release/src/router/mysql/strings/r_strinstr.c

   1 /* Copyright (c) 2000, 2001, 2004, 2007 MySQL AB
   2    Use is subject to license terms.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; version 2 of the License.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11    GNU General Public License for more details.
  12
  13    You should have received a copy of the GNU General Public License
  14    along with this program; if not, write to the Free Software
  15    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
  16 */
  17
  18 /*
  19   Author : David
  20   strintstr(src, from, pat) looks for an instance of pat in src
  21   backwards from pos from.  pat is not a regex(3) pattern, it is a literal
  22   string which must be matched exactly.
  23   The result 0 if the pattern was not found else it is the start char of
  24   the pattern counted from the begining of the string.
  25 */
  26
  27 #include <my_global.h>
  28 #include "m_string.h"
  29
  30 size_t r_strinstr(reg1 const char * str, size_t from, reg4 const char * search)
  31 {
  32   reg2 const char *i, *j;
  33   size_t        len = strlen(search);
  34   /* pointer to the last char of buff */
  35   const char *  start = str + from - 1;
  36   /* pointer to the last char of search */
  37   const char *  search_end = search + len - 1;
  38
  39  skip:
  40   while (start >= str)          /* Cant be != because the first char */
  41   {
  42     if (*start-- == *search_end)
  43     {
  44       i = start; j = search_end - 1;
  45       while (j >= search && start > str)
  46         if (*i-- != *j--)
  47           goto skip;
  48       return (size_t) ((start - len) - str + 3);
  49     }
  50   }
  51   return (0);
  52 }