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#include <unistd.h>
#include "memory-util.h"
size_t page_size(void) {
static thread_local size_t pgsz = 0;
long r;
if (_likely_(pgsz > 0))
return pgsz;
r = sysconf(_SC_PAGESIZE);
assert(r > 0);
pgsz = (size_t) r;
return pgsz;
}
bool memeqzero(const void *data, size_t length) {
/* Does the buffer consist entirely of NULs?
* Copied from https://github.com/systemd/casync/, copied in turn from
* https://github.com/rustyrussell/ccan/blob/master/ccan/mem/mem.c#L92,
* which is licensed CC-0.
*/
const uint8_t *p = data;
size_t i;
/* Check first 16 bytes manually */
for (i = 0; i < 16; i++, length--) {
if (length == 0)
return true;
if (p[i])
return false;
}
/* Now we know first 16 bytes are NUL, memcmp with self. */
return memcmp(data, p + i, length) == 0;
}
#if !HAVE_EXPLICIT_BZERO
/*
* The pointer to memset() is volatile so that compiler must de-reference the pointer and can't assume that
* it points to any function in particular (such as memset(), which it then might further "optimize"). This
* approach is inspired by openssl's crypto/mem_clr.c.
*/
typedef void *(*memset_t)(void *,int,size_t);
static volatile memset_t memset_func = memset;
void* explicit_bzero_safe(void *p, size_t l) {
if (l > 0)
memset_func(p, '\0', l);
return p;
}
#endif
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