xref: /freebsd/lib/libc/stdio/fopen.c (revision 17ee9d00bc1ae1e598c38f25826f861e4bc6c3ce)
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. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #if defined(LIBC_SCCS) && !defined(lint)
38 static char sccsid[] = "@(#)fopen.c	8.1 (Berkeley) 6/4/93";
39 #endif /* LIBC_SCCS and not lint */
40 
41 #include <sys/types.h>
42 #include <sys/stat.h>
43 #include <fcntl.h>
44 #include <stdio.h>
45 #include <errno.h>
46 #include "local.h"
47 
48 FILE *
49 fopen(file, mode)
50 	const char *file;
51 	const char *mode;
52 {
53 	register FILE *fp;
54 	register int f;
55 	int flags, oflags;
56 
57 	if ((flags = __sflags(mode, &oflags)) == 0)
58 		return (NULL);
59 	if ((fp = __sfp()) == NULL)
60 		return (NULL);
61 	if ((f = open(file, oflags, DEFFILEMODE)) < 0) {
62 		fp->_flags = 0;			/* release */
63 		return (NULL);
64 	}
65 	fp->_file = f;
66 	fp->_flags = flags;
67 	fp->_cookie = fp;
68 	fp->_read = __sread;
69 	fp->_write = __swrite;
70 	fp->_seek = __sseek;
71 	fp->_close = __sclose;
72 
73 	/*
74 	 * When opening in append mode, even though we use O_APPEND,
75 	 * we need to seek to the end so that ftell() gets the right
76 	 * answer.  If the user then alters the seek pointer, or
77 	 * the file extends, this will fail, but there is not much
78 	 * we can do about this.  (We could set __SAPP and check in
79 	 * fseek and ftell.)
80 	 */
81 	if (oflags & O_APPEND)
82 		(void) __sseek((void *)fp, (fpos_t)0, SEEK_END);
83 	return (fp);
84 }
85