cpython/Modules/faulthandler.c at pythoncapi · pythoncapi/cpython · GitHub

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#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

#ifdef MS_WINDOWS

# include <windows.h>

#endif

#ifdef HAVE_SYS_RESOURCE_H

# include <sys/resource.h>

#endif

/* Allocate at maximum 100 MiB of the stack to raise the stack overflow */

#define STACK_OVERFLOW_MAX_SIZE (100 * 1024 * 1024)

#define FAULTHANDLER_LATER

#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) _Py_write_noraise(fd, str, strlen(str))

_Py_IDENTIFIER(enable);

_Py_IDENTIFIER(fileno);

_Py_IDENTIFIER(flush);

_Py_IDENTIFIER(stderr);

#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;

#ifdef MS_WINDOWS

void *exc_handler;

#endif

} 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_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 */

#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 size_t faulthandler_nsignals = \

Py_ARRAY_LENGTH(faulthandler_handlers);

#ifdef HAVE_SIGALTSTACK

static stack_t stack;

static stack_t old_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.

If file is an integer, it will be treated as file descriptor.

On success, return the file descriptor and write the new file into *file_ptr.

On error, return -1. */

static int

faulthandler_get_fileno(PyObject **file_ptr)

{

PyObject *result;

long fd_long;

int fd;

PyObject *file = *file_ptr;

if (file == NULL || file == Py_None) {

file = _PySys_GetObjectId(&PyId_stderr);

if (file == NULL) {

PyErr_SetString(PyExc_RuntimeError, "unable to get sys.stderr");

return -1;

}

if (file == Py_None) {

PyErr_SetString(PyExc_RuntimeError, "sys.stderr is None");

return -1;

}

else if (PyLong_Check(file)) {

fd = _PyLong_AsInt(file);

if (fd == -1 && PyErr_Occurred())

return -1;

if (fd < 0) {

PyErr_SetString(PyExc_ValueError,

"file is not a valid file descripter");

return -1;

}

*file_ptr = NULL;

return fd;

}

result = _PyObject_CallMethodId(file, &PyId_fileno, NULL);

if (result == NULL)

return -1;

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 -1;

}

result = _PyObject_CallMethodId(file, &PyId_flush, NULL);

if (result != NULL)

Py_DECREF(result);

else {

/* ignore flush() error */

PyErr_Clear();

}

*file_ptr = file;

return fd;

}

/* 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_UncheckedGet();

if (tstate == NULL) {

/* just in case but very unlikely... */

PyErr_SetString(PyExc_RuntimeError,

"unable to get the current thread state");

return NULL;

}

return tstate;

}

static void

faulthandler_dump_traceback(int fd, int all_threads,

PyInterpreterState *interp)

{

static volatile int reentrant = 0;

PyThreadState *tstate;

if (reentrant)

return;

reentrant = 1;

/* 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 specific storage (TSS) instead: call

PyGILState_GetThisThreadState(). */

tstate = PyGILState_GetThisThreadState();

if (all_threads) {

(void)_Py_DumpTracebackThreads(fd, NULL, tstate);

}

else {

if (tstate != NULL)

_Py_DumpTraceback(fd, tstate);

}

reentrant = 0;

}

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;

fd = faulthandler_get_fileno(&file);

if (fd < 0)

return NULL;

tstate = get_thread_state();

if (tstate == NULL)

return NULL;

if (all_threads) {

errmsg = _Py_DumpTracebackThreads(fd, NULL, tstate);

if (errmsg != NULL) {

PyErr_SetString(PyExc_RuntimeError, errmsg);

return NULL;

}

else {

_Py_DumpTraceback(fd, tstate);

}

if (PyErr_CheckSignals())

return NULL;

Py_RETURN_NONE;

}

static void

faulthandler_disable_fatal_handler(fault_handler_t *handler)

{

if (!handler->enabled)

return;

handler->enabled = 0;

#ifdef HAVE_SIGACTION

(void)sigaction(handler->signum, &handler->previous, NULL);

#else

(void)signal(handler->signum, handler->previous);

