This is patch
[ 559250 ] more POSIX signal stuff
Adds support (and docs and tests and autoconfery) for posix signal
mask handling -- sigpending, sigprocmask and sigsuspend.
diff --git a/Doc/lib/libsignal.tex b/Doc/lib/libsignal.tex
index e3aa171..3029385 100644
--- a/Doc/lib/libsignal.tex
+++ b/Doc/lib/libsignal.tex
@@ -18,10 +18,6 @@
implementation.
\item
-There is no way to ``block'' signals temporarily from critical
-sections (since this is not supported by all \UNIX{} flavors).
-
-\item
Although Python signal handlers are called asynchronously as far as
the Python user is concerned, they can only occur between the
``atomic'' instructions of the Python interpreter. This means that
@@ -92,6 +88,16 @@
One more than the number of the highest signal number.
\end{datadesc}
+\begin{datadesc}{SIG_BLOCK}
+\end{datadesc}
+\begin{datadesc}{SIG_UNBLOCK}
+\end{datadesc}
+\begin{datadesc}{SIG_SETMASK}
+ These constants are for use as the first parameter of the
+ \function{sigprocmask} function described below.
+\end{datadesc}
+
+
The \module{signal} module defines the following functions:
\begin{funcdesc}{alarm}{time}
@@ -144,6 +150,46 @@
\obindex{frame}
\end{funcdesc}
+The following functions are supported if your platform does. Most
+modern \UNIX-alikes now do.
+
+\begin{funcdesc}{sigpending}{}
+ Return the set of pending signals, i.e. a list containing the
+ numbers of those signals that have been raised while blocked.
+ \versionadded{2.3}
+\end{funcdesc}
+
+\begin{funcdesc}{sigprocmask}{how, sigset}
+ Change the list of currently blocked signals. The parameter
+ \var{how} should be one of \constant{SIG_BLOCK},
+ \constant{SIG_UNBLOCK} or \constant{SIG_SETMASK} and \var{sigset}
+ should be a sequence of signal numbers. The behaviour of the call
+ depends on the value of \var{how}:
+
+ \begin{tableii}{l|l}{textrm}{Value of \var{how}}{Behaviour of call}
+ \lineii{\constant{SIG_BLOCK}}
+ {The set of blocked signals is the union of the current set
+ and \var{sigset}.}
+ \lineii{\constant{SIG_UNBLOCK}}
+ {The signals in \var{sigset} are removed from the current
+ set of blocked signals. It is legal to attempt to unblock
+ a signal which is not blocked.}
+ \lineii{\constant{SIG_SETMASK}}
+ {The set of blocked signals is set to the \var{sigset}.}
+ \end{tableii}
+
+ A list contating the numbers of the previously blocked signals is
+ returned.
+ \versionadded{2.3}
+\end{funcdesc}
+
+\begin{funcdesc}{sigsuspend}{sigset}
+ Temporarily replace the signal mask with \var{sigset} (which should
+ be a sequnce of signal numbers) and suspend the process until a
+ signal is received.
+ \versionadded{2.3}
+\end{funcdesc}
+
\subsection{Example}
\nodename{Signal Example}
diff --git a/Doc/whatsnew/whatsnew23.tex b/Doc/whatsnew/whatsnew23.tex
index cb5d6fd..489452d 100644
--- a/Doc/whatsnew/whatsnew23.tex
+++ b/Doc/whatsnew/whatsnew23.tex
@@ -532,6 +532,12 @@
functions: \function{get_history_item()},
\function{get_current_history_length()}, and \function{redisplay()}.
+\item Support for more advanced POSIX signal handling -- specifically
+the functions \function{sigpending}, \function{sigprocmask} and
+\function{sigsupend}, and depending on platform support -- was added
+to the \module{signal} module. These functions make some previously
+unavoidable race conditions avoidable.
