text: 
  /* Signal module -- many thanks to Lance Ellinghaus */
  
  /* XXX Signals should be recorded per thread, now we have thread state. */
  
  #include "Python.h"
  #include "internal/pyatomic.h"
  
  #ifndef MS_WINDOWS
  #include "posixmodule.h"
  #endif
  #ifdef MS_WINDOWS
  #include "socketmodule.h"   /* needed for SOCKET_T */
  #endif
  
  #ifdef MS_WINDOWS
  #include <windows.h>
  #ifdef HAVE_PROCESS_H
  #include <process.h>
  #endif
  #endif
  
  #ifdef HAVE_SIGNAL_H
  #include <signal.h>
  #endif
  #ifdef HAVE_SYS_STAT_H
  #include <sys/stat.h>
  #endif
  #ifdef HAVE_SYS_TIME_H
  #include <sys/time.h>
  #endif
  
  #if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK)
  #  define PYPTHREAD_SIGMASK
  #endif
  
  #if defined(PYPTHREAD_SIGMASK) && defined(HAVE_PTHREAD_H)
  #  include <pthread.h>
  #endif
  
  #ifndef SIG_ERR
  #define SIG_ERR ((PyOS_sighandler_t)(-1))
  #endif
  
  #ifndef NSIG
  # if defined(_NSIG)
  #  define NSIG _NSIG            /* For BSD/SysV */
  # elif defined(_SIGMAX)
  #  define NSIG (_SIGMAX + 1)    /* For QNX */
  # elif defined(SIGMAX)
  #  define NSIG (SIGMAX + 1)     /* For djgpp */
  # else
  #  define NSIG 64               /* Use a reasonable default value */
  # endif
  #endif
  
  #include "clinic/signalmodule.c.h"
  
  /*[clinic input]
  module signal
  [clinic start generated code]*/
  /*[clinic end generated code: output=da39a3ee5e6b4b0d input=b0301a3bde5fe9d3]*/
  
  /*[python input]
  
  class sigset_t_converter(CConverter):
      type = 'sigset_t'
      converter = '_Py_Sigset_Converter'
  
  [python start generated code]*/
  /*[python end generated code: output=da39a3ee5e6b4b0d input=b5689d14466b6823]*/
  
  /*
     NOTES ON THE INTERACTION BETWEEN SIGNALS AND THREADS
  
     When threads are supported, we want the following semantics:
  
     - only the main thread can set a signal handler
     - any thread can get a signal handler
     - signals are only delivered to the main thread
  
     I.e. we don't support "synchronous signals" like SIGFPE (catching
     this doesn't make much sense in Python anyway) nor do we support
     signals as a means of inter-thread communication, since not all
     thread implementations support that (at least our thread library
     doesn't).
  
     We still have the problem that in some implementations signals
     generated by the keyboard (e.g. SIGINT) are delivered to all
     threads (e.g. SGI), while in others (e.g. Solaris) such signals are
     delivered to one random thread (an intermediate possibility would
     be to deliver it to the main thread -- POSIX?).  For now, we have
     a working implementation that works in all three cases -- the
     handler ignores signals if getpid() isn't the same as in the main
     thread.  XXX This is a hack.
  */
  
  #include <sys/types.h> /* For pid_t */
  #include "pythread.h"
  static unsigned long main_thread;
  static pid_t main_pid;
  
  static volatile struct {
      _Py_atomic_int tripped;
      PyObject *func;
  } Handlers[NSIG];
  
  #ifdef MS_WINDOWS
  #define INVALID_FD ((SOCKET_T)-1)
  
  static volatile struct {
      SOCKET_T fd;
      int warn_on_full_buffer;
      int use_send;
  } wakeup = {.fd = INVALID_FD, .warn_on_full_buffer = 1, .use_send = 0};
  #else
  #define INVALID_FD (-1)
  static volatile struct {
      sig_atomic_t fd;
      int warn_on_full_buffer;
  } wakeup = {.fd = INVALID_FD, .warn_on_full_buffer = 1};
  #endif
  
  /* Speed up sigcheck() when none tripped */
  static _Py_atomic_int is_tripped;
  
  static PyObject *DefaultHandler;
  static PyObject *IgnoreHandler;
  static PyObject *IntHandler;
  
  #ifdef MS_WINDOWS
  static HANDLE sigint_event = NULL;
  #endif
  
  #ifdef HAVE_GETITIMER
  static PyObject *ItimerError;
  
  /* auxiliary functions for setitimer */
  static int
  timeval_from_double(PyObject *obj, struct timeval *tv)
  {
      if (obj == NULL) {
          tv->tv_sec = 0;
          tv->tv_usec = 0;
          return 0;
      }
  
      _PyTime_t t;
      if (_PyTime_FromSecondsObject(&t, obj, _PyTime_ROUND_CEILING) < 0) {
          return -1;
      }
      return _PyTime_AsTimeval(t, tv, _PyTime_ROUND_CEILING);
  }
  
  Py_LOCAL_INLINE(double)
  double_from_timeval(struct timeval *tv)
  {
      return tv->tv_sec + (double)(tv->tv_usec / 1000000.0);
  }
  
  static PyObject *
  itimer_retval(struct itimerval *iv)
  {
      PyObject *r, *v;
  
      r = PyTuple_New(2);
      if (r == NULL)
          return NULL;
  
      if(!(v = PyFloat_FromDouble(double_from_timeval(&iv->it_value)))) {
          Py_DECREF(r);
          return NULL;
      }
  
      PyTuple_SET_ITEM(r, 0, v);
  
      if(!(v = PyFloat_FromDouble(double_from_timeval(&iv->it_interval)))) {
          Py_DECREF(r);
          return NULL;
      }
  
      PyTuple_SET_ITEM(r, 1, v);
  
      return r;
  }
  #endif
  
  static PyObject *
  signal_default_int_handler(PyObject *self, PyObject *args)
  {
      PyErr_SetNone(PyExc_KeyboardInterrupt);
      return NULL;
  }
  
  PyDoc_STRVAR(default_int_handler_doc,
  "default_int_handler(...)\n\
  \n\
  The default handler for SIGINT installed by Python.\n\
  It raises KeyboardInterrupt.");
  
  
  static int
  report_wakeup_write_error(void *data)
  {
      int save_errno = errno;
      errno = (int) (intptr_t) data;
      PyErr_SetFromErrno(PyExc_OSError);
      PySys_WriteStderr("Exception ignored when trying to write to the "
                        "signal wakeup fd:\n");
      PyErr_WriteUnraisable(NULL);
      errno = save_errno;
      return 0;
  }
  
