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       1                 :            : /*-
       2                 :            :  * SPDX-License-Identifier: BSD-3-Clause
       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                 :            : #if defined(LIBC_SCCS) && !defined(lint)
      36                 :            : static char sccsid[] = "@(#)flags.c        8.1 (Berkeley) 6/4/93";
      37                 :            : #endif /* LIBC_SCCS and not lint */
      38                 :            : #include "bsd_compat.h"
      39                 :            : __FBSDID("$FreeBSD: head/lib/libc/stdio/flags.c 326025 2017-11-20 19:49:47Z pfg $");
      40                 :            : 
      41                 :            : #include <sys/types.h>
      42                 :            : #include <sys/file.h>
      43                 :            : #include <stdio.h>
      44                 :            : #include <errno.h>
      45                 :            : #include <fcntl.h>
      46                 :            : 
      47                 :            : /*
      48                 :            :  * Return the (stdio) flags for a given mode.  Store the flags
      49                 :            :  * to be passed to an _open() syscall through *optr.
      50                 :            :  * Return 1 on error.
      51                 :            :  */
      52                 :            : int
      53                 :          2 : checkflags(const char *mode, int *optr)
      54                 :            : {
      55                 :            :         int ret, m, o, known;
      56                 :          2 :         ret = 0;
      57                 :            : 
      58   [ +  -  +  - ]:          2 :         switch (*mode++) {
      59                 :            : 
      60                 :            :         case 'r':       /* open for reading */
      61                 :          1 :                 ret = 1;
      62                 :          1 :                 m = O_RDONLY;
      63                 :          1 :                 o = 0;
      64                 :          1 :                 break;
      65                 :            : 
      66                 :            :         case 'w':       /* open for writing */
      67                 :          1 :                 ret = 1;
      68                 :          1 :                 m = O_WRONLY;
      69                 :          1 :                 o = O_CREAT | O_TRUNC;
      70                 :          1 :                 break;
      71                 :            : 
      72                 :            :         case 'a':       /* open for appending */
      73                 :          0 :                 ret = 1;
      74                 :          0 :                 m = O_WRONLY;
      75                 :          0 :                 o = O_CREAT | O_APPEND;
      76                 :          0 :                 break;
      77                 :            : 
      78                 :            :         default:        /* illegal mode */
      79                 :          0 :                 errno = EINVAL;
      80                 :          0 :                 return (0);
      81                 :            :         }
      82                 :            : 
      83                 :          3 :         do {
      84                 :          3 :                 known = 1;
      85   [ +  -  +  -  :          3 :                 switch (*mode++) {
                      - ]
      86                 :            :                 case 'b':
      87                 :            :                         /* 'b' (binary) is ignored */
      88                 :          0 :                         break;
      89                 :            :                 case '+':
      90                 :            :                         /* [rwa][b]\+ means read and write */
      91                 :          1 :                         ret = 1;
      92                 :          1 :                         m = O_RDWR;
      93                 :          1 :                         break;
      94                 :            :                 case 'x':
      95                 :            :                         /* 'x' means exclusive (fail if the file exists) */
      96                 :          0 :                         o |= O_EXCL;
      97                 :          0 :                         break;
      98                 :            :                 case 'e':
      99                 :            :                         /* set close-on-exec */
     100                 :          0 :                         o |= O_CLOEXEC;
     101                 :          0 :                         break;
     102                 :            :                 default:
     103                 :          2 :                         known = 0;
     104                 :          2 :                         break;
     105                 :            :                 }
     106         [ +  + ]:          3 :         } while (known);
     107                 :            : 
     108   [ -  +  #  # ]:          2 :         if ((o & O_EXCL) != 0 && m == O_RDONLY) {
     109                 :          0 :                 errno = EINVAL;
     110                 :          0 :                 return (1);
     111                 :            :         }
     112                 :            : 
     113                 :          2 :         *optr = m | o;
     114                 :          2 :         return (ret);
     115                 :          2 : }