+
\end{itemize}
diff --git a/Lib/test/test_signal.py b/Lib/test/test_signal.py
index 05bdcab..78b90b7 100644
--- a/Lib/test/test_signal.py
+++ b/Lib/test/test_signal.py
@@ -1,8 +1,7 @@
# Test the signal module
-from test_support import verbose, TestSkipped
+from test_support import verbose, TestSkipped, TestFailed
import signal
-import os
-import sys
+import os, sys, time
if sys.platform[:3] in ('win', 'os2') or sys.platform=='riscos':
raise TestSkipped, "Can't test signal on %s" % sys.platform
@@ -64,3 +63,66 @@
except KeyboardInterrupt:
if verbose:
print "KeyboardInterrupt (assume the alarm() went off)"
+
+
+if hasattr(signal, "sigprocmask"):
+ class HupDelivered(Exception):
+ pass
+ def hup(signum, frame):
+ raise HupDelivered
+ def hup2(signum, frame):
+ signal.signal(signal.SIGHUP, hup)
+ return
+ signal.signal(signal.SIGHUP, hup)
+
+ if verbose:
+ print "blocking SIGHUP"
+
+ defaultmask = signal.sigprocmask(signal.SIG_BLOCK, [signal.SIGHUP])
+
+ if verbose:
+ print "sending SIGHUP"
+
+ try:
+ os.kill(pid, signal.SIGHUP)
+ except HupDelivered:
+ raise TestFailed, "HUP not blocked"
+
+ if signal.SIGHUP not in signal.sigpending():
+ raise TestFailed, "HUP not pending"
+
+ if verbose:
+ print "unblocking SIGHUP"
+
+ try:
+ signal.sigprocmask(signal.SIG_UNBLOCK, [signal.SIGHUP])
+ except HupDelivered:
+ pass
+ else:
+ raise TestFailed, "HUP not delivered"
+
+ if verbose:
+ print "testing sigsuspend"
+
+ signal.sigprocmask(signal.SIG_BLOCK, [signal.SIGHUP])
+ signal.signal(signal.SIGHUP, hup2)
+
+ if not os.fork():
+ time.sleep(2)
+ os.kill(pid, signal.SIGHUP)
+ time.sleep(2)
+ os.kill(pid, signal.SIGHUP)
+ os._exit(0)
+ else:
+ try:
+ signal.sigsuspend(defaultmask)
+ except:
+ raise TestFailed, "sigsuspend erroneously raised"
+
+ try:
+ signal.sigsuspend(defaultmask)
+ except HupDelivered:
+ pass
+ else:
+ raise TestFailed, "sigsupsend didn't raise"
+
diff --git a/Misc/NEWS b/Misc/NEWS
index f544af4..85da0d3 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -106,6 +106,9 @@
of sizeof(int)!=sizeof(long)!=sizeof(void*) is delayed until dl.open
is called.
+- signal.sigpending, signal.sigprocmask and signal.sigsuspend have
+ been added where available.
+
Library
- added degree/radian conversion functions to the math module.
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index f6027ab..3cea2dd 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -270,6 +270,153 @@
anything else -- the callable Python object used as a handler\n\
";
+#ifdef HAVE_SIGPROCMASK /* we assume that having SIGPROCMASK is enough
+ to guarantee full POSIX signal handling */
+/* returns 0 for success, <0 for failure (with exception set) */
+static int
+_signal_list_to_sigset(PyObject* seq, sigset_t* set, char* mesg)
+{
+ int i, len, val;
+
+ seq = PySequence_Fast(seq, mesg);
+ if (!seq)
+ return -1;
+
+ len = PySequence_Fast_GET_SIZE(seq);
+
+ sigemptyset(set);
+
+ for (i = 0; i < len; i++) {
+ val = PyInt_AsLong(PySequence_Fast_GET_ITEM(seq, i));
+ if (val == -1 && PyErr_Occurred()) {
+ Py_DECREF(seq);
+ return -1;
+ }
+ if (sigaddset(set, val) < 0) {
+ Py_DECREF(seq);
+ PyErr_SetFromErrno(PyExc_ValueError);
+ return -1;
+ }
+ }
+
+ Py_DECREF(seq);
+ return 0;
+}
+
+static PyObject*
+_signal_sigset_to_list(sigset_t* set)
+{
+ PyObject* ret;
+ PyObject* ob;
+ int i;
+
+ ret = PyList_New(0);
+ if (!ret)
+ return NULL;
+
+ for (i = 1; i < NSIG; i++) {
+ if (sigismember(set, i)) {
+ ob = PyInt_FromLong(i);
+ if (!ob) {
+ Py_DECREF(ret);
+ return NULL;
+ }
+ PyList_Append(ret, ob);
+ Py_DECREF(ob);
+ }
+ }
+
+ return ret;
+}
+
+static PyObject*
+signal_sigprocmask(PyObject* self, PyObject* args)
+{
+ int how;
+ sigset_t newset, oldset;
+ PyObject* seq;
+
+ if (!PyArg_ParseTuple(args, "iO", &how, &seq))
+ return NULL;
+
+ if (_signal_list_to_sigset(seq, &newset,
+ "sigprocmask requires a sequence") < 0)
+ return NULL;
+
+ if (sigprocmask(how, &newset, &oldset) < 0) {
+ return PyErr_SetFromErrno(PyExc_ValueError);
+ }
+
+ if (PyErr_CheckSignals())
+ return NULL;
+
+ return _signal_sigset_to_list(&oldset);
+}
+
+static char sigprocmask_doc[] =
+"sigprocmask(how, sigset) -> sigset\n\
+\n\
+Change the list of currently blocked signals. The parameter how should be\n\
+one of SIG_BLOCK, SIG_UNBLOCK or SIG_SETMASK and sigset should be a\n\
+sequence of signal numbers. The behaviour of the call depends on the value\n\
+of how:\n\
+\n\
+ SIG_BLOCK\n\
+ The set of blocked signals is the union of the current set and the\n\
+ sigset argument.\n\
+ SIG_UNBLOCK\n\
+ The signals in sigset are removed from the current set of blocked\n\
