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      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;
     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 	/* 'b' (binary) is ignored */
     82 	if (*mode == 'b')
     83 		mode++;
     84 
     85 	/* [rwa][b]\+ means read and write */
     86 	if (*mode == '+') {
     87 		mode++;
     88 		ret = __SRW;
     89 		m = O_RDWR;
     90 	}
     91 
     92 	/* 'b' (binary) can appear here, too -- and is ignored again */
     93 	if (*mode == 'b')
     94 		mode++;
     95 
     96 	/* 'x' means exclusive (fail if the file exists) */
     97 	if (*mode == 'x') {
     98 		mode++;
     99 		if (m == O_RDONLY) {
    100 			errno = EINVAL;
    101 			return (0);
    102 		}
    103 		o |= O_EXCL;
    104 	}
    105 
    106 	/* set close-on-exec */
    107 	if (*mode == 'e')
    108 		o |= O_CLOEXEC;
    109 
    110 	*optr = m | o;
    111 	return (ret);
    112 }
    113