stdio/fopen.c

   1 /* Copyright (C) 1991, 1992, 1993 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 <ansidecl.h>
  20 #include <ctype.h>
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25
  26
  27 #define badmode()       return ((errno = EINVAL), 0)
  28
  29 /* Dissect the given mode string into an __io_mode.  */
  30 int
  31 DEFUN(__getmode, (mode, mptr), CONST char *mode AND __io_mode *mptr)
  32 {
  33   register unsigned char i;
  34
  35   if (mode == NULL)
  36     badmode ();
  37
  38   memset ((PTR) mptr, 0, sizeof (*mptr));
  39
  40   switch (*mode)
  41     {
  42     case 'a':
  43       mptr->__write = mptr->__create = mptr->__append = 1;
  44       break;
  45     case 'w':
  46       mptr->__write = mptr->__create = mptr->__truncate = 1;
  47       break;
  48     case 'r':
  49       mptr->__read = 1;
  50       break;
  51     default:
  52       badmode ();
  53     }
  54
  55   for (i = 1; i < 3; ++i)
  56     {
  57       ++mode;
  58       if (*mode == '\0')
  59         break;
  60       switch (*mode)
  61         {
  62         case '+':
  63           mptr->__read = mptr->__write = 1;
  64           break;
  65         case 'b':
  66           mptr->__binary = 1;
  67           break;
  68         }
  69     }
  70
  71   if (!mptr->__read && !mptr->__write)
  72     badmode ();
  73
  74   mptr->__exclusive = *mode == 'x';
  75
  76   return 1;
  77 }
  78 \f
  79 /* Open a new stream on the given file.  */
  80 FILE *
  81 DEFUN(fopen, (filename, mode), CONST char *filename AND CONST char *mode)
  82 {
  83   FILE *stream;
  84   __io_mode m;
  85
  86   if (filename == NULL)
  87     {
  88       errno = EINVAL;
  89       return NULL;
  90     }
  91
  92   if (!__getmode (mode, &m))
  93     return NULL;
  94
  95   stream = __newstream ();
  96   if (stream == NULL)
  97     return NULL;
  98
  99   if (__stdio_open (filename, m, &stream->__cookie))
 100     {
 101       int save = errno;
 102       (void) fclose (stream);
 103       errno = save;
 104       return NULL;
 105     }
 106
 107   stream->__mode = m;
 108
 109   return stream;
 110 }