stdio/fopen.c

   1 /* Copyright (C) 1991, 92, 93, 96, 97, 98 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 not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, 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 (const char *mode, __io_mode *mptr)
  31 {
  32   register unsigned char i;
  33
  34   if (mode == NULL)
  35     badmode ();
  36
  37   memset ((void *) mptr, 0, sizeof (*mptr));
  38
  39   switch (*mode)
  40     {
  41     case 'a':
  42       mptr->__write = mptr->__create = mptr->__append = 1;
  43       break;
  44     case 'w':
  45       mptr->__write = mptr->__create = mptr->__truncate = 1;
  46       break;
  47     case 'r':
  48       mptr->__read = 1;
  49       break;
  50     default:
  51       badmode ();
  52     }
  53
  54   for (i = 1; i < 4; ++i)
  55     {
  56       switch (*++mode)
  57         {
  58         case '\0':
  59           break;
  60         case '+':
  61           mptr->__read = mptr->__write = 1;
  62           continue;
  63         case 'b':
  64           mptr->__binary = 1;
  65           continue;
  66         case 'x':
  67           mptr->__exclusive = 1;
  68           continue;
  69         }
  70       break;
  71     }
  72
  73   if (!mptr->__read && !mptr->__write)
  74     badmode ();
  75
  76   return 1;
  77 }
  78 \f
  79 /* Open a new stream on the given file.  */
  80 FILE *
  81 fopen (filename, mode)
  82      const char *filename;
  83      const char *mode;
  84 {
  85   FILE *stream;
  86   __io_mode m;
  87
  88   if (filename == NULL)
  89     {
  90       __set_errno (EINVAL);
  91       return NULL;
  92     }
  93
  94   if (!__getmode (mode, &m))
  95     return NULL;
  96
  97   stream = __newstream ();
  98   if (stream == NULL)
  99     return NULL;
 100
 101   if (__stdio_open (filename, m, &stream->__cookie))
 102     {
 103       int save = errno;
 104       (void) fclose (stream);
 105       __set_errno (save);
 106       return NULL;
 107     }
 108
 109   stream->__mode = m;
 110
 111   return stream;
 112 }