Merge 76320 - Implementation of an STL compatible allocator for Courgette on ...

courgette/ensemble_apply.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.
 
 // This file contains the code to apply a Courgette patch.
 
 #include "courgette/ensemble.h"
 
 #include "base/basictypes.h"
 #include "base/file_util.h"
@@ skipping 346 matching lines @@
                                              ensemble_correction, output);
   if (status != C_OK)
     return status;
 
   return C_OK;
 }
 
 Status ApplyEnsemblePatch(const FilePath::CharType* old_file_name,
                           const FilePath::CharType* patch_file_name,
                           const FilePath::CharType* new_file_name) {
-  Status status;
-
   // First read enough of the patch file to validate the header is well-formed.
   // A few varint32 numbers should fit in 100.
   FilePath patch_file_path(patch_file_name);
-  const int BIG_ENOUGH_FOR_HEADER = 100;
-  char buffer[BIG_ENOUGH_FOR_HEADER];
-  int read_count =
-      file_util::ReadFile(patch_file_path, buffer, sizeof(buffer));
-  if (read_count < 0)
+  file_util::MemoryMappedFile patch_file;
+  if (!patch_file.Initialize(patch_file_path))
     return C_READ_OPEN_ERROR;
 
   // 'Dry-run' the first step of the patch process to validate format of header.
   SourceStream patch_header_stream;
-  patch_header_stream.Init(buffer, read_count);
+  patch_header_stream.Init(patch_file.data(), patch_file.length());
   EnsemblePatchApplication patch_process;
-  status = patch_process.ReadHeader(&patch_header_stream);
+  Status status = patch_process.ReadHeader(&patch_header_stream);
   if (status != C_OK)
     return status;
 
-  // Header smells good so read the whole patch file for real.
-  int64 patch_file_size = 0;
-  if (!file_util::GetFileSize(patch_file_path, &patch_file_size))
-    return C_READ_ERROR;
-  std::string patch_file_buffer;
-  patch_file_buffer.reserve(static_cast<size_t>(patch_file_size));
-  if (!file_util::ReadFileToString(patch_file_path, &patch_file_buffer))
-    return C_READ_ERROR;
-
   // Read the old_file.
   FilePath old_file_path(old_file_name);
-  int64 old_file_size = 0;
-  if (!file_util::GetFileSize(old_file_path, &old_file_size))
-    return C_READ_ERROR;
-  std::string old_file_buffer;
-  old_file_buffer.reserve(static_cast<size_t>(old_file_size));
-  if (!file_util::ReadFileToString(old_file_path, &old_file_buffer))
+  file_util::MemoryMappedFile old_file;
+  if (!old_file.Initialize(old_file_path))
     return C_READ_ERROR;
 
   // Apply patch on streams.
   SourceStream old_source_stream;
   SourceStream patch_source_stream;
-  old_source_stream.Init(old_file_buffer);
-  patch_source_stream.Init(patch_file_buffer);
+  old_source_stream.Init(old_file.data(), old_file.length());
+  patch_source_stream.Init(patch_file.data(), patch_file.length());
   SinkStream new_sink_stream;
   status = ApplyEnsemblePatch(&old_source_stream, &patch_source_stream,
                               &new_sink_stream);
 
   // Write the patched data to |new_file_name|.
   FilePath new_file_path(new_file_name);
   int written =
       file_util::WriteFile(
           new_file_path,
           reinterpret_cast<const char*>(new_sink_stream.Buffer()),
           static_cast<int>(new_sink_stream.Length()));
   if (written == -1)
     return C_WRITE_OPEN_ERROR;
   if (static_cast<size_t>(written) != new_sink_stream.Length())
     return C_WRITE_ERROR;
 
   return C_OK;
 }
 
 }  // namespace