|
@@ -498,21 +498,29 @@ tor_memmem(const void *_haystack, size_t hlen,
|
|
|
#else
|
|
|
/* This isn't as fast as the GLIBC implementation, but it doesn't need to
|
|
|
* be. */
|
|
|
- const char *p, *end;
|
|
|
+ const char *p, *last_possible_start;
|
|
|
const char *haystack = (const char*)_haystack;
|
|
|
const char *needle = (const char*)_needle;
|
|
|
char first;
|
|
|
tor_assert(nlen);
|
|
|
|
|
|
+ if (nlen > hlen)
|
|
|
+ return NULL;
|
|
|
+
|
|
|
p = haystack;
|
|
|
- end = haystack + hlen;
|
|
|
+ /* Last position at which the needle could start. */
|
|
|
+ last_possible_start = haystack + hlen - nlen;
|
|
|
first = *(const char*)needle;
|
|
|
- while ((p = memchr(p, first, end-p))) {
|
|
|
- if (p+nlen > end)
|
|
|
- return NULL;
|
|
|
+ while ((p = memchr(p, first, last_possible_start + 1 - p))) {
|
|
|
if (fast_memeq(p, needle, nlen))
|
|
|
return p;
|
|
|
- ++p;
|
|
|
+ if (++p > last_possible_start) {
|
|
|
+ /* This comparison shouldn't be necessary, since if p was previously
|
|
|
+ * equal to last_possible_start, the next memchr call would be
|
|
|
+ * "memchr(p, first, 0)", which will return NULL. But it clarifies the
|
|
|
+ * logic. */
|
|
|
+ return NULL;
|
|
|
+ }
|
|
|
}
|
|
|
return NULL;
|
|
|
#endif
|