+ signals. It is legal to attempt to unblock a signal which is not\n\
+ blocked.\n\
+ SIG_SETMASK\n\
+ The set of blocked signals is set to the argument set.\n\
+\n\
+A list contating the numbers of the previously blocked signals is returned.";
+
+static PyObject*
+signal_sigpending(PyObject* self)
+{
+ sigset_t set;
+
+ if (sigpending(&set) < 0) {
+ return PyErr_SetFromErrno(PyExc_ValueError);
+ }
+
+ return _signal_sigset_to_list(&set);
+}
+
+static char sigpending_doc[] =
+"sigpending() -> sigset\n\
+\n\
+Return the set of pending signals, i.e. a list containing the numbers of\n\
+those signals that have been raised while blocked.";
+
+static PyObject*
+signal_sigsuspend(PyObject* self, PyObject* arg)
+{
+ sigset_t set;
+
+ if (_signal_list_to_sigset(arg, &set,
+ "sigsuspend requires a sequence") < 0)
+ return NULL;
+
+ Py_BEGIN_ALLOW_THREADS
+ sigsuspend(&set);
+ Py_END_ALLOW_THREADS
+
+ if (PyErr_CheckSignals())
+ return NULL;
+
+ Py_INCREF(Py_None);
+ return Py_None;
+}
+
+static char sigsuspend_doc[] =
+"sigsuspend(sigset) -> None\n\
+\n\
+Temporarily replace the signal mask with sigset (which should be a sequence\n\
+of signal numbers) and suspend the process until a signal is received.";
+#endif
/* List of functions defined in the module */
static PyMethodDef signal_methods[] = {
@@ -284,6 +431,14 @@
#endif
{"default_int_handler", signal_default_int_handler,
METH_VARARGS, default_int_handler_doc},
+#ifdef HAVE_SIGPROCMASK
+ {"sigprocmask", (PyCFunction)signal_sigprocmask,
+ METH_VARARGS, sigprocmask_doc},
+ {"sigpending", (PyCFunction)signal_sigpending,
+ METH_NOARGS, sigpending_doc},
+ {"sigsuspend", (PyCFunction)signal_sigsuspend,
+ METH_O, sigsuspend_doc},
+#endif
{NULL, NULL} /* sentinel */
};
@@ -299,6 +454,10 @@
pause() -- wait until a signal arrives [Unix only]\n\
default_int_handler() -- default SIGINT handler\n\
\n\
+sigpending() |\n\
+sigprocmask() |-- posix signal mask handling [Unix only]\n\
+sigsuspend() |\n\
+\n\
Constants:\n\
\n\
SIG_DFL -- used to refer to the system default handler\n\
@@ -547,6 +706,18 @@
PyDict_SetItemString(d, "SIGINFO", x);
Py_XDECREF(x);
#endif
+#ifdef HAVE_SIGPROCMASK
+ x = PyInt_FromLong(SIG_BLOCK);
+ PyDict_SetItemString(d, "SIG_BLOCK", x);
+ Py_XDECREF(x);
+ x = PyInt_FromLong(SIG_UNBLOCK);
+ PyDict_SetItemString(d, "SIG_UNBLOCK", x);
+ Py_XDECREF(x);
+ x = PyInt_FromLong(SIG_SETMASK);
+ PyDict_SetItemString(d, "SIG_SETMASK", x);
+ Py_XDECREF(x);
+#endif
+
if (!PyErr_Occurred())
return;
diff --git a/configure b/configure
index 21ca48b..aca0410 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
#! /bin/sh
-# From configure.in Revision: 1.316 .
+# From configure.in Revision: 1.317 .
# Guess values for system-dependent variables and create Makefiles.
# Generated by GNU Autoconf 2.53.
#
@@ -11278,6 +11278,7 @@
+
for ac_func in alarm chown chroot clock confstr ctermid ctermid_r execv \
fchdir flock fork fsync fdatasync fpathconf ftime ftruncate \
gai_strerror getgroups getlogin getpeername getpid getpwent getwd \
@@ -11286,8 +11287,8 @@
putenv readlink \
select setegid seteuid setgid setgroups \
setlocale setregid setreuid setsid setpgid setuid setvbuf snprintf \
- sigaction siginterrupt sigrelse strftime strptime symlink sysconf \
- tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
+ sigaction siginterrupt sigprocmask sigrelse strftime strptime symlink \
+ sysconf tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
truncate uname unsetenv waitpid _getpty getpriority
do
as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
diff --git a/configure.in b/configure.in
index dcae3d8..37c6f63 100644
--- a/configure.in
+++ b/configure.in
@@ -1593,8 +1593,8 @@
putenv readlink \
select setegid seteuid setgid setgroups \
setlocale setregid setreuid setsid setpgid setuid setvbuf snprintf \
- sigaction siginterrupt sigrelse strftime strptime symlink sysconf \
- tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
+ sigaction siginterrupt sigprocmask sigrelse strftime strptime symlink \
+ sysconf tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
truncate uname unsetenv waitpid _getpty getpriority)
# check for openpty and forkpty
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 8e96db2..c8fa5af 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -383,6 +383,9 @@
/* Define to 1 if you have the <signal.h> header file. */
#undef HAVE_SIGNAL_H
+/* Define to 1 if you have the `sigprocmask' function. */
+#undef HAVE_SIGPROCMASK
+
/* Define to 1 if you have the `sigrelse' function. */
#undef HAVE_SIGRELSE