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cpython/Modules/signalmodule.c
Antoine Pitrou 68245b7a10
bpo-43406: Fix possible race condition where `PyErr_CheckSignals` tries to execute a non-Python signal handler (GH-24756) 
We can receive signals (at the C level, in `trip_signal()` in signalmodule.c) while `signal.signal` is being called to modify the corresponding handler.  Later when `PyErr_CheckSignals()` is called to handle the given signal, the handler may be a non-callable object and would raise a cryptic asynchronous exception.
2021-03-05 10:32:50 +01:00

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/* Signal module -- many thanks to Lance Ellinghaus */
/* XXX Signals should be recorded per thread, now we have thread state. */
#include "Python.h"
#include "pycore_atomic.h"
#include "pycore_call.h"
#include "pycore_ceval.h"
#include "pycore_pyerrors.h"
#include "pycore_pystate.h" // _PyThreadState_GET()
#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_SYSCALL_H
#include <sys/syscall.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
We want the following semantics:
- only the main thread can set a signal handler
- only the main thread runs the signal handler
- signals can be delivered to any thread
- any thread can get a signal handler
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. On Linux, signals are delivered to
the main thread (unless the main thread is blocking the signal, for
example because it's already handling the same signal). Since we
allow signals to be delivered to any thread, this works fine. The
only oddity is that the thread executing the Python signal handler
may not be the thread that received the signal.
*/
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 {
#ifdef __VXWORKS__
int fd;
#else
sig_atomic_t fd;
#endif
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;
#ifdef MS_WINDOWS
static HANDLE sigint_event = NULL;
#endif
#if defined(HAVE_GETITIMER) || defined(HAVE_SETITIMER)
static PyObject *ItimerError;
#endif
#ifdef HAVE_GETITIMER
/* 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
/*[clinic input]
signal.default_int_handler
signalnum: int
frame: object
/
The default handler for SIGINT installed by Python.
It raises KeyboardInterrupt.
[clinic start generated code]*/
static PyObject *
signal_default_int_handler_impl(PyObject *module, int signalnum,
PyObject *frame)
/*[clinic end generated code: output=bb11c2eb115ace4e input=efcd4a56a207acfd]*/
{
PyErr_SetNone(PyExc_KeyboardInterrupt);
return NULL;
}
static int
report_wakeup_write_error(void *data)
{
PyObject *exc, *val, *tb;
int save_errno = errno;
errno = (int) (intptr_t) data;
PyErr_Fetch(&exc, &val, &tb);
PyErr_SetFromErrno(PyExc_OSError);
PySys_WriteStderr("Exception ignored when trying to write to the "
"signal wakeup fd:\n");
PyErr_WriteUnraisable(NULL);
PyErr_Restore(exc, val, tb);
errno = save_errno;
return 0;
}
#ifdef MS_WINDOWS
static int
report_wakeup_send_error(void* data)
{
PyObject *exc, *val, *tb;
PyErr_Fetch(&exc, &val, &tb);
/* 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);
PyErr_Restore(exc, val, tb);
return 0;
}
#endif /* MS_WINDOWS */
static void
trip_signal(int sig_num)
{
_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);
/* Signals are always handled by the main interpreter */
PyInterpreterState *interp = _PyRuntime.interpreters.main;
/* Notify ceval.c */
_PyEval_SignalReceived(interp);
/* 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.
*/
int fd;
#ifdef MS_WINDOWS
fd = Py_SAFE_DOWNCAST(wakeup.fd, SOCKET_T, int);
#else
fd = wakeup.fd;
#endif
if (fd != INVALID_FD) {
unsigned char byte = (unsigned char)sig_num;
#ifdef MS_WINDOWS
if (wakeup.use_send) {
Py_ssize_t rc = send(fd, &byte, 1, 0);
if (rc < 0) {
int last_error = GetLastError();
if (wakeup.warn_on_full_buffer ||
last_error != WSAEWOULDBLOCK)
{
/* _PyEval_AddPendingCall() isn't signal-safe, but we
still use it for this exceptional case. */
_PyEval_AddPendingCall(interp,
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). */
Py_ssize_t rc = _Py_write_noraise(fd, &byte, 1);
if (rc < 0) {
if (wakeup.warn_on_full_buffer ||
(errno != EWOULDBLOCK && errno != EAGAIN))
{
/* _PyEval_AddPendingCall() isn't signal-safe, but we
still use it for this exceptional case. */
_PyEval_AddPendingCall(interp,
report_wakeup_write_error,
(void *)(intptr_t)errno);
}
}
}
}
}
static void
signal_handler(int sig_num)
{
int save_errno = errno;
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.raise_signal
signalnum: int
/
Send a signal to the executing process.
