Rev 5180: (vila, for gz) Use signal only where available in file:///home/pqm/archives/thelove/bzr/%2Btrunk/

[Canonical.com Patch Queue Manager]

At file:///home/pqm/archives/thelove/bzr/%2Btrunk/

------------------------------------------------------------
revno: 5180 [merge]
revision-id: pqm at pqm.ubuntu.com-20100423134732-e01c947fwuvjwtl2
parent: pqm at pqm.ubuntu.com-20100423111122-a5zc2qm7v9qrcxmf
parent: v.ladeuil+lp at free.fr-20100423115706-92becetyxzu3j147
committer: Canonical.com Patch Queue Manager <pqm at pqm.ubuntu.com>
branch nick: +trunk
timestamp: Fri 2010-04-23 14:47:32 +0100
message:
  (vila, for gz) Use signal only where available
modified:
  bzrlib/osutils.py              osutils.py-20050309040759-eeaff12fbf77ac86
=== modified file 'bzrlib/osutils.py'
--- a/bzrlib/osutils.py	2010-04-14 06:47:18 +0000
+++ b/bzrlib/osutils.py	2010-04-23 09:28:29 +0000
@@ -39,7 +39,6 @@
 from shutil import (
     rmtree,
     )
-import signal
 import socket
 import subprocess
 import tempfile
@@ -1366,7 +1365,12 @@
         platform or Python version.
     """
     try:
+        import signal
         siginterrupt = signal.siginterrupt
+    except ImportError:
+        # This python implementation doesn't provide signal support, hence no
+        # handler exists
+        return None
     except AttributeError:
         # siginterrupt doesn't exist on this platform, or for this version
         # of Python.
@@ -1483,18 +1487,20 @@
 
 
 _registered_sigwinch = False
-
 def watch_sigwinch():
-    """Register for SIGWINCH, once and only once."""
+    """Register for SIGWINCH, once and only once.
+
+    Do nothing if the signal module is not available.
+    """
     global _registered_sigwinch
     if not _registered_sigwinch:
-        if sys.platform == 'win32':
-            # Martin (gz) mentioned WINDOW_BUFFER_SIZE_RECORD from
-            # ReadConsoleInput but I've no idea how to plug that in
-            # the current design -- vila 20091216
+        try:
+            import signal
+            if getattr(signal, "SIGWINCH", None) is not None:
+                set_signal_handler(signal.SIGWINCH, _terminal_size_changed)
+        except ImportError:
+            # python doesn't provide signal support, nothing we can do about it
             pass
-        else:
-            set_signal_handler(signal.SIGWINCH, _terminal_size_changed)
         _registered_sigwinch = True