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
38 static 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
__weak_alias(fdopen,_fdopen)60 __weak_alias(fdopen,_fdopen)
61 #endif
62
63 FILE *
64 fdopen(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