[clinic start generated code]*/
static PyObject *
signal_raise_signal_impl(PyObject *module, int signalnum)
/*[clinic end generated code: output=e2b014220aa6111d input=e90c0f9a42358de6]*/
{
int err;
Py_BEGIN_ALLOW_THREADS
_Py_BEGIN_SUPPRESS_IPH
err = raise(signalnum);
_Py_END_SUPPRESS_IPH
Py_END_ALLOW_THREADS
if (err) {
return PyErr_SetFromErrno(PyExc_OSError);
}
Py_RETURN_NONE;
}
/*[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
PyThreadState *tstate = _PyThreadState_GET();
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
_PyErr_SetString(tstate, PyExc_ValueError,
"signal only works in main thread "
"of the main interpreter");
return NULL;
}
if (signalnum < 1 || signalnum >= NSIG) {
_PyErr_SetString(tstate, 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(tstate, 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_CheckSignalsTstate(tstate)) {
return NULL;
}
if (PyOS_setsig(signalnum, func) == SIG_ERR) {
PyErr_SetFromErrno(PyExc_OSError);
return NULL;
}
old_handler = Handlers[signalnum].func;
Handlers[signalnum].func = Py_NewRef(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) {
return Py_NewRef(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;
}
#ifdef HAVE_SIGACTION
struct sigaction act;
(void) sigaction(signalnum, NULL, &act);
if (flag) {
act.sa_flags &= ~SA_RESTART;
}
else {
act.sa_flags |= SA_RESTART;
}
if (sigaction(signalnum, &act, NULL) < 0) {
#else
if (siginterrupt(signalnum, flag) < 0) {
#endif
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|$p:set_wakeup_fd", kwlist,
&fdobj, &warn_on_full_buffer))
return NULL;
sockfd = PyLong_AsSocket_t(fdobj);
if (sockfd == (SOCKET_T)(-1) && PyErr_Occurred())
return NULL;
#else
int fd;
if (!PyArg_ParseTupleAndKeywords(args, kwds, "i|$p:set_wakeup_fd", kwlist,
&fd, &warn_on_full_buffer))
return NULL;
#endif
PyThreadState *tstate = _PyThreadState_GET();
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
_PyErr_SetString(tstate, PyExc_ValueError,
"set_wakeup_fd only works in main thread "
"of the main interpreter");
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(tstate, 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(tstate, PyExc_ValueError,
"the fd %i must be in non-blocking mode",
fd);
return NULL;
}
}
int 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)
{
if (fd < 0) {
fd = -1;
}
#ifdef MS_WINDOWS
int old_fd = Py_SAFE_DOWNCAST(wakeup.fd, SOCKET_T, int);
#else
int 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;
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 */
struct itimerval old;
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 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)));
#ifdef __VXWORKS__
PyStructSequence_SET_ITEM(result, 2, PyLong_FromLong(0L));
PyStructSequence_SET_ITEM(result, 3, PyLong_FromLong(0L));
PyStructSequence_SET_ITEM(result, 4, PyLong_FromLong(0L));
PyStructSequence_SET_ITEM(result, 5, PyLong_FromLong(0L));
#else
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)));
#endif
#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;
if (PySys_Audit("signal.pthread_kill", "ki", thread_id, signalnum) < 0) {
return NULL;
}
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) */
#if defined(__linux__) && defined(__NR_pidfd_send_signal)
/*[clinic input]
signal.pidfd_send_signal
pidfd: int
signalnum: int
siginfo: object = None
flags: int = 0
/
Send a signal to a process referred to by a pid file descriptor.
