Add support for bsdiff of file system metadata blocks

test_utils.h

Index: test_utils.h
diff --git a/test_utils.h b/test_utils.h
index 4c8288892b37eb82dd4e904d0f40b62965efa8ee..68de48d7143836dfa273ebec5465a93b65dcc3f2 100644
--- a/test_utils.h
+++ b/test_utils.h
@@ -8,8 +8,10 @@
 #include <set>
 #include <string>
 #include <vector>
+
+#include <base/scoped_ptr.h>
 #include <gtest/gtest.h>
-#include "base/scoped_ptr.h"
+
 #include "update_engine/action.h"
 #include "update_engine/subprocess.h"
 #include "update_engine/utils.h"
@@ -92,6 +94,11 @@ const unsigned char kRandomString[] = {
 const char* const kMountPath = "/tmp/UpdateEngineTests_mnt";
 }  // namespace {}
 
+// Creates an empty ext image.
+void CreateEmptyExtImageAtPath(const std::string& path,
+                               size_t size,
+                               int block_size);
+
 // Creates an ext image with some files in it. The paths creates are
 // returned in out_paths.
 void CreateExtImageAtPath(const std::string& path,
@@ -211,6 +218,22 @@ struct ObjectCollectorAction : public Action<ObjectCollectorAction<T> > {
   T object_;
 };
 
+class ScopedLoopMounter {
+ public:
+  explicit ScopedLoopMounter(const std::string& file_path,
+                             std::string* mnt_path,
+                             unsigned long flags);
+
+ private:
+  // These objects must be destructed in the following order:

[petkov, 2010/12/15 23:30:16]

Does C++ standard ensure the destruction order?

[thieule, 2010/12/15 23:43:39]

Yes, nonstatic members are destroyed in reverse order.

On 2010/12/15 23:30:16, petkov wrote:

+  //   ScopedFilesystemUnmounter (the file system must be unmounted first)
+  //   ScopedLoopbackDeviceReleaser (then the loop device can be deleted)
+  //   ScopedDirRemover (then the mount point can be deleted)
+  scoped_ptr<ScopedDirRemover> dir_remover_;
+  scoped_ptr<ScopedLoopbackDeviceReleaser> loop_releaser_;
+  scoped_ptr<ScopedFilesystemUnmounter> unmounter_;
+};
+
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_TEST_UTILS_H__