latest sources commit

deps/mysqllite/mysys/my_memmem.c

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+/* Copyright (C) 2000 MySQL AB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+#include <my_global.h>
+#include <m_string.h>
+
+/*
+  my_memmem, port of a GNU extension.
+
+  Returns a pointer to the beginning of the substring, needle, or NULL if the
+  substring is not found in haystack.
+*/
+
+void *my_memmem(const void *haystack, size_t haystacklen,
+                const void *needle, size_t needlelen)
+{
+  const unsigned char *cursor;
+  const unsigned char *last_possible_needle_location =
+    (unsigned char *)haystack + haystacklen - needlelen;
+
+  /* Easy answers */
+  if (needlelen > haystacklen) return(NULL);
+  if (needle == NULL) return(NULL);
+  if (haystack == NULL) return(NULL);
+  if (needlelen == 0) return(NULL);
+  if (haystacklen == 0) return(NULL);
+
+  for (cursor = haystack; cursor <= last_possible_needle_location; cursor++) {
+    if (memcmp(needle, cursor, needlelen) == 0) {
+      return((void *) cursor);
+    }
+  }
+  return(NULL);
+}
+
+  
+
+#ifdef MAIN
+#include <assert.h>
+
+int main(int argc, char *argv[]) {
+  char haystack[10], needle[3];
+
+  memmove(haystack, "0123456789", 10);
+
+  memmove(needle, "no", 2);
+  assert(my_memmem(haystack, 10, needle, 2) == NULL);
+
+  memmove(needle, "345", 3);
+  assert(my_memmem(haystack, 10, needle, 3) != NULL);
+
+  memmove(needle, "789", 3);
+  assert(my_memmem(haystack, 10, needle, 3) != NULL);
+  assert(my_memmem(haystack, 9, needle, 3) == NULL);
+
+  memmove(needle, "012", 3);
+  assert(my_memmem(haystack, 10, needle, 3) != NULL);
+  assert(my_memmem(NULL, 10, needle, 3) == NULL);
+
+  assert(my_memmem(NULL, 10, needle, 3) == NULL);
+  assert(my_memmem(haystack, 0, needle, 3) == NULL);
+  assert(my_memmem(haystack, 10, NULL, 3) == NULL);
+  assert(my_memmem(haystack, 10, needle, 0) == NULL);
+
+  assert(my_memmem(haystack, 1, needle, 3) == NULL);
+
+  printf("success\n");
+  return(0);
+}
+
+#endif