The sha1_to_hex and find_unique_abbrev functions always
write into reusable static buffers. There are a few problems
with this:
- future calls overwrite our result. This is especially
annoying with find_unique_abbrev, which does not have a
ring of buffers, so you cannot even printf() a result
that has two abbreviated sha1s.
- if you want to put the result into another buffer, we
often strcpy, which looks suspicious when auditing for
overflows.
This patch introduces sha1_to_hex_r and find_unique_abbrev_r,
which write into a user-provided buffer. Of course this is
just punting on the overflow-auditing, as the buffer
obviously needs to be GIT_SHA1_HEXSZ + 1 bytes. But it is
much easier to audit, since that is a well-known size.
We retain the non-reentrant forms, which just become thin
wrappers around the reentrant ones. This patch also adds a
strbuf variant of find_unique_abbrev, which will be handy in
later patches.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are several utility functions (hashcmp and friends) that are used
for comparing object IDs (SHA-1 values). Using these functions, which
take pointers to unsigned char, with struct object_id requires tiresome
access to the sha1 member, which bloats code and violates the desired
encapsulation. Provide wrappers around these functions for struct
object_id for neater, more maintainable code. Use the new constants to
avoid the hard-coded 20s and 40s throughout the original functions.
These functions simply call the underlying pointer-to-unsigned-char
versions to ensure that any performance improvements will be passed
through to the new functions.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
41 bytes is the exact number of bytes needed for having the returned
hex string represented. 50 seems to be an arbitrary number, such
that there are no benefits from alignment to certain address boundaries.
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Previously, get_sha1_hex() would read one character past the end of a
null-terminated string whose strlen was an even number less than 40.
Although the function correctly returned -1 in these cases, the extra
memory access might have been to uninitialized (or even, conceivably,
unallocated) memory.
Add a check to avoid reading past the end of a string.
This problem was discovered by Thomas Rast <trast@student.ethz.ch>
using valgrind.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As the documentation says, this is primarily for debugging, and
in the longer term we should rename it to test-show-index or something.
In the meantime, just avoid xmalloc (which slurps in the rest of git), and
separating out the trivial hex functions into "hex.o".
This results in
[torvalds@nehalem git]$ size git-show-index
text data bss dec hex filename
222818 2276 112688 337782 52776 git-show-index (before)
5696 624 1264 7584 1da0 git-show-index (after)
which is a whole lot better.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King
brian m. carlson
Junio C Hamano
Stefan Beller
Michael Haggerty
Linus Torvalds