* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
-/*
- * This uses the "Not So Naive" algorithm, a very simple but
- * usually effective algorithm, see:
- * http://www-igm.univ-mlv.fr/~lecroq/string/
- */
+
#include <string.h>
-void *memmem(const void *haystack, size_t n, const void *needle, size_t m)
-{
- if (m > n || !m || !n)
- return NULL;
+void* memmem(const void* void_haystack, size_t n, const void* void_needle, size_t m) {
+ const unsigned char* haystack = reinterpret_cast<const unsigned char*>(void_haystack);
+ const unsigned char* needle = reinterpret_cast<const unsigned char*>(void_needle);
+
+ if (n < m) return nullptr;
+
+ if (m == 0) return const_cast<void*>(void_haystack);
+ if (m == 1) return memchr(haystack, needle[0], n);
- if (__builtin_expect((m > 1), 1)) {
- const unsigned char* y = (const unsigned char*) haystack;
- const unsigned char* x = (const unsigned char*) needle;
- size_t j = 0;
- size_t k = 1, l = 2;
+ // This uses the "Not So Naive" algorithm, a very simple but usually effective algorithm.
+ // http://www-igm.univ-mlv.fr/~lecroq/string/
+ const unsigned char* y = haystack;
+ const unsigned char* x = needle;
+ size_t j = 0;
+ size_t k = 1, l = 2;
- if (x[0] == x[1]) {
- k = 2;
- l = 1;
- }
- while (j <= n-m) {
- if (x[1] != y[j+1]) {
- j += k;
- } else {
- if (!memcmp(x+2, y+j+2, m-2) && x[0] == y[j])
- return (void*) &y[j];
- j += l;
- }
- }
+ if (x[0] == x[1]) {
+ k = 2;
+ l = 1;
+ }
+ while (j <= n-m) {
+ if (x[1] != y[j+1]) {
+ j += k;
} else {
- /* degenerate case */
- return memchr(haystack, ((unsigned char*)needle)[0], n);
+ if (!memcmp(x+2, y+j+2, m-2) && x[0] == y[j]) return const_cast<unsigned char*>(&y[j]);
+ j += l;
}
- return NULL;
+ }
+ return nullptr;
}
}
RunSingleBufferAlignTest(MEDIUM, DoMemcpySameTest);
}
+
+TEST(STRING_TEST, memmem_strstr_empty_needle) {
+ const char* some_haystack = "haystack";
+ const char* empty_haystack = "";
+
+ ASSERT_EQ(some_haystack, memmem(some_haystack, 8, "", 0));
+ ASSERT_EQ(empty_haystack, memmem(empty_haystack, 0, "", 0));
+
+ ASSERT_EQ(some_haystack, strstr(some_haystack, ""));
+ ASSERT_EQ(empty_haystack, strstr(empty_haystack, ""));
+}
+
+TEST(STRING_TEST, memmem_smoke) {
+ const char haystack[] = "big\0daddy\0giant\0haystacks";
+ ASSERT_EQ(haystack, memmem(haystack, sizeof(haystack), "", 0));
+ ASSERT_EQ(haystack + 3, memmem(haystack, sizeof(haystack), "", 1));
+ ASSERT_EQ(haystack + 0, memmem(haystack, sizeof(haystack), "b", 1));
+ ASSERT_EQ(haystack + 1, memmem(haystack, sizeof(haystack), "i", 1));
+ ASSERT_EQ(haystack + 4, memmem(haystack, sizeof(haystack), "da", 2));
+ ASSERT_EQ(haystack + 8, memmem(haystack, sizeof(haystack), "y\0g", 3));
+}
+
+TEST(STRING_TEST, strstr_smoke) {
+ const char* haystack = "big daddy/giant haystacks";
+ ASSERT_EQ(haystack, strstr(haystack, ""));
+ ASSERT_EQ(haystack + 0, strstr(haystack, "b"));
+ ASSERT_EQ(haystack + 1, strstr(haystack, "i"));
+ ASSERT_EQ(haystack + 4, strstr(haystack, "da"));
+}