git/compat/qsort.c
Brandon Casey 040a655116 cleanup: use internal memory allocation wrapper functions everywhere
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>
2011-10-06 13:54:32 -07:00

63 lines
1.1 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.
*/
static void msort_with_tmp(void *b, size_t n, size_t s,
int (*cmp)(const void *, const void *),
char *t)
{
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);
msort_with_tmp(b2, n2, s, cmp, t);
tmp = t;
while (n1 > 0 && n2 > 0) {
if (cmp(b1, b2) <= 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);
}
void git_qsort(void *b, size_t n, size_t s,
int (*cmp)(const void *, const void *))
{
const size_t size = n * s;
char buf[1024];
if (size < sizeof(buf)) {
/* The temporary array fits on the small on-stack buffer. */
msort_with_tmp(b, n, s, cmp, buf);
} else {
/* It's somewhat large, so malloc it. */
char *tmp = xmalloc(size);
msort_with_tmp(b, n, s, cmp, tmp);
free(tmp);
}
}