  #ifdef MS_WINDOWS
  static int
  report_wakeup_send_error(void* data)
  {
      /* PyErr_SetExcFromWindowsErr() invokes FormatMessage() which
         recognizes the error codes used by both GetLastError() and
         WSAGetLastError */
      PyErr_SetExcFromWindowsErr(PyExc_OSError, (int) (intptr_t) data);
      PySys_WriteStderr("Exception ignored when trying to send to the "
                        "signal wakeup fd:\n");
      PyErr_WriteUnraisable(NULL);
      return 0;
  }
  #endif   /* MS_WINDOWS */
  
  static void
  trip_signal(int sig_num)
  {
      unsigned char byte;
      int fd;
      Py_ssize_t rc;
  
      _Py_atomic_store_relaxed(&Handlers[sig_num].tripped, 1);
  
      /* Set is_tripped after setting .tripped, as it gets
         cleared in PyErr_CheckSignals() before .tripped. */
      _Py_atomic_store(&is_tripped, 1);
  
      /* Notify ceval.c */
      _PyEval_SignalReceived();
  
      /* And then write to the wakeup fd *after* setting all the globals and
         doing the _PyEval_SignalReceived. We used to write to the wakeup fd
         and then set the flag, but this allowed the following sequence of events
         (especially on windows, where trip_signal may run in a new thread):
  
         - main thread blocks on select([wakeup.fd], ...)
         - signal arrives
         - trip_signal writes to the wakeup fd
         - the main thread wakes up
         - the main thread checks the signal flags, sees that they're unset
         - the main thread empties the wakeup fd
         - the main thread goes back to sleep
         - trip_signal sets the flags to request the Python-level signal handler
           be run
         - the main thread doesn't notice, because it's asleep
  
         See bpo-30038 for more details.
      */
  
  #ifdef MS_WINDOWS
      fd = Py_SAFE_DOWNCAST(wakeup.fd, SOCKET_T, int);
  #else
      fd = wakeup.fd;
  #endif
  
      if (fd != INVALID_FD) {
          byte = (unsigned char)sig_num;
  #ifdef MS_WINDOWS
          if (wakeup.use_send) {
              rc = send(fd, &byte, 1, 0);
  
              if (rc < 0) {
                  int last_error = GetLastError();
                  if (wakeup.warn_on_full_buffer ||
                      last_error != WSAEWOULDBLOCK)
                  {
                      /* Py_AddPendingCall() isn't signal-safe, but we
                         still use it for this exceptional case. */
                      Py_AddPendingCall(report_wakeup_send_error,
                                        (void *)(intptr_t) last_error);
                  }
              }
          }
          else
  #endif
          {
              /* _Py_write_noraise() retries write() if write() is interrupted by
                 a signal (fails with EINTR). */
              rc = _Py_write_noraise(fd, &byte, 1);
  
              if (rc < 0) {
                  if (wakeup.warn_on_full_buffer ||
                      (errno != EWOULDBLOCK && errno != EAGAIN))
                  {
                      /* Py_AddPendingCall() isn't signal-safe, but we
                         still use it for this exceptional case. */
                      Py_AddPendingCall(report_wakeup_write_error,
                                        (void *)(intptr_t)errno);
                  }
              }
          }
      }
  }
  
  static void
  signal_handler(int sig_num)
  {
      int save_errno = errno;
  
      /* See NOTES section above */
      if (getpid() == main_pid)
      {
          trip_signal(sig_num);
      }
  
  #ifndef HAVE_SIGACTION
  #ifdef SIGCHLD
      /* To avoid infinite recursion, this signal remains
         reset until explicit re-instated.
         Don't clear the 'func' field as it is our pointer
         to the Python handler... */
      if (sig_num != SIGCHLD)
  #endif
      /* If the handler was not set up with sigaction, reinstall it.  See
       * Python/pylifecycle.c for the implementation of PyOS_setsig which
       * makes this true.  See also issue8354. */
      PyOS_setsig(sig_num, signal_handler);
  #endif
  
      /* Issue #10311: asynchronously executing signal handlers should not
         mutate errno under the feet of unsuspecting C code. */
      errno = save_errno;
  
  #ifdef MS_WINDOWS
      if (sig_num == SIGINT)
          SetEvent(sigint_event);
  #endif
  }
  
  
  #ifdef HAVE_ALARM
  
  /*[clinic input]
  signal.alarm -> long
  
      seconds: int
      /
  
  Arrange for SIGALRM to arrive after the given number of seconds.
  [clinic start generated code]*/
  
  static long
  signal_alarm_impl(PyObject *module, int seconds)
  /*[clinic end generated code: output=144232290814c298 input=0d5e97e0e6f39e86]*/
  {
      /* alarm() returns the number of seconds remaining */
      return (long)alarm(seconds);
  }
  
  #endif
  
  #ifdef HAVE_PAUSE
  
  /*[clinic input]
  signal.pause
  
  Wait until a signal arrives.
  [clinic start generated code]*/
  
  static PyObject *
  signal_pause_impl(PyObject *module)
  /*[clinic end generated code: output=391656788b3c3929 input=f03de0f875752062]*/
  {
      Py_BEGIN_ALLOW_THREADS
      (void)pause();
      Py_END_ALLOW_THREADS
      /* make sure that any exceptions that got raised are propagated
       * back into Python
       */
      if (PyErr_CheckSignals())
          return NULL;
  
      Py_RETURN_NONE;
  }
  
  #endif
  
  
  /*[clinic input]
  signal.signal
  
      signalnum: int
      handler:   object
      /
  
  Set the action for the given signal.
  
  The action can be SIG_DFL, SIG_IGN, or a callable Python object.
  The previous action is returned.  See getsignal() for possible return values.
  
