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..889d579e5764415b924b660c84cf60e4cfde943a 100644
--- a/test_utils.h
+++ b/test_utils.h
@@ -10,6 +10,7 @@
 #include <vector>
 #include <gtest/gtest.h>
 #include "base/scoped_ptr.h"
+#include "base/string_util.h"

[petkov, 2010/12/10 00:46:55]

since you've touched the headers -- "new" style is use <> for the library
includes, sort them together with gtest and add blank lines...

[thieule, 2010/12/14 23:11:21]

Done.

 #include "update_engine/action.h"
 #include "update_engine/subprocess.h"
 #include "update_engine/utils.h"
@@ -92,6 +93,11 @@ const unsigned char kRandomString[] = {
 const char* const kMountPath = "/tmp/UpdateEngineTests_mnt";
 }  // namespace {}
 
+// Creates an empty ext image.

[petkov, 2010/12/10 00:46:55]

ext2, ext3, ext4?

[thieule, 2010/12/14 23:11:21]

This is a little bit more involved than just here.  I'll do the ext3 to ext2
change in a separate CL.

+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 +217,28 @@ 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) {
+    EXPECT_TRUE(utils::MakeTempDirectory("/tmp/mnt.XXXXXX", mnt_path));

[petkov, 2010/12/10 00:46:55]

lots of code for a header file. could you please move the implementation into
the .cc file?

[thieule, 2010/12/14 23:11:21]

Done.

+    dir_remover_.reset(new ScopedDirRemover(*mnt_path));
+
+    std::string loop_dev = GetUnusedLoopDevice();
+    EXPECT_EQ(0, system(StringPrintf("losetup %s %s", loop_dev.c_str(),
+                                     file_path.c_str()).c_str()));
+    loop_releaser_.reset(new ScopedLoopbackDeviceReleaser(loop_dev));
+
+    EXPECT_TRUE(utils::MountFilesystem(loop_dev, *mnt_path, flags));
+    unmounter_.reset(new ScopedFilesystemUnmounter(*mnt_path));
+  }
+ private:

[petkov, 2010/12/10 00:46:55]

blank line before private

[thieule, 2010/12/14 23:11:21]

Done.

+  scoped_ptr<ScopedDirRemover> dir_remover_;

[petkov, 2010/12/10 00:46:55]

i guess this is not new code but... is there any rule that says what order these
objects will be destructed in? if no rule, then random order is bad.

[thieule, 2010/12/14 23:11:21]

There is an explicit order that these objects must be destructed.  I've added a
comment to indicate such order.

+  scoped_ptr<ScopedLoopbackDeviceReleaser> loop_releaser_;
+  scoped_ptr<ScopedFilesystemUnmounter> unmounter_;
+};
+
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_TEST_UTILS_H__