firmware/libc/strstr.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  *
   9  * Copyright (C) 2002     Manuel Novoa III
  10  * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
  11  *
  12  * Licensed under the LGPL v2.1, code originally in uclibc
  13  *
  14  ****************************************************************************/
  15 #include <string.h>
  16
  17 /* NOTE: This is the simple-minded O(len(s1) * len(s2)) worst-case approach. */
  18
  19 char *strstr(const char *s1, const char *s2)
  20 {
  21     register const char *s = s1;
  22     register const char *p = s2;
  23
  24     do {
  25         if (!*p) {
  26             return (char *) s1;
  27         }
  28         if (*p == *s) {
  29             ++p;
  30             ++s;
  31         } else {
  32             p = s2;
  33             if (!*s) {
  34                 return NULL;
  35             }
  36             s = ++s1;
  37         }
  38     } while (1);
  39 }