/*

  silcunixschedule.c

  Author: Pekka Riikonen <priikone@silcnet.org>

  Copyright (C) 1998 - 2004 Pekka Riikonen

  The contents of this file are subject to one of the Licenses specified 
  in the COPYING file;  You may not use this file except in compliance 
  with the License.

  The software distributed under the License is distributed on an "AS IS"
  basis, in the hope that it will be useful, but WITHOUT WARRANTY OF ANY
  KIND, either expressed or implied.  See the COPYING file for more
  information.

*/
/* $Id: silcunixschedule.c,v 1.11.2.3 2005/05/11 16:54:14 priikone Exp $ */

#include "silcincludes.h"
#include "silcschedule_i.h"

/* Calls normal select() system call. */

int silc_select(SilcScheduleFd fds, SilcUInt32 fds_count,
		struct timeval *timeout)
{
  fd_set in, out;
  int ret, i, max_fd = 0;

  FD_ZERO(&in);
  FD_ZERO(&out);

  for (i = 0; i < fds_count; i++) {
    if (!fds[i].events)
      continue;

#ifdef FD_SETSIZE
    if (fds[i].fd >= FD_SETSIZE)
      break;
#endif /* FD_SETSIZE */

    if (fds[i].fd > max_fd)
      max_fd = fds[i].fd;

    if (fds[i].events & SILC_TASK_READ)
      FD_SET(fds[i].fd, &in);
    if (fds[i].events & SILC_TASK_WRITE)
      FD_SET(fds[i].fd, &out);

    fds[i].revents = 0;
  }

  ret = select(max_fd + 1, &in, &out, NULL, timeout);
  if (ret <= 0)
    return ret;

  for (i = 0; i < fds_count; i++) {
    if (!fds[i].events)
      continue;

#ifdef FD_SETSIZE
    if (fds[i].fd >= FD_SETSIZE)
      break;
#endif /* FD_SETSIZE */

    if (FD_ISSET(fds[i].fd, &in))
      fds[i].revents |= SILC_TASK_READ;
    if (FD_ISSET(fds[i].fd, &out))
      fds[i].revents |= SILC_TASK_WRITE;
  }

  return ret;
}

#define SIGNAL_COUNT 32

typedef struct {
  SilcUInt32 signal;
  SilcTaskCallback callback;
  void *context;
  bool call;
} SilcUnixSignal;

/* Internal context. */
typedef struct {
  void *app_context;
  int wakeup_pipe[2];
  SilcTask wakeup_task;
  sigset_t signals;
  sigset_t signals_blocked;
  SilcUnixSignal signal_call[SIGNAL_COUNT];
} *SilcUnixScheduler;

#ifdef SILC_THREADS

SILC_TASK_CALLBACK(silc_schedule_wakeup_cb)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;
  unsigned char c;

  read(internal->wakeup_pipe[0], &c, 1);
}

#endif /* SILC_THREADS */

/* Initializes the platform specific scheduler.  This for example initializes
   the wakeup mechanism of the scheduler.  In multi-threaded environment
   the scheduler needs to be wakenup when tasks are added or removed from
   the task queues.  Returns context to the platform specific scheduler. */

void *silc_schedule_internal_init(SilcSchedule schedule,
				  void *app_context)
{
  SilcUnixScheduler internal;

  internal = silc_calloc(1, sizeof(*internal));
  if (!internal)
    return NULL;

  sigemptyset(&internal->signals);

#ifdef SILC_THREADS
  if (pipe(internal->wakeup_pipe)) {
    SILC_LOG_ERROR(("pipe() fails: %s", strerror(errno)));
    silc_free(internal);
    return NULL;
  }

  internal->wakeup_task =
    silc_schedule_task_add(schedule, internal->wakeup_pipe[0],
			   silc_schedule_wakeup_cb, internal,
			   0, 0, SILC_TASK_FD,
			   SILC_TASK_PRI_NORMAL);
  if (!internal->wakeup_task) {
    SILC_LOG_ERROR(("Could not add a wakeup task, threads won't work"));
    close(internal->wakeup_pipe[0]);
    close(internal->wakeup_pipe[1]);
    silc_free(internal);
    return NULL;
  }
#endif

  internal->app_context = app_context;

  return (void *)internal;
}

void silc_schedule_internal_signals_block(void *context);
void silc_schedule_internal_signals_unblock(void *context);

