From 04ee8b875b96c096c479132adca02fa734c3fa96 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ren=C3=A9=20Scharfe?= Date: Sun, 22 Jan 2017 18:51:11 +0100 Subject: compat: add qsort_s() The function qsort_s() was introduced with C11 Annex K; it provides the ability to pass a context pointer to the comparison function, supports the convention of using a NULL pointer for an empty array and performs a few safety checks. Add an implementation based on compat/qsort.c for platforms that lack a native standards-compliant qsort_s() (i.e. basically everyone). It doesn't perform the full range of possible checks: It uses size_t instead of rsize_t and doesn't check nmemb and size against RSIZE_MAX because we probably don't have the restricted size type defined. For the same reason it returns int instead of errno_t. Signed-off-by: Rene Scharfe Signed-off-by: Junio C Hamano --- compat/qsort_s.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 compat/qsort_s.c (limited to 'compat') diff --git a/compat/qsort_s.c b/compat/qsort_s.c new file mode 100644 index 000000000..52d1f0a73 --- /dev/null +++ b/compat/qsort_s.c @@ -0,0 +1,69 @@ +#include "../git-compat-util.h" + +/* + * A merge sort implementation, simplified from the qsort implementation + * by Mike Haertel, which is a part of the GNU C Library. + * Added context pointer, safety checks and return value. + */ + +static void msort_with_tmp(void *b, size_t n, size_t s, + int (*cmp)(const void *, const void *, void *), + char *t, void *ctx) +{ + char *tmp; + char *b1, *b2; + size_t n1, n2; + + if (n <= 1) + return; + + n1 = n / 2; + n2 = n - n1; + b1 = b; + b2 = (char *)b + (n1 * s); + + msort_with_tmp(b1, n1, s, cmp, t, ctx); + msort_with_tmp(b2, n2, s, cmp, t, ctx); + + tmp = t; + + while (n1 > 0 && n2 > 0) { + if (cmp(b1, b2, ctx) <= 0) { + memcpy(tmp, b1, s); + tmp += s; + b1 += s; + --n1; + } else { + memcpy(tmp, b2, s); + tmp += s; + b2 += s; + --n2; + } + } + if (n1 > 0) + memcpy(tmp, b1, n1 * s); + memcpy(b, t, (n - n2) * s); +} + +int git_qsort_s(void *b, size_t n, size_t s, + int (*cmp)(const void *, const void *, void *), void *ctx) +{ + const size_t size = st_mult(n, s); + char buf[1024]; + + if (!n) + return 0; + if (!b || !cmp) + return -1; + + if (size < sizeof(buf)) { + /* The temporary array fits on the small on-stack buffer. */ + msort_with_tmp(b, n, s, cmp, buf, ctx); + } else { + /* It's somewhat large, so malloc it. */ + char *tmp = xmalloc(size); + msort_with_tmp(b, n, s, cmp, tmp, ctx); + free(tmp); + } + return 0; +} -- cgit v1.2.1