#endif

}

/* 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;

size_t i;

fault_handler_t *handler = NULL;

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 */

faulthandler_disable_fatal_handler(handler);

PUTS(fd, "Fatal Python error: ");

PUTS(fd, handler->name);

PUTS(fd, "\n\n");

faulthandler_dump_traceback(fd, fatal_error.all_threads,

fatal_error.interp);

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 immediately if we use

sigaction() thanks to SA_NODEFER flag, otherwise it is deferred */

raise(signum);

}

#ifdef MS_WINDOWS

static int

faulthandler_ignore_exception(DWORD code)

{

/* bpo-30557: ignore exceptions which are not errors */

if (!(code & 0x80000000)) {

return 1;

}

/* bpo-31701: ignore MSC and COM exceptions

E0000000 + code */

if (code == 0xE06D7363 /* MSC exception ("Emsc") */

|| code == 0xE0434352 /* COM Callable Runtime exception ("ECCR") */) {

return 1;

}

/* Interesting exception: log it with the Python traceback */

return 0;

}

static LONG WINAPI

faulthandler_exc_handler(struct _EXCEPTION_POINTERS *exc_info)

{

const int fd = fatal_error.fd;

DWORD code = exc_info->ExceptionRecord->ExceptionCode;

DWORD flags = exc_info->ExceptionRecord->ExceptionFlags;

if (faulthandler_ignore_exception(code)) {

/* ignore the exception: call the next exception handler */

return EXCEPTION_CONTINUE_SEARCH;

}

PUTS(fd, "Windows fatal exception: ");

switch (code)

{

/* only format most common errors */

case EXCEPTION_ACCESS_VIOLATION: PUTS(fd, "access violation"); break;

case EXCEPTION_FLT_DIVIDE_BY_ZERO: PUTS(fd, "float divide by zero"); break;

case EXCEPTION_FLT_OVERFLOW: PUTS(fd, "float overflow"); break;

case EXCEPTION_INT_DIVIDE_BY_ZERO: PUTS(fd, "int divide by zero"); break;

case EXCEPTION_INT_OVERFLOW: PUTS(fd, "integer overflow"); break;

case EXCEPTION_IN_PAGE_ERROR: PUTS(fd, "page error"); break;

case EXCEPTION_STACK_OVERFLOW: PUTS(fd, "stack overflow"); break;

default:

PUTS(fd, "code 0x");

_Py_DumpHexadecimal(fd, code, 8);

}

PUTS(fd, "\n\n");

if (code == EXCEPTION_ACCESS_VIOLATION) {

/* disable signal handler for SIGSEGV */

for (size_t i=0; i < faulthandler_nsignals; i++) {

fault_handler_t *handler = &faulthandler_handlers[i];

if (handler->signum == SIGSEGV) {

faulthandler_disable_fatal_handler(handler);

break;

}

faulthandler_dump_traceback(fd, fatal_error.all_threads,

fatal_error.interp);

/* call the next exception handler */

return EXCEPTION_CONTINUE_SEARCH;

}

#endif

/* Install the handler for fatal signals, faulthandler_fatal_error(). */

static int

faulthandler_enable(void)

{

if (fatal_error.enabled) {

return 0;

}

fatal_error.enabled = 1;

for (size_t i=0; i < faulthandler_nsignals; i++) {

fault_handler_t *handler;

#ifdef HAVE_SIGACTION

struct sigaction action;

#endif

int err;

handler = &faulthandler_handlers[i];

assert(!handler->enabled);

#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 -1;

}

handler->enabled = 1;

}

#ifdef MS_WINDOWS

assert(fatal_error.exc_handler == NULL);

fatal_error.exc_handler = AddVectoredExceptionHandler(1, faulthandler_exc_handler);

#endif

return 0;

}

static PyObject*

faulthandler_py_enable(PyObject *self, PyObject *args, PyObject *kwargs)

{

static char *kwlist[] = {"file", "all_threads", NULL};

PyObject *file = NULL;

int all_threads = 1;

int fd;

