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#include "Python.h"
#include "pycore_ceval.h" // _PyEval_IsGILEnabled()
#include "pycore_initconfig.h" // _PyStatus_ERR()
#include "pycore_pyerrors.h" // _Py_DumpExtensionModules()
#include "pycore_fileutils.h" // _PyFile_Flush
#include "pycore_pystate.h" // _PyThreadState_GET()
#include "pycore_runtime.h" // _Py_ID()
#include "pycore_signal.h" // Py_NSIG
#include "pycore_sysmodule.h" // _PySys_GetRequiredAttr()
#include "pycore_time.h" // _PyTime_FromSecondsObject()
#include "pycore_traceback.h" // _Py_DumpTracebackThreads
#ifdef HAVE_UNISTD_H
# include <unistd.h> // _exit()
#endif
#include <signal.h> // sigaction()
#include <stdlib.h> // abort()
#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK) && defined(HAVE_PTHREAD_H)
# include <pthread.h>
#endif
#ifdef MS_WINDOWS
# include <windows.h>
#endif
#ifdef HAVE_SYS_RESOURCE_H
# include <sys/resource.h> // setrlimit()
#endif
#if defined(FAULTHANDLER_USE_ALT_STACK) && defined(HAVE_LINUX_AUXVEC_H) && defined(HAVE_SYS_AUXV_H)
# include <linux/auxvec.h> // AT_MINSIGSTKSZ
# include <sys/auxv.h> // getauxval()
#endif
/* Sentinel to ignore all_threads on free-threading */
#define FT_IGNORE_ALL_THREADS 2
/* Allocate at maximum 100 MiB of the stack to raise the stack overflow */
#define STACK_OVERFLOW_MAX_SIZE (100 * 1024 * 1024)
#define PUTS(fd, str) (void)_Py_write_noraise(fd, str, strlen(str))
typedef struct {
int signum;
int enabled;
const char* name;
_Py_sighandler_t previous;
int all_threads;
} fault_handler_t;
#define fatal_error _PyRuntime.faulthandler.fatal_error
#define thread _PyRuntime.faulthandler.thread
#ifdef FAULTHANDLER_USER
#define user_signals _PyRuntime.faulthandler.user_signals
typedef struct faulthandler_user_signal user_signal_t;
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 FAULTHANDLER_USE_ALT_STACK
# define stack _PyRuntime.faulthandler.stack
# define old_stack _PyRuntime.faulthandler.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_GetRequiredAttr(&_Py_ID(stderr));
if (file == NULL) {
return -1;
}
if (file == Py_None) {
PyErr_SetString(PyExc_RuntimeError, "sys.stderr is None");
Py_DECREF(file);
return -1;
}
}
else if (PyLong_Check(file)) {
if (PyBool_Check(file)) {
if (PyErr_WarnEx(PyExc_RuntimeWarning,
"bool is used as a file descriptor", 1))
{
return -1;
}
}
fd = PyLong_AsInt(file);
if (fd == -1 && PyErr_Occurred())
return -1;
if (fd < 0) {
PyErr_SetString(PyExc_ValueError,
"file is not a valid file descriptor");
return -1;
}
*file_ptr = NULL;
return fd;
}
else {
Py_INCREF(file);
}
result = PyObject_CallMethodNoArgs(file, &_Py_ID(fileno));
if (result == NULL) {
Py_DECREF(file);
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");
Py_DECREF(file);
return -1;
}
if (_PyFile_Flush(file) < 0) {
/* 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_GET();
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;
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(). */
PyThreadState *tstate = PyGILState_GetThisThreadState();
if (all_threads == 1) {
(void)_Py_DumpTracebackThreads(fd, NULL, tstate);
}
else {
if (all_threads == FT_IGNORE_ALL_THREADS) {
PUTS(fd, "<Cannot show all threads while the GIL is disabled>\n");
}
if (tstate != NULL)
_Py_DumpTraceback(fd, tstate);
}
reentrant = 0;
}
static void
faulthandler_dump_c_stack(int fd)
{
static volatile int reentrant = 0;
if (reentrant) {
return;
}
reentrant = 1;
if (fatal_error.c_stack) {
PUTS(fd, "\n");
_Py_DumpStack(fd);
}
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,
"|Op: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) {
Py_XDECREF(file);
return NULL;
}
if (all_threads) {
PyInterpreterState *interp = _PyInterpreterState_GET();
/* gh-128400: Accessing other thread states while they're running
* isn't safe if those threads are running. */
_PyEval_StopTheWorld(interp);
errmsg = _Py_DumpTracebackThreads(fd, NULL, tstate);
_PyEval_StartTheWorld(interp);
if (errmsg != NULL) {
PyErr_SetString(PyExc_RuntimeError, errmsg);
Py_XDECREF(file);
return NULL;
}
}
else {
_Py_DumpTraceback(fd, tstate);
}
Py_XDECREF(file);
if (PyErr_CheckSignals())
return NULL;
Py_RETURN_NONE;
}
static PyObject *
faulthandler_dump_c_stack_py(PyObject *self,
PyObject *args, PyObject *kwargs)
{
static char *kwlist[] = {"file", NULL};
PyObject *file = NULL;
if (!PyArg_ParseTupleAndKeywords(args, kwargs,
"|O:dump_c_stack", kwlist,
&file)) {
return NULL;
}
int fd = faulthandler_get_fileno(&file);
if (fd < 0) {
return NULL;
}
_Py_DumpStack(fd);
Py_XDECREF(file);
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
}
static int
deduce_all_threads(void)
{
#ifndef Py_GIL_DISABLED
return fatal_error.all_threads;
#else
if (fatal_error.all_threads == 0) {
return 0;
}
// We can't use _PyThreadState_GET, so use the stored GILstate one
PyThreadState *tstate = PyGILState_GetThisThreadState();
if (tstate == NULL) {
return 0;
}
/* In theory, it's safe to dump all threads if the GIL is enabled */
return _PyEval_IsGILEnabled(tstate)
? fatal_error.all_threads
: FT_IGNORE_ALL_THREADS;
#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;
int found = 0;
if (!fatal_error.enabled)
