From 28f540f45bbacd939bfd07f213bcad2bf730b1bf Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Sat, 18 Feb 1995 01:27:10 +0000 Subject: initial import --- sysdeps/generic/strstr.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 sysdeps/generic/strstr.c (limited to 'sysdeps/generic/strstr.c') diff --git a/sysdeps/generic/strstr.c b/sysdeps/generic/strstr.c new file mode 100644 index 0000000000..06681de931 --- /dev/null +++ b/sysdeps/generic/strstr.c @@ -0,0 +1,56 @@ +/* Copyright (C) 1991, 1992 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#include +#include +#include + +/* Return the first ocurrence of NEEDLE in HAYSTACK. */ +char * +DEFUN(strstr, (haystack, needle), + CONST char *CONST haystack AND + CONST char *CONST needle) +{ + register CONST char *CONST needle_end = strchr(needle, '\0'); + register CONST char *CONST haystack_end = strchr(haystack, '\0'); + register CONST size_t needle_len = needle_end - needle; + register CONST size_t needle_last = needle_len - 1; + register CONST char *begin; + + if (needle_len == 0) + return (char *) haystack; /* ANSI 4.11.5.7, line 25. */ + if ((size_t) (haystack_end - haystack) < needle_len) + return NULL; + + for (begin = &haystack[needle_last]; begin < haystack_end; ++begin) + { + register CONST char *n = &needle[needle_last]; + register CONST char *h = begin; + + do + if (*h != *n) + goto loop; /* continue for loop */ + while (--n >= needle && --h >= haystack); + + return (char *) h; + + loop:; + } + + return NULL; +} -- cgit v1.2.3