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flags.c revision 1.10 
      1 /*	$NetBSD: flags.c,v 1.10 1999/09/16 11:45:27 lukem 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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 #if 0
     42 static char sccsid[] = "@(#)flags.c	8.1 (Berkeley) 6/4/93";
     43 #else
     44 __RCSID("$NetBSD: flags.c,v 1.10 1999/09/16 11:45:27 lukem Exp $");
     45 #endif
     46 #endif /* LIBC_SCCS and not lint */
     47 
     48 #include <sys/types.h>
     49 #include <assert.h>
     50 #include <fcntl.h>
     51 #include <stdio.h>
     52 #include <errno.h>
     53 #include "local.h"
     54 
     55 /*
     56  * Return the (stdio) flags for a given mode.  Store the flags
     57  * to be passed to an open() syscall through *optr.
     58  * Return 0 on error.
     59  */
     60 int
     61 __sflags(mode, optr)
     62 	const char *mode;
     63 	int *optr;
     64 {
     65 	int ret, m, o;
     66 
     67 	_DIAGASSERT(mode != NULL);
     68 #ifdef _DIAGNOSTIC
     69 	if (mode == NULL)
     70 		return (0);
     71 #endif
     72 
     73 	switch (*mode++) {
     74 
     75 	case 'r':	/* open for reading */
     76 		ret = __SRD;
     77 		m = O_RDONLY;
     78 		o = 0;
     79 		break;
     80 
     81 	case 'w':	/* open for writing */
     82 		ret = __SWR;
     83 		m = O_WRONLY;
     84 		o = O_CREAT | O_TRUNC;
     85 		break;
     86 
     87 	case 'a':	/* open for appending */
     88 		ret = __SWR;
     89 		m = O_WRONLY;
     90 		o = O_CREAT | O_APPEND;
     91 		break;
     92 
     93 	default:	/* illegal mode */
     94 		errno = EINVAL;
     95 		return (0);
     96 	}
     97 
     98 	/* [rwa]\+ or [rwa]b\+ means read and write */
     99 	if (*mode == '+' || (*mode == 'b' && mode[1] == '+')) {
    100 		ret = __SRW;
    101 		m = O_RDWR;
    102 	}
    103 	*optr = m | o;
    104 	return (ret);
    105 }
    106