AU: Pass opened device fd from update engine to bspatch.

delta_performer.cc

 // Copyright (c) 2010 The Chromium OS 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/delta_performer.h"
 
 #include <endian.h>
 #include <errno.h>
 
 #include <algorithm>
@@ skipping 428 matching lines @@
                                             NULL));
   ScopedPathUnlinker path_unlinker(temp_filename);
   {
     int fd = open(temp_filename.c_str(), O_WRONLY | O_CREAT | O_TRUNC, 0644);
     ScopedFdCloser fd_closer(&fd);
     TEST_AND_RETURN_FALSE(
         utils::WriteAll(fd, &buffer_[0], operation.data_length()));
   }
 
   int fd = is_kernel_partition ? kernel_fd_ : fd_;
-  const string& path = is_kernel_partition ? kernel_path_ : path_;
+  const string& path = StringPrintf("/dev/fd/%d", fd);
 
   // If this is a non-idempotent operation, request a delayed exit and clear the
   // update state in case the operation gets interrupted. Do this as late as
   // possible.
   if (!IsIdempotentOperation(operation)) {
     Terminator::set_exit_blocked(true);
     ResetUpdateProgress(prefs_, true);
   }
 
   vector<string> cmd;
   cmd.push_back(kBspatchPath);
   cmd.push_back(path);
   cmd.push_back(path);
   cmd.push_back(temp_filename);
   cmd.push_back(input_positions);
   cmd.push_back(output_positions);
   int return_code = 0;
-  TEST_AND_RETURN_FALSE(Subprocess::SynchronousExec(cmd, &return_code));
+  TEST_AND_RETURN_FALSE(
+      Subprocess::SynchronousExecFlags(cmd,
+                                       &return_code,
+                                       G_SPAWN_LEAVE_DESCRIPTORS_OPEN));
   TEST_AND_RETURN_FALSE(return_code == 0);
 
   if (operation.dst_length() % block_size_) {
     // Zero out rest of final block.
     // TODO(adlr): build this into bspatch; it's more efficient that way.
     const Extent& last_extent =
         operation.dst_extents(operation.dst_extents_size() - 1);
     const uint64_t end_byte =
         (last_extent.start_block() + last_extent.num_blocks()) * block_size_;
     const uint64_t begin_byte =
@@ skipping 212 matching lines @@
   if (prefs_->GetInt64(kPrefsResumedUpdateFailures, &resumed_update_failures)) {
     resumed_update_failures++;
   } else {
     resumed_update_failures = 1;
   }
   prefs_->SetInt64(kPrefsResumedUpdateFailures, resumed_update_failures);
   return true;
 }
 
 }  // namespace chromeos_update_engine