[clinic start generated code]*/
static PyObject *
signal_pidfd_send_signal_impl(PyObject *module, int pidfd, int signalnum,
PyObject *siginfo, int flags)
/*[clinic end generated code: output=2d59f04a75d9cbdf input=2a6543a1f4ac2000]*/
{
if (siginfo != Py_None) {
PyErr_SetString(PyExc_TypeError, "siginfo must be None");
return NULL;
}
if (syscall(__NR_pidfd_send_signal, pidfd, signalnum, NULL, flags) < 0) {
PyErr_SetFromErrno(PyExc_OSError);
return NULL;
}
Py_RETURN_NONE;
}
#endif
/* 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[] = {
SIGNAL_DEFAULT_INT_HANDLER_METHODDEF
SIGNAL_ALARM_METHODDEF
SIGNAL_SETITIMER_METHODDEF
SIGNAL_GETITIMER_METHODDEF
SIGNAL_SIGNAL_METHODDEF
SIGNAL_RAISE_SIGNAL_METHODDEF
SIGNAL_STRSIGNAL_METHODDEF
SIGNAL_GETSIGNAL_METHODDEF
{"set_wakeup_fd", (PyCFunction)(void(*)(void))signal_set_wakeup_fd, METH_VARARGS | METH_KEYWORDS, set_wakeup_fd_doc},
SIGNAL_SIGINTERRUPT_METHODDEF
SIGNAL_PAUSE_METHODDEF
SIGNAL_PIDFD_SEND_SIGNAL_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 int
signal_add_constants(PyObject *module)
{
#define ADD_INT_MACRO(macro) \
if (PyModule_AddIntConstant(module, #macro, macro) < 0) { \
return -1; \
}
ADD_INT_MACRO(NSIG);
// SIG_xxx pthread_sigmask() constants
#ifdef SIG_BLOCK
ADD_INT_MACRO(SIG_BLOCK);
#endif
#ifdef SIG_UNBLOCK
ADD_INT_MACRO(SIG_UNBLOCK);
#endif
#ifdef SIG_SETMASK
ADD_INT_MACRO(SIG_SETMASK);
#endif
// SIGxxx signal number constants
#ifdef SIGHUP
ADD_INT_MACRO(SIGHUP);
#endif
#ifdef SIGINT
ADD_INT_MACRO(SIGINT);
#endif
#ifdef SIGBREAK
ADD_INT_MACRO(SIGBREAK);
#endif
#ifdef SIGQUIT
ADD_INT_MACRO(SIGQUIT);
#endif
#ifdef SIGILL
ADD_INT_MACRO(SIGILL);
#endif
#ifdef SIGTRAP
ADD_INT_MACRO(SIGTRAP);
#endif
#ifdef SIGIOT
ADD_INT_MACRO(SIGIOT);
#endif
#ifdef SIGABRT
ADD_INT_MACRO(SIGABRT);
#endif
#ifdef SIGEMT
ADD_INT_MACRO(SIGEMT);
#endif
#ifdef SIGFPE
ADD_INT_MACRO(SIGFPE);
#endif
#ifdef SIGKILL
ADD_INT_MACRO(SIGKILL);
#endif
#ifdef SIGBUS
ADD_INT_MACRO(SIGBUS);
#endif
#ifdef SIGSEGV
ADD_INT_MACRO(SIGSEGV);
#endif
#ifdef SIGSYS
ADD_INT_MACRO(SIGSYS);
#endif
#ifdef SIGPIPE
ADD_INT_MACRO(SIGPIPE);
#endif
#ifdef SIGALRM
ADD_INT_MACRO(SIGALRM);
#endif
#ifdef SIGTERM
ADD_INT_MACRO(SIGTERM);
#endif
#ifdef SIGUSR1
ADD_INT_MACRO(SIGUSR1);
#endif
#ifdef SIGUSR2
ADD_INT_MACRO(SIGUSR2);
