Save an restore docker permission

Fix #550

gns3server/modules/docker/docker_vm.py

@@ -402,7 +402,7 @@ class DockerVM(BaseVM):
                 "/gns3/bin/busybox",
                 "sh",
                 "-c",
-                "chmod -R u+rX {path} && chown {uid}:{gid} -R {path}".format(uid=os.getuid(), gid=os.getgid(), path=volume))
+                "(/gns3/bin/busybox find \"{path}\" -depth -print0 | xargs -0 stat -c '%a:%u:%g:%n' > \"{path}/.gns3_perms\") && /gns3/bin/busybox chmod -R u+rX \"{path}\" && /gns3/bin/busybox chown {uid}:{gid} -R \"{path}\"".format(uid=os.getuid(), gid=os.getgid(), path=volume))
             yield from process.wait()
 
     @asyncio.coroutine

gns3server/modules/docker/resources/init.sh

@@ -28,6 +28,21 @@ if [ ! -d /tmp/gns3/bin ]; then
 	/gns3/bin/busybox --install -s /tmp/gns3/bin
 fi
 
+#  Restore file permission
+for i in $(echo "$GNS3_VOLUMES" | tr ":" "\n")
+do
+    cd $i
+    if [ -f .gns3_perms ]
+    then
+        while IFS=: read PERMS OWNER GROUP FILE
+        do
+            chmod "$PERMS" "$FILE"
+            chown "${OWNER}:${GROUP}" "$FILE"
+        done < .gns3_perms
+    fi
+done
+
+
 # /etc/hosts
 [ -s /etc/hosts ] || cat > /etc/hosts << __EOF__
 127.0.1.1	$HOSTNAME