/* -*-C-*-

$Id: os2file.c,v 1.3 1999/01/02 06:11:34 cph Exp $

Copyright (c) 1994-1999 Massachusetts Institute of Technology

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "os2.h"
#include "osfile.h"

static ULONG set_file_pointer (Tchannel, ULONG, LONG);

#define OS2_OPEN_MODE(m)						\
  (((((m) & CHANNEL_READ) == 0)						\
    ? (OPEN_ACCESS_WRITEONLY | OPEN_SHARE_DENYWRITE)			\
    : (((m) & CHANNEL_WRITE) == 0)					\
    ? (OPEN_ACCESS_READONLY  | OPEN_SHARE_DENYNONE)			\
    : (OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYWRITE))			\
   | OPEN_FLAGS_NOINHERIT)

static Tchannel
open_file (const char * filename, ULONG attr, ULONG flags, unsigned int mode)
{
  HFILE handle;
  ULONG action;
  STD_API_CALL
    (dos_open, (((char *) filename), (&handle), (&action), 0, attr, flags,
		(OS2_OPEN_MODE (mode)), 0));
  return (OS2_make_channel (handle, mode));
}

Tchannel
OS_open_input_file (const char * filename)
{
  return
    (open_file (filename,
		FILE_NORMAL,
		(OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_FAIL_IF_NEW),
		CHANNEL_READ));
}

Tchannel
OS_open_output_file (const char * filename)
{
  return
    (open_file (filename,
		FILE_NORMAL,
		(OPEN_ACTION_REPLACE_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW),
		CHANNEL_WRITE));
}

Tchannel
OS_open_io_file (const char * filename)
{
  return
    (open_file (filename,
		FILE_NORMAL,
		(OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW),
		(CHANNEL_READ | CHANNEL_WRITE)));
}

Tchannel
OS_open_append_file (const char * filename)
{
  Tchannel channel =
    (open_file (filename,
		FILE_NORMAL,
		(OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW),
		CHANNEL_WRITE));
  transaction_begin ();
  OS_channel_close_on_abort (channel);
  (void) set_file_pointer (channel, FILE_END, 0);
  transaction_commit ();
  return (channel);
}

static Tchannel
open_file_noerror (const char * filename, ULONG attr, ULONG flags,
		   unsigned int mode)
{
  HFILE handle;
  ULONG action;
  if ((dos_open (((char *) filename), (&handle), (&action), 0, attr, flags,
		 (OS2_OPEN_MODE (mode)), 0))
      != NO_ERROR)
    return (NO_CHANNEL);
  {
    Tchannel channel = (OS2_make_channel (handle, mode));
    if ((CHANNEL_TYPE (channel)) == channel_type_file)
      return (channel);
    OS_channel_close_noerror (channel);
    return (NO_CHANNEL);
  }
}

Tchannel
OS_open_load_file (const char * filename)
{
  return
    (open_file_noerror
     (filename,
      FILE_NORMAL,
      (OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_FAIL_IF_NEW),
      CHANNEL_READ));
}

Tchannel
OS_open_dump_file (const char * filename)
{
  return
    (open_file_noerror
     (filename,
      FILE_NORMAL,
      (OPEN_ACTION_REPLACE_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW),
      CHANNEL_WRITE));
}

off_t
OS_file_length (Tchannel channel)
{
  FILESTATUS3 buffer;
  if ((CHANNEL_TYPE (channel)) != channel_type_file)
    OS2_error_system_call (ERROR_INVALID_HANDLE, syscall_dos_query_file_info);
  STD_API_CALL
    (dos_query_file_info,
     ((CHANNEL_HANDLE (channel)), FIL_STANDARD,
      (&buffer), (sizeof (buffer))));
  return (buffer.cbFile);
}

off_t
OS_file_position (Tchannel channel)
{
  return (set_file_pointer (channel, FILE_CURRENT, 0));
}

void
OS_file_set_position (Tchannel channel, off_t position)
{
  if ((set_file_pointer (channel, FILE_BEGIN, position)) != position)
    OS2_error_anonymous ();
}

static ULONG
set_file_pointer (Tchannel channel, ULONG type, LONG distance)
{
  ULONG fp;
  if ((CHANNEL_TYPE (channel)) != channel_type_file)
    OS2_error_system_call (ERROR_INVALID_HANDLE, syscall_dos_set_file_ptr);
  STD_API_CALL
    (dos_set_file_ptr, ((CHANNEL_HANDLE (channel)), distance, type, (&fp)));
  return (fp);
}