fopen.c revision 290544 
1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)fopen.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: stable/10/lib/libc/stdio/fopen.c 290544 2015-11-08 13:37:16Z ache $");
38
39#include "namespace.h"
40#include <sys/types.h>
41#include <sys/stat.h>
42#include <fcntl.h>
43#include <unistd.h>
44#include <stdio.h>
45#include <errno.h>
46#include <limits.h>
47#include "un-namespace.h"
48
49#include "local.h"
50
51FILE *
52fopen(const char * __restrict file, const char * __restrict mode)
53{
54	FILE *fp;
55	int f;
56	int flags, oflags;
57
58	if ((flags = __sflags(mode, &oflags)) == 0)
59		return (NULL);
60	if ((fp = __sfp()) == NULL)
61		return (NULL);
62	if ((f = _open(file, oflags, DEFFILEMODE)) < 0) {
63		fp->_flags = 0;			/* release */
64		return (NULL);
65	}
66	/*
67	 * File descriptors are a full int, but _file is only a short.
68	 * If we get a valid file descriptor that is greater than
69	 * SHRT_MAX, then the fd will get sign-extended into an
70	 * invalid file descriptor.  Handle this case by failing the
71	 * open.
72	 */
73	if (f > SHRT_MAX) {
74		fp->_flags = 0;			/* release */
75		_close(f);
76		errno = EMFILE;
77		return (NULL);
78	}
79	fp->_file = f;
80	fp->_flags = flags;
81	fp->_cookie = fp;
82	fp->_read = __sread;
83	fp->_write = __swrite;
84	fp->_seek = __sseek;
85	fp->_close = __sclose;
86	/*
87	 * When opening in append mode, even though we use O_APPEND,
88	 * we need to seek to the end so that ftell() gets the right
89	 * answer.  If the user then alters the seek pointer, or
90	 * the file extends, this will fail, but there is not much
91	 * we can do about this.  (We could set __SAPP and check in
92	 * fseek and ftell.)
93	 */
94	if (oflags & O_APPEND) {
95		fp->_flags2 |= __S2OAP;
96		(void)_sseek(fp, (fpos_t)0, SEEK_END);
97	}
98	return (fp);
99}
100