Merge with 3.2.

1 files changed, 1329 insertions, 0 deletions

diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
new file mode 100644
index 0000000000..51c66bdd65
--- /dev/null
+++ b/Modules/faulthandler.c
@@ -0,0 +1,1329 @@
+#include "Python.h"
+#include "pythread.h"
+#include <signal.h>
+#include <object.h>
+#include <frameobject.h>
+#include <signal.h>
+#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK)
+#include <pthread.h>
+#endif
+
+/* Allocate at maximum 100 MB of the stack to raise the stack overflow */
+#define STACK_OVERFLOW_MAX_SIZE (100*1024*1024)
+
+#ifdef WITH_THREAD
+#  define FAULTHANDLER_LATER
+#  define FAULTHANDLER_WATCHDOG
+#endif
+
+#ifndef MS_WINDOWS
+   /* register() is useless on Windows, because only SIGSEGV, SIGABRT and
+      SIGILL can be handled by the process, and these signals can only be used
+      with enable(), not using register() */
+#  define FAULTHANDLER_USER
+#endif
+
+#define PUTS(fd, str) write(fd, str, strlen(str))
+
+#ifdef HAVE_SIGACTION
+typedef struct sigaction _Py_sighandler_t;
+#else
+typedef PyOS_sighandler_t _Py_sighandler_t;
+#endif
+
+typedef struct {
+    int signum;
+    int enabled;
+    const char* name;
+    _Py_sighandler_t previous;
+    int all_threads;
+} fault_handler_t;
+
+static struct {
+    int enabled;
+    PyObject *file;
+    int fd;
+    int all_threads;
+    PyInterpreterState *interp;
+} fatal_error = {0, NULL, -1, 0};
+
+#ifdef FAULTHANDLER_LATER
+static struct {
+    PyObject *file;
+    int fd;
+    PY_TIMEOUT_T timeout_us;   /* timeout in microseconds */
+    int repeat;
+    PyInterpreterState *interp;
+    int exit;
+    char *header;
+    size_t header_len;
+    /* The main thread always holds this lock. It is only released when
+       faulthandler_thread() is interrupted before this thread exits, or at
+       Python exit. */
+    PyThread_type_lock cancel_event;
+    /* released by child thread when joined */
+    PyThread_type_lock running;
+} thread;
+#endif
+
+#ifdef FAULTHANDLER_WATCHDOG
+static struct {
+    int rfd;
+    int wfd;
+    PY_TIMEOUT_T period_us;   /* period in microseconds */
+    /* The main thread always holds this lock. It is only released when
+       faulthandler_watchdog() is interrupted before this thread exits, or at
+       Python exit. */
+    PyThread_type_lock cancel_event;
+    /* released by child thread when joined */
+    PyThread_type_lock running;
+} watchdog;
+#endif
+
+#ifdef FAULTHANDLER_USER
+typedef struct {
+    int enabled;
+    PyObject *file;
+    int fd;
+    int all_threads;
+    int chain;
+    _Py_sighandler_t previous;
+    PyInterpreterState *interp;
+} user_signal_t;
+
+static user_signal_t *user_signals;
+
+/* the following macros come from Python: Modules/signalmodule.c */
+#if defined(PYOS_OS2) && !defined(PYCC_GCC)
+#define NSIG 12
+#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
+
+static void faulthandler_user(int signum);
+#endif /* FAULTHANDLER_USER */
+
+
+static fault_handler_t faulthandler_handlers[] = {
+#ifdef SIGBUS
+    {SIGBUS, 0, "Bus error", },
+#endif
+#ifdef SIGILL
+    {SIGILL, 0, "Illegal instruction", },
+#endif
+    {SIGFPE, 0, "Floating point exception", },
+    {SIGABRT, 0, "Aborted", },
+    /* define SIGSEGV at the end to make it the default choice if searching the
+       handler fails in faulthandler_fatal_error() */
+    {SIGSEGV, 0, "Segmentation fault", }
+};
+static const unsigned char faulthandler_nsignals = \
+    Py_ARRAY_LENGTH(faulthandler_handlers);
+
+#ifdef HAVE_SIGALTSTACK
+static stack_t stack;
+#endif
+
+
+/* Get the file descriptor of a file by calling its fileno() method and then
+   call its flush() method.
+
+   If file is NULL or Py_None, use sys.stderr as the new file.
+
+   On success, return the new file and write the file descriptor into *p_fd.
