mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 05:51:10 +00:00
1261b97d10
* sysdeps/generic/memmem.c (memmem): Check arguments to avoid possibly searching through the whole memory. Closes PR libc/1730, reported by Greg Hudson <ghudson@mit.edu>.
55 lines
1.8 KiB
C
55 lines
1.8 KiB
C
/* Copyright (C) 1991,92,93,94,96,97,98,2000 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., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include <stddef.h>
|
|
#include <string.h>
|
|
|
|
#undef memmem
|
|
|
|
/* Return the first occurrence of NEEDLE in HAYSTACK. */
|
|
void *
|
|
memmem (haystack, haystack_len, needle, needle_len)
|
|
const void *haystack;
|
|
size_t haystack_len;
|
|
const void *needle;
|
|
size_t needle_len;
|
|
{
|
|
const char *begin;
|
|
const char *const last_possible
|
|
= (const char *) haystack + haystack_len - needle_len;
|
|
|
|
if (needle_len == 0)
|
|
/* The first occurrence of the empty string is deemed to occur at
|
|
the beginning of the string. */
|
|
return (void *) haystack;
|
|
|
|
/* Sanity check, otherwise the loop might search through the whole
|
|
memory. */
|
|
if (__builtin_expect (haystack_len < needle_len, 0))
|
|
return NULL;
|
|
|
|
for (begin = (const char *) haystack; begin <= last_possible; ++begin)
|
|
if (begin[0] == ((const char *) needle)[0] &&
|
|
!memcmp ((const void *) &begin[1],
|
|
(const void *) ((const char *) needle + 1),
|
|
needle_len - 1))
|
|
return (void *) begin;
|
|
|
|
return NULL;
|
|
}
|