mirror of https://github.com/python/cpython
Patch #1583 by Adam Olsen.
This adds signal.set_wakeup_fd(fd) which sets a file descriptor to which a zero byte will be written whenever a C exception handler runs. I added a simple C API as well, PySignal_SetWakeupFd(fd).
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@ -375,6 +375,16 @@ is a separate error indicator for each thread.
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.. % thread.interrupt_main() (used from IDLE), so it's still needed.
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.. cfunction:: int PySignal_SetWakeupFd(int fd)
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This utility function specifies a file descriptor to which a ``'\0'`` byte will
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be written whenever a signal is received. It returns the previous such file
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descriptor. The value ``-1`` disables the feature; this is the initial state.
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This is equivalent to :func:`signal.set_wakeup_fd` in Python, but without any
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error checking. *fd* should be a valid file descriptor. The function should
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only be called from the main thread.
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.. cfunction:: PyObject* PyErr_NewException(char *name, PyObject *base, PyObject *dict)
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This utility function creates and returns a new exception object. The *name*
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@ -110,6 +110,20 @@ The :mod:`signal` module defines the following functions:
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:manpage:`signal(2)`.)
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.. function:: set_wakeup_fd(fd)
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Set the wakeup fd to *fd*. When a signal is received, a ``'\0'`` byte is
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written to the fd. This can be used by a library to wakeup a poll or select
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call, allowing the signal to be fully processed.
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The old wakeup fd is returned. *fd* must be non-blocking. It is up to the
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library to remove any bytes before calling poll or select again.
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When threads are enabled, this function can only be called from the main thread;
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attempting to call it from other threads will cause a :exc:`ValueError`
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exception to be raised.
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.. function:: signal(signalnum, handler)
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Set the handler for signal *signalnum* to the function *handler*. *handler* can
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@ -238,6 +238,9 @@ PyAPI_FUNC(int) PyErr_WarnExplicit(PyObject *, const char *,
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PyAPI_FUNC(int) PyErr_CheckSignals(void);
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PyAPI_FUNC(void) PyErr_SetInterrupt(void);
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/* In signalmodule.c */
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int PySignal_SetWakeupFd(int fd);
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/* Support for adding program text to SyntaxErrors */
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PyAPI_FUNC(void) PyErr_SyntaxLocation(const char *, int);
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PyAPI_FUNC(PyObject *) PyErr_ProgramText(const char *, int);
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@ -165,12 +165,59 @@ class BasicSignalTests(unittest.TestCase):
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self.assertRaises(TypeError, signal.signal,
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signal.SIGUSR1, None)
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class WakeupSignalTests(unittest.TestCase):
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TIMEOUT_FULL = 10
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TIMEOUT_HALF = 5
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def test_wakeup_fd_early(self):
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import select
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signal.alarm(1)
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before_time = time.time()
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# We attempt to get a signal during the sleep,
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# before select is called
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time.sleep(self.TIMEOUT_FULL)
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mid_time = time.time()
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self.assert_(mid_time - before_time < self.TIMEOUT_HALF)
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select.select([self.read], [], [], self.TIMEOUT_FULL)
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after_time = time.time()
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self.assert_(after_time - mid_time < self.TIMEOUT_HALF)
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def test_wakeup_fd_during(self):
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import select
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signal.alarm(1)
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before_time = time.time()
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# We attempt to get a signal during the select call
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self.assertRaises(select.error, select.select,
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[self.read], [], [], self.TIMEOUT_FULL)
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after_time = time.time()
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self.assert_(after_time - before_time < self.TIMEOUT_HALF)
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def setUp(self):
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import fcntl
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self.alrm = signal.signal(signal.SIGALRM, lambda x,y:None)
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self.read, self.write = os.pipe()
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flags = fcntl.fcntl(self.write, fcntl.F_GETFL, 0)
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flags = flags | os.O_NONBLOCK
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fcntl.fcntl(self.write, fcntl.F_SETFL, flags)
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self.old_wakeup = signal.set_wakeup_fd(self.write)
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def tearDown(self):
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signal.set_wakeup_fd(self.old_wakeup)
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os.close(self.read)
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os.close(self.write)
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signal.signal(signal.SIGALRM, self.alrm)
