signal.c

 
#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