Add support for reading blobs when using the network service.

content/browser/blob_storage/blob_url_loader_factory.cc

+// Copyright 2017 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/blob_storage/blob_url_loader_factory.h"
+
+#include <stddef.h>
+#include "base/bind.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "content/browser/blob_storage/chrome_blob_storage_context.h"
+#include "content/browser/storage_partition_impl.h"
+#include "content/common/net_adapters.h"
+#include "content/common/url_loader.mojom.h"
+#include "content/public/browser/browser_thread.h"
+#include "mojo/public/cpp/system/simple_watcher.h"
+#include "net/base/io_buffer.h"
+#include "net/http/http_byte_range.h"
+#include "net/http/http_request_headers.h"
+#include "net/http/http_response_headers.h"
+#include "net/http/http_status_code.h"
+#include "net/http/http_util.h"
+#include "storage/browser/blob/blob_data_handle.h"
+#include "storage/browser/blob/blob_reader.h"
+#include "storage/browser/blob/blob_storage_context.h"
+#include "storage/browser/blob/blob_url_request_job.h"
+#include "storage/browser/fileapi/file_system_context.h"
+
+namespace content {
+
+namespace {
+constexpr size_t kDefaultAllocationSize = 512 * 1024;
+
+// Note: some of this code is duplicated from storage::BlobURLRequestJob.

[kinuko, 2017/05/30 06:27:32]

Could you also add a short comment about the lifetime? (E.g. this is a
self-destruct object and deletes itself when handling a request completes (see
DeleteIfNeeded))

[jam, 2017/05/30 15:54:18]

Done.

+class BlobURLLoader : public mojom::URLLoader {
+ public:
+  BlobURLLoader(mojom::URLLoaderRequest url_loader_request,
+                const ResourceRequest& request,
+                mojom::URLLoaderClientPtr client,
+                storage::BlobStorageContext* blob_storage_context,
+                storage::FileSystemContext* file_system_context)
+      : binding_(this, std::move(url_loader_request)),
+        request_(request),
+        client_(std::move(client)),
+        byte_range_set_(false),
+        writable_handle_watcher_(FROM_HERE,
+                                 mojo::SimpleWatcher::ArmingPolicy::MANUAL),
+        peer_closed_handle_watcher_(FROM_HERE,
+                                    mojo::SimpleWatcher::ArmingPolicy::MANUAL),
+        weak_factory_(this) {
+    DCHECK_CURRENTLY_ON(BrowserThread::IO);
+    blob_handle_ = blob_storage_context->GetBlobDataFromPublicURL(request.url);
+
+    // PostTask since it might destruct.
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE,
+        base::Bind(&BlobURLLoader::Start, weak_factory_.GetWeakPtr(), request,
+                   make_scoped_refptr(file_system_context)));
+  }
+
+  void Start(const ResourceRequest& request,
+             scoped_refptr<storage::FileSystemContext> file_system_context) {
+    if (!blob_handle_) {
+      NotifyCompleted(net::ERR_FILE_NOT_FOUND);
+      return;
+    }
+
+    base::SequencedTaskRunner* file_task_runner =
+        BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE).get();
+    blob_reader_ =
+        blob_handle_->CreateReader(file_system_context.get(), file_task_runner);
+
+    // We only support GET request per the spec.
+    if (request.method != "GET") {
+      NotifyCompleted(net::ERR_METHOD_NOT_SUPPORTED);
+      return;
+    }
+
+    if (blob_reader_->net_error()) {
+      NotifyCompleted(blob_reader_->net_error());
+      return;
+    }
+
+    net::HttpRequestHeaders request_headers;
+    request_headers.AddHeadersFromString(request.headers);
+    std::string range_header;
+    if (request_headers.GetHeader(net::HttpRequestHeaders::kRange,
+                                  &range_header)) {
+      // We only care about "Range" header here.
+      std::vector<net::HttpByteRange> ranges;
+      if (net::HttpUtil::ParseRangeHeader(range_header, &ranges)) {
+        if (ranges.size() == 1) {
+          byte_range_set_ = true;
+          byte_range_ = ranges[0];
+        } else {
+          // We don't support multiple range requests in one single URL request,
+          // because we need to do multipart encoding here.
+          // TODO(jianli): Support multipart byte range requests.
+          NotifyCompleted(net::ERR_REQUEST_RANGE_NOT_SATISFIABLE);
+        }
+      }
+    }
+
+    storage::BlobReader::Status size_status =
+        blob_reader_->CalculateSize(base::Bind(&BlobURLLoader::DidCalculateSize,
+                                               weak_factory_.GetWeakPtr()));
+    switch (size_status) {
+      case storage::BlobReader::Status::NET_ERROR:
+        NotifyCompleted(blob_reader_->net_error());
+        return;
+      case storage::BlobReader::Status::IO_PENDING:
+        return;
+      case storage::BlobReader::Status::DONE:
+        DidCalculateSize(net::OK);
+        return;
+    }

[kinuko, 2017/05/30 06:27:32]

nit: NOTREACHED() here

[jam, 2017/05/30 15:54:18]

Done.