  *** IMPORTANT NOTICE ***
  A signal handler function is called with two arguments:
  the first is the signal number, the second is the interrupted stack frame.
  [clinic start generated code]*/
  
  static PyObject *
  signal_signal_impl(PyObject *module, int signalnum, PyObject *handler)
  /*[clinic end generated code: output=b44cfda43780f3a1 input=deee84af5fa0432c]*/
  {
      PyObject *old_handler;
      void (*func)(int);
  #ifdef MS_WINDOWS
      /* Validate that signalnum is one of the allowable signals */
      switch (signalnum) {
          case SIGABRT: break;
  #ifdef SIGBREAK
          /* Issue #10003: SIGBREAK is not documented as permitted, but works
             and corresponds to CTRL_BREAK_EVENT. */
          case SIGBREAK: break;
  #endif
          case SIGFPE: break;
          case SIGILL: break;
          case SIGINT: break;
          case SIGSEGV: break;
          case SIGTERM: break;
          default:
              PyErr_SetString(PyExc_ValueError, "invalid signal value");
              return NULL;
      }
  #endif
      if (PyThread_get_thread_ident() != main_thread) {
          PyErr_SetString(PyExc_ValueError,
                          "signal only works in main thread");
          return NULL;
      }
      if (signalnum < 1 || signalnum >= NSIG) {
          PyErr_SetString(PyExc_ValueError,
                          "signal number out of range");
          return NULL;
      }
      if (handler == IgnoreHandler)
          func = SIG_IGN;
      else if (handler == DefaultHandler)
          func = SIG_DFL;
      else if (!PyCallable_Check(handler)) {
          PyErr_SetString(PyExc_TypeError,
  "signal handler must be signal.SIG_IGN, signal.SIG_DFL, or a callable object");
                  return NULL;
      }
      else
          func = signal_handler;
      /* Check for pending signals before changing signal handler */
      if (PyErr_CheckSignals()) {
          return NULL;
      }
      if (PyOS_setsig(signalnum, func) == SIG_ERR) {
          PyErr_SetFromErrno(PyExc_OSError);
          return NULL;
      }
      old_handler = Handlers[signalnum].func;
      Py_INCREF(handler);
      Handlers[signalnum].func = handler;
      if (old_handler != NULL)
          return old_handler;
      else
          Py_RETURN_NONE;
  }
  
  
  /*[clinic input]
  signal.getsignal
  
      signalnum: int
      /
  
  Return the current action for the given signal.
  
  The return value can be:
    SIG_IGN -- if the signal is being ignored
    SIG_DFL -- if the default action for the signal is in effect
    None    -- if an unknown handler is in effect
    anything else -- the callable Python object used as a handler
  [clinic start generated code]*/
  
  static PyObject *
  signal_getsignal_impl(PyObject *module, int signalnum)
  /*[clinic end generated code: output=35b3e0e796fd555e input=ac23a00f19dfa509]*/
  {
      PyObject *old_handler;
      if (signalnum < 1 || signalnum >= NSIG) {
          PyErr_SetString(PyExc_ValueError,
                          "signal number out of range");
          return NULL;
      }
      old_handler = Handlers[signalnum].func;
      if (old_handler != NULL) {
          Py_INCREF(old_handler);
          return old_handler;
      }
      else {
          Py_RETURN_NONE;
      }
  }
  
  
  /*[clinic input]
  signal.strsignal
  
      signalnum: int
      /
  
  Return the system description of the given signal.
  
  The return values can be such as "Interrupt", "Segmentation fault", etc.
  Returns None if the signal is not recognized.
  [clinic start generated code]*/
  
  static PyObject *
  signal_strsignal_impl(PyObject *module, int signalnum)
  /*[clinic end generated code: output=44e12e1e3b666261 input=b77914b03f856c74]*/
  {
      char *res;
  
      if (signalnum < 1 || signalnum >= NSIG) {
          PyErr_SetString(PyExc_ValueError,
                  "signal number out of range");
          return NULL;
      }
  
  #ifndef HAVE_STRSIGNAL
      switch (signalnum) {
          /* Though being a UNIX, HP-UX does not provide strsignal(3). */
  #ifndef MS_WINDOWS
          case SIGHUP:
              res = "Hangup";
              break;
          case SIGALRM:
              res = "Alarm clock";
              break;
          case SIGPIPE:
              res = "Broken pipe";
              break;
          case SIGQUIT:
              res = "Quit";
              break;
          case SIGCHLD:
              res = "Child exited";
              break;
  #endif
          /* Custom redefinition of POSIX signals allowed on Windows. */
          case SIGINT:
              res = "Interrupt";
              break;
          case SIGILL:
              res = "Illegal instruction";
              break;
          case SIGABRT:
              res = "Aborted";
              break;
          case SIGFPE:
              res = "Floating point exception";
              break;
          case SIGSEGV:
              res = "Segmentation fault";
              break;
          case SIGTERM:
              res = "Terminated";
              break;
          default:
              Py_RETURN_NONE;
      }
  #else
      errno = 0;
      res = strsignal(signalnum);
  
      if (errno || res == NULL || strstr(res, "Unknown signal") != NULL)
          Py_RETURN_NONE;
  #endif
  
      return Py_BuildValue("s", res);
  }
  
  #ifdef HAVE_SIGINTERRUPT
  
  /*[clinic input]
  signal.siginterrupt
  
      signalnum: int
      flag:      int
      /
  
  Change system call restart behaviour.
  
  If flag is False, system calls will be restarted when interrupted by
  signal sig, else system calls will be interrupted.
  [clinic start generated code]*/
  
  static PyObject *
  signal_siginterrupt_impl(PyObject *module, int signalnum, int flag)
  /*[clinic end generated code: output=063816243d85dd19 input=4160acacca3e2099]*/
  {
      if (signalnum < 1 || signalnum >= NSIG) {
          PyErr_SetString(PyExc_ValueError,
                          "signal number out of range");
          return NULL;
      }
      if (siginterrupt(signalnum, flag)<0) {
          PyErr_SetFromErrno(PyExc_OSError);
          return NULL;
      }
      Py_RETURN_NONE;
  }
  
  #endif
  
  
  static PyObject*
  signal_set_wakeup_fd(PyObject *self, PyObject *args, PyObject *kwds)
  {
      struct _Py_stat_struct status;
      static char *kwlist[] = {
          "", "warn_on_full_buffer", NULL,
      };
      int warn_on_full_buffer = 1;
  #ifdef MS_WINDOWS
      PyObject *fdobj;
      SOCKET_T sockfd, old_sockfd;
      int res;
      int res_size = sizeof res;
      PyObject *mod;
      int is_socket;
  
      if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|$p:set_wakeup_fd", kwlist,
                                       &fdobj, &warn_on_full_buffer))
          return NULL;
  
      sockfd = PyLong_AsSocket_t(fdobj);
      if (sockfd == (SOCKET_T)(-1) && PyErr_Occurred())
          return NULL;
  #else
      int fd, old_fd;
  
      if (!PyArg_ParseTupleAndKeywords(args, kwds, "i|$p:set_wakeup_fd", kwlist,
                                       &fd, &warn_on_full_buffer))
          return NULL;
  #endif
  
      if (PyThread_get_thread_ident() != main_thread) {
          PyErr_SetString(PyExc_ValueError,
                          "set_wakeup_fd only works in main thread");
          return NULL;
      }
  
  #ifdef MS_WINDOWS
      is_socket = 0;
      if (sockfd != INVALID_FD) {
          /* Import the _socket module to call WSAStartup() */
          mod = PyImport_ImportModuleNoBlock("_socket");
          if (mod == NULL)
              return NULL;
          Py_DECREF(mod);
  
