mirror of
https://github.com/git/git
synced 2024-08-27 11:39:22 +00:00
![René Scharfe](/assets/img/avatar_default.png)
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 <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
70 lines
1.3 KiB
C
70 lines
1.3 KiB
C
#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;
|
|
}
|