+   On error, return NULL. */
+
+static PyObject*
+faulthandler_get_fileno(PyObject *file, int *p_fd)
+{
+    PyObject *result;
+    _Py_IDENTIFIER(fileno);
+    _Py_IDENTIFIER(flush);
+    long fd_long;
+    int fd;
+
+    if (file == NULL || file == Py_None) {
+        file = PySys_GetObject("stderr");
+        if (file == NULL) {
+            PyErr_SetString(PyExc_RuntimeError, "unable to get sys.stderr");
+            return NULL;
+        }
+    }
+
+    result = _PyObject_CallMethodId(file, &PyId_fileno, "");
+    if (result == NULL)
+        return NULL;
+
+    fd = -1;
+    if (PyLong_Check(result)) {
+        fd_long = PyLong_AsLong(result);
+        if (0 <= fd_long && fd_long < INT_MAX)
+            fd = (int)fd_long;
+    }
+    Py_DECREF(result);
+
+    if (fd == -1) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "file.fileno() is not a valid file descriptor");
+        return NULL;
+    }
+
+    result = _PyObject_CallMethodId(file, &PyId_flush, "");
+    if (result != NULL)
+        Py_DECREF(result);
+    else {
+        /* ignore flush() error */
+        PyErr_Clear();
+    }
+    *p_fd = fd;
+    return file;
+}
+
+/* Get the state of the current thread: only call this function if the current
+   thread holds the GIL. Raise an exception on error. */
+static PyThreadState*
+get_thread_state(void)
+{
+    PyThreadState *tstate = PyThreadState_Get();
+    if (tstate == NULL) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "unable to get the current thread state");
+        return NULL;
+    }
+    return tstate;
+}
+
+static PyObject*
+faulthandler_dump_traceback_py(PyObject *self,
+                               PyObject *args, PyObject *kwargs)
+{
+    static char *kwlist[] = {"file", "all_threads", NULL};
+    PyObject *file = NULL;
+    int all_threads = 1;
+    PyThreadState *tstate;
+    const char *errmsg;
+    int fd;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+        "|Oi:dump_traceback", kwlist,
+        &file, &all_threads))
+        return NULL;
+
+    file = faulthandler_get_fileno(file, &fd);
+    if (file == NULL)
+        return NULL;
+
+    tstate = get_thread_state();
+    if (tstate == NULL)
+        return NULL;
+
+    if (all_threads) {
+        errmsg = _Py_DumpTracebackThreads(fd, tstate->interp, tstate);
+        if (errmsg != NULL) {
+            PyErr_SetString(PyExc_RuntimeError, errmsg);
+            return NULL;
+        }
+    }
+    else {
+        _Py_DumpTraceback(fd, tstate);
+    }
+    Py_RETURN_NONE;
+}
+
+
+/* Handler for SIGSEGV, SIGFPE, SIGABRT, SIGBUS and SIGILL signals.
+
+   Display the current Python traceback, restore the previous handler and call
+   the previous handler.
+
+   On Windows, don't explicitly call the previous handler, because the Windows
+   signal handler would not be called (for an unknown reason). The execution of
+   the program continues at faulthandler_fatal_error() exit, but the same
+   instruction will raise the same fault (signal), and so the previous handler
+   will be called.
+
+   This function is signal-safe and should only call signal-safe functions. */
+
+static void
+faulthandler_fatal_error(int signum)
+{
+    const int fd = fatal_error.fd;
+    unsigned int i;
+    fault_handler_t *handler = NULL;
+    PyThreadState *tstate;
+    int save_errno = errno;
+
+    if (!fatal_error.enabled)
+        return;
+
+    for (i=0; i < faulthandler_nsignals; i++) {
+        handler = &faulthandler_handlers[i];
+        if (handler->signum == signum)
+            break;
+    }
+    if (handler == NULL) {
+        /* faulthandler_nsignals == 0 (unlikely) */
+        return;
+    }
+
+    /* restore the previous handler */
+#ifdef HAVE_SIGACTION
+    (void)sigaction(signum, &handler->previous, NULL);
+#else
+    (void)signal(signum, handler->previous);
+#endif
+    handler->enabled = 0;
+
+    PUTS(fd, "Fatal Python error: ");
+    PUTS(fd, handler->name);
+    PUTS(fd, "\n\n");
+
+#ifdef WITH_THREAD
+    /* SIGSEGV, SIGFPE, SIGABRT, SIGBUS and SIGILL are synchronous signals and
+       are thus delivered to the thread that caused the fault. Get the Python
+       thread state of the current thread.
+
+       PyThreadState_Get() doesn't give the state of the thread that caused the
+       fault if the thread released the GIL, and so this function cannot be
+       used. Read the thread local storage (TLS) instead: call
+       PyGILState_GetThisThreadState(). */
+    tstate = PyGILState_GetThisThreadState();
+#else
+    tstate = PyThreadState_Get();
+#endif
+
+    if (fatal_error.all_threads)
+        _Py_DumpTracebackThreads(fd, fatal_error.interp, tstate);
+    else {
+        if (tstate != NULL)
+            _Py_DumpTraceback(fd, tstate);
+    }
+
+    errno = save_errno;
+#ifdef MS_WINDOWS
+    if (signum == SIGSEGV) {
+        /* don't explicitly call the previous handler for SIGSEGV in this signal
