1 #include <stdlib.h>
2 #include <stdint.h>
3 #include <string.h>
4 #include <errno.h>
5 #include "dynlink.h"
6
mal0_clear(char * p,size_t n)7 static size_t mal0_clear(char *p, size_t n)
8 {
9 const size_t pagesz = 4096; /* arbitrary */
10 if (n < pagesz) return n;
11 #ifdef __GNUC__
12 typedef uint64_t __attribute__((__may_alias__)) T;
13 #else
14 typedef unsigned char T;
15 #endif
16 char *pp = p + n;
17 size_t i = (uintptr_t)pp & (pagesz - 1);
18 for (;;) {
19 pp = memset(pp - i, 0, i);
20 if (pp - p < pagesz) return pp - p;
21 for (i = pagesz; i; i -= 2*sizeof(T), pp -= 2*sizeof(T))
22 if (((T *)pp)[-1] | ((T *)pp)[-2])
23 break;
24 }
25 }
26
allzerop(void * p)27 static int allzerop(void *p)
28 {
29 return 0;
30 }
31 weak_alias(allzerop, __malloc_allzerop);
32
calloc(size_t m,size_t n)33 void *calloc(size_t m, size_t n)
34 {
35 if (n && m > (size_t)-1/n) {
36 errno = ENOMEM;
37 return 0;
38 }
39 n *= m;
40 void *p = malloc(n);
41 if (!p || (!__malloc_replaced && __malloc_allzerop(p)))
42 return p;
43 n = mal0_clear(p, n);
44 return memset(p, 0, n);
45 }
46