Merge pull request #270 from federicotdn/master

Allow Screen class to set signal handlers using a function provided by the event loop

2 files changed, 80 insertions, 6 deletions

diff --git a/urwid/main_loop.py b/urwid/main_loop.py
index 442c27d..3d18c52 100755
--- a/urwid/main_loop.py
+++ b/urwid/main_loop.py
@@ -27,6 +27,7 @@ import time
 import heapq
 import select
 import os
+import signal
 from functools import wraps
 from itertools import count
 from weakref import WeakKeyDictionary
@@ -129,6 +130,11 @@ class MainLoop(object):
             event_loop = SelectEventLoop()
         self.event_loop = event_loop
 
+        if hasattr(self.screen, 'signal_handler_setter'):
+            # Tell the screen what function it must use to set
+            # signal handlers
+            self.screen.signal_handler_setter = self.event_loop.set_signal_handler
+
         self._watch_pipes = {}
 
     def _set_widget(self, widget):
@@ -645,6 +651,12 @@ class SelectEventLoop(object):
             return True
         return False
 
+    def set_signal_handler(self, signum, handler):
+        """
+        Proxy function to signal.signal()
+        """
+        return signal.signal(signum, handler)
+
     def enter_idle(self, callback):
         """
         Add a callback for entering idle.
@@ -740,6 +752,7 @@ class GLibEventLoop(object):
         self._loop = GLib.MainLoop()
         self._exc_info = None
         self._enable_glib_idle()
+        self._signal_handlers = {}
 
     def alarm(self, seconds, callback):
         """
@@ -760,6 +773,40 @@ class GLibEventLoop(object):
         self._alarms.append(fd)
         return (fd, callback)
 
+    def set_signal_handler(self, signum, handler):
+        """
+        Sets a handler for a specified signal.  This method's behaviour
+        method tries to imitate the signal() function from the signal
+        module.
+        """
+        glib_signals = [
+            signal.SIGHUP,
+            signal.SIGINT,
+            signal.SIGTERM,
+            signal.SIGUSR1,
+            signal.SIGUSR2,
+            signal.SIGWINCH
+        ]
+
+        if signum not in glib_signals:
+            # The GLib event loop supports only the signals listed above
+            return
+
+        if signum in self._signal_handlers:
+            self.GLib.source_remove(self._signal_handlers.pop(signum))
+
+        if handler == signal.SIG_IGN:
+            handler = lambda x: None
+        elif handler == signal.SIG_DFL:
+            return
+
+        def final_handler(signal_number):
+            handler(signal_number)
+            return self.GLib.SOURCE_CONTINUE
+
+        source = self.GLib.unix_signal_add(self.GLib.PRIORITY_DEFAULT, signum, final_handler, signum)
+        self._signal_handlers[signum] = source
+
     def remove_alarm(self, handle):
         """
         Remove an alarm.
@@ -987,6 +1034,12 @@ class TornadoEventLoop(object):
             self._ioloop.remove_handler(fd)
             return True
 
+    def set_signal_handler(self, signum, handler):
+        """
+        Proxy function to signal.signal()
+        """
+        return signal.signal(signum, handler)
+
     def enter_idle(self, callback):
         self._max_idle_handle += 1
         handle   = self._max_idle_handle
@@ -1132,6 +1185,12 @@ class TwistedEventLoop(object):
             return True
         return False
 
+    def set_signal_handler(self, signum, handler):
+        """
+        Proxy function to signal.signal()
+        """
+        return signal.signal(signum, handler)
+
     def enter_idle(self, callback):
         """
         Add a callback for entering idle.
@@ -1279,6 +1338,12 @@ class AsyncioEventLoop(object):
         """
         return self._loop.remove_reader(handle)
 
+    def set_signal_handler(self, signum, handler):
+        """
+        Proxy function to signal.signal()
+        """
+        return signal.signal(signum, handler)
+
     def enter_idle(self, callback):
         """
         Add a callback for entering idle.
diff --git a/urwid/raw_display.py b/urwid/raw_display.py
index 365e311..626891d 100644
--- a/urwid/raw_display.py
+++ b/urwid/raw_display.py
@@ -81,6 +81,7 @@ class Screen(BaseScreen, RealTerminal):
         self.back_color_erase = not self.term.startswith("screen")
         self.register_palette_entry( None, 'default','default')
         self._next_timeout = None
+        self.signal_handler_setter = signal.signal
 
         # Our connections to the world
         self._term_output_file = output
@@ -121,13 +122,21 @@ class Screen(BaseScreen, RealTerminal):
         self.complete_wait = complete_wait
         self.resize_wait = resize_wait
 
-    def _sigwinch_handler(self, signum, frame):
+    def _sigwinch_handler(self, signum, frame=None):
+        """
+        frame -- will always be None when the GLib event loop is being used.
+        """
+
         if not self._resized:
             os.write(self._resize_pipe_wr, B('R'))
         self._resized = True
         self.screen_buf = None
 
-    def _sigcont_handler(self, signum, frame):
+    def _sigcont_handler(self, signum, frame=None):
+        """
+        frame -- will always be None when the GLib event loop is being used.
+        """
+
         self.stop()
         self.start()
         self._sigwinch_handler(None, None)
@@ -140,8 +149,8 @@ class Screen(BaseScreen, RealTerminal):
         Override this function to call from main thread in threaded
         applications.
         """
-        signal.signal(signal.SIGWINCH, self._sigwinch_handler)
-        signal.signal(signal.SIGCONT, self._sigcont_handler)
+        self.signal_handler_setter(signal.SIGWINCH, self._sigwinch_handler)
+        self.signal_handler_setter(signal.SIGCONT, self._sigcont_handler)
 
     def signal_restore(self):
         """
@@ -151,8 +160,8 @@ class Screen(BaseScreen, RealTerminal):
         Override this function to call from main thread in threaded
         applications.
         """
-        signal.signal(signal.SIGCONT, signal.SIG_DFL)
-        signal.signal(signal.SIGWINCH, signal.SIG_DFL)
+        self.signal_handler_setter(signal.SIGCONT, signal.SIG_DFL)
+        self.signal_handler_setter(signal.SIGWINCH, signal.SIG_DFL)
 
     def set_mouse_tracking(self, enable=True):
         """