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cpython/Modules/signalmodule.c
Eric Snow fdf282d609
bpo-35423: Stop using the "pending calls" machinery for signals. (gh-10972) 
This change separates the signal handling trigger in the eval loop from the "pending calls" machinery. There is no semantic change and the difference in performance is insignificant.

The change makes both components less confusing. It also eliminates the risk of changes to the pending calls affecting signal handling. This is particularly relevant for some upcoming pending calls changes I have in the works.
2019-01-11 14:26:55 -07:00

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