return;
for (i=0; i < faulthandler_nsignals; i++) {
handler = &faulthandler_handlers[i];
if (handler->signum == signum) {
found = 1;
break;
}
}
if (handler == NULL) {
/* faulthandler_nsignals == 0 (unlikely) */
return;
}
/* restore the previous handler */
faulthandler_disable_fatal_handler(handler);
if (found) {
PUTS(fd, "Fatal Python error: ");
PUTS(fd, handler->name);
PUTS(fd, "\n\n");
}
else {
char unknown_signum[23] = {0,};
snprintf(unknown_signum, 23, "%d", signum);
PUTS(fd, "Fatal Python error from unexpected signum: ");
PUTS(fd, unknown_signum);
PUTS(fd, "\n\n");
}
faulthandler_dump_traceback(fd, deduce_all_threads(),
fatal_error.interp);
faulthandler_dump_c_stack(fd);
_Py_DumpExtensionModules(fd, 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;
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, deduce_all_threads(),
fatal_error.interp);
faulthandler_dump_c_stack(fd);
/* call the next exception handler */
return EXCEPTION_CONTINUE_SEARCH;
}
#endif
#ifdef FAULTHANDLER_USE_ALT_STACK
static int
faulthandler_allocate_stack(void)
{
if (stack.ss_sp != NULL) {
return 0;
}
/* Allocate an alternate stack for faulthandler() signal handler
to be able to execute a signal handler on a stack overflow error */
stack.ss_sp = PyMem_Malloc(stack.ss_size);
if (stack.ss_sp == NULL) {
PyErr_NoMemory();
return -1;
}
int err = sigaltstack(&stack, &old_stack);
if (err) {
PyErr_SetFromErrno(PyExc_OSError);
/* Release the stack to retry sigaltstack() next time */
PyMem_Free(stack.ss_sp);
stack.ss_sp = NULL;
return -1;
}
return 0;
}
#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;
#ifdef FAULTHANDLER_USE_ALT_STACK
if (faulthandler_allocate_stack() < 0) {
return -1;
}
#endif
// gh-137185: Initialize C stack trace dumping outside of the signal
// handler. Specifically, we call backtrace() to ensure that libgcc is
// dynamically loaded outside of the signal handler.
_Py_InitDumpStack();
for (size_t i=0; i < faulthandler_nsignals; i++) {
fault_handler_t *handler;
int err;
handler = &faulthandler_handlers[i];
assert(!handler->enabled);
#ifdef HAVE_SIGACTION
struct sigaction action;
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 FAULTHANDLER_USE_ALT_STACK
assert(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", "c_stack", NULL};
PyObject *file = NULL;
int all_threads = 1;
int fd;
int c_stack = 1;
PyThreadState *tstate;
if (!PyArg_ParseTupleAndKeywords(args, kwargs,
"|Opp:enable", kwlist, &file, &all_threads, &c_stack))
return NULL;
fd = faulthandler_get_fileno(&file);
if (fd < 0)
return NULL;
tstate = get_thread_state();
if (tstate == NULL) {
Py_XDECREF(file);
return NULL;
}
Py_XSETREF(fatal_error.file, file);
fatal_error.fd = fd;
fatal_error.all_threads = all_threads;
fatal_error.interp = PyThreadState_GetInterpreter(tstate);
fatal_error.c_stack = c_stack;
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);
}
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);
(void)_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)
{
/* If not scheduled, nothing to cancel */
if (!thread.cancel_event) {
return;
}
/* 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;
}
if (!thread.running) {
thread.running = PyThread_allocate_lock();
if (!thread.running) {
Py_XDECREF(file);
return PyErr_NoMemory();
}
}
if (!thread.cancel_event) {
thread.cancel_event = PyThread_allocate_lock();
if (!thread.cancel_event || !thread.running) {
Py_XDECREF(file);
return PyErr_NoMemory();
}
/* cancel_event starts to be acquired: it's only released to cancel
the thread. */
PyThread_acquire_lock(thread.cancel_event, 1);
}
/* format the timeout */
header = format_timeout(timeout_us);
if (header == NULL) {
Py_XDECREF(file);
return PyErr_NoMemory();
}
header_len = strlen(header);
/* Cancel previous thread, if running */
cancel_dump_traceback_later();
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 = PyThreadState_GetInterpreter(tstate);
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;
}
#ifdef FAULTHANDLER_USER
static int
faulthandler_register(int signum, int chain, _Py_sighandler_t *previous_p)
{
#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 FAULTHANDLER_USE_ALT_STACK
assert(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, previous_p);
#else
_Py_sighandler_t previous;
previous = signal(signum, faulthandler_user);
if (previous_p != NULL) {
*previous_p = 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 && user->previous != NULL) {
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 || Py_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|Opp: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_Calloc(Py_NSIG, sizeof(user_signal_t));
if (user_signals == NULL) {
Py_XDECREF(file);
return PyErr_NoMemory();
}
}
user = &user_signals[signum];
if (!user->enabled) {
#ifdef FAULTHANDLER_USE_ALT_STACK
if (faulthandler_allocate_stack() < 0) {
Py_XDECREF(file);
return NULL;
}
#endif
err = faulthandler_register(signum, chain, &previous);
if (err) {
PyErr_SetFromErrno(PyExc_OSError);
Py_XDECREF(file);
return NULL;
}
user->previous = previous;
}
Py_XSETREF(user->file, file);
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