+           handler, because the Windows signal handler would not be called */
+        return;
+    }
+#endif
+    /* call the previous signal handler: it is called immediatly if we use
+       sigaction() thanks to SA_NODEFER flag, otherwise it is deferred */
+    raise(signum);
+}
+
+/* Install the handler for fatal signals, faulthandler_fatal_error(). */
+
+static PyObject*
+faulthandler_enable(PyObject *self, PyObject *args, PyObject *kwargs)
+{
+    static char *kwlist[] = {"file", "all_threads", NULL};
+    PyObject *file = NULL;
+    int all_threads = 1;
+    unsigned int i;
+    fault_handler_t *handler;
+#ifdef HAVE_SIGACTION
+    struct sigaction action;
+#endif
+    int err;
+    int fd;
+    PyThreadState *tstate;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+        "|Oi:enable", kwlist, &file, &all_threads))
+        return NULL;
+
+    file = faulthandler_get_fileno(file, &fd);
+    if (file == NULL)
+        return NULL;
+
+    tstate = get_thread_state();
+    if (tstate == NULL)
+        return NULL;
+
+    Py_XDECREF(fatal_error.file);
+    Py_INCREF(file);
+    fatal_error.file = file;
+    fatal_error.fd = fd;
+    fatal_error.all_threads = all_threads;
+    fatal_error.interp = tstate->interp;
+
+    if (!fatal_error.enabled) {
+        fatal_error.enabled = 1;
+
+        for (i=0; i < faulthandler_nsignals; i++) {
+            handler = &faulthandler_handlers[i];
+#ifdef HAVE_SIGACTION
+            action.sa_handler = faulthandler_fatal_error;
+            sigemptyset(&action.sa_mask);
+            /* Do not prevent the signal from being received from within
+               its own signal handler */
+            action.sa_flags = SA_NODEFER;
+#ifdef HAVE_SIGALTSTACK
+            if (stack.ss_sp != NULL) {
+                /* Call the signal handler on an alternate signal stack
+                   provided by sigaltstack() */
+                action.sa_flags |= SA_ONSTACK;
+            }
+#endif
+            err = sigaction(handler->signum, &action, &handler->previous);
+#else
+            handler->previous = signal(handler->signum,
+                                       faulthandler_fatal_error);
+            err = (handler->previous == SIG_ERR);
+#endif
+            if (err) {
+                PyErr_SetFromErrno(PyExc_RuntimeError);
+                return NULL;
+            }
+            handler->enabled = 1;
+        }
+    }
+    Py_RETURN_NONE;
+}
+
+static void
+faulthandler_disable(void)
+{
+    unsigned int i;
+    fault_handler_t *handler;
+
+    if (fatal_error.enabled) {
+        fatal_error.enabled = 0;
+        for (i=0; i < faulthandler_nsignals; i++) {
+            handler = &faulthandler_handlers[i];
+            if (!handler->enabled)
+                continue;
+#ifdef HAVE_SIGACTION
+            (void)sigaction(handler->signum, &handler->previous, NULL);
+#else
+            (void)signal(handler->signum, handler->previous);
+#endif
+            handler->enabled = 0;
+        }
+    }
+
+    Py_CLEAR(fatal_error.file);
+}
+
+static PyObject*
+faulthandler_disable_py(PyObject *self)
+{
+    if (!fatal_error.enabled) {
+        Py_INCREF(Py_False);
+        return Py_False;
+    }
+    faulthandler_disable();
+    Py_INCREF(Py_True);
+    return Py_True;
+}
+
+static PyObject*
+faulthandler_is_enabled(PyObject *self)
+{
+    return PyBool_FromLong(fatal_error.enabled);
+}
+
+#ifdef FAULTHANDLER_LATER
+
+static void
+faulthandler_thread(void *unused)
+{
+    PyLockStatus st;
+    const char* errmsg;
+    PyThreadState *current;
+    int ok;
+#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK)
+    sigset_t set;
+
+    /* we don't want to receive any signal */
+    sigfillset(&set);
+    pthread_sigmask(SIG_SETMASK, &set, NULL);
+#endif
+
+    do {
+        st = PyThread_acquire_lock_timed(thread.cancel_event,
+                                         thread.timeout_us, 0);
+        if (st == PY_LOCK_ACQUIRED) {
+            PyThread_release_lock(thread.cancel_event);
+            break;
+        }
+        /* Timeout => dump traceback */
+        assert(st == PY_LOCK_FAILURE);
+
+        /* get the thread holding the GIL, NULL if no thread hold the GIL */
+        current = _Py_atomic_load_relaxed(&_PyThreadState_Current);
+
+        write(thread.fd, thread.header, thread.header_len);
+
+        errmsg = _Py_DumpTracebackThreads(thread.fd, thread.interp, current);
+        ok = (errmsg == NULL);
+
+        if (thread.exit)
+            _exit(1);
+    } while (ok && thread.repeat);
+
+    /* The only way out */
+    PyThread_release_lock(thread.running);
+}
+
+static void
+cancel_dump_tracebacks_later(void)
+{
+    /* Notify cancellation */
+    PyThread_release_lock(thread.cancel_event);
+
+    /* Wait for thread to join */
+    PyThread_acquire_lock(thread.running, 1);
+    PyThread_release_lock(thread.running);
+
+    /* The main thread should always hold the cancel_event lock */
