CC-3299: Media monitor changes the owner of watched files?

- media monitor now tries to set the permission to www-data if the file/dir
cannot be read by www-data

python_apps/media-monitor/airtimefilemonitor/mediamonitorcommon.py

@@ -46,9 +46,13 @@ class MediaMonitorCommon:
             return False
 
     #check if file is readable by "nobody"
-    def has_correct_permissions(self, filepath):
+    def has_correct_permissions(self, filepath, euid='nobody', egid='nogroup'):
+        uid = pwd.getpwnam(euid)[2]
+        gid = grp.getgrnam(egid)[2]
+        
         #drop root permissions and become "nobody"
-        os.seteuid(65534)
+        os.seteuid(uid)
+        os.setegid(gid)
 
         try:
             open(filepath)
@@ -65,19 +69,18 @@ class MediaMonitorCommon:
 
         return readable
 
+    # the function only changes the permission if its not readable by www-data
     def set_needed_file_permissions(self, item, is_dir):
         try:
             omask = os.umask(0)
-
-            uid = pwd.getpwnam('www-data')[2]
-            gid = grp.getgrnam('www-data')[2]
-
-            os.chown(item, uid, gid)
-
-            if is_dir is True:
-                os.chmod(item, 02777)
-            else:
-                os.chmod(item, 0666)
+            
+            if not has_correct_permissions(item, 'www-data', 'www-data'):
+                os.chown(item, uid, gid)
+    
+                if is_dir is True:
+                    os.chmod(item, 02777)
+                else:
+                    os.chmod(item, 0666)
 
         except Exception, e:
             self.logger.error("Failed to change file's owner/group/permissions. %s", e)