lib/sh/strcasestr.c

   1 /* strcasestr.c - Find if one string appears as a substring of another string,
   2                   without regard to case. */
   3
   4 /* Copyright (C) 2000 Free Software Foundation, Inc.
   5
   6    This file is part of GNU Bash, the Bourne Again SHell.
   7
   8    Bash is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    Bash is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include <config.h>
  23
  24 #include <bashansi.h>
  25 #include <chartypes.h>
  26
  27 #include <stdc.h>
  28
  29 /* Determine if s2 occurs in s1.  If so, return a pointer to the
  30    match in s1.  The compare is case insensitive.  This is a
  31    case-insensitive strstr(3). */
  32 char *
  33 strcasestr (s1, s2)
  34      const char *s1;
  35      const char *s2;
  36 {
  37   register int i, l, len, c;
  38
  39   c = TOLOWER ((unsigned char)s2[0]);
  40   len = strlen (s1);
  41   l = strlen (s2);
  42   for (i = 0; (len - i) >= l; i++)
  43     if ((TOLOWER ((unsigned char)s1[i]) == c) && (strncasecmp (s1 + i, s2, l) == 0))
  44       return ((char *)s1 + i);
  45   return ((char *)0);
  46 }