          /* test the socket */
          if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR,
                         (char *)&res, &res_size) != 0) {
              int fd, err;
  
              err = WSAGetLastError();
              if (err != WSAENOTSOCK) {
                  PyErr_SetExcFromWindowsErr(PyExc_OSError, err);
                  return NULL;
              }
  
              fd = (int)sockfd;
              if ((SOCKET_T)fd != sockfd) {
                  PyErr_SetString(PyExc_ValueError, "invalid fd");
                  return NULL;
              }
  
              if (_Py_fstat(fd, &status) != 0)
                  return NULL;
  
              /* on Windows, a file cannot be set to non-blocking mode */
          }
          else {
              is_socket = 1;
  
              /* Windows does not provide a function to test if a socket
                 is in non-blocking mode */
          }
      }
  
      old_sockfd = wakeup.fd;
      wakeup.fd = sockfd;
      wakeup.warn_on_full_buffer = warn_on_full_buffer;
      wakeup.use_send = is_socket;
  
      if (old_sockfd != INVALID_FD)
          return PyLong_FromSocket_t(old_sockfd);
      else
          return PyLong_FromLong(-1);
  #else
      if (fd != -1) {
          int blocking;
  
          if (_Py_fstat(fd, &status) != 0)
              return NULL;
  
          blocking = _Py_get_blocking(fd);
          if (blocking < 0)
              return NULL;
          if (blocking) {
              PyErr_Format(PyExc_ValueError,
                           "the fd %i must be in non-blocking mode",
                           fd);
              return NULL;
          }
      }
  
      old_fd = wakeup.fd;
      wakeup.fd = fd;
      wakeup.warn_on_full_buffer = warn_on_full_buffer;
  
      return PyLong_FromLong(old_fd);
  #endif
  }
  
  PyDoc_STRVAR(set_wakeup_fd_doc,
  "set_wakeup_fd(fd, *, warn_on_full_buffer=True) -> fd\n\
  \n\
  Sets the fd to be written to (with the signal number) when a signal\n\
  comes in.  A library can use this to wakeup select or poll.\n\
  The previous fd or -1 is returned.\n\
  \n\
  The fd must be non-blocking.");
  
  /* C API for the same, without all the error checking */
  int
  PySignal_SetWakeupFd(int fd)
  {
      int old_fd;
      if (fd < 0)
          fd = -1;
  
  #ifdef MS_WINDOWS
      old_fd = Py_SAFE_DOWNCAST(wakeup.fd, SOCKET_T, int);
  #else
      old_fd = wakeup.fd;
  #endif
      wakeup.fd = fd;
      wakeup.warn_on_full_buffer = 1;
      return old_fd;
  }
  
  
  #ifdef HAVE_SETITIMER
  
  /*[clinic input]
  signal.setitimer
  
      which:    int
      seconds:  object
      interval: object(c_default="NULL") = 0.0
      /
  
  Sets given itimer (one of ITIMER_REAL, ITIMER_VIRTUAL or ITIMER_PROF).
  
  The timer will fire after value seconds and after that every interval seconds.
  The itimer can be cleared by setting seconds to zero.
  
  Returns old values as a tuple: (delay, interval).
  [clinic start generated code]*/
  
  static PyObject *
  signal_setitimer_impl(PyObject *module, int which, PyObject *seconds,
                        PyObject *interval)
  /*[clinic end generated code: output=65f9dcbddc35527b input=de43daf194e6f66f]*/
  {
      struct itimerval new, old;
  
      if (timeval_from_double(seconds, &new.it_value) < 0) {
          return NULL;
      }
      if (timeval_from_double(interval, &new.it_interval) < 0) {
          return NULL;
      }
  
      /* Let OS check "which" value */
      if (setitimer(which, &new, &old) != 0) {
          PyErr_SetFromErrno(ItimerError);
          return NULL;
      }
  
      return itimer_retval(&old);
  }
  
  #endif
  
  
  #ifdef HAVE_GETITIMER
  
  /*[clinic input]
  signal.getitimer
  
      which:    int
      /
  
  Returns current value of given itimer.
  [clinic start generated code]*/
  
  static PyObject *
  signal_getitimer_impl(PyObject *module, int which)
  /*[clinic end generated code: output=9e053175d517db40 input=f7d21d38f3490627]*/
  {
      struct itimerval old;
  
      if (getitimer(which, &old) != 0) {
          PyErr_SetFromErrno(ItimerError);
          return NULL;
      }
  
      return itimer_retval(&old);
  }
  
  #endif
  
  #if defined(PYPTHREAD_SIGMASK) || defined(HAVE_SIGPENDING)
  static PyObject*
  sigset_to_set(sigset_t mask)
  {
      PyObject *signum, *result;
      int sig;
  
      result = PySet_New(0);
      if (result == NULL)
          return NULL;
  
      for (sig = 1; sig < NSIG; sig++) {
          if (sigismember(&mask, sig) != 1)
              continue;
  
          /* Handle the case where it is a member by adding the signal to
             the result list.  Ignore the other cases because they mean the
             signal isn't a member of the mask or the signal was invalid,
             and an invalid signal must have been our fault in constructing
             the loop boundaries. */
          signum = PyLong_FromLong(sig);
          if (signum == NULL) {
              Py_DECREF(result);
              return NULL;
          }
          if (PySet_Add(result, signum) == -1) {
              Py_DECREF(signum);
              Py_DECREF(result);
              return NULL;
          }
          Py_DECREF(signum);
      }
      return result;
  }
  #endif
  
  #ifdef PYPTHREAD_SIGMASK
  
  /*[clinic input]
  signal.pthread_sigmask
  
      how:  int
      mask: sigset_t
      /
  
  Fetch and/or change the signal mask of the calling thread.
  [clinic start generated code]*/
  
  static PyObject *
  signal_pthread_sigmask_impl(PyObject *module, int how, sigset_t mask)
  /*[clinic end generated code: output=0562c0fb192981a8 input=85bcebda442fa77f]*/
  {
      sigset_t previous;
      int err;
  
      err = pthread_sigmask(how, &mask, &previous);
      if (err != 0) {
          errno = err;
          PyErr_SetFromErrno(PyExc_OSError);
          return NULL;
      }
  
      /* if signals was unblocked, signal handlers have been called */
      if (PyErr_CheckSignals())
          return NULL;
  
      return sigset_to_set(previous);
  }
  
  #endif   /* #ifdef PYPTHREAD_SIGMASK */
  
  
  #ifdef HAVE_SIGPENDING
  
  /*[clinic input]
  signal.sigpending
  
  Examine pending signals.
  
