NORMAL and in such an error case reader->line points at NULL. So any code that assumed reader->line was populated needs to be updated.
Makes sense.
Show 37 quoted lines
> Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
> ---
> fetch-pack.c | 19 +++++++++++--------
> 1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/fetch-pack.c b/fetch-pack.c
> index 4e1e88eea0..6d0d271259 100644
> --- a/fetch-pack.c
> +++ b/fetch-pack.c
> @@ -1370,17 +1370,20 @@ static int send_fetch_request(struct fetch_negotiator *negotiator, int fd_out,
> static int process_section_header(struct packet_reader *reader,
> const char *section, int peek)
> {
> - int ret;
> -
> - if (packet_reader_peek(reader) != PACKET_READ_NORMAL)
> - die(_("error reading section header '%s'"), section);
> + int ret = 0;
>
> - ret = !strcmp(reader->line, section);
> + if (packet_reader_peek(reader) == PACKET_READ_NORMAL &&
> + !strcmp(reader->line, section))
> + ret = 1;
>
> if (!peek) {
> - if (!ret)
> - die(_("expected '%s', received '%s'"),
> - section, reader->line);
> + if (!ret) {
> + if (reader->line)
> + die(_("expected '%s', received '%s'"),
> + section, reader->line);
> + else
> + die(_("expected '%s'"), section);
> + }
> packet_reader_read(reader);
> }