xref: /openbsd/lib/libc/stdio/fopen.c (revision db3296cf)
1 /*-
2  * Copyright (c) 1990, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Chris Torek.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char rcsid[] = "$OpenBSD: fopen.c,v 1.3 2003/06/02 20:18:37 millert Exp $";
35 #endif /* LIBC_SCCS and not lint */
36 
37 #include <sys/types.h>
38 #include <sys/stat.h>
39 #include <fcntl.h>
40 #include <stdio.h>
41 #include <errno.h>
42 #include "local.h"
43 
44 FILE *
45 fopen(file, mode)
46 	const char *file;
47 	const char *mode;
48 {
49 	register FILE *fp;
50 	register int f;
51 	int flags, oflags;
52 
53 	if ((flags = __sflags(mode, &oflags)) == 0)
54 		return (NULL);
55 	if ((fp = __sfp()) == NULL)
56 		return (NULL);
57 	if ((f = open(file, oflags, DEFFILEMODE)) < 0) {
58 		fp->_flags = 0;			/* release */
59 		return (NULL);
60 	}
61 	fp->_file = f;
62 	fp->_flags = flags;
63 	fp->_cookie = fp;
64 	fp->_read = __sread;
65 	fp->_write = __swrite;
66 	fp->_seek = __sseek;
67 	fp->_close = __sclose;
68 
69 	/*
70 	 * When opening in append mode, even though we use O_APPEND,
71 	 * we need to seek to the end so that ftell() gets the right
72 	 * answer.  If the user then alters the seek pointer, or
73 	 * the file extends, this will fail, but there is not much
74 	 * we can do about this.  (We could set __SAPP and check in
75 	 * fseek and ftell.)
76 	 */
77 	if (oflags & O_APPEND)
78 		(void) __sseek((void *)fp, (fpos_t)0, SEEK_END);
79 	return (fp);
80 }
81