mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-23 11:20:07 +00:00
57 lines
1.8 KiB
C
57 lines
1.8 KiB
C
|
/* 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 <ansidecl.h>
|
||
|
|
#include <stddef.h>
|
||
|
|
#include <string.h>
|
||
|
|
|
||
|
|
/* 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;
|
||
|
|
}
|