Merge branch 'master' into 2.0

gns3server/compute/qemu/qcow2.py

@@ -61,7 +61,11 @@ class Qcow2:
         struct_format = ">IIQi"
         with open(self._path, 'rb') as f:
             content = f.read(struct.calcsize(struct_format))
-            self.magic, self.version, self.backing_file_offset, self.backing_file_size = struct.unpack_from(struct_format, content)
+            try:
+                self.magic, self.version, self.backing_file_offset, self.backing_file_size = struct.unpack_from(struct_format, content)
+
+            except struct.error:
+                raise Qcow2Error("Invalid file header for {}".format(self._path))
 
         if self.magic != 1363560955:  # The first 4 bytes contain the characters 'Q', 'F', 'I' followed by 0xfb.
             raise Qcow2Error("Invalid magic for {}".format(self._path))