/* Uninitializes the platform specific scheduler context. */

void silc_schedule_internal_uninit(void *context)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;

  if (!internal)
    return;

#ifdef SILC_THREADS
  close(internal->wakeup_pipe[0]);
  close(internal->wakeup_pipe[1]);
#endif

  silc_free(internal);
}

/* Wakes up the scheduler */

void silc_schedule_internal_wakeup(void *context)
{
#ifdef SILC_THREADS
  SilcUnixScheduler internal = (SilcUnixScheduler)context;

  if (!internal)
    return;

  write(internal->wakeup_pipe[1], "!", 1);
#endif
}

void silc_schedule_internal_signal_register(void *context,
					    SilcUInt32 signal,
                                            SilcTaskCallback callback,
                                            void *callback_context)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;
  int i;

  if (!internal)
    return;

  SILC_LOG_DEBUG(("Registering signal %d", signal));

  silc_schedule_internal_signals_block(context);

  for (i = 0; i < SIGNAL_COUNT; i++) {
    if (!internal->signal_call[i].signal) {
      internal->signal_call[i].signal = signal;
      internal->signal_call[i].callback = callback;
      internal->signal_call[i].context = callback_context;
      internal->signal_call[i].call = FALSE;
      break;
    }
  }

  silc_schedule_internal_signals_unblock(context);
  sigaddset(&internal->signals, signal);
}

void silc_schedule_internal_signal_unregister(void *context,
					      SilcUInt32 signal,
                                              SilcTaskCallback callback,
                                              void *callback_context)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;
  int i;

  if (!internal)
    return;

  SILC_LOG_DEBUG(("Unregistering signal %d", signal));

  silc_schedule_internal_signals_block(context);

  for (i = 0; i < SIGNAL_COUNT; i++) {
    if (internal->signal_call[i].signal == signal &&
	internal->signal_call[i].callback == callback &&
	internal->signal_call[i].context == callback_context) {
      internal->signal_call[i].signal = 0;
      internal->signal_call[i].callback = NULL;
      internal->signal_call[i].context = NULL;
      internal->signal_call[i].call = FALSE;
    }
  }

  silc_schedule_internal_signals_unblock(context);
  sigdelset(&internal->signals, signal);
}

/* Mark signal to be called later. */

void silc_schedule_internal_signal_call(void *context, SilcUInt32 signal)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;
  int i;

  if (!internal)
    return;

  silc_schedule_internal_signals_block(context);

  for (i = 0; i < SIGNAL_COUNT; i++) {
    if (internal->signal_call[i].signal == signal) {
      internal->signal_call[i].call = TRUE;
      SILC_LOG_DEBUG(("Scheduling signal %d to be called",
		      internal->signal_call[i].signal));
    }
  }

  silc_schedule_internal_signals_unblock(context);
}

/* Call all signals */

void silc_schedule_internal_signals_call(void *context,
                                         SilcSchedule schedule)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;
  int i;

  SILC_LOG_DEBUG(("Start"));

  if (!internal)
    return;

  silc_schedule_internal_signals_block(context);

  for (i = 0; i < SIGNAL_COUNT; i++) {
    if (internal->signal_call[i].call &&
        internal->signal_call[i].callback) {
      SILC_LOG_DEBUG(("Calling signal %d callback",
		      internal->signal_call[i].signal));
      internal->signal_call[i].callback(schedule, internal->app_context,
					SILC_TASK_INTERRUPT,
					internal->signal_call[i].signal,
					internal->signal_call[i].context);
      internal->signal_call[i].call = FALSE;
    }
  }

  silc_schedule_internal_signals_unblock(context);
}

/* Block registered signals in scheduler. */

void silc_schedule_internal_signals_block(void *context)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;

  if (!internal)
    return;

  sigprocmask(SIG_BLOCK, &internal->signals, &internal->signals_blocked);
}

/* Unblock registered signals in schedule. */

void silc_schedule_internal_signals_unblock(void *context)
{
  SilcUnixScheduler internal = (SilcUnixScheduler)context;

  if (!internal)
    return;

  sigprocmask(SIG_SETMASK, &internal->signals_blocked, NULL);
}