PyThreadState *tstate;

if (!PyArg_ParseTupleAndKeywords(args, kwargs,

"|Oi:enable", kwlist, &file, &all_threads))

return NULL;

fd = faulthandler_get_fileno(&file);

if (fd < 0)

return NULL;

tstate = get_thread_state();

if (tstate == NULL)

return NULL;

Py_XINCREF(file);

Py_XSETREF(fatal_error.file, file);

fatal_error.fd = fd;

fatal_error.all_threads = all_threads;

fatal_error.interp = tstate->interp;

if (faulthandler_enable() < 0) {

return NULL;

}

Py_RETURN_NONE;

}

static void

faulthandler_disable(void)

{

if (fatal_error.enabled) {

fatal_error.enabled = 0;

for (size_t i=0; i < faulthandler_nsignals; i++) {

fault_handler_t *handler;

handler = &faulthandler_handlers[i];

faulthandler_disable_fatal_handler(handler);

}

#ifdef MS_WINDOWS

if (fatal_error.exc_handler != NULL) {

RemoveVectoredExceptionHandler(fatal_error.exc_handler);

fatal_error.exc_handler = NULL;

}

#endif

Py_CLEAR(fatal_error.file);

}

static PyObject*

faulthandler_disable_py(PyObject *self, PyObject *Py_UNUSED(ignored))

{

if (!fatal_error.enabled) {

Py_RETURN_FALSE;

}

faulthandler_disable();

Py_RETURN_TRUE;

}

static PyObject*

faulthandler_is_enabled(PyObject *self, PyObject *Py_UNUSED(ignored))

{

return PyBool_FromLong(fatal_error.enabled);

}

#ifdef FAULTHANDLER_LATER

static void

faulthandler_thread(void *unused)

{

PyLockStatus st;

const char* errmsg;

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);

_Py_write_noraise(thread.fd, thread.header, (int)thread.header_len);

errmsg = _Py_DumpTracebackThreads(thread.fd, thread.interp, NULL);

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_traceback_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) {

PyMem_Free(thread.header);

thread.header = NULL;

}

#define SEC_TO_US (1000 * 1000)

static char*

format_timeout(_PyTime_t us)

{

unsigned long sec, min, hour;

char buffer[100];

/* the downcast is safe: the caller check that 0 < us <= LONG_MAX */

sec = (unsigned long)(us / SEC_TO_US);

us %= SEC_TO_US;

min = sec / 60;

sec %= 60;

hour = min / 60;

min %= 60;

if (us != 0) {

PyOS_snprintf(buffer, sizeof(buffer),

"Timeout (%lu:%02lu:%02lu.%06u)!\n",

hour, min, sec, (unsigned int)us);

}

else {

PyOS_snprintf(buffer, sizeof(buffer),

"Timeout (%lu:%02lu:%02lu)!\n",

hour, min, sec);

}

return _PyMem_Strdup(buffer);

}

static PyObject*

faulthandler_dump_traceback_later(PyObject *self,

PyObject *args, PyObject *kwargs)

{

static char *kwlist[] = {"timeout", "repeat", "file", "exit", NULL};

PyObject *timeout_obj;

_PyTime_t timeout, 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,

"O|iOi:dump_traceback_later", kwlist,

&timeout_obj, &repeat, &file, &exit))

return NULL;

if (_PyTime_FromSecondsObject(&timeout, timeout_obj,

_PyTime_ROUND_TIMEOUT) < 0) {

return NULL;

}

timeout_us = _PyTime_AsMicroseconds(timeout, _PyTime_ROUND_TIMEOUT);

if (timeout_us <= 0) {

PyErr_SetString(PyExc_ValueError, "timeout must be greater than 0");

return NULL;

}

/* Limit to LONG_MAX seconds for format_timeout() */

if (timeout_us >= PY_TIMEOUT_MAX || timeout_us / SEC_TO_US >= LONG_MAX) {

PyErr_SetString(PyExc_OverflowError,

"timeout value is too large");

return NULL;

