/* open for MMIXware.

   Copyright (C) 2001 Hans-Peter Nilsson.

   Permission to use, copy, modify, and distribute this software is freely
   granted, provided that this notice is preserved with no changes.
   THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
   IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   PURPOSE.  */

#include <fcntl.h>
#include <_ansi.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "sys/syscall.h"
#include <errno.h>

/* Let's keep the filehandle array here, since this is a primary
   initializer of it.  */
unsigned char _MMIX_allocated_filehandle[32] =
 {
   1,
   1,
   1,
   0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0
 };

int
_open (const char *path,
       int flags, ...)
{
  long fileno;
  unsigned char mode;
  long fffile = 0;
  long ret;

  for (fileno = 0;
       fileno < (sizeof (_MMIX_allocated_filehandle) /
          sizeof (_MMIX_allocated_filehandle[0]));
       fileno++)
    if (_MMIX_allocated_filehandle[fileno] == 0)
      break;

  if (fileno == (sizeof (_MMIX_allocated_filehandle) /
               sizeof (_MMIX_allocated_filehandle[0])))
    {
      errno = EMFILE;
      return -1;
    }

  /* We map this to a fopen call.  The flags parameter is stymied because
     we don't support more other than these flags.  */
  if (flags & ~(O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_APPEND | O_TRUNC))
    {
      UNIMPLEMENTED (("path: %s, flags: %d", path, flags));
      errno = ENOSYS;
      return -1;
    }

  if ((flags & O_ACCMODE) == O_RDONLY)
    mode = BinaryRead;
  else if ((flags & (O_WRONLY | O_APPEND)) == (O_WRONLY | O_APPEND))
    {
      mode = BinaryReadWrite;
      fffile = 1;
    }
  else if ((flags & (O_RDWR | O_APPEND)) == (O_RDWR | O_APPEND))
    {
      mode = BinaryReadWrite;
      fffile = 1;
    }
  else if ((flags & (O_WRONLY | O_CREAT)) == (O_WRONLY | O_CREAT)
         || (flags & (O_WRONLY | O_TRUNC)) == (O_WRONLY | O_TRUNC))
    mode = BinaryWrite;
  else if ((flags & (O_RDWR | O_CREAT)) == (O_RDWR | O_CREAT))
    mode = BinaryReadWrite;
  else if (flags & O_RDWR)
    mode = BinaryReadWrite;
  else
    {
      errno = EINVAL;
      return -1;
    }

  ret = TRAP3f (SYS_Fopen, fileno, path, mode);
  if (ret < 0)
    {
      /* It's totally unknown what the error was.  We'll just take our
       chances and assume ENOENT.  */
      errno = ENOENT;
      return -1;
    }

  _MMIX_allocated_filehandle[fileno] = 1;

  if (fffile)
    {
      TRAP2f (SYS_Fseek, fileno, -1);
    }

  return fileno;
}