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pkt-line: prepare buffer before handling ERR packets 

Since 2d103c31c2 (pack-protocol.txt: accept error packets in any
context, 2018-12-29), the pktline code will detect an ERR packet and die
automatically, saving the caller from dealing with it. But we do so too
early in the function, before we have terminated the buffer with a NUL.

As a result, passing the ERR message to die() may result in us printing
random cruft from a previous packet. This doesn't trigger memory tools
like ASan because we reuse the same buffer over and over (so the
contents are valid and initialized; they're just stale).

We can see demonstrate this by tightening the regex we use to match the
error message in t5516; without this patch, git-fetch will accidentally
print the capabilities from the (much longer) initial packet we
received.

By moving the ERR code later in the function we get a few other
benefits, too:

  - we'll now chomp any newline sent by the other side (which is what we
    want, since die() will add its own newline)

  - we'll now mention the ERR packet with GIT_TRACE_PACKET

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2019-04-13 01:54:02 -04:00 committed by Junio C Hamano
parent 014ade7484
commit 533ddba47e
2 changed files with 6 additions and 5 deletions
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9
pkt-line.c
View File

@ -350,16 +350,17 @@ enum packet_read_status packet_read_with_status(int fd, char **src_buffer,
return PACKET_READ_EOF;
}
if ((options & PACKET_READ_DIE_ON_ERR_PACKET) &&
starts_with(buffer, "ERR "))
die(_("remote error: %s"), buffer + 4);
if ((options & PACKET_READ_CHOMP_NEWLINE) &&
len && buffer[len-1] == '\n')
len--;
buffer[len] = 0;
packet_trace(buffer, len, 0);
if ((options & PACKET_READ_DIE_ON_ERR_PACKET) &&
starts_with(buffer, "ERR "))
die(_("remote error: %s"), buffer + 4);
*pktlen = len;
return PACKET_READ_NORMAL;
}

2
t/t5516-fetch-push.sh
View File

@ -1241,7 +1241,7 @@ do
git fetch ../testrepo/.git $SHA1_2 &&
git cat-file commit $SHA1_2 &&
test_must_fail git fetch ../testrepo/.git $SHA1_3 2>err &&
test_i18ngrep "remote error:.*not our ref" err
test_i18ngrep "remote error:.*not our ref.*$SHA1_3\$" err
)
'
done