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flags.c revision 1.5 
      1 /*	$NetBSD: flags.c,v 1.5 1995/02/02 02:09:19 jtc 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 #if defined(LIBC_SCCS) && !defined(lint)
     40 #if 0
     41 static char sccsid[] = "@(#)flags.c	8.1 (Berkeley) 6/4/93";
     42 #endif
     43 static char rcsid[] = "$NetBSD: flags.c,v 1.5 1995/02/02 02:09:19 jtc Exp $";
     44 #endif /* LIBC_SCCS and not lint */
     45 
     46 #include <sys/types.h>
     47 #include <sys/file.h>
     48 #include <stdio.h>
     49 #include <errno.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  */
     56 int
     57 __sflags(mode, optr)
     58 	register 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