added persistence option to HostWithPrivateDirs. also attached mount namespaces when mnexec -a is specified

examples/bind.py

@@ -20,7 +20,9 @@ from functools import partial
 def testHostWithPrivateDirs():
     "Test bind mounts"
     topo = SingleSwitchTopo( 10 )
-    privateDirs = [ '/var/log', '/var/run' ]
+    privateDirs = [ ( '/var/log', '/onos/%(name)s/var/log' ), 
+                    ( '/var/run', '/ovx/%(name)s/var/run' ), 
+                      '/mn' ]
     host = partial( HostWithPrivateDirs,
                     privateDirs=privateDirs )
     net = Mininet( topo=topo, host=host )

mininet/node.py

@@ -728,14 +728,28 @@ class CPULimitedHost( Host ):
 class HostWithPrivateDirs( Host ):
     "Host with private directories"
 
-    def __init__(self, *args, **kwargs ):
+    def __init__(self, name, *args, **kwargs ):
         """privateDirs: list of private directories"""
-
+        self.name = name
         self.privateDirs = kwargs.pop( 'privateDirs', [] )
-        Host.__init__( self, *args, **kwargs )
+        Host.__init__( self, name, *args, **kwargs )
         self.mountPrivateDirs()
 
     def mountPrivateDirs( self ):
+        "mount the directories that have specified mountpoints"
+        for directory in self.privateDirs:
+            if isinstance( directory, tuple ):
+                privateDir = directory[ 1 ] %self.__dict__ 
+                mountPoint = directory[ 0 ]
+                self.cmd( 'mkdir -p %s' %privateDir )
+                self.cmd( 'mkdir -p %s' %mountPoint )
+                self.cmd( 'mount --bind %s %s' %( privateDir, mountPoint ) )
+            else:
+                self.cmd( 'mkdir -p %s' %directory ) 
+                self.cmd( 'mount -n -t tmpfs tmpfs %s' %directory )
+
+
+    def mountTempDirs( self ):
         "Mount tmpfs for each private directory"
         for dir_ in self.privateDirs:
             self.cmd( 'mkdir -p ' + dir_ )

mnexec.c

@@ -133,6 +133,7 @@ int main(int argc, char *argv[])
                 perror("mount");
                 return 1;
             }
+
             break;
         case 'p':
             /* print pid */
@@ -140,7 +141,7 @@ int main(int argc, char *argv[])
             fflush(stdout);
             break;
         case 'a':
-            /* Attach to pid's network namespace */
+            /* Attach to pid's network namespace and mount namespace*/
             pid = atoi(optarg);
             sprintf(path, "/proc/%d/ns/net", pid );
             nsid = open(path, O_RDONLY);
@@ -152,6 +153,18 @@ int main(int argc, char *argv[])
                 perror("setns");
                 return 1;
             }
+            sprintf(path, "/proc/%d/ns/mnt", pid );
+            nsid = open(path, O_RDONLY);
+            if (nsid < 0) {
+                perror(path);
+                return 1;
+            }
+            if (setns(nsid, 0) != 0) {
+                perror("setns");
+                return 1;
+            }
+
+
             break;
         case 'g':
             /* Attach to cgroup */