fdopen.c revision 176629 
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 * 4. 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: head/lib/libc/stdio/fdopen.c 176629 2008-02-27 21:25:19Z jhb $");
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(fd, mode)
51	int fd;
52	const char *mode;
53{
54	FILE *fp;
55	static int nofile;
56	int flags, oflags, fdflags, tmp;
57
58	if (nofile == 0)
59		nofile = getdtablesize();
60
61	/*
62	 * File descriptors are a full int, but _file is only a short.
63	 * If we get a valid file descriptor that is greater than
64	 * SHRT_MAX, then the fd will get sign-extended into an
65	 * invalid file descriptor.  Handle this case by failing the
66	 * open.
67	 */
68	if (fd > SHRT_MAX) {
69		errno = EMFILE;
70		return (NULL);
71	}
72
73	if ((flags = __sflags(mode, &oflags)) == 0)
74		return (NULL);
75
76	/* Make sure the mode the user wants is a subset of the actual mode. */
77	if ((fdflags = _fcntl(fd, F_GETFL, 0)) < 0)
78		return (NULL);
79	tmp = fdflags & O_ACCMODE;
80	if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
81		errno = EINVAL;
82		return (NULL);
83	}
84
85	if ((fp = __sfp()) == NULL)
86		return (NULL);
87	fp->_flags = flags;
88	/*
89	 * If opened for appending, but underlying descriptor does not have
90	 * O_APPEND bit set, assert __SAPP so that __swrite() caller
91	 * will _sseek() to the end before write.
92	 */
93	if ((oflags & O_APPEND) && !(fdflags & O_APPEND))
94		fp->_flags |= __SAPP;
95	fp->_file = fd;
96	fp->_cookie = fp;
97	fp->_read = __sread;
98	fp->_write = __swrite;
99	fp->_seek = __sseek;
100	fp->_close = __sclose;
101	return (fp);
102}
103