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def test_main():
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if sys.platform[:3] in ('win', 'os2') or sys.platform == 'riscos':
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raise test_support.TestSkipped("Can't test signal on %s" % \
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sys.platform)
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test_support.run_unittest(BasicSignalTests, InterProcessSignalTests)
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test_support.run_unittest(BasicSignalTests, InterProcessSignalTests,
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WakeupSignalTests)
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if __name__ == "__main__":
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@ -12,6 +12,8 @@
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#include <signal.h>
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#include <sys/stat.h>
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#ifndef SIG_ERR
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#define SIG_ERR ((PyOS_sighandler_t)(-1))
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#endif
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@ -75,6 +77,8 @@ static struct {
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PyObject *func;
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} Handlers[NSIG];
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static sig_atomic_t wakeup_fd = -1;
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/* Speed up sigcheck() when none tripped */
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static volatile sig_atomic_t is_tripped = 0;
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@ -128,6 +132,8 @@ signal_handler(int sig_num)
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cleared in PyErr_CheckSignals() before .tripped. */
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is_tripped = 1;
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Py_AddPendingCall(checksignals_witharg, NULL);
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if (wakeup_fd != -1)
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write(wakeup_fd, "\0", 1);
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#ifdef WITH_THREAD
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}
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#endif
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@ -267,6 +273,50 @@ None -- if an unknown handler is in effect\n\
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anything else -- the callable Python object used as a handler");
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static PyObject *
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signal_set_wakeup_fd(PyObject *self, PyObject *args)
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{
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struct stat buf;
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int fd, old_fd;
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if (!PyArg_ParseTuple(args, "i:set_wakeup_fd", &fd))
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return NULL;
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#ifdef WITH_THREAD
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if (PyThread_get_thread_ident() != main_thread) {
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PyErr_SetString(PyExc_ValueError,
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"set_wakeup_fd only works in main thread");
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return NULL;
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}
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#endif
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if (fd != -1 && fstat(fd, &buf) != 0) {
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PyErr_SetString(PyExc_ValueError, "invalid fd");
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return NULL;
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}
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old_fd = wakeup_fd;
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wakeup_fd = fd;
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return PyLong_FromLong(old_fd);
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}
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PyDoc_STRVAR(set_wakeup_fd_doc,
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"set_wakeup_fd(fd) -> fd\n\
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\n\
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Sets the fd to be written to (with '\\0') when a signal\n\
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comes in. A library can use this to wakeup select or poll.\n\
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The previous fd is returned.\n\
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\n\
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The fd must be non-blocking.");
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/* C API for the same, without all the error checking */
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int
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PySignal_SetWakeupFd(int fd)
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{
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int old_fd = wakeup_fd;
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if (fd < 0)
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fd = -1;
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wakeup_fd = fd;
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return old_fd;
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}
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/* List of functions defined in the module */
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static PyMethodDef signal_methods[] = {
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#ifdef HAVE_ALARM
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@ -274,11 +324,12 @@ static PyMethodDef signal_methods[] = {
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#endif
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{"signal", signal_signal, METH_VARARGS, signal_doc},
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{"getsignal", signal_getsignal, METH_VARARGS, getsignal_doc},
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{"set_wakeup_fd", signal_set_wakeup_fd, METH_VARARGS, set_wakeup_fd_doc},
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#ifdef HAVE_PAUSE
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{"pause", (PyCFunction)signal_pause,
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METH_NOARGS,pause_doc},
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#endif
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{"default_int_handler", signal_default_int_handler,
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{"default_int_handler", signal_default_int_handler,
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METH_VARARGS, default_int_handler_doc},
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{NULL, NULL} /* sentinel */
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};
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