From 354bb40e75d94466e91fe6960523612c9d17ccfb Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 2 Nov 2017 23:11:29 +0300
Subject: Add implementation

---
 mysql/mysys/my_memmem.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 mysql/mysys/my_memmem.c

(limited to 'mysql/mysys/my_memmem.c')

diff --git a/mysql/mysys/my_memmem.c b/mysql/mysys/my_memmem.c
new file mode 100644
index 0000000..e15dedf
--- /dev/null
+++ b/mysql/mysys/my_memmem.c
@@ -0,0 +1,84 @@
+/* Copyright (c) 2000, 2006, 2007 MySQL AB
+   Use is subject to license terms
+
+   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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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
-- 
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