freebsd-dev/lib/libc/stdio/fread.c
David Xu 3b52e4d1b7 With current pthread implementations, a mutex initialization will
allocate a memory block. sscanf calls __svfscanf which in turn calls
fread, fread triggers mutex initialization but the mutex is not
destroyed in sscanf, this leads to memory leak. To avoid the memory
leak and performance issue, we create a none MT-safe version of fread:
__fread, and instead let __svfscanf call __fread.

PR: threads/90392
Patch submitted by: dhartmei
MFC after: 7 days
2005-12-16 02:50:53 +00:00

101 lines
3.2 KiB
C

/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fread.c 8.2 (Berkeley) 12/11/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <stdio.h>
#include <string.h>
#include "un-namespace.h"
#include "local.h"
#include "libc_private.h"
/*
* MT-safe version
*/
size_t
fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
{
int ret;
FLOCKFILE(fp);
ret = __fread(buf, size, count, fp);
FUNLOCKFILE(fp);
return (ret);
}
size_t
__fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict fp)
{
size_t resid;
char *p;
int r;
size_t total;
/*
* The ANSI standard requires a return value of 0 for a count
* or a size of 0. Peculiarily, it imposes no such requirements
* on fwrite; it only requires fread to be broken.
*/
if ((resid = count * size) == 0)
return (0);
ORIENT(fp, -1);
if (fp->_r < 0)
fp->_r = 0;
total = resid;
p = buf;
while (resid > (r = fp->_r)) {
(void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
fp->_p += r;
/* fp->_r = 0 ... done in __srefill */
p += r;
resid -= r;
if (__srefill(fp)) {
/* no more input: return partial result */
return ((total - resid) / size);
}
}
(void)memcpy((void *)p, (void *)fp->_p, resid);
fp->_r -= resid;
fp->_p += resid;
return (count);
}