/* Code shared between all event loops that use select() and have a
   different input descriptor for each device.
   Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
   Copyright (C) 1995 Board of Trustees, University of Illinois.
   Copyright (C) 1995 Sun Microsystems, Inc.
   Copyright (C) 1995, 1996, 2001, 2002, 2003 Ben Wing.

This file is part of XEmacs.

XEmacs 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 3 of the License, or (at your
option) any later version.

XEmacs 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 XEmacs.  If not, see <http://www.gnu.org/licenses/>. */

/* Synched up with: Not in FSF. */

/* This file has been Mule-ized. */

#include <config.h>
#include "lisp.h"

#include "console-stream-impl.h"
#include "console-tty-impl.h"
#include "device-impl.h"
#include "events.h"
#include "lstream.h"
#include "process.h"

#include "sysdep.h"
#include "sysfile.h"
#include "sysproc.h"		/* select stuff */
#include "systime.h"

/* Mask of bits indicating the descriptors that we wait for input on.
   These work as follows:

   In event-tty.c we call select() directly on this
   to retrieve an event.  In event-Xt.c we use
   XtAppAddInput() and the call to select() is down in
   the guts of Xt, but we still use the masks when checking for pending input, even in event-Xt.c. (We can't use XtAppPending() because of the presence of the signal event pipe.)

   input_wait_mask == mask of all file descriptors we select() on,
                      including TTY/stream console descriptors,
		      process descriptors, and the signal event pipe.

   non_fake_input_wait_mask == same as input_wait_mask but minus the
                               signal event pipe.  Also only used in
			       event-tty.c.

   process_only_mask == only the process descriptors.

   tty_only_mask == only the TTY/stream console descriptors.
   */
SELECT_TYPE input_wait_mask, non_fake_input_wait_mask;
SELECT_TYPE process_only_mask, tty_only_mask;

/* This is used to terminate the select(), when an event came in
   through a signal (e.g. window-change or C-g on controlling TTY). */
int signal_event_pipe[2];

int signal_event_pipe_initialized;

int fake_event_occurred;

struct console *
find_tty_or_stream_console_from_fd (int fd)
{
  Lisp_Object concons;

  CONSOLE_LOOP (concons)
    {
      struct console *c;

      c = XCONSOLE (XCAR (concons));
      if ((CONSOLE_TTY_P (c) && CONSOLE_TTY_DATA (c)->infd == fd) ||
	  (CONSOLE_STREAM_P (c) && fileno (CONSOLE_STREAM_DATA (c)->in) == fd))
	return c;
    }

  return 0;
}

int
read_event_from_tty_or_stream_desc (Lisp_Event *event, struct console *con)
{
  Ichar ch;
  Lisp_Object console = wrap_console (con);

  if (CONSOLE_TTY_P (con))
    ch = Lstream_get_ichar (XLSTREAM (CONSOLE_TTY_DATA (con)->instream));
  else
    {
      Ibyte ibyte;
      /* #### Definitely something strange here.  We should be setting
	 the stdio handle unbuffered and reading from it instead of mixing
	 stdio and raw io calls. */
      int nread = retry_read (fileno (CONSOLE_STREAM_DATA (con)->in),
			      &ibyte, 1);
      if (nread <= 0)
	ch = -1;
      else
        ch = ibyte;
    }

  if (ch < 0)
    {
      /* deleting the console might not be safe right now ... */
      enqueue_magic_eval_event (io_error_delete_console, console);
      /* but we definitely need to unselect it to avoid infinite
	 loops reading EOF's */
      Fconsole_disable_input (console);
    }
  else
    {
      character_to_event (ch, event, con, use_console_meta_flag, 1);
      event->channel = console;
      return 1;
    }
  return 0;
}

void
signal_fake_event (void)
{
  Rawbyte rbyte = 0;
  /* We do the write always.  Formerly I tried to "optimize" this
     by setting a flag indicating whether we're blocking and only
     doing the write in that case, but there is a race condition
     if the signal occurs after we've checked for the signal
     occurrence (which could occur in many places throughout
     an iteration of the command loop, e.g. in status_notify()),
     but before we set the blocking flag.