}

tstate = get_thread_state();

if (tstate == NULL)

return NULL;

fd = faulthandler_get_fileno(&file);

if (fd < 0)

return NULL;

/* format the timeout */

header = format_timeout(timeout_us);

if (header == NULL)

return PyErr_NoMemory();

header_len = strlen(header);

/* Cancel previous thread, if running */

cancel_dump_traceback_later();

Py_XINCREF(file);

Py_XSETREF(thread.file, file);

thread.fd = fd;

/* the downcast is safe: we check that 0 < timeout_us < PY_TIMEOUT_MAX */

thread.timeout_us = (PY_TIMEOUT_T)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) == PYTHREAD_INVALID_THREAD_ID) {

PyThread_release_lock(thread.running);

Py_CLEAR(thread.file);

PyMem_Free(header);

thread.header = NULL;

PyErr_SetString(PyExc_RuntimeError,

"unable to start watchdog thread");

return NULL;

}

Py_RETURN_NONE;

}

static PyObject*

faulthandler_cancel_dump_traceback_later_py(PyObject *self,

PyObject *Py_UNUSED(ignored))

{

cancel_dump_traceback_later();

Py_RETURN_NONE;

}

#endif /* FAULTHANDLER_LATER */

#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;

int save_errno = errno;

user = &user_signals[signum];

if (!user->enabled)

return;

faulthandler_dump_traceback(user->fd, user->all_threads, user->interp);

#ifdef HAVE_SIGACTION

if (user->chain) {

(void)sigaction(signum, &user->previous, NULL);

errno = save_errno;

/* call the previous signal handler */

raise(signum);

save_errno = errno;

(void)faulthandler_register(signum, user->chain, NULL);

errno = save_errno;

}

#else

if (user->chain) {

errno = save_errno;

/* call the previous signal handler */

user->previous(signum);

}

#endif

}

static int

check_signum(int signum)

{

for (size_t 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;

fd = faulthandler_get_fileno(&file);

if (fd < 0)

return NULL;

if (user_signals == NULL) {

user_signals = PyMem_Malloc(NSIG * sizeof(user_signal_t));

if (user_signals == NULL)

return PyErr_NoMemory();

memset(user_signals, 0, NSIG * sizeof(user_signal_t));

}

user = &user_signals[signum];

if (!user->enabled) {

err = faulthandler_register(signum, chain, &previous);

if (err) {

PyErr_SetFromErrno(PyExc_OSError);

return NULL;

}

user->previous = previous;

}

Py_XINCREF(file);

Py_XSETREF(user->file, file);

user->fd = fd;

user->all_threads = all_threads;

user->chain = chain;

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 void

faulthandler_suppress_crash_report(void)

{

#ifdef MS_WINDOWS

UINT mode;

/* Configure Windows to not display the Windows Error Reporting dialog */

mode = SetErrorMode(SEM_NOGPFAULTERRORBOX);

SetErrorMode(mode | SEM_NOGPFAULTERRORBOX);

#endif

#ifdef HAVE_SYS_RESOURCE_H

struct rlimit rl;

/* Disable creation of core dump */

if (getrlimit(RLIMIT_CORE, &rl) == 0) {

rl.rlim_cur = 0;

setrlimit(RLIMIT_CORE, &rl);

}

#endif

#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

}

static PyObject *

faulthandler_read_null(PyObject *self, PyObject *args)

{

volatile int *x;

volatile int y;

faulthandler_suppress_crash_report();

x = NULL;

y = *x;

return PyLong_FromLong(y);

}

static void

faulthandler_raise_sigsegv(void)

{

faulthandler_suppress_crash_report();

#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

}

static PyObject *

faulthandler_sigsegv(PyObject *self, PyObject *args)

{

int release_gil = 0;

if (!PyArg_ParseTuple(args, "|i:_sigsegv", &release_gil))

return NULL;

if (release_gil) {

Py_BEGIN_ALLOW_THREADS

faulthandler_raise_sigsegv();

Py_END_ALLOW_THREADS

} else {

faulthandler_raise_sigsegv();

}

Py_RETURN_NONE;

}

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