Work around bug in Python subprocess for remctl

[invirt/packages/invirt-autoinstaller.git] / files / usr / sbin / sipb-xen-lvcopy

diff --git a/files/usr/sbin/sipb-xen-lvcopy b/files/usr/sbin/sipb-xen-lvcopy
index 5b83460..317b88a 100755 (executable)
--- a/files/usr/sbin/sipb-xen-lvcopy
+++ b/files/usr/sbin/sipb-xen-lvcopy
@@ -7,28 +7,14 @@ import tempfile
 import time
 from subprocess import call, check_call, Popen, PIPE
 
+# Make sure to use up fd 0 to avoid a bug in subprocess in Python <= 2.5.1
+# NB we need to do this on every Python remctl script.
+# See r53624 in Python svn.
+sys.stdin = open('/dev/null')
+
 def losetup(source, offset=0):
-  # XXX we avoid colliding with other instances of ourself,
-  #     but when it comes to other loop-device users we just
-  #     pick a range things don't seem to use and hope...
-  lockfilename = '/tmp/losetup.lock'
-  os.close(os.open(lockfilename, os.O_CREAT+os.O_EXCL)) #lock
-  try:
-    loopdevice = None
-    for i in xrange(32,60): # totally arbitrary, just looks to be unused on black-mesa
-      filename = '/dev/loop%d'%i
-      if 0 == len(file(filename).read(1)):
-        loopdevice = filename # it's empty
-        break
-    if loopdevice is not None:
-      call(['losetup', '-o', str(offset), loopdevice, source])
-    else:
-      raise RuntimeError('out of loop devices for copying VM image: too many at once?')
-  finally:
-    os.unlink(lockfilename) #unlock
-  return loopdevice
-  # XX this means we can duplicate 28 at once.  Since it takes around 30s,
-  # this seems like an adequate capacity.
+  p = Popen(['sipb-xen-losetup', source, str(offset)], stdout=PIPE)
+  return p.communicate()[0].strip()
 
 def frob_copy_in_vm(target, *args):
   '''UNUSED: maybe we'll use this someday; it does isolate the frobber.'''