Adds ImageWriterPrivate.destroyPartitions operation.

chrome/browser/extensions/api/image_writer_private/destroy_partitions_operation.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/file_util.h"
+#include "chrome/browser/extensions/api/image_writer_private/destroy_partitions_operation.h"
+#include "chrome/browser/extensions/api/image_writer_private/error_messages.h"
+
+namespace extensions {
+namespace image_writer {
+
+// Number of bytes for the maximum partition table size.  By wiping this many
+// bytes we can essentially guarantee the header and associated information will
+// be wiped. See http://crbug.com/328246 for more information.
+const int kPartitionTableSize = 32 * 1024;
+
+namespace {
+
+// Small wrapper to remove the temporary file and display an error if it fails.

[tbarzic, 2013/12/14 01:01:04]

display error where?
If you meant DLOG part, I don't think it's worth mentioning in the comment.

[Drew Haven, 2013/12/16 20:15:33]

Good point.  It's such a trivial function, but I felt it should have a comment
anyway.

+void RemoveTempFile(const base::FilePath& path) {
+  if (!DeleteFile(path, false))
+    DLOG(ERROR) << "Unable to delete temporary file: " << path.value();
+}
+
+}

[tbarzic, 2013/12/14 01:01:04]

  // namespace

[Drew Haven, 2013/12/16 20:15:33]

Done.

+
+DestroyPartitionsOperation::DestroyPartitionsOperation(
+    base::WeakPtr<OperationManager> manager,
+    const ExtensionId& extension_id,
+    const std::string& storage_unit_id)
+  : Operation(manager, extension_id, storage_unit_id) {

[tbarzic, 2013/12/14 01:01:04]

indent+=2

[Drew Haven, 2013/12/16 20:15:33]

Done.

+    // Turn off the verification step.
+    verify_write_ = false;

[tbarzic, 2013/12/14 01:01:04]

I'd add this to initializer list

[Drew Haven, 2013/12/16 20:15:33]

It's a protected variable of the superclass, so I can't put it in the
initializer list, I believe.

[tbarzic, 2013/12/16 20:33:45]

ok. Though, it may make sense to pass verify_write value as the Operation ctor
argument (instead of resetting it here)

[Drew Haven, 2013/12/16 22:05:25]

I think we'll set that up when/if we need it.

+}
+
+DestroyPartitionsOperation::~DestroyPartitionsOperation() {
+}

[tbarzic, 2013/12/14 01:01:04]

no need for a nl here

[Drew Haven, 2013/12/16 20:15:33]

Done.

+
+void DestroyPartitionsOperation::Start() {
+  if (!base::CreateTemporaryFile(&image_path_)) {
+    Error(error::kTempFile);
+    return;
+  }
+
+  AddCleanUpFunction(base::Bind(&RemoveTempFile, image_path_));
+
+  char buffer[kPartitionTableSize];

[tbarzic, 2013/12/14 01:01:04]

I'd use scoped_array<char> here (32kB is not that small)

[Drew Haven, 2013/12/16 20:15:33]

I'm not finding scoped_arrays in base.  Though they show up in a few of our
third_party libraries.

+  memset(buffer, 0, kPartitionTableSize);
+
+  if (file_util::WriteFile(image_path_, buffer, kPartitionTableSize) !=
+      kPartitionTableSize) {
+    Error(error::kTempFile);
+    return;
+  }
+
+  WriteStart();
+}
+
+}  // namespace image_writer
+}  // namespace extensions