bool memeqzero(const void *data, size_t length)
{
const unsigned char *p = data;
- static unsigned long zeroes[16];
+ size_t len;
- while (length > sizeof(zeroes)) {
- if (memcmp(zeroes, p, sizeof(zeroes)))
+ /* Check first 16 bytes manually */
+ for (len = 0; len < 16; len++) {
+ if (!length)
+ return true;
+ if (*p)
return false;
- p += sizeof(zeroes);
- length -= sizeof(zeroes);
+ p++;
+ length--;
}
- return memcmp(zeroes, p, length) == 0;
+
+ /* Now we know that's zero, memcmp with self. */
+ return memcmp(data, p, length) == 0;
+}
+
+void memtaint(void *data, size_t len)
+{
+ /* Using 16 bytes is a bit quicker than 4 */
+ const unsigned tainter[]
+ = { 0xdeadbeef, 0xdeadbeef, 0xdeadbeef, 0xdeadbeef };
+ char *p = data;
+
+ while (len >= sizeof(tainter)) {
+ memcpy(p, tainter, sizeof(tainter));
+ p += sizeof(tainter);
+ len -= sizeof(tainter);
+ }
+ memcpy(p, tainter, len);
+
+#if HAVE_VALGRIND_MEMCHECK_H
+ VALGRIND_MAKE_MEM_UNDEFINED(data, len);
+#endif
}