xref: /freebsd/lib/libc/stdio/flags.c (revision 264104f26834fdb27974e0c5fdedf8f2f5a90383)
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 sccsid[] = "@(#)flags.c	8.1 (Berkeley) 6/4/93";
35  #endif /* LIBC_SCCS and not lint */
36  #include <sys/cdefs.h>
37  __FBSDID("$FreeBSD$");
38  
39  #include <sys/types.h>
40  #include <sys/file.h>
41  #include <stdio.h>
42  #include <errno.h>
43  
44  #include "local.h"
45  
46  /*
47   * Return the (stdio) flags for a given mode.  Store the flags
48   * to be passed to an _open() syscall through *optr.
49   * Return 0 on error.
50   */
51  int
52  __sflags(const char *mode, int *optr)
53  {
54  	int ret, m, o, known;
55  
56  	switch (*mode++) {
57  
58  	case 'r':	/* open for reading */
59  		ret = __SRD;
60  		m = O_RDONLY;
61  		o = 0;
62  		break;
63  
64  	case 'w':	/* open for writing */
65  		ret = __SWR;
66  		m = O_WRONLY;
67  		o = O_CREAT | O_TRUNC;
68  		break;
69  
70  	case 'a':	/* open for appending */
71  		ret = __SWR;
72  		m = O_WRONLY;
73  		o = O_CREAT | O_APPEND;
74  		break;
75  
76  	default:	/* illegal mode */
77  		errno = EINVAL;
78  		return (0);
79  	}
80  
81  	do {
82  		known = 1;
83  		switch (*mode++) {
84  		case 'b':
85  			/* 'b' (binary) is ignored */
86  			break;
87  		case '+':
88  			/* [rwa][b]\+ means read and write */
89  			ret = __SRW;
90  			m = O_RDWR;
91  			break;
92  		case 'x':
93  			/* 'x' means exclusive (fail if the file exists) */
94  			o |= O_EXCL;
95  			break;
96  		case 'e':
97  			/* set close-on-exec */
98  			o |= O_CLOEXEC;
99  			break;
100  		case 'v':
101  			/* verify */
102  			o |= O_VERIFY;
103  			break;
104  		default:
105  			known = 0;
106  			break;
107  		}
108  	} while (known);
109  
110  	if ((o & O_EXCL) != 0 && m == O_RDONLY) {
111  		errno = EINVAL;
112  		return (0);
113  	}
114  
115  	*optr = m | o;
116  	return (ret);
117  }
118