1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)fdopen.c 8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include "namespace.h"
39 #include <sys/types.h>
40 #include <fcntl.h>
41 #include <unistd.h>
42 #include <stdio.h>
43 #include <errno.h>
44 #include <limits.h>
45 #include "un-namespace.h"
46 #include "local.h"
47
48 FILE *
fdopen(int fd,const char * mode)49 fdopen(int fd, const char *mode)
50 {
51 FILE *fp;
52 int flags, oflags, fdflags, tmp;
53
54 /*
55 * File descriptors are a full int, but _file is only a short.
56 * If we get a valid file descriptor that is greater than
57 * SHRT_MAX, then the fd will get sign-extended into an
58 * invalid file descriptor. Handle this case by failing the
59 * open.
60 */
61 if (fd > SHRT_MAX) {
62 errno = EMFILE;
63 return (NULL);
64 }
65
66 if ((flags = __sflags(mode, &oflags)) == 0)
67 return (NULL);
68
69 /* Make sure the mode the user wants is a subset of the actual mode. */
70 if ((fdflags = _fcntl(fd, F_GETFL, 0)) < 0)
71 return (NULL);
72 /* Work around incorrect O_ACCMODE. */
73 tmp = fdflags & (O_ACCMODE | O_EXEC);
74 if (tmp != O_RDWR && (tmp != (oflags & O_ACCMODE))) {
75 errno = EINVAL;
76 return (NULL);
77 }
78
79 if ((fp = __sfp()) == NULL)
80 return (NULL);
81
82 if ((oflags & O_CLOEXEC) && _fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
83 fp->_flags = 0;
84 return (NULL);
85 }
86
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 (fdflags & O_APPEND)
94 fp->_flags2 |= __S2OAP;
95 else if (oflags & O_APPEND)
96 fp->_flags |= __SAPP;
97 fp->_file = fd;
98 fp->_cookie = fp;
99 fp->_read = __sread;
100 fp->_write = __swrite;
101 fp->_seek = __sseek;
102 fp->_close = __sclose;
103 return (fp);
104 }
105