/*
 * Libraries and headers for PDC release 3.3 (C) 1989 Lionel Hummel.
 * PDC Software Distribution (C) 1989 Lionel Hummel and Paul Petersen.
 * PDC I/O Library (C) 1987 by J.A. Lydiatt.
 *
 * This code is freely redistributable upon the conditions that this
 * notice remains intact and that modified versions of this file not
 * be included as part of the PDC Software Distribution without the
 * express consent of the copyright holders.  No warrantee of any
 * kind is provided with this code.  For further information, contact:
 *
 *  PDC Software Distribution    Internet:                     BIX:
 *  P.O. Box 4006             or hummel@cs.uiuc.edu            lhummel
 *  Urbana, IL  61801-8801       petersen@uicsrd.csrd.uiuc.edu
 */

/* open.c -
 *      creat(char *name, int pmode)    - creates a new file
 *      open(char *name, int mode)      - opens a file
 */

#include        <exec/types.h>
#include        <libraries/dos.h>
#include        <functions.h>

#include        <errno.h>
#include        <fcntl.h>

/*
 * returns the max. number of entries available in the file descrptor table
 */

int 
getdtablesize ()
{
  extern short _numdev;

  return (int) _numdev;
}

/*
 open a file for unbuffered I/O.

  open(path, flags, mode)
  char *path;
  int   flags;
  int   mode;

 The file mode flag is presently ignored - This may not be the case in
 the future, so it is recommended that you use the value DEF_PMODE defined
 in fcntl.h if you have the O_CREAT flag set.
 */

open (path, flags, mode)
     char *path;
     int flags;
     int mode;
{
  struct _device *p;
  int fd;
  BPTR fh;
  extern void Chk_Abort ();
  extern struct _device *_devtab;

  Chk_Abort ();

  /*
   * Find the first empty entry in the device table.
   */

  p = &_devtab[0];

  for (fd = 0; fd < _numdev; ++fd)
    if (!p[fd]._fileHandle)
      break;

  if (fd >= _numdev)
    {
      errno = EMFILE;
      return -1;
    }

  if (flags & O_TRUNC)
    {
      if (fh = Lock (path, ACCESS_WRITE))
	{
	  UnLock (fh);
	  if (!DeleteFile (path))
	    {
	      errno = IoErr ();
	      return -1;
	    }
	}
    }

  fh = Open (path, MODE_OLDFILE);
  if (!fh)
    {
      if (!(flags & O_CREAT))
	{
	  errno = ENOENT;
	  return -1;
	}
      fh = Open (path, MODE_NEWFILE);
      if (!fh)
	{
	  errno = IoErr ();
	  return -1;
	}
    }
  else if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
    {
      Close (fh);
      errno = EEXIST;
      return -1;
    }

  p[fd]._fileHandle = fh;
  p[fd]._mode = flags;

  if (flags & O_APPEND)
    Seek (fh, 0L, OFFSET_END);

  return fd;
}


/*
 * creates a new file with the requested file modes
 */

int
creat (name, pmode)
     char *name;
     int pmode;
{
  return open (name, O_WRONLY | O_TRUNC | O_CREAT, pmode);
}