  Returns a set of signal numbers that are pending for delivery to
  the calling thread.
  [clinic start generated code]*/
  
  static PyObject *
  signal_sigpending_impl(PyObject *module)
  /*[clinic end generated code: output=53375ffe89325022 input=e0036c016f874e29]*/
  {
      int err;
      sigset_t mask;
      err = sigpending(&mask);
      if (err)
          return PyErr_SetFromErrno(PyExc_OSError);
      return sigset_to_set(mask);
  }
  
  #endif   /* #ifdef HAVE_SIGPENDING */
  
  
  #ifdef HAVE_SIGWAIT
  
  /*[clinic input]
  signal.sigwait
  
      sigset: sigset_t
      /
  
  Wait for a signal.
  
  Suspend execution of the calling thread until the delivery of one of the
  signals specified in the signal set sigset.  The function accepts the signal
  and returns the signal number.
  [clinic start generated code]*/
  
  static PyObject *
  signal_sigwait_impl(PyObject *module, sigset_t sigset)
  /*[clinic end generated code: output=f43770699d682f96 input=a6fbd47b1086d119]*/
  {
      int err, signum;
  
      Py_BEGIN_ALLOW_THREADS
      err = sigwait(&sigset, &signum);
      Py_END_ALLOW_THREADS
      if (err) {
          errno = err;
          return PyErr_SetFromErrno(PyExc_OSError);
      }
  
      return PyLong_FromLong(signum);
  }
  
  #endif   /* #ifdef HAVE_SIGWAIT */
  
  
  #if defined(HAVE_SIGFILLSET) || defined(MS_WINDOWS)
  
  /*[clinic input]
  signal.valid_signals
  
  Return a set of valid signal numbers on this platform.
  
  The signal numbers returned by this function can be safely passed to
  functions like `pthread_sigmask`.
  [clinic start generated code]*/
  
  static PyObject *
  signal_valid_signals_impl(PyObject *module)
  /*[clinic end generated code: output=1609cffbcfcf1314 input=86a3717ff25288f2]*/
  {
  #ifdef MS_WINDOWS
  #ifdef SIGBREAK
      PyObject *tup = Py_BuildValue("(iiiiiii)", SIGABRT, SIGBREAK, SIGFPE,
                                    SIGILL, SIGINT, SIGSEGV, SIGTERM);
  #else
      PyObject *tup = Py_BuildValue("(iiiiii)", SIGABRT, SIGFPE, SIGILL,
                                    SIGINT, SIGSEGV, SIGTERM);
  #endif
      if (tup == NULL) {
          return NULL;
      }
      PyObject *set = PySet_New(tup);
      Py_DECREF(tup);
      return set;
  #else
      sigset_t mask;
      if (sigemptyset(&mask) || sigfillset(&mask)) {
          return PyErr_SetFromErrno(PyExc_OSError);
      }
      return sigset_to_set(mask);
  #endif
  }
  
  #endif   /* #if defined(HAVE_SIGFILLSET) || defined(MS_WINDOWS) */
  
  
  #if defined(HAVE_SIGWAITINFO) || defined(HAVE_SIGTIMEDWAIT)
  static int initialized;
  static PyStructSequence_Field struct_siginfo_fields[] = {
      {"si_signo",        "signal number"},
      {"si_code",         "signal code"},
      {"si_errno",        "errno associated with this signal"},
      {"si_pid",          "sending process ID"},
      {"si_uid",          "real user ID of sending process"},
      {"si_status",       "exit value or signal"},
      {"si_band",         "band event for SIGPOLL"},
      {0}
  };
  
  PyDoc_STRVAR(struct_siginfo__doc__,
  "struct_siginfo: Result from sigwaitinfo or sigtimedwait.\n\n\
  This object may be accessed either as a tuple of\n\
  (si_signo, si_code, si_errno, si_pid, si_uid, si_status, si_band),\n\
  or via the attributes si_signo, si_code, and so on.");
  
  static PyStructSequence_Desc struct_siginfo_desc = {
      "signal.struct_siginfo",           /* name */
      struct_siginfo__doc__,       /* doc */
      struct_siginfo_fields,       /* fields */
      7          /* n_in_sequence */
  };
  
  static PyTypeObject SiginfoType;
  
  static PyObject *
  fill_siginfo(siginfo_t *si)
  {
      PyObject *result = PyStructSequence_New(&SiginfoType);
      if (!result)
          return NULL;
  
      PyStructSequence_SET_ITEM(result, 0, PyLong_FromLong((long)(si->si_signo)));
      PyStructSequence_SET_ITEM(result, 1, PyLong_FromLong((long)(si->si_code)));
      PyStructSequence_SET_ITEM(result, 2, PyLong_FromLong((long)(si->si_errno)));
      PyStructSequence_SET_ITEM(result, 3, PyLong_FromPid(si->si_pid));
      PyStructSequence_SET_ITEM(result, 4, _PyLong_FromUid(si->si_uid));
      PyStructSequence_SET_ITEM(result, 5,
                                  PyLong_FromLong((long)(si->si_status)));
  #ifdef HAVE_SIGINFO_T_SI_BAND
      PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(si->si_band));
  #else
      PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(0L));
  #endif
      if (PyErr_Occurred()) {
          Py_DECREF(result);
          return NULL;
      }
  
      return result;
  }
  #endif
  
  #ifdef HAVE_SIGWAITINFO
  
  /*[clinic input]
  signal.sigwaitinfo
  
      sigset: sigset_t
      /
  
  Wait synchronously until one of the signals in *sigset* is delivered.
  
  Returns a struct_siginfo containing information about the signal.
  [clinic start generated code]*/
  
  static PyObject *
  signal_sigwaitinfo_impl(PyObject *module, sigset_t sigset)
  /*[clinic end generated code: output=1eb2f1fa236fdbca input=3d1a7e1f27fc664c]*/
  {
      siginfo_t si;
      int err;
      int async_err = 0;
  
      do {
          Py_BEGIN_ALLOW_THREADS
          err = sigwaitinfo(&sigset, &si);
          Py_END_ALLOW_THREADS
      } while (err == -1
               && errno == EINTR && !(async_err = PyErr_CheckSignals()));
      if (err == -1)
          return (!async_err) ? PyErr_SetFromErrno(PyExc_OSError) : NULL;
  
      return fill_siginfo(&si);
  }
  
  #endif   /* #ifdef HAVE_SIGWAITINFO */
  
  #ifdef HAVE_SIGTIMEDWAIT
  
  /*[clinic input]
  signal.sigtimedwait
  
      sigset: sigset_t
      timeout as timeout_obj: object
      /
  
  Like sigwaitinfo(), but with a timeout.
  
