/**

 * FreeRDP: A Remote Desktop Protocol Implementation

 * Signal handling

 *

 * Copyright 2011 Shea Levy <shea@shealevy.com>

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <freerdp/config.h>

#include <stddef.h>

#include <errno.h>

#include <string.h>

#include <winpr/crt.h>

#include <freerdp/utils/signal.h>

#include <freerdp/log.h>

#ifndef _WIN32

#include <signal.h>

#include <termios.h>

#endif

#define TAG FREERDP_TAG("utils.signal")

#ifdef _WIN32

int freerdp_handle_signals(void)

{

  errno = ENOSYS;

  return -1;

}

BOOL freerdp_add_signal_cleanup_handler(void* context, freerdp_signal_handler_t fkt)

{

  return FALSE;

}

BOOL freerdp_del_signal_cleanup_handler(void* context, freerdp_signal_handler_t fkt)

{

  return FALSE;

}

#else

#include <pthread.h>

#include <winpr/debug.h>

static BOOL handlers_registered = FALSE;

static pthread_mutex_t signal_handler_lock = PTHREAD_MUTEX_INITIALIZER;

typedef struct

{

  void* context;

  freerdp_signal_handler_t handler;

} cleanup_handler_t;

static size_t cleanup_handler_count = 0;

static cleanup_handler_t cleanup_handlers[20] = { 0 };

static void lock(void)

{

  const int rc = pthread_mutex_lock(&signal_handler_lock);

  if (rc != 0)

  {

    char ebuffer[256] = { 0 };

    WLog_ERR(TAG, "[pthread_mutex_lock] failed with %s [%d]",

             winpr_strerror(rc, ebuffer, sizeof(ebuffer)), rc);

  }

}

static void unlock(void)

{

  const int rc = pthread_mutex_unlock(&signal_handler_lock);

  if (rc != 0)

  {

    char ebuffer[256] = { 0 };

    WLog_ERR(TAG, "[pthread_mutex_lock] failed with %s [%d]",

             winpr_strerror(rc, ebuffer, sizeof(ebuffer)), rc);

  }

}

static void term_handler(int signum)

{

  static BOOL recursive = FALSE;

  if (!recursive)

  {

    recursive = TRUE;

    WLog_ERR(TAG, "Caught signal '%s' [%d]", strsignal(signum), signum);

  }

  lock();

  for (size_t x = 0; x < cleanup_handler_count; x++)

  {

    const cleanup_handler_t empty = { 0 };

    cleanup_handler_t* cur = &cleanup_handlers[x];

    if (cur->handler)

      cur->handler(signum, strsignal(signum), cur->context);

    *cur = empty;

  }

  cleanup_handler_count = 0;

  unlock();

}

static void fatal_handler(int signum)

{

  struct sigaction default_sigaction;

  sigset_t this_mask;

  static BOOL recursive = FALSE;

  if (!recursive)

  {

    recursive = TRUE;

    WLog_ERR(TAG, "Caught signal '%s' [%d]", strsignal(signum), signum);

    winpr_log_backtrace(TAG, WLOG_ERROR, 20);

  }

  default_sigaction.sa_handler = SIG_DFL;

  sigfillset(&(default_sigaction.sa_mask));

  default_sigaction.sa_flags = 0;

  sigaction(signum, &default_sigaction, NULL);

  sigemptyset(&this_mask);

  sigaddset(&this_mask, signum);

  pthread_sigmask(SIG_UNBLOCK, &this_mask, NULL);

  (void)raise(signum);

}

static const int term_signals[] = { SIGINT, SIGKILL, SIGQUIT, SIGSTOP, SIGTERM };

static const int fatal_signals[] = { SIGABRT,   SIGALRM, SIGBUS,  SIGFPE,  SIGHUP,  SIGILL,

                                   SIGSEGV,   SIGTSTP, SIGTTIN, SIGTTOU, SIGUSR1, SIGUSR2,

#ifdef SIGPOLL

                                   SIGPOLL,

#endif

#ifdef SIGPROF

                                   SIGPROF,

#endif

#ifdef SIGSYS

                                   SIGSYS,

#endif

                                   SIGTRAP,

#ifdef SIGVTALRM

                                   SIGVTALRM,

#endif

                                   SIGXCPU,   SIGXFSZ };

static BOOL register_handlers(const int* signals, size_t count, void (*handler)(int))

{

  WINPR_ASSERT(signals || (count == 0));

  WINPR_ASSERT(handler);

  sigset_t orig_set = { 0 };

  struct sigaction saction = { 0 };

  pthread_sigmask(SIG_BLOCK, &(saction.sa_mask), &orig_set);

  sigfillset(&(saction.sa_mask));

  sigdelset(&(saction.sa_mask), SIGCONT);

  saction.sa_handler = handler;

  saction.sa_flags = 0;

  for (size_t x = 0; x < count; x++)

  {

    struct sigaction orig_sigaction = { 0 };

    if (sigaction(signals[x], NULL, &orig_sigaction) == 0)

    {

      if (orig_sigaction.sa_handler != SIG_IGN)

      {

        sigaction(signals[x], &saction, NULL);

      }

    }

  }

  pthread_sigmask(SIG_SETMASK, &orig_set, NULL);

  return TRUE;

}

int freerdp_handle_signals(void)

{

  int rc = -1;

  lock();

  WLog_DBG(TAG, "Registering signal hook...");

  if (!register_handlers(fatal_signals, ARRAYSIZE(fatal_signals), fatal_handler))

    goto fail;

  if (!register_handlers(term_signals, ARRAYSIZE(term_signals), term_handler))

    goto fail;

  /* Ignore SIGPIPE signal. */

  (void)signal(SIGPIPE, SIG_IGN);

  handlers_registered = TRUE;

  rc = 0;

fail:

  unlock();

  return rc;

}

BOOL freerdp_add_signal_cleanup_handler(void* context, freerdp_signal_handler_t handler)

{

  BOOL rc = FALSE;

  lock();

  if (handlers_registered)

  {

    if (cleanup_handler_count < ARRAYSIZE(cleanup_handlers))

    {

      cleanup_handler_t* cur = &cleanup_handlers[cleanup_handler_count++];

      cur->context = context;

      cur->handler = handler;

    }

    else

      WLog_WARN(TAG, "Failed to register cleanup handler, only %" PRIuz " handlers supported",

                ARRAYSIZE(cleanup_handlers));

  }

  rc = TRUE;

  unlock();

  return rc;

}

BOOL freerdp_del_signal_cleanup_handler(void* context, freerdp_signal_handler_t handler)

{

  BOOL rc = FALSE;

  lock();

  if (handlers_registered)

  {

    for (size_t x = 0; x < cleanup_handler_count; x++)

    {

      cleanup_handler_t* cur = &cleanup_handlers[x];

      if ((cur->context == context) && (cur->handler == handler))

      {

        const cleanup_handler_t empty = { 0 };

        for (size_t y = x + 1; y < cleanup_handler_count - 1; y++)

        {

          *cur++ = cleanup_handlers[y];

        }

        *cur = empty;

        cleanup_handler_count--;

        break;

      }

    }

  }

  rc = TRUE;

  unlock();

  return rc;

}

#endif