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If our size computation overflows size_t, we may allocate a
much smaller buffer than we expected and overflow it. It's
probably impossible to trigger an overflow in most of these
sites in practice, but it is easy enough convert their
additions and multiplications into overflow-checking
variants. This may be fixing real bugs, and it makes
auditing the code easier.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The "x"-prefixed versions of strdup, malloc, etc. will check whether the
allocation was successful and terminate the process otherwise.
A few uses of malloc were left alone since they already implemented a
graceful path of failure or were in a quasi external library like xdiff.
Additionally, the call to malloc in compat/win32/syslog.c was not modified
since the syslog() implemented there is a die handler and a call to the
x-wrappers within a die handler could result in recursion should memory
allocation fail. This will have to be addressed separately.
Signed-off-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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qsort in Windows 2000 (and various other C libraries) is a Quicksort
with the usual O(n^2) worst case. Unfortunately, sorting Git trees
seems to get very close to that worst case quite often:
$ /git/gitbad runstatus
# On branch master
qsort, nmemb = 30842
done, 237838087 comparisons.
This patch adds a simplified version of the merge sort that is glibc's
qsort(3). As a merge sort, this needs a temporary array equal in size
to the array that is to be sorted, but has a worst-case performance of
O(n log n).
The complexity that was removed is:
* Doing direct stores for word-size and -aligned data.
* Falling back to quicksort if the allocation required to perform the
merge sort would likely push the machine into swap.
Even with these simplifications, this seems to outperform the Windows
qsort(3) implementation, even in Windows XP (where it is "fixed" and
doesn't trigger O(n^2) complexity on trees).
[jes: moved into compat/qsort.c, as per Johannes Sixt's suggestion]
[bcd: removed gcc-ism, thanks to Edgar Toernig. renamed make variable
per Junio's comment.]
Signed-off-by: Brian Downing <bdowning@lavos.net>
Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Jeff King
Brandon Casey
Brian Downing