1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3 #include <unistd.h>
4
5 #include "memory-util.h"
6
page_size(void)7 size_t page_size(void) {
8 static thread_local size_t pgsz = 0;
9 long r;
10
11 if (_likely_(pgsz > 0))
12 return pgsz;
13
14 r = sysconf(_SC_PAGESIZE);
15 assert(r > 0);
16
17 pgsz = (size_t) r;
18 return pgsz;
19 }
20
memeqbyte(uint8_t byte,const void * data,size_t length)21 bool memeqbyte(uint8_t byte, const void *data, size_t length) {
22 /* Does the buffer consist entirely of the same specific byte value?
23 * Copied from https://github.com/systemd/casync/, copied in turn from
24 * https://github.com/rustyrussell/ccan/blob/master/ccan/mem/mem.c#L92,
25 * which is licensed CC-0.
26 */
27
28 const uint8_t *p = data;
29
30 /* Check first 16 bytes manually */
31 for (size_t i = 0; i < 16; i++, length--) {
32 if (length == 0)
33 return true;
34 if (p[i] != byte)
35 return false;
36 }
37
38 /* Now we know first 16 bytes match, memcmp() with self. */
39 return memcmp(data, p + 16, length) == 0;
40 }
41
42 #if !HAVE_EXPLICIT_BZERO
43 /*
44 * The pointer to memset() is volatile so that compiler must de-reference the pointer and can't assume that
45 * it points to any function in particular (such as memset(), which it then might further "optimize"). This
46 * approach is inspired by openssl's crypto/mem_clr.c.
47 */
48 typedef void *(*memset_t)(void *,int,size_t);
49
50 static volatile memset_t memset_func = memset;
51
explicit_bzero_safe(void * p,size_t l)52 void* explicit_bzero_safe(void *p, size_t l) {
53 if (l > 0)
54 memset_func(p, '\0', l);
55
56 return p;
57 }
58 #endif
59