1/* Copyright (C) 1991, 1992 Free Software Foundation, Inc. 2This file is part of the GNU C Library. 3 4The GNU C Library is free software; you can redistribute it and/or 5modify it under the terms of the GNU Library General Public License as 6published by the Free Software Foundation; either version 2 of the 7License, or (at your option) any later version. 8 9The GNU C Library is distributed in the hope that it will be useful, 10but WITHOUT ANY WARRANTY; without even the implied warranty of 11MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12Library General Public License for more details. 13 14You should have received a copy of the GNU Library General Public 15License along with the GNU C Library; see the file COPYING.LIB. If 16not, write to the Free Software Foundation, Inc., 59 Temple Place - 17Suite 330, Boston, MA 02111-1307, USA. 18 19This file was modified slightly by Ian Lance Taylor, May 1992, for 20Taylor UUCP. */ 21 22#include "uucp.h" 23 24/* Return the first ocurrence of NEEDLE in HAYSTACK. */ 25char * 26strstr (haystack, needle) 27 const char *const haystack; 28 const char *const needle; 29{ 30 register const char *const needle_end = strchr(needle, '\0'); 31 register const char *const haystack_end = strchr(haystack, '\0'); 32 register const size_t needle_len = needle_end - needle; 33 register const size_t needle_last = needle_len - 1; 34 register const char *begin; 35 36 if (needle_len == 0) 37 return (char *) haystack_end; 38 if ((size_t) (haystack_end - haystack) < needle_len) 39 return NULL; 40 41 for (begin = &haystack[needle_last]; begin < haystack_end; ++begin) 42 { 43 register const char *n = &needle[needle_last]; 44 register const char *h = begin; 45 do 46 if (*h != *n) 47 goto loop; 48 while (--n >= needle && --h >= haystack); 49 50 return (char *) h; 51 loop:; 52 } 53 54 return NULL; 55} 56