+    PyThread_acquire_lock(thread.cancel_event, 1);
+
+    Py_CLEAR(thread.file);
+    if (thread.header) {
+        free(thread.header);
+        thread.header = NULL;
+    }
+}
+
+static char*
+format_timeout(double timeout)
+{
+    unsigned long us, sec, min, hour;
+    double intpart, fracpart;
+    char buffer[100];
+
+    fracpart = modf(timeout, &intpart);
+    sec = (unsigned long)intpart;
+    us = (unsigned long)(fracpart * 1e6);
+    min = sec / 60;
+    sec %= 60;
+    hour = min / 60;
+    min %= 60;
+
+    if (us != 0)
+        PyOS_snprintf(buffer, sizeof(buffer),
+                      "Timeout (%lu:%02lu:%02lu.%06lu)!\n",
+                      hour, min, sec, us);
+    else
+        PyOS_snprintf(buffer, sizeof(buffer),
+                      "Timeout (%lu:%02lu:%02lu)!\n",
+                      hour, min, sec);
+
+    return strdup(buffer);
+}
+
+static PyObject*
+faulthandler_dump_tracebacks_later(PyObject *self,
+                                   PyObject *args, PyObject *kwargs)
+{
+    static char *kwlist[] = {"timeout", "repeat", "file", "exit", NULL};
+    double timeout;
+    PY_TIMEOUT_T timeout_us;
+    int repeat = 0;
+    PyObject *file = NULL;
+    int fd;
+    int exit = 0;
+    PyThreadState *tstate;
+    char *header;
+    size_t header_len;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+        "d|iOi:dump_tracebacks_later", kwlist,
+        &timeout, &repeat, &file, &exit))
+        return NULL;
+    if ((timeout * 1e6) >= (double) PY_TIMEOUT_MAX) {
+        PyErr_SetString(PyExc_OverflowError,  "timeout value is too large");
+        return NULL;
+    }
+    timeout_us = (PY_TIMEOUT_T)(timeout * 1e6);
+    if (timeout_us <= 0) {
+        PyErr_SetString(PyExc_ValueError, "timeout must be greater than 0");
+        return NULL;
+    }
+
+    tstate = get_thread_state();
+    if (tstate == NULL)
+        return NULL;
+
+    file = faulthandler_get_fileno(file, &fd);
+    if (file == NULL)
+        return NULL;
+
+    /* format the timeout */
+    header = format_timeout(timeout);
+    if (header == NULL)
+        return PyErr_NoMemory();
+    header_len = strlen(header);
+
+    /* Cancel previous thread, if running */
+    cancel_dump_tracebacks_later();
+
+    Py_XDECREF(thread.file);
+    Py_INCREF(file);
+    thread.file = file;
+    thread.fd = fd;
+    thread.timeout_us = timeout_us;
+    thread.repeat = repeat;
+    thread.interp = tstate->interp;
+    thread.exit = exit;
+    thread.header = header;
+    thread.header_len = header_len;
+
+    /* Arm these locks to serve as events when released */
+    PyThread_acquire_lock(thread.running, 1);
+
+    if (PyThread_start_new_thread(faulthandler_thread, NULL) == -1) {
+        PyThread_release_lock(thread.running);
+        Py_CLEAR(thread.file);
+        free(header);
+        thread.header = NULL;
+        PyErr_SetString(PyExc_RuntimeError,
+                        "unable to start watchdog thread");
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
+
+static PyObject*
+faulthandler_cancel_dump_tracebacks_later_py(PyObject *self)
+{
+    cancel_dump_tracebacks_later();
+    Py_RETURN_NONE;
+}
+#endif  /* FAULTHANDLER_LATER */
+
+#ifdef FAULTHANDLER_WATCHDOG
+
+static void
+file_watchdog(void *unused)
+{
+    PyLockStatus st;
+    PY_TIMEOUT_T timeout;
+
+#define MAXDATA 1024
+    char buf1[MAXDATA], buf2[MAXDATA];
+    char *data = buf1, *old_data = buf2;
+    Py_ssize_t data_len, old_data_len = -1;
+
+#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK)
+    sigset_t set;
+
+    /* we don't want to receive any signal */
+    sigfillset(&set);
+    pthread_sigmask(SIG_SETMASK, &set, NULL);
+#endif
+
+    /* On first pass, feed file contents immediately */
+    timeout = 0;
+    do {
+        st = PyThread_acquire_lock_timed(watchdog.cancel_event,
+                                         timeout, 0);
+        timeout = watchdog.period_us;
+        if (st == PY_LOCK_ACQUIRED) {
+            PyThread_release_lock(watchdog.cancel_event);
+            break;
+        }
+        /* Timeout => read and write data */
+        assert(st == PY_LOCK_FAILURE);
+
+        if (lseek(watchdog.rfd, 0, SEEK_SET) < 0) {
+            break;
+        }
+        data_len = read(watchdog.rfd, data, MAXDATA);
+        if (data_len < 0) {
+            break;
+        }
+        if (data_len != old_data_len || memcmp(data, old_data, data_len)) {
+            char *tdata;
+            Py_ssize_t tlen;
+            /* Contents changed, feed them to wfd */
+            long x = (long) data_len;
+            /* We can't do anything if the consumer is too slow, just bail out */
+            if (write(watchdog.wfd, (void *) &x, sizeof(x)) < sizeof(x))
+                break;
+            if (write(watchdog.wfd, data, data_len) < data_len)
+                break;
+            tdata = data;
+            data = old_data;