  The timeout is specified in seconds, with floating point numbers allowed.
  [clinic start generated code]*/
  
  static PyObject *
  signal_sigtimedwait_impl(PyObject *module, sigset_t sigset,
                           PyObject *timeout_obj)
  /*[clinic end generated code: output=59c8971e8ae18a64 input=87fd39237cf0b7ba]*/
  {
      struct timespec ts;
      siginfo_t si;
      int res;
      _PyTime_t timeout, deadline, monotonic;
  
      if (_PyTime_FromSecondsObject(&timeout,
                                    timeout_obj, _PyTime_ROUND_CEILING) < 0)
          return NULL;
  
      if (timeout < 0) {
          PyErr_SetString(PyExc_ValueError, "timeout must be non-negative");
          return NULL;
      }
  
      deadline = _PyTime_GetMonotonicClock() + timeout;
  
      do {
          if (_PyTime_AsTimespec(timeout, &ts) < 0)
              return NULL;
  
          Py_BEGIN_ALLOW_THREADS
          res = sigtimedwait(&sigset, &si, &ts);
          Py_END_ALLOW_THREADS
  
          if (res != -1)
              break;
  
          if (errno != EINTR) {
              if (errno == EAGAIN)
                  Py_RETURN_NONE;
              else
                  return PyErr_SetFromErrno(PyExc_OSError);
          }
  
          /* sigtimedwait() was interrupted by a signal (EINTR) */
          if (PyErr_CheckSignals())
              return NULL;
  
          monotonic = _PyTime_GetMonotonicClock();
          timeout = deadline - monotonic;
          if (timeout < 0)
              break;
      } while (1);
  
      return fill_siginfo(&si);
  }
  
  #endif   /* #ifdef HAVE_SIGTIMEDWAIT */
  
  
  #if defined(HAVE_PTHREAD_KILL)
  
  /*[clinic input]
  signal.pthread_kill
  
      thread_id:  unsigned_long(bitwise=True)
      signalnum:  int
      /
  
  Send a signal to a thread.
  [clinic start generated code]*/
  
  static PyObject *
  signal_pthread_kill_impl(PyObject *module, unsigned long thread_id,
                           int signalnum)
  /*[clinic end generated code: output=7629919b791bc27f input=1d901f2c7bb544ff]*/
  {
      int err;
  
      err = pthread_kill((pthread_t)thread_id, signalnum);
      if (err != 0) {
          errno = err;
          PyErr_SetFromErrno(PyExc_OSError);
          return NULL;
      }
  
      /* the signal may have been send to the current thread */
      if (PyErr_CheckSignals())
          return NULL;
  
      Py_RETURN_NONE;
  }
  
  #endif   /* #if defined(HAVE_PTHREAD_KILL) */
  
  
  
  /* List of functions defined in the module -- some of the methoddefs are
     defined to nothing if the corresponding C function is not available. */
  static PyMethodDef signal_methods[] = {
      {"default_int_handler", signal_default_int_handler, METH_VARARGS, default_int_handler_doc},
      SIGNAL_ALARM_METHODDEF
      SIGNAL_SETITIMER_METHODDEF
      SIGNAL_GETITIMER_METHODDEF
      SIGNAL_SIGNAL_METHODDEF
      SIGNAL_STRSIGNAL_METHODDEF
      SIGNAL_GETSIGNAL_METHODDEF
      {"set_wakeup_fd", (PyCFunction)signal_set_wakeup_fd, METH_VARARGS | METH_KEYWORDS, set_wakeup_fd_doc},
      SIGNAL_SIGINTERRUPT_METHODDEF
      SIGNAL_PAUSE_METHODDEF
      SIGNAL_PTHREAD_KILL_METHODDEF
      SIGNAL_PTHREAD_SIGMASK_METHODDEF
      SIGNAL_SIGPENDING_METHODDEF
      SIGNAL_SIGWAIT_METHODDEF
      SIGNAL_SIGWAITINFO_METHODDEF
      SIGNAL_SIGTIMEDWAIT_METHODDEF
  #if defined(HAVE_SIGFILLSET) || defined(MS_WINDOWS)
      SIGNAL_VALID_SIGNALS_METHODDEF
  #endif
      {NULL, NULL}           /* sentinel */
  };
  
  
  PyDoc_STRVAR(module_doc,
  "This module provides mechanisms to use signal handlers in Python.\n\
  \n\
  Functions:\n\
  \n\
  alarm() -- cause SIGALRM after a specified time [Unix only]\n\
  setitimer() -- cause a signal (described below) after a specified\n\
                 float time and the timer may restart then [Unix only]\n\
  getitimer() -- get current value of timer [Unix only]\n\
  signal() -- set the action for a given signal\n\
  getsignal() -- get the signal action for a given signal\n\
  pause() -- wait until a signal arrives [Unix only]\n\
  default_int_handler() -- default SIGINT handler\n\
  \n\
  signal constants:\n\
  SIG_DFL -- used to refer to the system default handler\n\
  SIG_IGN -- used to ignore the signal\n\
  NSIG -- number of defined signals\n\
  SIGINT, SIGTERM, etc. -- signal numbers\n\
  \n\
  itimer constants:\n\
  ITIMER_REAL -- decrements in real time, and delivers SIGALRM upon\n\
                 expiration\n\
  ITIMER_VIRTUAL -- decrements only when the process is executing,\n\
                 and delivers SIGVTALRM upon expiration\n\
  ITIMER_PROF -- decrements both when the process is executing and\n\
                 when the system is executing on behalf of the process.\n\
                 Coupled with ITIMER_VIRTUAL, this timer is usually\n\
                 used to profile the time spent by the application\n\
                 in user and kernel space. SIGPROF is delivered upon\n\
                 expiration.\n\
  \n\n\
  *** IMPORTANT NOTICE ***\n\
  A signal handler function is called with two arguments:\n\
  the first is the signal number, the second is the interrupted stack frame.");
  
  static struct PyModuleDef signalmodule = {
      PyModuleDef_HEAD_INIT,
      "_signal",
      module_doc,
      -1,
      signal_methods,
      NULL,
      NULL,
      NULL,
      NULL
  };
  
  PyMODINIT_FUNC
  PyInit__signal(void)
  {
      PyObject *m, *d, *x;
      int i;
  
      main_thread = PyThread_get_thread_ident();
      main_pid = getpid();
  
      /* Create the module and add the functions */
      m = PyModule_Create(&signalmodule);
      if (m == NULL)
          return NULL;
  
