fopen.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#if defined(LIBC_SCCS) && !defined(lint)
36static char sccsid[] = "@(#)fopen.c	8.1 (Berkeley) 6/4/93";
37#endif /* LIBC_SCCS and not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: stable/11/lib/libc/stdio/fopen.c 330897 2018-03-14 03:19:51Z eadler $");
40
41#include "namespace.h"
42#include <sys/types.h>
43#include <sys/stat.h>
44#include <fcntl.h>
45#include <unistd.h>
46#include <stdio.h>
47#include <errno.h>
48#include <limits.h>
49#include "un-namespace.h"
50
51#include "local.h"
52
53FILE *
54fopen(const char * __restrict file, const char * __restrict mode)
55{
56	FILE *fp;
57	int f;
58	int flags, oflags;
59
60	if ((flags = __sflags(mode, &oflags)) == 0)
61		return (NULL);
62	if ((fp = __sfp()) == NULL)
63		return (NULL);
64	if ((f = _open(file, oflags, DEFFILEMODE)) < 0) {
65		fp->_flags = 0;			/* release */
66		return (NULL);
67	}
68	/*
69	 * File descriptors are a full int, but _file is only a short.
70	 * If we get a valid file descriptor that is greater than
71	 * SHRT_MAX, then the fd will get sign-extended into an
72	 * invalid file descriptor.  Handle this case by failing the
73	 * open.
74	 */
75	if (f > SHRT_MAX) {
76		fp->_flags = 0;			/* release */
77		_close(f);
78		errno = EMFILE;
79		return (NULL);
80	}
81	fp->_file = f;
82	fp->_flags = flags;
83	fp->_cookie = fp;
84	fp->_read = __sread;
85	fp->_write = __swrite;
86	fp->_seek = __sseek;
87	fp->_close = __sclose;
88	/*
89	 * When opening in append mode, even though we use O_APPEND,
90	 * we need to seek to the end so that ftell() gets the right
91	 * answer.  If the user then alters the seek pointer, or
92	 * the file extends, this will fail, but there is not much
93	 * we can do about this.  (We could set __SAPP and check in
94	 * fseek and ftell.)
95	 */
96	if (oflags & O_APPEND) {
97		fp->_flags2 |= __S2OAP;
98		(void)_sseek(fp, (fpos_t)0, SEEK_END);
99	}
100	return (fp);
101}
102