Compressing .pak resources with new option: "type=GZIPPABLE_BINDATA"

content/browser/webui/web_ui_data_source_impl.cc

 // Copyright (c) 2012 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 "content/browser/webui/web_ui_data_source_impl.h"
 
 #include <stddef.h>
 
 #include <string>
 
 #include "base/bind.h"
+#include "base/bit_cast.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/grit/content_resources.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/common/content_client.h"
+#include "third_party/zlib/zlib.h"
 #include "ui/base/template_expressions.h"
 #include "ui/base/webui/jstemplate_builder.h"
 #include "ui/base/webui/web_ui_util.h"
 
 namespace content {
 
 // static
 WebUIDataSource* WebUIDataSource::Create(const std::string& source_name) {
   return new WebUIDataSourceImpl(source_name);
 }
@@ skipping 203 matching lines @@
   std::map<std::string, int>::iterator result;
   // Remove the query string for named resource lookups.
   std::string file_path = path.substr(0, path.find_first_of('?'));
   result = path_to_idr_map_.find(file_path);
   if (result != path_to_idr_map_.end())
     resource_id = result->second;
   DCHECK_NE(resource_id, -1);
   scoped_refptr<base::RefCountedMemory> response(
       GetContentClient()->GetDataResourceBytes(resource_id));
 
+  const unsigned char* response_array = response->front();
+  if (response_array[0] == 0x1f && response_array[1] == 0x8b) {

[agrieve, 2016/05/11 18:29:52]

I think this is a big enough chunk of logic that it would be better to put it in
a local helper function (within an anonymous namespace at the top of this file)

[smaier, 2016/05/13 15:27:25]

Done.

+    // We are assuming that since we have hit the "magic header" (1f:8b) of a
+    // gzipped file, we can now decode it.
+    z_stream infstream;
+    infstream.zalloc = Z_NULL;
+    infstream.zfree = Z_NULL;
+    infstream.opaque = Z_NULL;
+
+    infstream.avail_in = response->size();                 // size of input
+    infstream.next_in = bit_cast<Bytef*>(response_array);  // input buffer

[agrieve, 2016/05/11 18:29:52]

nit: I don't think bit_cast<> is meant for pointer types. I think you can just
use reinterpret_cast / const_cast here (and below)

[smaier, 2016/05/13 15:27:25]

Done.

+
+    // Size of output comes from footer of gzip file format, found as the last 4
+    // bytes in the compressed file.
+    infstream.avail_out = *reinterpret_cast<const uint32_t*>(

[agrieve, 2016/05/11 18:29:52]

This assumes a certain endianness. Probably better to use an explicit endian
helper function here.

[smaier, 2016/05/13 15:27:25]

Done.

+        &response_array[response->size() - 4]);
+
+    std::string output;
+    output.resize(infstream.avail_out);
+    infstream.next_out = bit_cast<Bytef*>(&output[0]);  // output buffer
+
+    CHECK(inflateInit2(&infstream, 16) == Z_OK);
+    CHECK(inflate(&infstream, Z_FINISH) == Z_STREAM_END);
+    CHECK(inflateEnd(&infstream) == Z_OK);
+
+    response = base::RefCountedString::TakeString(&output);
+  }
+
   // TODO(dschuyler): improve filtering of which resource to run template
   // expansion upon.
   if (GetMimeType(path) == "text/html") {
     std::string replaced = ui::ReplaceTemplateExpressions(
         base::StringPiece(response->front_as<char>(), response->size()),
         replacements_);
     response = base::RefCountedString::TakeString(&replaced);
   }
 
   callback.Run(response.get());
 }
 
 void WebUIDataSourceImpl::SendLocalizedStringsAsJSON(
     const URLDataSource::GotDataCallback& callback) {
   std::string template_data;
   webui::AppendJsonJS(&localized_strings_, &template_data);
   callback.Run(base::RefCountedString::TakeString(&template_data));
 }
 
 }  // namespace content