     This should be OK as long as write() is reentrant, which I'm fairly
     sure it is since it's a system call. */

  if (signal_event_pipe_initialized)
    /* In case a signal comes through while we're dumping */
    {
      int old_errno = errno;
      retry_write (signal_event_pipe[1], &rbyte, 1);
      errno = old_errno;
    }
}

void
drain_signal_event_pipe (void)
{
  Rawbyte chars[128];
  /* The input end of the pipe has been set to non-blocking. */
  while (retry_read (signal_event_pipe[0], chars, sizeof (chars)) > 0)
    ;
}

void
drain_tty_devices (void)
{
  Lisp_Object devcons, concons;
  CONSOLE_LOOP (concons)
    {
      struct console *con = XCONSOLE (XCAR (concons));
      if (!con->input_enabled)
	continue;

      CONSOLE_DEVICE_LOOP (devcons, con)
	{
	  struct device *d = XDEVICE (XCAR (devcons));
	  if (DEVICE_TTY_P (d))
	    {
	      SELECT_TYPE temp_mask;
	      int infd = DEVICE_INFD (d);

	      FD_ZERO (&temp_mask);
	      FD_SET (infd, &temp_mask);

	      while (1)
		{
		  Lisp_Object event;

		  if (!poll_fds_for_input (temp_mask))
		    break;

		  event = Fmake_event (Qnil, Qnil);
		  if (!read_event_from_tty_or_stream_desc (XEVENT (event),
							   con))
		    /* EOF, or something ... */
		    break;

		  /* queue the read event to be read for real later. */
		  enqueue_dispatch_event (event);
		}
	    }
	}
    }
}

int
event_stream_unixoid_select_console (struct console *con)
{
  int infd;

  if (CONSOLE_STREAM_P (con))
    infd = fileno (CONSOLE_STREAM_DATA (con)->in);
  else
    {
      assert (CONSOLE_TTY_P (con));
      infd = CONSOLE_TTY_DATA (con)->infd;
    }

  assert (infd >= 0);

  FD_SET (infd, &input_wait_mask);
  FD_SET (infd, &non_fake_input_wait_mask);
  FD_SET (infd, &tty_only_mask);
  return infd;
}

int
event_stream_unixoid_unselect_console (struct console *con)
{
  int infd;

  if (CONSOLE_STREAM_P (con))
    infd = fileno (CONSOLE_STREAM_DATA (con)->in);
  else
    {
      assert (CONSOLE_TTY_P (con));
      infd = CONSOLE_TTY_DATA (con)->infd;
    }

  assert (infd >= 0);

  FD_CLR (infd, &input_wait_mask);
  FD_CLR (infd, &non_fake_input_wait_mask);
  FD_CLR (infd, &tty_only_mask);
  return infd;
}

static int
get_process_infd (Lisp_Process *p)
{
  Lisp_Object instr, outstr, errstr;
  get_process_streams (p, &instr, &outstr, &errstr);
  assert (!NILP (instr));
  return filedesc_stream_fd (XLSTREAM (instr));
}

static int
get_process_errfd (Lisp_Process *p)
{
  Lisp_Object instr, outstr, errstr;
  get_process_streams (p, &instr, &outstr, &errstr);
  if (!NILP (errstr))
    return filedesc_stream_fd (XLSTREAM (errstr));
  else
    return -1;
}

void
event_stream_unixoid_select_process (Lisp_Process *proc, int doin, int doerr,
				     int *infd, int *errfd)
{
  if (doin)
    {
      *infd = get_process_infd (proc);
      FD_SET (*infd, &input_wait_mask);
      FD_SET (*infd, &non_fake_input_wait_mask);
      FD_SET (*infd, &process_only_mask);
    }

  if (doerr)
    {
      *errfd = get_process_errfd (proc);

      if (*errfd >= 0)
	{
	  FD_SET (*errfd, &input_wait_mask);
	  FD_SET (*errfd, &non_fake_input_wait_mask);
	  FD_SET (*errfd, &process_only_mask);
	}
    }
}

void
event_stream_unixoid_unselect_process (Lisp_Process *proc, int doin, int doerr,
				       int *infd, int *errfd)
{
  if (doin)
    {
      *infd = get_process_infd (proc);
      FD_CLR (*infd, &input_wait_mask);
      FD_CLR (*infd, &non_fake_input_wait_mask);
      FD_CLR (*infd, &process_only_mask);
    }

  if (doerr)
    {
      *errfd = get_process_errfd (proc);

      if (*errfd >= 0)
	{
	  FD_CLR (*errfd, &input_wait_mask);
	  FD_CLR (*errfd, &non_fake_input_wait_mask);
	  FD_CLR (*errfd, &process_only_mask);
	}
    }
}

int
poll_fds_for_input (SELECT_TYPE mask)
{
  EMACS_TIME sometime;
  EMACS_SELECT_TIME select_time;
  SELECT_TYPE temp_mask;
  int retval;