+            old_data = tdata;
+            tlen = data_len;
+            data_len = old_data_len;
+            old_data_len = tlen;
+        }
+    } while (1);
+
+    close(watchdog.rfd);
+    close(watchdog.wfd);
+
+    /* The only way out */
+    PyThread_release_lock(watchdog.running);
+#undef MAXDATA
+}
+
+static void
+cancel_file_watchdog(void)
+{
+    /* Notify cancellation */
+    PyThread_release_lock(watchdog.cancel_event);
+
+    /* Wait for thread to join */
+    PyThread_acquire_lock(watchdog.running, 1);
+    PyThread_release_lock(watchdog.running);
+
+    /* The main thread should always hold the cancel_event lock */
+    PyThread_acquire_lock(watchdog.cancel_event, 1);
+}
+
+static PyObject*
+faulthandler_file_watchdog(PyObject *self,
+                           PyObject *args, PyObject *kwargs)
+{
+    static char *kwlist[] = {"rfd", "wfd", "period", NULL};
+    double period;
+    PY_TIMEOUT_T period_us;
+    int rfd, wfd;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+        "iid:_file_watchdog", kwlist,
+        &rfd, &wfd, &period))
+        return NULL;
+    if ((period * 1e6) >= (double) PY_TIMEOUT_MAX) {
+        PyErr_SetString(PyExc_OverflowError,  "period value is too large");
+        return NULL;
+    }
+    period_us = (PY_TIMEOUT_T)(period * 1e6);
+    if (period_us <= 0) {
+        PyErr_SetString(PyExc_ValueError, "period must be greater than 0");
+        return NULL;
+    }
+
+    /* Cancel previous thread, if running */
+    cancel_file_watchdog();
+
+    watchdog.rfd = rfd;
+    watchdog.wfd = wfd;
+    watchdog.period_us = period_us;
+
+    /* Arm these locks to serve as events when released */
+    PyThread_acquire_lock(watchdog.running, 1);
+
+    if (PyThread_start_new_thread(file_watchdog, NULL) == -1) {
+        PyThread_release_lock(watchdog.running);
+        PyErr_SetString(PyExc_RuntimeError,
+                        "unable to start file watchdog thread");
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
+
+static PyObject*
+faulthandler_cancel_file_watchdog(PyObject *self)
+{
+    cancel_file_watchdog();
+    Py_RETURN_NONE;
+}
+#endif  /* FAULTHANDLER_WATCHDOG */
+
+#ifdef FAULTHANDLER_USER
+static int
+faulthandler_register(int signum, int chain, _Py_sighandler_t *p_previous)
+{
+#ifdef HAVE_SIGACTION
+    struct sigaction action;
+    action.sa_handler = faulthandler_user;
+    sigemptyset(&action.sa_mask);
+    /* if the signal is received while the kernel is executing a system
+       call, try to restart the system call instead of interrupting it and
+       return EINTR. */
+    action.sa_flags = SA_RESTART;
+    if (chain) {
+        /* do not prevent the signal from being received from within its
+           own signal handler */
+        action.sa_flags = SA_NODEFER;
+    }
+#ifdef HAVE_SIGALTSTACK
+    if (stack.ss_sp != NULL) {
+        /* Call the signal handler on an alternate signal stack
+           provided by sigaltstack() */
+        action.sa_flags |= SA_ONSTACK;
+    }
+#endif
+    return sigaction(signum, &action, p_previous);
+#else
+    _Py_sighandler_t previous;
+    previous = signal(signum, faulthandler_user);
+    if (p_previous != NULL)
+        *p_previous = previous;
+    return (previous == SIG_ERR);
+#endif
+}
+
+/* Handler of user signals (e.g. SIGUSR1).
+
+   Dump the traceback of the current thread, or of all threads if
+   thread.all_threads is true.
+
+   This function is signal safe and should only call signal safe functions. */
+
+static void
+faulthandler_user(int signum)
+{
+    user_signal_t *user;
+    PyThreadState *tstate;
+    int save_errno = errno;
+
+    user = &user_signals[signum];
+    if (!user->enabled)
+        return;
+
+#ifdef WITH_THREAD
+    /* PyThreadState_Get() doesn't give the state of the current thread if
+       the thread doesn't hold the GIL. Read the thread local storage (TLS)
+       instead: call PyGILState_GetThisThreadState(). */
+    tstate = PyGILState_GetThisThreadState();
+#else
+    tstate = PyThreadState_Get();
+#endif
+
+    if (user->all_threads)
+        _Py_DumpTracebackThreads(user->fd, user->interp, tstate);
+    else {
+        if (tstate == NULL)
+            return;
+        _Py_DumpTraceback(user->fd, tstate);
+    }
+#ifdef HAVE_SIGACTION
+    if (user->chain) {
+        (void)sigaction(signum, &user->previous, NULL);
+        /* call the previous signal handler */
+        raise(signum);
+        (void)faulthandler_register(signum, user->chain, NULL);
+    }
+#else
+    if (user->chain) {
+        /* call the previous signal handler */
+        user->previous(signum);
+    }
+#endif
+    errno = save_errno;
+}
+
+static int
+check_signum(int signum)
+{
+    unsigned int i;
+
+    for (i=0; i < faulthandler_nsignals; i++) {
+        if (faulthandler_handlers[i].signum == signum) {
+            PyErr_Format(PyExc_RuntimeError,
+                         "signal %i cannot be registered, "
