minix/lib/libc/stdio/refill.c

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/* $NetBSD: refill.c,v 1.16 2012/03/27 15:05:42 christos 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 <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)refill.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: refill.c,v 1.16 2012/03/27 15:05:42 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include "reentrant.h"
#include "local.h"
#ifdef _REENTRANT
extern rwlock_t __sfp_lock;
#endif
static int
lflush(FILE *fp)
{
_DIAGASSERT(fp != NULL);
if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
return __sflush(fp);
return 0;
}
/*
* Refill a stdio buffer.
* Return EOF on eof or error, 0 otherwise.
*/
int
__srefill(FILE *fp)
{
_DIAGASSERT(fp != NULL);
/* 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);
if ((fp->_r = fp->_ur) != 0) {
fp->_p = fp->_up;
return 0;
}
}
}
if (fp->_bf._base == NULL)
__smakebuf(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)) {
rwlock_rdlock(&__sfp_lock);
(void) _fwalk(lflush);
rwlock_unlock(&__sfp_lock);
}
fp->_p = fp->_bf._base;
fp->_r = (int)(*fp->_read)(fp->_cookie, (char *)fp->_p,
(size_t)fp->_bf._size);
fp->_flags &= ~__SMOD; /* buffer contents are again pristine */
if (fp->_r <= 0) {
if (fp->_r == 0)
fp->_flags |= __SEOF;
else {
fp->_r = 0;
fp->_flags |= __SERR;
}
return EOF;
}
return 0;
}