xref: /freebsd/lib/libc/stdio/flags.c (revision ae83180158c4c937f170e31eff311b18c0286a93)
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[] = "@(#)flags.c	8.1 (Berkeley) 6/4/93";
39 #endif /* LIBC_SCCS and not lint */
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
42 
43 #include <sys/types.h>
44 #include <sys/file.h>
45 #include <stdio.h>
46 #include <errno.h>
47 
48 #include "local.h"
49 
50 /*
51  * Return the (stdio) flags for a given mode.  Store the flags
52  * to be passed to an _open() syscall through *optr.
53  * Return 0 on error.
54  */
55 int
56 __sflags(mode, optr)
57 	const char *mode;
58 	int *optr;
59 {
60 	int ret, m, o;
61 
62 	switch (*mode++) {
63 
64 	case 'r':	/* open for reading */
65 		ret = __SRD;
66 		m = O_RDONLY;
67 		o = 0;
68 		break;
69 
70 	case 'w':	/* open for writing */
71 		ret = __SWR;
72 		m = O_WRONLY;
73 		o = O_CREAT | O_TRUNC;
74 		break;
75 
76 	case 'a':	/* open for appending */
77 		ret = __SWR;
78 		m = O_WRONLY;
79 		o = O_CREAT | O_APPEND;
80 		break;
81 
82 	default:	/* illegal mode */
83 		errno = EINVAL;
84 		return (0);
85 	}
86 
87 	/* [rwa]\+ or [rwa]b\+ means read and write */
88 	if (*mode == '+' || (*mode == 'b' && mode[1] == '+')) {
89 		ret = __SRW;
90 		m = O_RDWR;
91 	}
92 	*optr = m | o;
93 	return (ret);
94 }
95