extras-buildsys/common ExecUtils.py,1.2,1.2.2.1

[Daniel Williams (dcbw)]

Author: dcbw

Update of /cvs/fedora/extras-buildsys/common
In directory cvs-int.fedora.redhat.com:/tmp/cvs-serv4836/common

Modified Files:
      Tag: STABLE_0_4
	ExecUtils.py 
Log Message:
2005-11-13  Dan Williams  <dcbw at redhat.com>

    * common/ExecUtils.py
        - On python 2.3 and lower, unblock signals before execing
            processes.  Requires py_pthread_sigmask module.




Index: ExecUtils.py
===================================================================
RCS file: /cvs/fedora/extras-buildsys/common/ExecUtils.py,v
retrieving revision 1.2
retrieving revision 1.2.2.1
diff -u -r1.2 -r1.2.2.1
--- ExecUtils.py	31 Aug 2005 01:56:38 -0000	1.2
+++ ExecUtils.py	14 Nov 2005 01:47:31 -0000	1.2.2.1
@@ -17,6 +17,35 @@
 import types
 import select
 
+#
+# pthread_sigmask
+#
+# Python 2.3 and earlier use pthread_sigmask to block all
+# signals right before creating a new thread.  Since exec-ed
+# processes inherit the signal mask of the thread that's
+# executing them, this causes problems if the exec-ed process
+# is expecting a sane signal mask.  Some symptoms include
+# unreaped children and parents stuck in waitpid(), among others.
+#
+use_pthread_sigmask = False
+if sys.version_info[:3] < (2, 4, 0):
+    try:
+        import signal
+        import pthread_sigmask
+        use_pthread_sigmask = True
+
+        i = 1
+        unblock_signal_list = []
+        while i < signal.NSIG:
+            unblock_signal_list.append(i)
+            i = i + 1
+    except:
+        print """WARNING: You might want to install the pthread_sigmask module.
+Python versions earlier than 2.4 have problems with signals and
+spawned processes."""
+        pass
+
+
 def getfd(filespec, readOnly = 0):
     if type(filespec) == types.IntType:
         return filespec
@@ -54,6 +83,13 @@
             os.dup2(stderr, 2)
             os.close(stderr)
 
+        # Set signal mask to something sane if we can
+        if use_pthread_sigmask:
+            # Unblock all signals before execing
+            (ret, oldmask) = pthread_sigmask.pthread_sigmask(
+                    pthread_sigmask.SIG_UNBLOCK,
+                    unblock_signal_list)
+
         try:
             os.execv(cmd, argv)
         except OSError, e:
@@ -62,13 +98,3 @@
 
     return childpid
 
-
-def foo():
-    status = -1
-    try:
-        (pid, status) = os.waitpid(childpid, 0)
-    except OSError, (errno, msg):
-        print __name__, "waitpid:", msg
-
-    return status
-