#endif
#ifdef SIGCLD
ADD_INT_MACRO(SIGCLD);
#endif
#ifdef SIGCHLD
ADD_INT_MACRO(SIGCHLD);
#endif
#ifdef SIGPWR
ADD_INT_MACRO(SIGPWR);
#endif
#ifdef SIGIO
ADD_INT_MACRO(SIGIO);
#endif
#ifdef SIGURG
ADD_INT_MACRO(SIGURG);
#endif
#ifdef SIGWINCH
ADD_INT_MACRO(SIGWINCH);
#endif
#ifdef SIGPOLL
ADD_INT_MACRO(SIGPOLL);
#endif
#ifdef SIGSTOP
ADD_INT_MACRO(SIGSTOP);
#endif
#ifdef SIGTSTP
ADD_INT_MACRO(SIGTSTP);
#endif
#ifdef SIGCONT
ADD_INT_MACRO(SIGCONT);
#endif
#ifdef SIGTTIN
ADD_INT_MACRO(SIGTTIN);
#endif
#ifdef SIGTTOU
ADD_INT_MACRO(SIGTTOU);
#endif
#ifdef SIGVTALRM
ADD_INT_MACRO(SIGVTALRM);
#endif
#ifdef SIGPROF
ADD_INT_MACRO(SIGPROF);
#endif
#ifdef SIGXCPU
ADD_INT_MACRO(SIGXCPU);
#endif
#ifdef SIGXFSZ
ADD_INT_MACRO(SIGXFSZ);
#endif
#ifdef SIGRTMIN
ADD_INT_MACRO(SIGRTMIN);
#endif
#ifdef SIGRTMAX
ADD_INT_MACRO(SIGRTMAX);
#endif
#ifdef SIGINFO
ADD_INT_MACRO(SIGINFO);
#endif
// ITIMER_xxx constants
#ifdef ITIMER_REAL
ADD_INT_MACRO(ITIMER_REAL);
#endif
#ifdef ITIMER_VIRTUAL
ADD_INT_MACRO(ITIMER_VIRTUAL);
#endif
#ifdef ITIMER_PROF
ADD_INT_MACRO(ITIMER_PROF);
#endif
// CTRL_xxx Windows signals
#ifdef CTRL_C_EVENT
ADD_INT_MACRO(CTRL_C_EVENT);
#endif
#ifdef CTRL_BREAK_EVENT
ADD_INT_MACRO(CTRL_BREAK_EVENT);
#endif
return 0;
#undef ADD_INT_MACRO
}
static int
signal_module_exec(PyObject *m)
{
assert(!PyErr_Occurred());
if (signal_add_constants(m) < 0) {
return -1;
}
/* Add some symbolic constants to the module */
PyObject *d = PyModule_GetDict(m);
if (PyDict_SetItemString(d, "SIG_DFL", DefaultHandler) < 0) {
return -1;
}
if (PyDict_SetItemString(d, "SIG_IGN", IgnoreHandler) < 0) {
return -1;
}
#if defined(HAVE_GETITIMER) || defined(HAVE_SETITIMER)
if (PyDict_SetItemString(d, "ItimerError", ItimerError) < 0) {
return -1;
}
#endif
#if defined(HAVE_SIGWAITINFO) || defined(HAVE_SIGTIMEDWAIT)
if (PyModule_AddType(m, &SiginfoType) < 0) {
return -1;
}
#endif
// Get signal handlers
for (int signum = 1; signum < NSIG; signum++) {
void (*c_handler)(int) = PyOS_getsig(signum);
PyObject *func;
if (c_handler == SIG_DFL) {
func = DefaultHandler;
}
else if (c_handler == SIG_IGN) {
func = IgnoreHandler;
}
else {
func = Py_None; // None of our business
}
// If signal_module_exec() is called more than one, we must
// clear the strong reference to the previous function.
