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Michael W. Hudson
committed
Take out my (long since disabled) POSIX signal mask handling code.
I'm not going to have the time or energy to get this working x-platform -- anyone who does is welcome to the code!
1 parent 94afd30 commit 43ed43b

5 files changed

Lines changed: 6 additions & 289 deletions

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‎Doc/lib/libsignal.tex‎

Lines changed: 4 additions & 50 deletions
Original file line numberDiff line numberDiff line change
@@ -17,6 +17,10 @@ \section{\module{signal} ---
1717
the handler for \constant{SIGCHLD}, which follows the underlying
1818
implementation.
1919

20+
\item
21+
There is no way to ``block'' signals temporarily from critical
22+
sections (since this is not supported by all \UNIX{} flavors).
23+
2024
\item
2125
Although Python signal handlers are called asynchronously as far as
2226
the Python user is concerned, they can only occur between the
@@ -88,16 +92,6 @@ \section{\module{signal} ---
8892
One more than the number of the highest signal number.
8993
\end{datadesc}
9094

91-
\begin{datadesc}{SIG_BLOCK}
92-
\end{datadesc}
93-
\begin{datadesc}{SIG_UNBLOCK}
94-
\end{datadesc}
95-
\begin{datadesc}{SIG_SETMASK}
96-
These constants are for use as the first parameter of the
97-
\function{sigprocmask} function described below.
98-
\end{datadesc}
99-
100-
10195
The \module{signal} module defines the following functions:
10296

10397
\begin{funcdesc}{alarm}{time}
@@ -150,46 +144,6 @@ \section{\module{signal} ---
150144
\obindex{frame}
151145
\end{funcdesc}
152146

153-
The following functions are supported if your platform does. Most
154-
modern \UNIX-alikes now do.
155-
156-
\begin{funcdesc}{sigpending}{}
157-
Return the set of pending signals, i.e. a list containing the
158-
numbers of those signals that have been raised while blocked.
159-
\versionadded{2.3}
160-
\end{funcdesc}
161-
162-
\begin{funcdesc}{sigprocmask}{how, sigset}
163-
Change the list of currently blocked signals. The parameter
164-
\var{how} should be one of \constant{SIG_BLOCK},
165-
\constant{SIG_UNBLOCK} or \constant{SIG_SETMASK} and \var{sigset}
166-
should be a sequence of signal numbers. The behaviour of the call
167-
depends on the value of \var{how}:
168-
169-
\begin{tableii}{l|l}{textrm}{Value of \var{how}}{Behaviour of call}
170-
\lineii{\constant{SIG_BLOCK}}
171-
{The set of blocked signals is the union of the current set
172-
and \var{sigset}.}
173-
\lineii{\constant{SIG_UNBLOCK}}
174-
{The signals in \var{sigset} are removed from the current
175-
set of blocked signals. It is legal to attempt to unblock
176-
a signal which is not blocked.}
177-
\lineii{\constant{SIG_SETMASK}}
178-
{The set of blocked signals is set to the \var{sigset}.}
179-
\end{tableii}
180-
181-
A list contating the numbers of the previously blocked signals is
182-
returned.
183-
\versionadded{2.3}
184-
\end{funcdesc}
185-
186-
\begin{funcdesc}{sigsuspend}{sigset}
187-
Temporarily replace the signal mask with \var{sigset} (which should
188-
be a sequnce of signal numbers) and suspend the process until a
189-
signal is received.
190-
\versionadded{2.3}
191-
\end{funcdesc}
192-
193147
\subsection{Example}
194148
\nodename{Signal Example}
195149

‎Doc/whatsnew/whatsnew23.tex‎

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1485,10 +1485,8 @@ \section{New, Improved, and Deprecated Modules}
14851485
location.
14861486

14871487
\item Support for more advanced POSIX signal handling was added
1488-
to the \module{signal} module by adding the \function{sigpending},
1489-
\function{sigprocmask} and \function{sigsuspend} functions where supported
1490-
by the platform. These functions make it possible to avoid some previously
1491-
unavoidable race conditions with signal handling.
1488+
to the \module{signal} but then removed again as it proved impossible
1489+
to make it work reliably across platforms.
14921490

14931491
\item The \module{socket} module now supports timeouts. You
14941492
can call the \method{settimeout(\var{t})} method on a socket object to

‎Lib/test/test_signal.py‎

Lines changed: 0 additions & 61 deletions
Original file line numberDiff line numberDiff line change
@@ -64,64 +64,3 @@ def handlerB(*args):
6464
if verbose:
6565
print "KeyboardInterrupt (assume the alarm() went off)"
6666

