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      1 /*	$NetBSD: flags.c,v 1.19 2017/11/09 20:30:02 christos 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. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/cdefs.h>
     36 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char sccsid[] = "@(#)flags.c	8.1 (Berkeley) 6/4/93";
     39 #else
     40 __RCSID("$NetBSD: flags.c,v 1.19 2017/11/09 20:30:02 christos Exp $");
     41 #endif
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include <sys/types.h>
     45 #include <assert.h>
     46 #include <fcntl.h>
     47 #include <stdio.h>
     48 #include <errno.h>
     49 #include "reentrant.h"
     50 #include "local.h"
     51 
     52 /*
     53  * Return the (stdio) flags for a given mode.  Store the flags
     54  * to be passed to an open() syscall through *optr.
     55  * Return 0 on error.
     56  */
     57 int
     58 __sflags(const char *mode, int *optr)
     59 {
     60 	int ret, m, o;
     61 
     62 	_DIAGASSERT(mode != NULL);
     63 
     64 	switch (*mode++) {
     65 
     66 	case 'r':	/* open for reading */
     67 		ret = __SRD;
     68 		m = O_RDONLY;
     69 		o = 0;
     70 		break;
     71 
     72 	case 'w':	/* open for writing */
     73 		ret = __SWR;
     74 		m = O_WRONLY;
     75 		o = O_CREAT | O_TRUNC;
     76 		break;
     77 
     78 	case 'a':	/* open for appending */
     79 		ret = __SWR;
     80 		m = O_WRONLY;
     81 		o = O_CREAT | O_APPEND;
     82 		break;
     83 
     84 	default:	/* illegal mode */
     85 		errno = EINVAL;
     86 		return 0;
     87 	}
     88 
     89 	/*
     90 	 * [rwa]\+ or [rwa]b\+ means read and write
     91 	 * e means set close on exec.
     92 	 * f means open only plain files.
     93 	 * l means don't follow symlinks.
     94 	 * x means exclusive open.
     95 	 */
     96 	for (; *mode; mode++)
     97 		switch (*mode) {
     98 		case '+':
     99 			ret = __SRW;
    100 			m = O_RDWR;
    101 			break;
    102 		case 'b':
    103 			break;
    104 		case 'e':
    105 			o |= O_CLOEXEC;
    106 			break;
    107 		case 'f':
    108 			o |= O_REGULAR;
    109 			break;
    110 		case 'l':
    111 			o |= O_NOFOLLOW;
    112 			break;
    113 		case 'x':
    114 			o |= O_EXCL;
    115 			break;
    116 		default:	/* We could produce a warning here */
    117 			break;
    118 		}
    119 
    120 	*optr = m | o;
    121 	return ret;
    122 }
    123