stdio/fopen.c

   1 /* Copyright (C) 1991, 1992, 1993, 1996 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ctype.h>
  20 #include <errno.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24
  25
  26 #define badmode()       return ((__set_errno (EINVAL)), 0)
  27
  28 /* Dissect the given mode string into an __io_mode.  */
  29 int
  30 __getmode (mode, mptr)
  31      const char *mode;
  32      __io_mode *mptr;
  33 {
  34   register unsigned char i;
  35
  36   if (mode == NULL)
  37     badmode ();
  38
  39   memset ((void *) mptr, 0, sizeof (*mptr));
  40
  41   switch (*mode)
  42     {
  43     case 'a':
  44       mptr->__write = mptr->__create = mptr->__append = 1;
  45       break;
  46     case 'w':
  47       mptr->__write = mptr->__create = mptr->__truncate = 1;
  48       break;
  49     case 'r':
  50       mptr->__read = 1;
  51       break;
  52     default:
  53       badmode ();
  54     }
  55
  56   for (i = 1; i < 3; ++i)
  57     {
  58       ++mode;
  59       if (*mode == '\0')
  60         break;
  61       switch (*mode)
  62         {
  63         case '+':
  64           mptr->__read = mptr->__write = 1;
  65           break;
  66         case 'b':
  67           mptr->__binary = 1;
  68           break;
  69         }
  70     }
  71
  72   if (!mptr->__read && !mptr->__write)
  73     badmode ();
  74
  75   mptr->__exclusive = *mode == 'x';
  76
  77   return 1;
  78 }
  79 \f
  80 /* Open a new stream on the given file.  */
  81 FILE *
  82 fopen (filename, mode)
  83      const char *filename;
  84      const char *mode;
  85 {
  86   FILE *stream;
  87   __io_mode m;
  88
  89   if (filename == NULL)
  90     {
  91       __set_errno (EINVAL);
  92       return NULL;
  93     }
  94
  95   if (!__getmode (mode, &m))
  96     return NULL;
  97
  98   stream = __newstream ();
  99   if (stream == NULL)
 100     return NULL;
 101
 102   if (__stdio_open (filename, m, &stream->__cookie))
 103     {
 104       int save = errno;
 105       (void) fclose (stream);
 106       __set_errno (save);
 107       return NULL;
 108     }
 109
 110   stream->__mode = m;
 111
 112   return stream;
 113 }