1/*	$NetBSD: fdopen.c,v 1.18 2017/11/09 20:30:02 christos Exp $	*/
2
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#include <sys/cdefs.h>
36#if defined(LIBC_SCCS) && !defined(lint)
37#if 0
38static char sccsid[] = "@(#)fdopen.c	8.1 (Berkeley) 6/4/93";
39#else
40__RCSID("$NetBSD: fdopen.c,v 1.18 2017/11/09 20:30:02 christos Exp $");
41#endif
42#endif /* LIBC_SCCS and not lint */
43
44#include "namespace.h"
45
46#include <sys/types.h>
47#include <sys/stat.h>
48
49#include <assert.h>
50#include <errno.h>
51#include <fcntl.h>
52#include <unistd.h>
53#include <stdio.h>
54#include <limits.h>
55
56#include "reentrant.h"
57#include "local.h"
58
59#ifdef __weak_alias
60__weak_alias(fdopen,_fdopen)
61#endif
62
63FILE *
64fdopen(int fd, const char *mode)
65{
66	FILE *fp;
67	int flags, oflags, fdflags, tmp;
68
69	_DIAGASSERT(fd != -1);
70
71	/*
72	 * File descriptors are a full int, but _file is only a short.
73	 * If we get a valid file descriptor that is greater or equal to
74	 * USHRT_MAX, then the fd will get sign-extended into an
75	 * invalid file descriptor.  Handle this case by failing the
76	 * open. (We treat the short as unsigned, and special-case -1).
77	 */
78	if (fd >= USHRT_MAX) {
79		errno = EMFILE;
80		return NULL;
81	}
82
83	if ((flags = __sflags(mode, &oflags)) == 0)
84		return NULL;
85
86	/* Make sure the mode the user wants is a subset of the actual mode. */
87	if ((fdflags = fcntl(fd, F_GETFL, 0)) < 0)
88		return NULL;
89	tmp = fdflags & O_ACCMODE;
90	if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
91		errno = EINVAL;
92		return NULL;
93	}
94
95	if (oflags & O_REGULAR) {
96		struct stat st;
97		if (fstat(fd, &st) == -1) {
98			return NULL;
99		}
100		if (!S_ISREG(st.st_mode)) {
101			errno = EFTYPE;
102			return NULL;
103		}
104	}
105
106	if ((fp = __sfp()) == NULL)
107		return NULL;
108	fp->_flags = flags;
109	/*
110	 * If opened for appending, but underlying descriptor does not have
111	 * O_APPEND bit set, assert __SAPP so that __swrite() will lseek to
112	 * end before each write.
113	 */
114	if ((oflags & O_APPEND) && !(fdflags & O_APPEND))
115		fp->_flags |= __SAPP;
116	fp->_file = fd;
117	fp->_cookie = fp;
118	fp->_read = __sread;
119	fp->_write = __swrite;
120	fp->_seek = __sseek;
121	fp->_close = __sclose;
122	return fp;
123}
124