fdopen.c revision 331722 
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[] = "@(#)fdopen.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: stable/11/lib/libc/stdio/fdopen.c 331722 2018-03-29 02:50:57Z eadler $");
38
39#include "namespace.h"
40#include <sys/types.h>
41#include <fcntl.h>
42#include <unistd.h>
43#include <stdio.h>
44#include <errno.h>
45#include <limits.h>
46#include "un-namespace.h"
47#include "local.h"
48
49FILE *
50fdopen(int fd, const char *mode)
51{
52	FILE *fp;
53	int flags, oflags, fdflags, tmp;
54
55	/*
56	 * File descriptors are a full int, but _file is only a short.
57	 * If we get a valid file descriptor that is greater than
58	 * SHRT_MAX, then the fd will get sign-extended into an
59	 * invalid file descriptor.  Handle this case by failing the
60	 * open.
61	 */
62	if (fd > SHRT_MAX) {
63		errno = EMFILE;
64		return (NULL);
65	}
66
67	if ((flags = __sflags(mode, &oflags)) == 0)
68		return (NULL);
69
70	/* Make sure the mode the user wants is a subset of the actual mode. */
71	if ((fdflags = _fcntl(fd, F_GETFL, 0)) < 0)
72		return (NULL);
73	/* Work around incorrect O_ACCMODE. */
74	tmp = fdflags & (O_ACCMODE | O_EXEC);
75	if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
76		errno = EINVAL;
77		return (NULL);
78	}
79
80	if ((fp = __sfp()) == NULL)
81		return (NULL);
82
83	if ((oflags & O_CLOEXEC) && _fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
84		fp->_flags = 0;
85		return (NULL);
86	}
87
88	fp->_flags = flags;
89	/*
90	 * If opened for appending, but underlying descriptor does not have
91	 * O_APPEND bit set, assert __SAPP so that __swrite() caller
92	 * will _sseek() to the end before write.
93	 */
94	if (fdflags & O_APPEND)
95		fp->_flags2 |= __S2OAP;
96	else if (oflags & O_APPEND)
97		fp->_flags |= __SAPP;
98	fp->_file = fd;
99	fp->_cookie = fp;
100	fp->_read = __sread;
101	fp->_write = __swrite;
102	fp->_seek = __sseek;
103	fp->_close = __sclose;
104	return (fp);
105}
106