  while (1)
    {
      EMACS_SET_SECS_USECS (sometime, 0, 0);
      EMACS_TIME_TO_SELECT_TIME (sometime, select_time);
      temp_mask = mask;
      /* To effect a poll, tell select() to block for zero seconds. */
      retval = select (MAXDESC, &temp_mask, 0, 0, &select_time);
      if (retval >= 0)
	return retval;
      if (errno != EINTR)
	{
	  /* Something went seriously wrong; don't abort since maybe
	     the TTY just died at the wrong time. */
	  stderr_out ("xemacs: select failed: errno = %d\n", errno);
	  return 0;
	}
      /* else, we got interrupted by a signal, so try again. */
    }

  RETURN_NOT_REACHED (0);
}

/****************************************************************************/
/*     Unixoid (file descriptors based) process I/O streams routines        */
/****************************************************************************/

void
event_stream_unixoid_create_io_streams (void* inhandle, void* outhandle,
					void *errhandle, Lisp_Object* instream,
					Lisp_Object* outstream,
					Lisp_Object* errstream,
					USID* in_usid,
					USID* err_usid,
					int flags)
{
  int infd, outfd, errfd;
  /* Decode inhandle and outhandle. Their meaning depends on
     the process implementation being used. */
  /* We are passed plain old file descs, which are ints, so */
  /* if sizeof(EMACS_INT) > sizeof(int) it's OK. */
  infd  = (EMACS_INT) inhandle;
  outfd = (EMACS_INT) outhandle;
  errfd = (EMACS_INT) errhandle;

  *instream = (infd >= 0
	       ? make_filedesc_input_stream (infd, 0, -1, 0)
	       : Qnil);

  *outstream = (outfd >= 0
		? make_filedesc_output_stream (outfd, 0, -1, LSTR_BLOCKED_OK)
		: Qnil);

  *errstream = (errfd >= 0
	       ? make_filedesc_input_stream (errfd, 0, -1, 0)
	       : Qnil);

  /* FLAGS is process->pty_flag for UNIX_PROCESSES */
  if ((flags & STREAM_PTY_FLUSHING) && outfd >= 0)
    {
      Ibyte eof_char = get_eof_char (outfd);
      int pty_max_bytes = get_pty_max_bytes (outfd);
      filedesc_stream_set_pty_flushing (XLSTREAM (*outstream), pty_max_bytes,
					eof_char);
    }

  *in_usid = FD_TO_USID (infd);
  *err_usid = FD_TO_USID (errfd);
}

void
event_stream_unixoid_delete_io_streams (Lisp_Object instream,
					Lisp_Object outstream,
					Lisp_Object errstream,
					USID *in_usid,
					USID *err_usid)
{
  int in = (NILP (instream) ? -1
	    : filedesc_stream_fd (XLSTREAM (instream)));
  int out = (NILP (outstream) ? -1
	     : filedesc_stream_fd (XLSTREAM (outstream)));
  int err = (NILP (errstream) ? -1
	     : filedesc_stream_fd (XLSTREAM (errstream)));

  if (in >= 0)
    retry_close (in);
  if (out != in && out >= 0)
    retry_close (out);
  if (err != in && err != out && err >= 0)
    retry_close (err);

  *in_usid = FD_TO_USID (in);
  *err_usid = FD_TO_USID (err);
}


void
init_event_unixoid (void)
{
  /* Do this first; the init_event_*_late() functions
     pay attention to it. */
  if (pipe (signal_event_pipe) < 0)
    {
      perror ("XEmacs: can't open pipe");
      exit (-1);
    }
  signal_event_pipe_initialized = 1;

  /* Set it non-blocking so we can drain its output. */
  set_descriptor_non_blocking (signal_event_pipe[0]);

  /* Also set the write descriptor non-blocking so we don't
     hang in case a long time passes between times when
     we drain the pipe. */
  set_descriptor_non_blocking (signal_event_pipe[1]);

  /* WARNING: In order for the signal-event pipe to work correctly
     and not cause lockups, the following need to be followed:

     1) event_pending_p() must ignore input on the signal-event pipe.
     2) As soon as next_event() notices input on the signal-event
     pipe, it must drain it. */
  FD_ZERO (&input_wait_mask);
  FD_ZERO (&non_fake_input_wait_mask);
  FD_ZERO (&process_only_mask);
  FD_ZERO (&tty_only_mask);

  FD_SET (signal_event_pipe[0], &input_wait_mask);
}