67-
68-
if hasattr(signal, "sigprocmask"):
69-
class HupDelivered(Exception):
70-
pass
71-
def hup(signum, frame):
72-
raise HupDelivered
73-
def hup2(signum, frame):
74-
signal.signal(signal.SIGHUP, hup)
75-
return
76-
signal.signal(signal.SIGHUP, hup)
77-
78-
if verbose:
79-
print "blocking SIGHUP"
80-
81-
defaultmask = signal.sigprocmask(signal.SIG_BLOCK, [signal.SIGHUP])
82-
83-
if verbose:
84-
print "sending SIGHUP"
85-
86-
try:
87-
os.kill(pid, signal.SIGHUP)
88-
except HupDelivered:
89-
raise TestFailed, "HUP not blocked"
90-
91-
if signal.SIGHUP not in signal.sigpending():
92-
raise TestFailed, "HUP not pending"
93-
94-
if verbose:
95-
print "unblocking SIGHUP"
96-
97-
try:
98-
signal.sigprocmask(signal.SIG_UNBLOCK, [signal.SIGHUP])
99-
except HupDelivered:
100-
pass
101-
else:
102-
raise TestFailed, "HUP not delivered"
103-
104-
if verbose:
105-
print "testing sigsuspend"
106-
107-
signal.sigprocmask(signal.SIG_BLOCK, [signal.SIGHUP])
108-
signal.signal(signal.SIGHUP, hup2)
109-
110-
if not os.fork():
111-
time.sleep(2)
112-
os.kill(pid, signal.SIGHUP)
113-
time.sleep(2)
114-
os.kill(pid, signal.SIGHUP)
115-
os._exit(0)
116-
else:
117-
try:
118-
signal.sigsuspend(defaultmask)
119-
except:
120-
raise TestFailed, "sigsuspend erroneously raised"
121-
122-
try:
123-
signal.sigsuspend(defaultmask)
124-
except HupDelivered:
125-
pass
126-
else:
127-
raise TestFailed, "sigsupsend didn't raise"

‎Misc/NEWS‎

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -982,9 +982,6 @@ Extension modules
982982
of sizeof(int)!=sizeof(long)!=sizeof(void*) is delayed until dl.open
983983
is called.
984984

985-
- signal.sigpending, signal.sigprocmask and signal.sigsuspend have
986-
been added where available.
987-
988985
- The sys module acquired a new attribute, api_version, which evaluates
989986
to the value of the PYTHON_API_VERSION macro with which the
990987
interpreter was compiled.

‎Modules/signalmodule.c‎

Lines changed: 0 additions & 171 deletions
Original file line numberDiff line numberDiff line change
@@ -269,153 +269,6 @@ SIG_DFL -- if the default action for the signal is in effect\n\
269269
None -- if an unknown handler is in effect\n\
270270
anything else -- the callable Python object used as a handler");
271271