Py_XSETREF(Handlers[signum].func, Py_NewRef(func));
}
// Instal Python SIGINT handler which raises KeyboardInterrupt
if (Handlers[SIGINT].func == DefaultHandler) {
PyObject *int_handler = PyMapping_GetItemString(d, "default_int_handler");
if (!int_handler) {
return -1;
}
Py_SETREF(Handlers[SIGINT].func, int_handler);
PyOS_setsig(SIGINT, signal_handler);
}
assert(!PyErr_Occurred());
return 0;
}
static PyModuleDef_Slot signal_slots[] = {
{Py_mod_exec, signal_module_exec},
{0, NULL}
};
static struct PyModuleDef signal_module = {
PyModuleDef_HEAD_INIT,
"_signal",
.m_doc = module_doc,
.m_size = 0,
.m_methods = signal_methods,
.m_slots = signal_slots,
};
PyMODINIT_FUNC
PyInit__signal(void)
{
return PyModuleDef_Init(&signal_module);
}
void
_PySignal_Fini(void)
{
// Restore default signals and clear handlers
for (int signum = 1; signum < NSIG; signum++) {
PyObject *func = Handlers[signum].func;
_Py_atomic_store_relaxed(&Handlers[signum].tripped, 0);
Handlers[signum].func = NULL;
if (func != NULL
&& func != Py_None
&& func != DefaultHandler
&& func != IgnoreHandler)
{
PyOS_setsig(signum, SIG_DFL);
}
Py_XDECREF(func);
}
#ifdef MS_WINDOWS
if (sigint_event != NULL) {
CloseHandle(sigint_event);
sigint_event = NULL;
}
#endif
Py_CLEAR(DefaultHandler);
Py_CLEAR(IgnoreHandler);
#if defined(HAVE_GETITIMER) || defined(HAVE_SETITIMER)
Py_CLEAR(ItimerError);
#endif
}
/* Declared in pyerrors.h */
int
PyErr_CheckSignals(void)
{
PyThreadState *tstate = _PyThreadState_GET();
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
return 0;
}
return _PyErr_CheckSignalsTstate(tstate);
}
/* Declared in cpython/pyerrors.h */
int
_PyErr_CheckSignalsTstate(PyThreadState *tstate)
{
if (!_Py_atomic_load(&is_tripped)) {
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);
PyObject *frame = (PyObject *)tstate->frame;
if (!frame) {
frame = Py_None;
}
for (int i = 1; i < NSIG; i++) {
if (!_Py_atomic_load_relaxed(&Handlers[i].tripped)) {
continue;
}
_Py_atomic_store_relaxed(&Handlers[i].tripped, 0);
/* Signal handlers can be modified while a signal is received,
* and therefore the fact that trip_signal() or PyErr_SetInterrupt()
* was called doesn't guarantee that there is still a Python
* signal handler for it by the time PyErr_CheckSignals() is called
* (see bpo-43406).
*/
PyObject *func = Handlers[i].func;
if (func == NULL || func == Py_None || func == IgnoreHandler ||
func == DefaultHandler) {
/* No Python signal handler due to aforementioned race condition.
* We can't call raise() as it would break the assumption
* that PyErr_SetInterrupt() only *simulates* an incoming
* signal (i.e. it will never kill the process).
* We also don't want to interrupt user code with a cryptic
* asynchronous exception, so instead just write out an
* unraisable error.
*/
PyErr_Format(PyExc_OSError,
"Signal %i ignored due to race condition",
i);
PyErr_WriteUnraisable(Py_None);
continue;
}
PyObject *arglist = Py_BuildValue("(iO)", i, frame);
PyObject *result;
if (arglist) {
result = _PyObject_Call(tstate, func, arglist, NULL);
Py_DECREF(arglist);
}
else {
result = NULL;
}
if (!result) {
/* On error, re-schedule a call to _PyErr_CheckSignalsTstate() */
_Py_atomic_store(&is_tripped, 1);
return -1;
}
Py_DECREF(result);
}
return 0;
}
int
_PyErr_CheckSignals(void)
{
PyThreadState *tstate = _PyThreadState_GET();
return _PyErr_CheckSignalsTstate(tstate);
}
/* Simulate the effect of a signal.SIGINT signal arriving. The next time
PyErr_CheckSignals is called, the Python SIGINT signal handler will be
raised.