  #if defined(HAVE_SIGWAITINFO) || defined(HAVE_SIGTIMEDWAIT)
      if (!initialized) {
          if (PyStructSequence_InitType2(&SiginfoType, &struct_siginfo_desc) < 0)
              return NULL;
      }
      Py_INCREF((PyObject*) &SiginfoType);
      PyModule_AddObject(m, "struct_siginfo", (PyObject*) &SiginfoType);
      initialized = 1;
  #endif
  
      /* Add some symbolic constants to the module */
      d = PyModule_GetDict(m);
  
      x = DefaultHandler = PyLong_FromVoidPtr((void *)SIG_DFL);
      if (!x || PyDict_SetItemString(d, "SIG_DFL", x) < 0)
          goto finally;
  
      x = IgnoreHandler = PyLong_FromVoidPtr((void *)SIG_IGN);
      if (!x || PyDict_SetItemString(d, "SIG_IGN", x) < 0)
          goto finally;
  
      x = PyLong_FromLong((long)NSIG);
      if (!x || PyDict_SetItemString(d, "NSIG", x) < 0)
          goto finally;
      Py_DECREF(x);
  
  #ifdef SIG_BLOCK
      if (PyModule_AddIntMacro(m, SIG_BLOCK))
           goto finally;
  #endif
  #ifdef SIG_UNBLOCK
      if (PyModule_AddIntMacro(m, SIG_UNBLOCK))
           goto finally;
  #endif
  #ifdef SIG_SETMASK
      if (PyModule_AddIntMacro(m, SIG_SETMASK))
           goto finally;
  #endif
  
      x = IntHandler = PyDict_GetItemString(d, "default_int_handler");
      if (!x)
          goto finally;
      Py_INCREF(IntHandler);
  
      _Py_atomic_store_relaxed(&Handlers[0].tripped, 0);
      for (i = 1; i < NSIG; i++) {
          void (*t)(int);
          t = PyOS_getsig(i);
          _Py_atomic_store_relaxed(&Handlers[i].tripped, 0);
          if (t == SIG_DFL)
              Handlers[i].func = DefaultHandler;
          else if (t == SIG_IGN)
              Handlers[i].func = IgnoreHandler;
          else
              Handlers[i].func = Py_None; /* None of our business */
          Py_INCREF(Handlers[i].func);
      }
      if (Handlers[SIGINT].func == DefaultHandler) {
          /* Install default int handler */
          Py_INCREF(IntHandler);
          Py_SETREF(Handlers[SIGINT].func, IntHandler);
          PyOS_setsig(SIGINT, signal_handler);
      }
  
  #ifdef SIGHUP
      if (PyModule_AddIntMacro(m, SIGHUP))
           goto finally;
  #endif
  #ifdef SIGINT
      if (PyModule_AddIntMacro(m, SIGINT))
           goto finally;
  #endif
  #ifdef SIGBREAK
      if (PyModule_AddIntMacro(m, SIGBREAK))
           goto finally;
  #endif
  #ifdef SIGQUIT
      if (PyModule_AddIntMacro(m, SIGQUIT))
           goto finally;
  #endif
  #ifdef SIGILL
      if (PyModule_AddIntMacro(m, SIGILL))
           goto finally;
  #endif
  #ifdef SIGTRAP
      if (PyModule_AddIntMacro(m, SIGTRAP))
           goto finally;
  #endif
  #ifdef SIGIOT
      if (PyModule_AddIntMacro(m, SIGIOT))
           goto finally;
  #endif
  #ifdef SIGABRT
      if (PyModule_AddIntMacro(m, SIGABRT))
           goto finally;
  #endif
  #ifdef SIGEMT
      if (PyModule_AddIntMacro(m, SIGEMT))
           goto finally;
  #endif
  #ifdef SIGFPE
      if (PyModule_AddIntMacro(m, SIGFPE))
           goto finally;
  #endif
  #ifdef SIGKILL
      if (PyModule_AddIntMacro(m, SIGKILL))
           goto finally;
  #endif
  #ifdef SIGBUS
      if (PyModule_AddIntMacro(m, SIGBUS))
           goto finally;
  #endif
  #ifdef SIGSEGV
      if (PyModule_AddIntMacro(m, SIGSEGV))
           goto finally;
  #endif
  #ifdef SIGSYS
      if (PyModule_AddIntMacro(m, SIGSYS))
           goto finally;
  #endif
  #ifdef SIGPIPE
      if (PyModule_AddIntMacro(m, SIGPIPE))
           goto finally;
  #endif
  #ifdef SIGALRM
      if (PyModule_AddIntMacro(m, SIGALRM))
           goto finally;
  #endif
  #ifdef SIGTERM
      if (PyModule_AddIntMacro(m, SIGTERM))
           goto finally;
  #endif
  #ifdef SIGUSR1
      if (PyModule_AddIntMacro(m, SIGUSR1))
           goto finally;
  #endif
  #ifdef SIGUSR2
      if (PyModule_AddIntMacro(m, SIGUSR2))
           goto finally;
  #endif
  #ifdef SIGCLD
      if (PyModule_AddIntMacro(m, SIGCLD))
           goto finally;
  #endif
  #ifdef SIGCHLD
      if (PyModule_AddIntMacro(m, SIGCHLD))
           goto finally;
  #endif
  #ifdef SIGPWR
      if (PyModule_AddIntMacro(m, SIGPWR))
           goto finally;
  #endif
  #ifdef SIGIO
      if (PyModule_AddIntMacro(m, SIGIO))
           goto finally;
  #endif
  #ifdef SIGURG
      if (PyModule_AddIntMacro(m, SIGURG))
           goto finally;
  #endif
  #ifdef SIGWINCH
      if (PyModule_AddIntMacro(m, SIGWINCH))
           goto finally;
  #endif
  #ifdef SIGPOLL
      if (PyModule_AddIntMacro(m, SIGPOLL))
           goto finally;
  #endif
  #ifdef SIGSTOP
      if (PyModule_AddIntMacro(m, SIGSTOP))
           goto finally;
  #endif
  #ifdef SIGTSTP
      if (PyModule_AddIntMacro(m, SIGTSTP))
           goto finally;
  #endif
  #ifdef SIGCONT
      if (PyModule_AddIntMacro(m, SIGCONT))
           goto finally;
  #endif
  #ifdef SIGTTIN
      if (PyModule_AddIntMacro(m, SIGTTIN))
           goto finally;
  #endif
  #ifdef SIGTTOU
      if (PyModule_AddIntMacro(m, SIGTTOU))
           goto finally;
  #endif
  #ifdef SIGVTALRM
      if (PyModule_AddIntMacro(m, SIGVTALRM))
           goto finally;
  #endif
  #ifdef SIGPROF
      if (PyModule_AddIntMacro(m, SIGPROF))
           goto finally;
  #endif
  #ifdef SIGXCPU
      if (PyModule_AddIntMacro(m, SIGXCPU))
           goto finally;
  #endif
  #ifdef SIGXFSZ
      if (PyModule_AddIntMacro(m, SIGXFSZ))
           goto finally;
  #endif
  #ifdef SIGRTMIN
      if (PyModule_AddIntMacro(m, SIGRTMIN))
           goto finally;
  #endif
  #ifdef SIGRTMAX
      if (PyModule_AddIntMacro(m, SIGRTMAX))
           goto finally;
  #endif
  #ifdef SIGINFO
      if (PyModule_AddIntMacro(m, SIGINFO))
           goto finally;
  #endif
  
