Merge branch 'jk/perf-no-dups'
[git/git.git] / compat / memmem.c
1 #include "../git-compat-util.h"
2
3 void *gitmemmem(const void *haystack, size_t haystack_len,
4 const void *needle, size_t needle_len)
5 {
6 const char *begin = haystack;
7 const char *last_possible = begin + haystack_len - needle_len;
8 const char *tail = needle;
9 char point;
10
11 /*
12 * The first occurrence of the empty string is deemed to occur at
13 * the beginning of the string.
14 */
15 if (needle_len == 0)
16 return (void *)begin;
17
18 /*
19 * Sanity check, otherwise the loop might search through the whole
20 * memory.
21 */
22 if (haystack_len < needle_len)
23 return NULL;
24
25 point = *tail++;
26 for (; begin <= last_possible; begin++) {
27 if (*begin == point && !memcmp(begin + 1, tail, needle_len - 1))
28 return (void *)begin;
29 }
30
31 return NULL;
32 }