272-
#ifdef HAVE_SIGPROCMASK /* we assume that having SIGPROCMASK is enough
273-
to guarantee full POSIX signal handling */
274-
/* returns 0 for success, <0 for failure (with exception set) */
275-
static int
276-
_signal_list_to_sigset(PyObject* seq, sigset_t* set, char* mesg)
277-
{
278-
int i, len, val;
279-
280-
seq = PySequence_Fast(seq, mesg);
281-
if (!seq)
282-
return -1;
283-
284-
len = PySequence_Fast_GET_SIZE(seq);
285-
286-
sigemptyset(set);
287-
288-
for (i = 0; i < len; i++) {
289-
val = PyInt_AsLong(PySequence_Fast_GET_ITEM(seq, i));
290-
if (val == -1 && PyErr_Occurred()) {
291-
Py_DECREF(seq);
292-
return -1;
293-
}
294-
if (sigaddset(set, val) < 0) {
295-
Py_DECREF(seq);
296-
PyErr_SetFromErrno(PyExc_ValueError);
297-
return -1;
298-
}
299-
}
300-
301-
Py_DECREF(seq);
302-
return 0;
303-
}
304-
305-
static PyObject*
306-
_signal_sigset_to_list(sigset_t* set)
307-
{
308-
PyObject* ret;
309-
PyObject* ob;
310-
int i;
311-
312-
ret = PyList_New(0);
313-
if (!ret)
314-
return NULL;
315-
316-
for (i = 1; i < NSIG; i++) {
317-
if (sigismember(set, i)) {
318-
ob = PyInt_FromLong(i);
319-
if (!ob) {
320-
Py_DECREF(ret);
321-
return NULL;
322-
}
323-
PyList_Append(ret, ob);
324-
Py_DECREF(ob);
325-
}
326-
}
327-
328-
return ret;
329-
}
330-
331-
static PyObject*
332-
signal_sigprocmask(PyObject* self, PyObject* args)
333-
{
334-
int how;
335-
sigset_t newset, oldset;
336-
PyObject* seq;
337-
338-
if (!PyArg_ParseTuple(args, "iO", &how, &seq))
339-
return NULL;
340-
341-
if (_signal_list_to_sigset(seq, &newset,
342-
"sigprocmask requires a sequence") < 0)
343-
return NULL;
344-
345-
if (sigprocmask(how, &newset, &oldset) < 0) {
346-
return PyErr_SetFromErrno(PyExc_ValueError);
347-
}
348-
349-
if (PyErr_CheckSignals())
350-
return NULL;
351-
352-
return _signal_sigset_to_list(&oldset);
353-
}
354-
355-
PyDoc_STRVAR(sigprocmask_doc,
356-
"sigprocmask(how, sigset) -> sigset\n\
357-
\n\
358-
Change the list of currently blocked signals. The parameter how should be\n\
359-
one of SIG_BLOCK, SIG_UNBLOCK or SIG_SETMASK and sigset should be a\n\
360-
sequence of signal numbers. The behaviour of the call depends on the value\n\
361-
of how:\n\
362-
\n\
363-
SIG_BLOCK\n\
364-
The set of blocked signals is the union of the current set and the\n\
365-
sigset argument.\n\
366-
SIG_UNBLOCK\n\
367-
The signals in sigset are removed from the current set of blocked\n\
368-
signals. It is legal to attempt to unblock a signal which is not\n\
369-
blocked.\n\
370-
SIG_SETMASK\n\
371-
The set of blocked signals is set to the argument set.\n\
372-
\n\
373-
A list contating the numbers of the previously blocked signals is returned.");
374-
375-
static PyObject*
376-
signal_sigpending(PyObject* self)
377-
{
378-
sigset_t set;
379-
380-
if (sigpending(&set) < 0) {
381-
return PyErr_SetFromErrno(PyExc_ValueError);
382-
}
383-
384-
return _signal_sigset_to_list(&set);
385-
}
386-
387-
PyDoc_STRVAR(sigpending_doc,
388-
"sigpending() -> sigset\n\
389-
\n\
390-
Return the set of pending signals, i.e. a list containing the numbers of\n\
391-
those signals that have been raised while blocked.");
392-
393-
static PyObject*
394-
signal_sigsuspend(PyObject* self, PyObject* arg)
395-
{
396-
sigset_t set;
397-
398-
if (_signal_list_to_sigset(arg, &set,
399-
"sigsuspend requires a sequence") < 0)
400-
return NULL;
401-
402-
Py_BEGIN_ALLOW_THREADS
403-
sigsuspend(&set);
404-
Py_END_ALLOW_THREADS
405-
406-
if (PyErr_CheckSignals())
407-
return NULL;
408-
409-
Py_INCREF(Py_None);
410-
return Py_None;
411-
}
412-
413-
PyDoc_STRVAR(sigsuspend_doc,
414-
"sigsuspend(sigset) -> None\n\
415-
\n\
416-
Temporarily replace the signal mask with sigset (which should be a sequence\n\
417-
of signal numbers) and suspend the process until a signal is received.");
418-
#endif
419272

420273
/* List of functions defined in the module */
421274
static PyMethodDef signal_methods[] = {
@@ -430,14 +283,6 @@ static PyMethodDef signal_methods[] = {
430283
#endif
431284
{"default_int_handler", signal_default_int_handler,
432285
METH_VARARGS, default_int_handler_doc},
433-
#ifdef HAVE_SIGPROCMASK
434-
{"sigprocmask", (PyCFunction)signal_sigprocmask,
435-
METH_VARARGS, sigprocmask_doc},
436-
{"sigpending", (PyCFunction)signal_sigpending,
437-
METH_NOARGS, sigpending_doc},
438-
{"sigsuspend", (PyCFunction)signal_sigsuspend,
439-
METH_O, sigsuspend_doc},
440-
#endif
441286
{NULL, NULL} /* sentinel */
442287
};
443288

@@ -453,10 +298,6 @@ getsignal() -- get the signal action for a given signal\n\
453298
pause() -- wait until a signal arrives [Unix only]\n\
454299
default_int_handler() -- default SIGINT handler\n\
455300
\n\
456-
sigpending() |\n\
457-
sigprocmask() |-- posix signal mask handling [Unix only]\n\
458-
sigsuspend() |\n\
459-
\n\
460301
Constants:\n\
461302
\n\
462303
SIG_DFL -- used to refer to the system default handler\n\
@@ -705,18 +546,6 @@ initsignal(void)
705546
PyDict_SetItemString(d, "SIGINFO", x);
706547
Py_XDECREF(x);
707548
#endif
708-
#ifdef HAVE_SIGPROCMASK
709-
x = PyInt_FromLong(SIG_BLOCK);
710-
PyDict_SetItemString(d, "SIG_BLOCK", x);
711-
Py_XDECREF(x);
712-
x = PyInt_FromLong(SIG_UNBLOCK);
713-
PyDict_SetItemString(d, "SIG_UNBLOCK", x);
714-
Py_XDECREF(x);
715-
x = PyInt_FromLong(SIG_SETMASK);
716-
PyDict_SetItemString(d, "SIG_SETMASK", x);
717-
Py_XDECREF(x);
718-
#endif
719-
720549
if (!PyErr_Occurred())
721550
return;
722551

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