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