flags.c revision 22993 
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#if 0
39static char sccsid[] = "@(#)flags.c	8.1 (Berkeley) 6/4/93";
40#endif
41static const char rcsid[] =
42		"$Id$";
43#endif /* LIBC_SCCS and not lint */
44
45#include <sys/types.h>
46#include <sys/file.h>
47#include <stdio.h>
48#include <errno.h>
49#include "local.h"
50
51/*
52 * Return the (stdio) flags for a given mode.  Store the flags
53 * to be passed to an open() syscall through *optr.
54 * Return 0 on error.
55 */
56int
57__sflags(mode, optr)
58	register const char *mode;
59	int *optr;
60{
61	register int ret, m, o;
62
63	switch (*mode++) {
64
65	case 'r':	/* open for reading */
66		ret = __SRD;
67		m = O_RDONLY;
68		o = 0;
69		break;
70
71	case 'w':	/* open for writing */
72		ret = __SWR;
73		m = O_WRONLY;
74		o = O_CREAT | O_TRUNC;
75		break;
76
77	case 'a':	/* open for appending */
78		ret = __SWR;
79		m = O_WRONLY;
80		o = O_CREAT | O_APPEND;
81		break;
82
83	default:	/* illegal mode */
84		errno = EINVAL;
85		return (0);
86	}
87
88	/* [rwa]\+ or [rwa]b\+ means read and write */
89	if (*mode == '+' || (*mode == 'b' && mode[1] == '+')) {
90		ret = __SRW;
91		m = O_RDWR;
92	}
93	*optr = m | o;
94	return (ret);
95}
96