libc/string/strcasestr.c

   1 /*
   2  * Copyright (C) 2002     Manuel Novoa III
   3  * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
   4  *
   5  * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
   6  */
   7
   8 #include "_string.h"
   9 #include <ctype.h>
  10
  11 char *strcasestr(const char *s1, const char *s2)
  12 {
  13         register const char *s = s1;
  14         register const char *p = s2;
  15
  16 #if 1
  17         do {
  18                 if (!*p) {
  19                         return (char *) s1;;
  20                 }
  21                 if ((*p == *s)
  22                         || (tolower(*((unsigned char *)p)) == tolower(*((unsigned char *)s)))
  23                         ) {
  24                         ++p;
  25                         ++s;
  26                 } else {
  27                         p = s2;
  28                         if (!*s) {
  29                                 return NULL;
  30                         }
  31                         s = ++s1;
  32                 }
  33         } while (1);
  34 #else
  35         while (*p && *s) {
  36                 if ((*p == *s)
  37                         || (tolower(*((unsigned char *)p)) == tolower(*((unsigned char *)s)))
  38                         ) {
  39                         ++p;
  40                         ++s;
  41                 } else {
  42                         p = s2;
  43                         s = ++s1;
  44                 }
  45         }
  46
  47         return (*p) ? NULL : (char *) s1;
  48 #endif
  49 }
  50 libc_hidden_def(strcasestr)