add utility function to detect SELinux status and use it

Add a utility function selinuxEnabled() that returns true
if SELinux is enabled on the host and false otherwise. Use
this in _setupDev() method of the Root object to avoid shelling
out unnecessarily to 'chcon'.

Signed-off-by: Clark Williams <williams@redhat.com>

2 files changed, 18 insertions, 3 deletions

diff --git a/py/mock/backend.py b/py/mock/backend.py
index bcadc3e..7ca6a1d 100644
--- a/py/mock/backend.py
+++ b/py/mock/backend.py
@@ -101,6 +101,9 @@ class Root(object):
         self.state("init plugins")
         self._initPlugins()
 
+        # figure out if SELinux is enabled on the host
+        self.selinux = mock.util.selinuxEnabled()
+
         # officially set state so it is logged
         self.state("start")
 
@@ -322,9 +325,10 @@ class Root(object):
             os.mknod( self.makeChrootPath(i[2]), i[0], i[1])
             # set context. (only necessary if host running selinux enabled.)
             # fails gracefully if chcon not installed.
-            mock.util.do(
-                ["chcon", "--reference=/%s"% i[2], self.makeChrootPath(i[2])]
-                , raiseExc=0, shell=False)
+            if self.selinux:
+                mock.util.do(
+                    ["chcon", "--reference=/%s"% i[2], self.makeChrootPath(i[2])]
+                    , raiseExc=0, shell=False)
 
         os.symlink("/proc/self/fd/0", self.makeChrootPath("dev/stdin"))
         os.symlink("/proc/self/fd/1", self.makeChrootPath("dev/stdout"))
diff --git a/py/mock/util.py b/py/mock/util.py
index f52003e..07bcba0 100644
--- a/py/mock/util.py
+++ b/py/mock/util.py
@@ -262,6 +262,17 @@ def logOutput(fds, logger, returnOutput=1, start=0, timeout=0):
         logger.debug(tail)
     return output
 
+decorate(traceLog())
+def selinuxEnabled():
+    p = subprocess.Popen(["/usr/sbin/getenforce"], 
+                         shell=True, 
+                         stdout=subprocess.PIPE, 
+                         close_fds=True)
+    p.wait()
+    if p.stdout.read().strip() == "Disabled":
+        return False
+    return True
+
 # logger =
 # output = [1|0]
 # chrootPath