1/*	$OpenBSD: fdopen.c,v 1.7 2014/08/31 02:21:18 guenther Exp $ */
2/*-
3 * Copyright (c) 1990, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Chris Torek.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <sys/types.h>
35#include <fcntl.h>
36#include <limits.h>
37#include <unistd.h>
38#include <stdio.h>
39#include <errno.h>
40#include "local.h"
41
42FILE *
43fdopen(int fd, const char *mode)
44{
45	FILE *fp;
46	int flags, oflags, fdflags, tmp;
47
48	/* _file is only a short */
49	if (fd > SHRT_MAX) {
50		errno = EMFILE;
51		return (NULL);
52	}
53
54	if ((flags = __sflags(mode, &oflags)) == 0)
55		return (NULL);
56
57	/* Make sure the mode the user wants is a subset of the actual mode. */
58	if ((fdflags = fcntl(fd, F_GETFL, 0)) < 0)
59		return (NULL);
60	tmp = fdflags & O_ACCMODE;
61	if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
62		errno = EINVAL;
63		return (NULL);
64	}
65
66	if ((fp = __sfp()) == NULL)
67		return (NULL);
68	fp->_flags = flags;
69
70	/*
71	 * If opened for appending, but underlying descriptor does not have
72	 * O_APPEND bit set, assert __SAPP so that __swrite() will lseek to
73	 * end before each write.
74	 */
75	if ((oflags & O_APPEND) && !(fdflags & O_APPEND))
76		fp->_flags |= __SAPP;
77
78	/*
79	 * If close-on-exec was requested, then turn it on if not already
80	 */
81	if ((oflags & O_CLOEXEC) && !((tmp = fcntl(fd, F_GETFD)) & FD_CLOEXEC))
82		fcntl(fd, F_SETFD, tmp | FD_CLOEXEC);
83
84	fp->_file = fd;
85	fp->_cookie = fp;
86	fp->_read = __sread;
87	fp->_write = __swrite;
88	fp->_seek = __sseek;
89	fp->_close = __sclose;
90	return (fp);
91}
92