+                         "use enable() instead",
+                         signum);
+            return 0;
+        }
+    }
+    if (signum < 1 || NSIG <= signum) {
+        PyErr_SetString(PyExc_ValueError, "signal number out of range");
+        return 0;
+    }
+    return 1;
+}
+
+static PyObject*
+faulthandler_register_py(PyObject *self,
+                         PyObject *args, PyObject *kwargs)
+{
+    static char *kwlist[] = {"signum", "file", "all_threads", "chain", NULL};
+    int signum;
+    PyObject *file = NULL;
+    int all_threads = 1;
+    int chain = 0;
+    int fd;
+    user_signal_t *user;
+    _Py_sighandler_t previous;
+    PyThreadState *tstate;
+    int err;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+        "i|Oii:register", kwlist,
+        &signum, &file, &all_threads, &chain))
+        return NULL;
+
+    if (!check_signum(signum))
+        return NULL;
+
+    tstate = get_thread_state();
+    if (tstate == NULL)
+        return NULL;
+
+    file = faulthandler_get_fileno(file, &fd);
+    if (file == NULL)
+        return NULL;
+
+    if (user_signals == NULL) {
+        user_signals = calloc(NSIG, sizeof(user_signal_t));
+        if (user_signals == NULL)
+            return PyErr_NoMemory();
+    }
+    user = &user_signals[signum];
+
+    if (!user->enabled) {
+        err = faulthandler_register(signum, chain, &previous);
+        if (err) {
+            PyErr_SetFromErrno(PyExc_OSError);
+            return NULL;
+        }
+    }
+
+    Py_XDECREF(user->file);
+    Py_INCREF(file);
+    user->file = file;
+    user->fd = fd;
+    user->all_threads = all_threads;
+    user->chain = chain;
+    user->previous = previous;
+    user->interp = tstate->interp;
+    user->enabled = 1;
+
+    Py_RETURN_NONE;
+}
+
+static int
+faulthandler_unregister(user_signal_t *user, int signum)
+{
+    if (!user->enabled)
+        return 0;
+    user->enabled = 0;
+#ifdef HAVE_SIGACTION
+    (void)sigaction(signum, &user->previous, NULL);
+#else
+    (void)signal(signum, user->previous);
+#endif
+    Py_CLEAR(user->file);
+    user->fd = -1;
+    return 1;
+}
+
+static PyObject*
+faulthandler_unregister_py(PyObject *self, PyObject *args)
+{
+    int signum;
+    user_signal_t *user;
+    int change;
+
+    if (!PyArg_ParseTuple(args, "i:unregister", &signum))
+        return NULL;
+
+    if (!check_signum(signum))
+        return NULL;
+
+    if (user_signals == NULL)
+        Py_RETURN_FALSE;
+
+    user = &user_signals[signum];
+    change = faulthandler_unregister(user, signum);
+    return PyBool_FromLong(change);
+}
+#endif   /* FAULTHANDLER_USER */
+
+
+static PyObject *
+faulthandler_read_null(PyObject *self, PyObject *args)
+{
+    int *x = NULL, y;
+    int release_gil = 0;
+    if (!PyArg_ParseTuple(args, "|i:_read_null", &release_gil))
+        return NULL;
+    if (release_gil) {
+        Py_BEGIN_ALLOW_THREADS
+        y = *x;
+        Py_END_ALLOW_THREADS
+    } else
+        y = *x;
+    return PyLong_FromLong(y);
+
+}
+
+static PyObject *
+faulthandler_sigsegv(PyObject *self, PyObject *args)
+{
+#if defined(MS_WINDOWS)
+    /* For SIGSEGV, faulthandler_fatal_error() restores the previous signal
+       handler and then gives back the execution flow to the program (without
+       explicitly calling the previous error handler). In a normal case, the
+       SIGSEGV was raised by the kernel because of a fault, and so if the
+       program retries to execute the same instruction, the fault will be
+       raised again.
+
+       Here the fault is simulated by a fake SIGSEGV signal raised by the
+       application. We have to raise SIGSEGV at lease twice: once for
+       faulthandler_fatal_error(), and one more time for the previous signal
+       handler. */
+    while(1)
+        raise(SIGSEGV);
+#else
+    raise(SIGSEGV);
+#endif
+    Py_RETURN_NONE;
+}
+
+static PyObject *
+faulthandler_sigfpe(PyObject *self, PyObject *args)
+{
+    /* Do an integer division by zero: raise a SIGFPE on Intel CPU, but not on
+       PowerPC. Use volatile to disable compile-time optimizations. */
+    volatile int x = 1, y = 0, z;
+    z = x / y;
+    /* If the division by zero didn't raise a SIGFPE (e.g. on PowerPC),
+       raise it manually. */
+    raise(SIGFPE);
+    /* This line is never reached, but we pretend to make something with z
+       to silence a compiler warning. */
+    return PyLong_FromLong(z);
+}
+
+static PyObject *
+faulthandler_sigabrt(PyObject *self, PyObject *args)
+{
+#ifdef _MSC_VER
+    /* Visual Studio: configure abort() to not display an error message nor
+       open a popup asking to report the fault. */
+    _set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT);
+#endif
+    abort();
+    Py_RETURN_NONE;
+}
+
+#ifdef SIGBUS
+static PyObject *
+faulthandler_sigbus(PyObject *self, PyObject *args)
+{
+    raise(SIGBUS);