  #ifdef ITIMER_REAL
      if (PyModule_AddIntMacro(m, ITIMER_REAL))
           goto finally;
  #endif
  #ifdef ITIMER_VIRTUAL
      if (PyModule_AddIntMacro(m, ITIMER_VIRTUAL))
           goto finally;
  #endif
  #ifdef ITIMER_PROF
      if (PyModule_AddIntMacro(m, ITIMER_PROF))
           goto finally;
  #endif
  
  #if defined (HAVE_SETITIMER) || defined (HAVE_GETITIMER)
      ItimerError = PyErr_NewException("signal.ItimerError",
              PyExc_OSError, NULL);
      if (ItimerError != NULL)
          PyDict_SetItemString(d, "ItimerError", ItimerError);
  #endif
  
  #ifdef CTRL_C_EVENT
      if (PyModule_AddIntMacro(m, CTRL_C_EVENT))
           goto finally;
  #endif
  
  #ifdef CTRL_BREAK_EVENT
      if (PyModule_AddIntMacro(m, CTRL_BREAK_EVENT))
           goto finally;
  #endif
  
  #ifdef MS_WINDOWS
      /* Create manual-reset event, initially unset */
      sigint_event = CreateEvent(NULL, TRUE, FALSE, FALSE);
  #endif
  
      if (PyErr_Occurred()) {
          Py_DECREF(m);
          m = NULL;
      }
  
    finally:
      return m;
  }
  
  static void
  finisignal(void)
  {
      int i;
      PyObject *func;
  
      for (i = 1; i < NSIG; i++) {
          func = Handlers[i].func;
          _Py_atomic_store_relaxed(&Handlers[i].tripped, 0);
          Handlers[i].func = NULL;
          if (func != NULL && func != Py_None &&
              func != DefaultHandler && func != IgnoreHandler)
              PyOS_setsig(i, SIG_DFL);
          Py_XDECREF(func);
      }
  
      Py_CLEAR(IntHandler);
      Py_CLEAR(DefaultHandler);
      Py_CLEAR(IgnoreHandler);
  }
  
  
  /* Declared in pyerrors.h */
  int
  PyErr_CheckSignals(void)
  {
      int i;
      PyObject *f;
  
      if (!_Py_atomic_load(&is_tripped))
          return 0;
  
      if (PyThread_get_thread_ident() != main_thread)
          return 0;
  
      /*
       * The is_tripped variable is meant to speed up the calls to
       * PyErr_CheckSignals (both directly or via pending calls) when no
       * signal has arrived. This variable is set to 1 when a signal arrives
       * and it is set to 0 here, when we know some signals arrived. This way
       * we can run the registered handlers with no signals blocked.
       *
       * NOTE: with this approach we can have a situation where is_tripped is
       *       1 but we have no more signals to handle (Handlers[i].tripped
       *       is 0 for every signal i). This won't do us any harm (except
       *       we're gonna spent some cycles for nothing). This happens when
       *       we receive a signal i after we zero is_tripped and before we
       *       check Handlers[i].tripped.
       */
      _Py_atomic_store(&is_tripped, 0);
  
      if (!(f = (PyObject *)PyEval_GetFrame()))
          f = Py_None;
  
      for (i = 1; i < NSIG; i++) {
          if (_Py_atomic_load_relaxed(&Handlers[i].tripped)) {
              PyObject *result = NULL;
              PyObject *arglist = Py_BuildValue("(iO)", i, f);
              _Py_atomic_store_relaxed(&Handlers[i].tripped, 0);
  
              if (arglist) {
                  result = PyEval_CallObject(Handlers[i].func,
                                             arglist);
                  Py_DECREF(arglist);
              }
              if (!result) {
                  _Py_atomic_store(&is_tripped, 1);
                  return -1;
              }
  
              Py_DECREF(result);
          }
      }
  
      return 0;
  }
  
  
  /* Replacements for intrcheck.c functionality
   * Declared in pyerrors.h
   */
  void
  PyErr_SetInterrupt(void)
  {
      trip_signal(SIGINT);
  }
  
  void
  PyOS_InitInterrupts(void)
  {
      PyObject *m = PyImport_ImportModule("_signal");
      if (m) {
          Py_DECREF(m);
      }
  }
  
  void
  PyOS_FiniInterrupts(void)
  {
      finisignal();
  }
  
  int
  PyOS_InterruptOccurred(void)
  {
      if (_Py_atomic_load_relaxed(&Handlers[SIGINT].tripped)) {
          if (PyThread_get_thread_ident() != main_thread)
              return 0;
          _Py_atomic_store_relaxed(&Handlers[SIGINT].tripped, 0);
          return 1;
      }
      return 0;
  }
  
  static void
  _clear_pending_signals(void)
  {
      int i;
      if (!_Py_atomic_load(&is_tripped))
          return;
      _Py_atomic_store(&is_tripped, 0);
      for (i = 1; i < NSIG; ++i) {
          _Py_atomic_store_relaxed(&Handlers[i].tripped, 0);
      }
  }
  
  void
  _PySignal_AfterFork(void)
  {
      /* Clear the signal flags after forking so that they aren't handled
       * in both processes if they came in just before the fork() but before
       * the interpreter had an opportunity to call the handlers.  issue9535. */
      _clear_pending_signals();
      main_thread = PyThread_get_thread_ident();
      main_pid = getpid();
  }
  
  int
  _PyOS_IsMainThread(void)
  {
      return PyThread_get_thread_ident() == main_thread;
  }
  
  #ifdef MS_WINDOWS
  void *_PyOS_SigintEvent(void)
  {
      /* Returns a manual-reset event which gets tripped whenever
         SIGINT is received.
  
         Python.h does not include windows.h so we do cannot use HANDLE
         as the return type of this function.  We use void* instead. */
      return sigint_event;
  }
  #endif
  