xref: /netbsd-src/lib/libc/stdio/fopen.c (revision 1f2744e6e4915c9da2a3f980279398c4cf7d5e6d)
1 /*	$NetBSD: fopen.c,v 1.4 1995/02/02 02:09:23 jtc 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. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  */
38 
39 #if defined(LIBC_SCCS) && !defined(lint)
40 #if 0
41 static char sccsid[] = "@(#)fopen.c	8.1 (Berkeley) 6/4/93";
42 #endif
43 static char rcsid[] = "$NetBSD: fopen.c,v 1.4 1995/02/02 02:09:23 jtc Exp $";
44 #endif /* LIBC_SCCS and not lint */
45 
46 #include <sys/types.h>
47 #include <sys/stat.h>
48 #include <fcntl.h>
49 #include <stdio.h>
50 #include <errno.h>
51 #include "local.h"
52 
53 FILE *
54 fopen(file, mode)
55 	const char *file;
56 	const char *mode;
57 {
58 	register FILE *fp;
59 	register int f;
60 	int flags, oflags;
61 
62 	if ((flags = __sflags(mode, &oflags)) == 0)
63 		return (NULL);
64 	if ((fp = __sfp()) == NULL)
65 		return (NULL);
66 	if ((f = open(file, oflags, DEFFILEMODE)) < 0) {
67 		fp->_flags = 0;			/* release */
68 		return (NULL);
69 	}
70 	fp->_file = f;
71 	fp->_flags = flags;
72 	fp->_cookie = fp;
73 	fp->_read = __sread;
74 	fp->_write = __swrite;
75 	fp->_seek = __sseek;
76 	fp->_close = __sclose;
77 
78 	/*
79 	 * When opening in append mode, even though we use O_APPEND,
80 	 * we need to seek to the end so that ftell() gets the right
81 	 * answer.  If the user then alters the seek pointer, or
82 	 * the file extends, this will fail, but there is not much
83 	 * we can do about this.  (We could set __SAPP and check in
84 	 * fseek and ftell.)
85 	 */
86 	if (oflags & O_APPEND)
87 		(void) __sseek((void *)fp, (fpos_t)0, SEEK_END);
88 	return (fp);
89 }
90