+    Py_RETURN_NONE;
+}
+#endif
+
+#ifdef SIGILL
+static PyObject *
+faulthandler_sigill(PyObject *self, PyObject *args)
+{
+    raise(SIGILL);
+    Py_RETURN_NONE;
+}
+#endif
+
+static PyObject *
+faulthandler_fatal_error_py(PyObject *self, PyObject *args)
+{
+    char *message;
+    if (!PyArg_ParseTuple(args, "y:fatal_error", &message))
+        return NULL;
+    Py_FatalError(message);
+    Py_RETURN_NONE;
+}
+
+#if defined(HAVE_SIGALTSTACK) && defined(HAVE_SIGACTION)
+static void*
+stack_overflow(void *min_sp, void *max_sp, size_t *depth)
+{
+    /* allocate 4096 bytes on the stack at each call */
+    unsigned char buffer[4096];
+    void *sp = &buffer;
+    *depth += 1;
+    if (sp < min_sp || max_sp < sp)
+        return sp;
+    buffer[0] = 1;
+    buffer[4095] = 0;
+    return stack_overflow(min_sp, max_sp, depth);
+}
+
+static PyObject *
+faulthandler_stack_overflow(PyObject *self)
+{
+    size_t depth, size;
+    char *sp = (char *)&depth, *stop;
+
+    depth = 0;
+    stop = stack_overflow(sp - STACK_OVERFLOW_MAX_SIZE,
+                          sp + STACK_OVERFLOW_MAX_SIZE,
+                          &depth);
+    if (sp < stop)
+        size = stop - sp;
+    else
+        size = sp - stop;
+    PyErr_Format(PyExc_RuntimeError,
+        "unable to raise a stack overflow (allocated %zu bytes "
+        "on the stack, %zu recursive calls)",
+        size, depth);
+    return NULL;
+}
+#endif
+
+
+static int
+faulthandler_traverse(PyObject *module, visitproc visit, void *arg)
+{
+#ifdef FAULTHANDLER_USER
+    unsigned int signum;
+#endif
+
+#ifdef FAULTHANDLER_LATER
+    Py_VISIT(thread.file);
+#endif
+#ifdef FAULTHANDLER_USER
+    if (user_signals != NULL) {
+        for (signum=0; signum < NSIG; signum++)
+            Py_VISIT(user_signals[signum].file);
+    }
+#endif
+    Py_VISIT(fatal_error.file);
+    return 0;
+}
+
+PyDoc_STRVAR(module_doc,
+"faulthandler module.");
+
+static PyMethodDef module_methods[] = {
+    {"enable",
+     (PyCFunction)faulthandler_enable, METH_VARARGS|METH_KEYWORDS,
+     PyDoc_STR("enable(file=sys.stderr, all_threads=True): "
+               "enable the fault handler")},
+    {"disable", (PyCFunction)faulthandler_disable_py, METH_NOARGS,
+     PyDoc_STR("disable(): disable the fault handler")},
+    {"is_enabled", (PyCFunction)faulthandler_is_enabled, METH_NOARGS,
+     PyDoc_STR("is_enabled()->bool: check if the handler is enabled")},
+    {"dump_traceback",
+     (PyCFunction)faulthandler_dump_traceback_py, METH_VARARGS|METH_KEYWORDS,
+     PyDoc_STR("dump_traceback(file=sys.stderr, all_threads=True): "
+               "dump the traceback of the current thread, or of all threads "
+               "if all_threads is True, into file")},
+#ifdef FAULTHANDLER_LATER
+    {"dump_tracebacks_later",
+     (PyCFunction)faulthandler_dump_tracebacks_later, METH_VARARGS|METH_KEYWORDS,
+     PyDoc_STR("dump_tracebacks_later(timeout, repeat=False, file=sys.stderrn, exit=False):\n"
+               "dump the traceback of all threads in timeout seconds,\n"
+               "or each timeout seconds if repeat is True. If exit is True, "
+               "call _exit(1) which is not safe.")},
+    {"cancel_dump_tracebacks_later",
+     (PyCFunction)faulthandler_cancel_dump_tracebacks_later_py, METH_NOARGS,
+     PyDoc_STR("cancel_dump_tracebacks_later():\ncancel the previous call "
+               "to dump_tracebacks_later().")},
+#endif
+
+#ifdef FAULTHANDLER_WATCHDOG
+    {"_file_watchdog",
+     (PyCFunction)faulthandler_file_watchdog, METH_VARARGS|METH_KEYWORDS,
+     PyDoc_STR("_file_watchdog(rfd, wfd, period):\n"
+               "feed the contents of 'rfd' to 'wfd', if changed,\n"
+               "every 'period seconds'.")},
+    {"_cancel_file_watchdog",
+     (PyCFunction)faulthandler_cancel_file_watchdog, METH_NOARGS,
+     PyDoc_STR("_cancel_file_watchdog():\ncancel the previous call "
+               "to _file_watchdog().")},
+#endif
+
+#ifdef FAULTHANDLER_USER
+    {"register",
+     (PyCFunction)faulthandler_register_py, METH_VARARGS|METH_KEYWORDS,
+     PyDoc_STR("register(signum, file=sys.stderr, all_threads=True, chain=False): "
+               "register an handler for the signal 'signum': dump the "
+               "traceback of the current thread, or of all threads if "
+               "all_threads is True, into file")},
+    {"unregister",
+     faulthandler_unregister_py, METH_VARARGS|METH_KEYWORDS,
+     PyDoc_STR("unregister(signum): unregister the handler of the signal "
+                "'signum' registered by register()")},
+#endif
+
+    {"_read_null", faulthandler_read_null, METH_VARARGS,
+     PyDoc_STR("_read_null(release_gil=False): read from NULL, raise "
+               "a SIGSEGV or SIGBUS signal depending on the platform")},
+    {"_sigsegv", faulthandler_sigsegv, METH_VARARGS,
+     PyDoc_STR("_sigsegv(): raise a SIGSEGV signal")},
