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path: root/compat/qsort.c
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2016-02-22use st_add and st_mult for allocation size computationLibravatar Jeff King1-1/+1
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>
2011-10-06cleanup: use internal memory allocation wrapper functions everywhereLibravatar Brandon Casey1-1/+1
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>
2008-02-06compat: Add simplified merge sort implementation from glibcLibravatar Brian Downing1-0/+62
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>