minix/lib/libc/stdio/fopen.c

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/* $NetBSD: fopen.c,v 1.13 2008/03/13 15:40:00 christos Exp $ */
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/*-
* 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.
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*
* 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.
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*
* 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.
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*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)fopen.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: fopen.c,v 1.13 2008/03/13 15:40:00 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <sys/stat.h>
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <limits.h>
#include "reentrant.h"
#include "local.h"
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FILE *
fopen(file, mode)
const char *file;
const char *mode;
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{
FILE *fp;
int f;
int flags, oflags;
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_DIAGASSERT(file != NULL);
if ((flags = __sflags(mode, &oflags)) == 0)
return (NULL);
if ((fp = __sfp()) == NULL)
return (NULL);
if ((f = open(file, oflags, DEFFILEMODE)) < 0)
goto release;
if (oflags & O_NONBLOCK) {
struct stat st;
if (fstat(f, &st) == -1) {
int sverrno = errno;
(void)close(f);
errno = sverrno;
goto release;
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}
if (!S_ISREG(st.st_mode)) {
(void)close(f);
errno = EFTYPE;
goto release;
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}
}
/*
* File descriptors are a full int, but _file is only a short.
* If we get a valid file descriptor that is greater or equal to
* USHRT_MAX, then the fd will get sign-extended into an
* invalid file descriptor. Handle this case by failing the
* open. (We treat the short as unsigned, and special-case -1).
*/
if (f >= USHRT_MAX) {
errno = EMFILE;
goto release;
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}
fp->_file = f;
fp->_flags = flags;
fp->_cookie = fp;
fp->_read = __sread;
fp->_write = __swrite;
fp->_seek = __sseek;
fp->_close = __sclose;
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/*
* When opening in append mode, even though we use O_APPEND,
* we need to seek to the end so that ftell() gets the right
* answer. If the user then alters the seek pointer, or
* the file extends, this will fail, but there is not much
* we can do about this. (We could set __SAPP and check in
* fseek and ftell.)
*/
if (oflags & O_APPEND)
(void) __sseek((void *)fp, (fpos_t)0, SEEK_END);
return (fp);
release:
fp->_flags = 0; /* release */
return (NULL);
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}