When we try to load an object from disk and fail, our
general strategy is to see if we can get it from somewhere
else (e.g., a loose object). That lets users fix corruption
problems by copying known-good versions of objects into the
object database.
We already handle the case where we were not able to read
the delta from disk. However, when we find that the delta we
read does not apply, we simply die. This case is harder to
trigger, as corruption in the delta data itself would
trigger a crc error from zlib. However, a corruption that
pointed us at the wrong delta base might cause it.
We can do the same "fail and try to find the object
elsewhere" trick instead of dying. This not only gives us a
chance to recover, but also puts us on code paths that will
alert the user to the problem (with the current message,
they do not even know which sha1 caused the problem).
Note that unlike some other pack corruptions, we do not
recover automatically from this case when doing a repack.
There is nothing apparently wrong with the delta, as it
points to a valid, accessible object, and we realize the
error only when the resulting size does not match up. And in
theory, one could even have a case where the corrupted size
is the same, and the problem would only be noticed by
recomputing the sha1.
We can get around this by recomputing the deltas with
--no-reuse-delta, which our test does (and this is probably
good advice for anyone recovering from pack corruption).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test corrupts pack objects by using "dd" with a seek
command. It passes "count=1 bs=1" to munge just a single
byte. However, the test added in commit b3118bdc wants to
munge two bytes, and the second byte of corruption is
silently ignored.
This turned out not to impact the test, however. The idea
was to reduce the "size of this entry" part of the header so
that zlib runs out of input bytes while inflating the entry.
That header is two bytes long, and the test reduced the
value of both bytes; since we experience the problem if we
are off by even 1 byte, it is sufficient to munge only the
first one.
Even though the test would have worked with only a single
byte munged, and we could simply tweak the test to use a
single byte, it makes sense to lift this 1-byte restriction
from do_corrupt_object. It will allow future tests that do
need to change multiple bytes to do so.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Otherwise it will be split at a space after "Program" when it is set
to "\\Program Files\perl" or something silly like that.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
GIT-BUILD-OPTIONS defines PERL_PATH to be used in the test suite. Only a
few tests already actually use this variable when perl is needed. The
other test just call 'perl' and it might happen that the wrong perl
interpreter is used.
This becomes problematic on Windows, when the perl interpreter that is
compiled and installed on the Windows system is used, because this perl
interpreter might introduce some unexpected LF->CRLF conversions.
This patch makes sure that $PERL_PATH is used everywhere in the test suite
and that the correct perl interpreter is used.
Signed-off-by: Vincent van Ravesteijn <vfr@lyx.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some types of corruption to a pack may confuse the deflate stream
which stores an object. In Andy's reported case a 36 byte region
of the pack was overwritten, leading to what appeared to be a valid
deflate stream that was trying to produce a result larger than our
allocated output buffer could accept.
Z_BUF_ERROR is returned from inflate() if either the input buffer
needs more input bytes, or the output buffer has run out of space.
Previously we only considered the former case, as it meant we needed
to move the stream's input buffer to the next window in the pack.
We now abort the loop if inflate() returns Z_BUF_ERROR without
consuming the entire input buffer it was given, or has filled
the entire output buffer but has not yet returned Z_STREAM_END.
Either state is a clear indicator that this loop is not working
as expected, and should not continue.
This problem cannot occur with loose objects as we open the entire
loose object as a single buffer and treat Z_BUF_ERROR as an error.
Reported-by: Andy Isaacson <adi@hexapodia.org>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We do not have /dev/zero on Windows. This replaces it by data generated
with printf, perl, or echo. Most of the cases do not depend on that the
data is a stream of zero bytes, so we use something printable; nor is an
unlimited stream of data needed, so we produce only as many bytes as the
test cases need.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
printf "\x01" is bad; write printf "\001" for portability.
Testing with dash is a good way to find this kind of POSIX.1 violation
breakages.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The perldiag(1) has following to say about this:
"Can't do inplace edit without backup"
(F) You're on a system such as MS-DOS that gets confused if
you try reading from a deleted (but still opened) file. You
have to say -i.bak, or some such.
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