+    {"_sigabrt", faulthandler_sigabrt, METH_VARARGS,
+     PyDoc_STR("_sigabrt(): raise a SIGABRT signal")},
+    {"_sigfpe", (PyCFunction)faulthandler_sigfpe, METH_NOARGS,
+     PyDoc_STR("_sigfpe(): raise a SIGFPE signal")},
+#ifdef SIGBUS
+    {"_sigbus", (PyCFunction)faulthandler_sigbus, METH_NOARGS,
+     PyDoc_STR("_sigbus(): raise a SIGBUS signal")},
+#endif
+#ifdef SIGILL
+    {"_sigill", (PyCFunction)faulthandler_sigill, METH_NOARGS,
+     PyDoc_STR("_sigill(): raise a SIGILL signal")},
+#endif
+    {"_fatal_error", faulthandler_fatal_error_py, METH_VARARGS,
+     PyDoc_STR("_fatal_error(message): call Py_FatalError(message)")},
+#if defined(HAVE_SIGALTSTACK) && defined(HAVE_SIGACTION)
+    {"_stack_overflow", (PyCFunction)faulthandler_stack_overflow, METH_NOARGS,
+     PyDoc_STR("_stack_overflow(): recursive call to raise a stack overflow")},
+#endif
+    {NULL, NULL}  /* sentinel */
+};
+
+static struct PyModuleDef module_def = {
+    PyModuleDef_HEAD_INIT,
+    "faulthandler",
+    module_doc,
+    0, /* non-negative size to be able to unload the module */
+    module_methods,
+    NULL,
+    faulthandler_traverse,
+    NULL,
+    NULL
+};
+
+PyMODINIT_FUNC
+PyInit_faulthandler(void)
+{
+    return PyModule_Create(&module_def);
+}
+
+/* Call faulthandler.enable() if the PYTHONFAULTHANDLER environment variable
+   is defined, or if sys._xoptions has a 'faulthandler' key. */
+
+static int
+faulthandler_env_options(void)
+{
+    PyObject *xoptions, *key, *module, *res;
+    _Py_IDENTIFIER(enable);
+
+    if (!Py_GETENV("PYTHONFAULTHANDLER")) {
+        int has_key;
+
+        xoptions = PySys_GetXOptions();
+        if (xoptions == NULL)
+            return -1;
+
+        key = PyUnicode_FromString("faulthandler");
+        if (key == NULL)
+            return -1;
+
+        has_key = PyDict_Contains(xoptions, key);
+        Py_DECREF(key);
+        if (!has_key)
+            return 0;
+    }
+
+    module = PyImport_ImportModule("faulthandler");
+    if (module == NULL) {
+        return -1;
+    }
+    res = _PyObject_CallMethodId(module, &PyId_enable, "");
+    Py_DECREF(module);
+    if (res == NULL)
+        return -1;
+    Py_DECREF(res);
+    return 0;
+}
+
+int _PyFaulthandler_Init(void)
+{
+#ifdef HAVE_SIGALTSTACK
+    int err;
+
+    /* Try to allocate an alternate stack for faulthandler() signal handler to
+     * be able to allocate memory on the stack, even on a stack overflow. If it
+     * fails, ignore the error. */
+    stack.ss_flags = 0;
+    stack.ss_size = SIGSTKSZ;
+    stack.ss_sp = PyMem_Malloc(stack.ss_size);
+    if (stack.ss_sp != NULL) {
+        err = sigaltstack(&stack, NULL);
+        if (err) {
+            PyMem_Free(stack.ss_sp);
+            stack.ss_sp = NULL;
+        }
+    }
+#endif
+#ifdef FAULTHANDLER_LATER
+    thread.file = NULL;
+    thread.cancel_event = PyThread_allocate_lock();
+    thread.running = PyThread_allocate_lock();
+    if (!thread.cancel_event || !thread.running) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "could not allocate locks for faulthandler");
+        return -1;
+    }
+    PyThread_acquire_lock(thread.cancel_event, 1);
+#endif
+#ifdef FAULTHANDLER_WATCHDOG
+    watchdog.cancel_event = PyThread_allocate_lock();
+    watchdog.running = PyThread_allocate_lock();
+    if (!watchdog.cancel_event || !watchdog.running) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "could not allocate locks for faulthandler");
+        return -1;
+    }
+    PyThread_acquire_lock(watchdog.cancel_event, 1);
+#endif
+
+    return faulthandler_env_options();
+}
+
+void _PyFaulthandler_Fini(void)
+{
+#ifdef FAULTHANDLER_USER
+    unsigned int signum;
+#endif
+
+#ifdef FAULTHANDLER_LATER
+    /* later */
+    cancel_dump_tracebacks_later();
+    if (thread.cancel_event) {
+        PyThread_release_lock(thread.cancel_event);
+        PyThread_free_lock(thread.cancel_event);
+        thread.cancel_event = NULL;
+    }
+    if (thread.running) {
+        PyThread_free_lock(thread.running);
+        thread.running = NULL;
+    }
+#endif
+
+#ifdef FAULTHANDLER_WATCHDOG
+    /* file watchdog */
+    cancel_file_watchdog();
+    if (watchdog.cancel_event) {
+        PyThread_release_lock(watchdog.cancel_event);
+        PyThread_free_lock(watchdog.cancel_event);
+        watchdog.cancel_event = NULL;
+    }
+    if (watchdog.running) {
+        PyThread_free_lock(watchdog.running);
+        watchdog.running = NULL;
+    }
+#endif
+
+#ifdef FAULTHANDLER_USER
+    /* user */
+    if (user_signals != NULL) {
+        for (signum=0; signum < NSIG; signum++)
+            faulthandler_unregister(&user_signals[signum], signum);
+        free(user_signals);
+        user_signals = NULL;
+    }
+#endif
+
+    /* fatal */
+    faulthandler_disable();
+#ifdef HAVE_SIGALTSTACK
+    if (stack.ss_sp != NULL) {
+        PyMem_Free(stack.ss_sp);
+        stack.ss_sp = NULL;
+    }
+#endif
+}