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/* $OpenBSD: fread.c,v 1.6 2005/08/08 08:05:36 espie Exp $ */
/*-
* 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. 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.
*/
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "local.h"
static int
lflush(FILE *fp)
{
if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
return (__sflush(fp));
return (0);
}
size_t
fread(void *buf, size_t size, size_t count, FILE *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);
if (fp->_r < 0)
fp->_r = 0;
total = resid;
p = buf;
#if 1 /* BIONIC: optimize unbuffered reads */
if (fp->_flags & __SNBF && fp->_ur == 0)
{
/* the following comes mainly from __srefill(), with slight
* modifications
*/
/* make sure stdio is set up */
if (!__sdidinit)
__sinit();
fp->_r = 0; /* largely a convenience for callers */
/* SysV does not make this test; take it out for compatibility */
if (fp->_flags & __SEOF)
return (EOF);
/* if not already reading, have to be reading and writing */
if ((fp->_flags & __SRD) == 0) {
if ((fp->_flags & __SRW) == 0) {
errno = EBADF;
fp->_flags |= __SERR;
return (EOF);
}
/* switch to reading */
if (fp->_flags & __SWR) {
if (__sflush(fp))
return (EOF);
fp->_flags &= ~__SWR;
fp->_w = 0;
fp->_lbfsize = 0;
}
fp->_flags |= __SRD;
} else {
/*
* We were reading. If there is an ungetc buffer,
* we must have been reading from that. Drop it,
* restoring the previous buffer (if any). If there
* is anything in that buffer, return.
*/
if (HASUB(fp)) {
FREEUB(fp);
}
}
/*
* Before reading from a line buffered or unbuffered file,
* flush all line buffered output files, per the ANSI C
* standard.
*/
if (fp->_flags & (__SLBF|__SNBF))
(void) _fwalk(lflush);
while (resid > 0) {
int len = (*fp->_read)(fp->_cookie, p, resid );
fp->_flags &= ~__SMOD;
if (len <= 0) {
if (len == 0)
fp->_flags |= __SEOF;
else {
fp->_flags |= __SERR;
}
return ((total - resid) / size);
}
p += len;
resid -= len;
}
return (count);
}
else
#endif
{
while (resid > (size_t)(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);
}
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