Missing signal handler for the SIGINT signal is silently ignored. */
void
PyErr_SetInterrupt(void)
{
if ((Handlers[SIGINT].func != IgnoreHandler) &&
(Handlers[SIGINT].func != DefaultHandler)) {
trip_signal(SIGINT);
}
}
static int
signal_install_handlers(void)
{
#ifdef SIGPIPE
PyOS_setsig(SIGPIPE, SIG_IGN);
#endif
#ifdef SIGXFZ
PyOS_setsig(SIGXFZ, SIG_IGN);
#endif
#ifdef SIGXFSZ
PyOS_setsig(SIGXFSZ, SIG_IGN);
#endif
// Import _signal to install the Python SIGINT handler
PyObject *module = PyImport_ImportModule("_signal");
if (!module) {
return -1;
}
Py_DECREF(module);
return 0;
}
/* Restore signals that the interpreter has called SIG_IGN on to SIG_DFL.
*
* All of the code in this function must only use async-signal-safe functions,
* listed at `man 7 signal` or
* http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html.
*
* If this function is updated, update also _posix_spawn() of subprocess.py.
*/
void
_Py_RestoreSignals(void)
{
#ifdef SIGPIPE
PyOS_setsig(SIGPIPE, SIG_DFL);
#endif
#ifdef SIGXFZ
PyOS_setsig(SIGXFZ, SIG_DFL);
#endif
#ifdef SIGXFSZ
PyOS_setsig(SIGXFSZ, SIG_DFL);
#endif
}
int
_PySignal_Init(int install_signal_handlers)
{
DefaultHandler = PyLong_FromVoidPtr((void *)SIG_DFL);
if (!DefaultHandler) {
return -1;
}
IgnoreHandler = PyLong_FromVoidPtr((void *)SIG_IGN);
if (!IgnoreHandler) {
return -1;
}
#if defined(HAVE_GETITIMER) || defined(HAVE_SETITIMER)
ItimerError = PyErr_NewException("signal.ItimerError",
PyExc_OSError, NULL);
if (!ItimerError) {
return -1;
}
#endif
#ifdef MS_WINDOWS
/* Create manual-reset event, initially unset */
sigint_event = CreateEvent(NULL, TRUE, FALSE, FALSE);
if (sigint_event == NULL) {
PyErr_SetFromWindowsErr(0);
return -1;
}
#endif
#if defined(HAVE_SIGWAITINFO) || defined(HAVE_SIGTIMEDWAIT)
if (SiginfoType.tp_name == NULL) {
if (PyStructSequence_InitType2(&SiginfoType, &struct_siginfo_desc) < 0) {
return -1;
}
}
#endif
for (int signum = 1; signum < NSIG; signum++) {
_Py_atomic_store_relaxed(&Handlers[signum].tripped, 0);
}
if (install_signal_handlers) {
if (signal_install_handlers() < 0) {
return -1;
}
}
return 0;
}
// The caller doesn't have to hold the GIL
int
_PyOS_InterruptOccurred(PyThreadState *tstate)
{
_Py_EnsureTstateNotNULL(tstate);
if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
return 0;
}
if (!_Py_atomic_load_relaxed(&Handlers[SIGINT].tripped)) {
return 0;
}
_Py_atomic_store_relaxed(&Handlers[SIGINT].tripped, 0);
return 1;
}
// The caller must to hold the GIL
int
PyOS_InterruptOccurred(void)
{
PyThreadState *tstate = _PyThreadState_GET();
return _PyOS_InterruptOccurred(tstate);
}
#ifdef HAVE_FORK
static void
_clear_pending_signals(void)
{
if (!_Py_atomic_load(&is_tripped)) {
return;
}
_Py_atomic_store(&is_tripped, 0);
for (int 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();
}
#endif /* HAVE_FORK */
int
_PyOS_IsMainThread(void)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
return _Py_ThreadCanHandleSignals(interp);
}
#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
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