freebsd-skq/lib/libc/stdio/fread.c
Ed Schouten 77822acff7 Fix fwrite() to return 0 when size or nmemb are zero.
Right now nmemb is returned when size is 0. In newer versions of the
standards, it is explicitly required that fwrite() should return 0.

Submitted by:	Christoph Mallon
Approved by:	re (kib)
2009-07-12 13:09:43 +00:00

95 lines
2.9 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.
* 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)
{
size_t 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;
/*
* ANSI and SUSv2 require a return value of 0 if size or count are 0.
*/
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);
}