AU: Update Downloader to support our image formats.

src/platform/update_engine/filesystem_copier_action.cc

 // Copyright (c) 2010 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 "update_engine/filesystem_copier_action.h"
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
@@ skipping 29 matching lines @@
     return;
   }
   install_plan_ = GetInputObject();
 
   if (install_plan_.is_full_update) {
     // No copy needed. Done!
     abort_action_completer.set_success(true);
     return;
   }
 
-  const string source =
-      copy_source_.empty() ? utils::BootDevice() : copy_source_;
-  LOG(INFO) << "Copying from " << source << " to "
-            << install_plan_.install_path;
+  string source = copy_source_;
+  if (source.empty()) {
+    source = copying_kernel_install_path_ ?
+        utils::BootKernelDevice(utils::BootDevice()) :
+        utils::BootDevice();
+  }
+
+  const string destination = copying_kernel_install_path_ ?
+      install_plan_.kernel_install_path :
+      install_plan_.install_path;
   
   int src_fd = open(source.c_str(), O_RDONLY);
   if (src_fd < 0) {
     PLOG(ERROR) << "Unable to open " << source << " for reading:";
     return;
   }
-  int dst_fd = open(install_plan_.install_path.c_str(),
+  int dst_fd = open(destination.c_str(),
                     O_WRONLY | O_TRUNC | O_CREAT,
                     0644);
   if (dst_fd < 0) {
     close(src_fd);
     PLOG(ERROR) << "Unable to open " << install_plan_.install_path
                 << " for writing:";
     return;
   }
 
   src_stream_ = g_unix_input_stream_new(src_fd, TRUE);
@@ skipping 91 matching lines @@
       src_stream_,
       &buffer_[0],
       buffer_.size(),
       G_PRIORITY_DEFAULT,
       canceller_,
       &FilesystemCopierAction::StaticAsyncReadyCallback,
       this);
 }
 
 }  // namespace chromeos_update_engine