Restore SIGPIPE default action for subprocesses

Python ignores SIGPIPE on startup, because it prefers to check every
write and raise an IOError exception rather than taking the signal. Most
Unix subprocesses don't expect to work this way. This patch (adapted
from Colin Watson's post at http://tinyurl.com/2a7mzh5) sets SIGPIPE
back to the default action for quantum.agent.linux.utils.execute,
quantum.common.utils.execute and quantum-rootwrap created subprocesses.

Fixes bug 1053364

Change-Id: Ib805f1f8846c245b75a5ea64278c840b823c1fb2

1 files changed, 8 insertions, 0 deletions

diff --git a/bin/quantum-rootwrap b/bin/quantum-rootwrap
index bb7fbc0d5d..96939ae2ff 100755
--- a/bin/quantum-rootwrap
+++ b/bin/quantum-rootwrap
@@ -38,6 +38,7 @@
 
 import ConfigParser
 import os
+import signal
 import subprocess
 import sys
 
@@ -47,6 +48,12 @@ RC_NOCOMMAND = 98
 RC_BADCONFIG = 97
 
 
+def _subprocess_setup():
+    # Python installs a SIGPIPE handler by default. This is usually not what
+    # non-Python subprocesses expect.
+    signal.signal(signal.SIGPIPE, signal.SIG_DFL)
+
+
 if __name__ == '__main__':
     # Split arguments, require at least a command
     execname = sys.argv.pop(0)
@@ -84,6 +91,7 @@ if __name__ == '__main__':
                                stdin=sys.stdin,
                                stdout=sys.stdout,
                                stderr=sys.stderr,
+                               preexec_fn=_subprocess_setup,
                                env=filtermatch.get_environment(userargs))
         obj.wait()
         sys.exit(obj.returncode)