1 /* $OpenBSD: fdopen.c,v 1.6 2008/04/21 12:28:35 otto 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
42 FILE *
fdopen(int fd,const char * mode)43 fdopen(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 * If opened for appending, but underlying descriptor does not have
71 * O_APPEND bit set, assert __SAPP so that __swrite() will lseek to
72 * end before each write.
73 */
74 if ((oflags & O_APPEND) && !(fdflags & O_APPEND))
75 fp->_flags |= __SAPP;
76 fp->_file = fd;
77 fp->_cookie = fp;
78 fp->_read = __sread;
79 fp->_write = __swrite;
80 fp->_seek = __sseek;
81 fp->_close = __sclose;
82 return (fp);
83 }
84