fdopen.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[] = "@(#)fdopen.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/fdopen.c 330897 2018-03-14 03:19:51Z eadler $");
40
41#include "namespace.h"
42#include <sys/types.h>
43#include <fcntl.h>
44#include <unistd.h>
45#include <stdio.h>
46#include <errno.h>
47#include <limits.h>
48#include "un-namespace.h"
49#include "local.h"
50
51FILE *
52fdopen(int fd, const char *mode)
53{
54	FILE *fp;
55	int flags, oflags, fdflags, tmp;
56
57	/*
58	 * File descriptors are a full int, but _file is only a short.
59	 * If we get a valid file descriptor that is greater than
60	 * SHRT_MAX, then the fd will get sign-extended into an
61	 * invalid file descriptor.  Handle this case by failing the
62	 * open.
63	 */
64	if (fd > SHRT_MAX) {
65		errno = EMFILE;
66		return (NULL);
67	}
68
69	if ((flags = __sflags(mode, &oflags)) == 0)
70		return (NULL);
71
72	/* Make sure the mode the user wants is a subset of the actual mode. */
73	if ((fdflags = _fcntl(fd, F_GETFL, 0)) < 0)
74		return (NULL);
75	/* Work around incorrect O_ACCMODE. */
76	tmp = fdflags & (O_ACCMODE | O_EXEC);
77	if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
78		errno = EINVAL;
79		return (NULL);
80	}
81
82	if ((fp = __sfp()) == NULL)
83		return (NULL);
84
85	if ((oflags & O_CLOEXEC) && _fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
86		fp->_flags = 0;
87		return (NULL);
88	}
89
90	fp->_flags = flags;
91	/*
92	 * If opened for appending, but underlying descriptor does not have
93	 * O_APPEND bit set, assert __SAPP so that __swrite() caller
94	 * will _sseek() to the end before write.
95	 */
96	if (fdflags & O_APPEND)
97		fp->_flags2 |= __S2OAP;
98	else if (oflags & O_APPEND)
99		fp->_flags |= __SAPP;
100	fp->_file = fd;
101	fp->_cookie = fp;
102	fp->_read = __sread;
103	fp->_write = __swrite;
104	fp->_seek = __sseek;
105	fp->_close = __sclose;
106	return (fp);
107}
108