+  }
+
+  ~BlobURLLoader() override {}
+
+ private:
+  // mojom::URLLoader implementation:
+  void FollowRedirect() override { NOTREACHED(); }
+
+  void SetPriority(net::RequestPriority priority,
+                   int32_t intra_priority_value) override {}
+
+  void NotifyCompleted(int error_code) {
+    ResourceRequestCompletionStatus request_complete_data;
+    request_complete_data.error_code = error_code;
+    client_->OnComplete(request_complete_data);
+
+    DeleteIfNeeded();
+  }
+
+  void DidCalculateSize(int result) {
+    if (result != net::OK) {
+      NotifyCompleted(result);
+      return;
+    }
+
+    // Apply the range requirement.
+    if (!byte_range_.ComputeBounds(blob_reader_->total_size())) {
+      NotifyCompleted(net::ERR_REQUEST_RANGE_NOT_SATISFIABLE);
+      return;
+    }
+
+    DCHECK_LE(byte_range_.first_byte_position(),
+              byte_range_.last_byte_position() + 1);
+    uint64_t length =
+        base::checked_cast<uint64_t>(byte_range_.last_byte_position() -
+                                     byte_range_.first_byte_position() + 1);
+
+    if (byte_range_set_)
+      blob_reader_->SetReadRange(byte_range_.first_byte_position(), length);
+
+    net::HttpStatusCode status_code = net::HTTP_OK;
+    if (byte_range_set_ && byte_range_.IsValid()) {
+      status_code = net::HTTP_PARTIAL_CONTENT;
+    } else {
+      // TODO(horo): When the requester doesn't need the side data
+      // (ex:FileReader) we should skip reading the side data.
+      if (blob_reader_->has_side_data() &&
+          blob_reader_->ReadSideData(base::Bind(&BlobURLLoader::DidReadMetadata,
+                                                weak_factory_.GetWeakPtr())) ==
+              storage::BlobReader::Status::IO_PENDING) {
+        return;
+      }
+    }
+
+    HeadersCompleted(status_code);
+  }
+
+  void DidReadMetadata(storage::BlobReader::Status result) {
+    if (result != storage::BlobReader::Status::DONE) {
+      NotifyCompleted(blob_reader_->net_error());
+      return;
+    }
+    HeadersCompleted(net::HTTP_OK);
+  }
+
+  void HeadersCompleted(net::HttpStatusCode status_code) {
+    ResourceResponseHead response;
+    response.content_length = 0;
+    response.headers = storage::BlobURLRequestJob::GenerateHeaders(
+        status_code, blob_handle_.get(), blob_reader_.get(), &byte_range_,
+        &response.content_length);
+
+    std::string mime_type;
+    response.headers->GetMimeType(&mime_type);
+    // Match logic in StreamURLRequestJob::HeadersCompleted.
+    if (mime_type.empty())
+      mime_type = "text/plain";
+    response.mime_type = mime_type;
+
+    // TODO(jam): some of this code can be shared with
+    // content/network/url_loader_impl.h
+    client_->OnReceiveResponse(response, base::nullopt, nullptr);
+
+    net::IOBufferWithSize* metadata = blob_reader_->side_data();
+    if (metadata) {
+      const uint8_t* data = reinterpret_cast<const uint8_t*>(metadata->data());
+      client_->OnReceiveCachedMetadata(
+          std::vector<uint8_t>(data, data + metadata->size()));
+    }
+
+    mojo::DataPipe data_pipe(kDefaultAllocationSize);
+    response_body_stream_ = std::move(data_pipe.producer_handle);
+    response_body_consumer_handle_ = std::move(data_pipe.consumer_handle);
+    peer_closed_handle_watcher_.Watch(
+        response_body_stream_.get(), MOJO_HANDLE_SIGNAL_PEER_CLOSED,
+        base::Bind(&BlobURLLoader::OnResponseBodyStreamClosed,
+                   base::Unretained(this)));
+    peer_closed_handle_watcher_.ArmOrNotify();
+
+    writable_handle_watcher_.Watch(
+        response_body_stream_.get(), MOJO_HANDLE_SIGNAL_WRITABLE,
+        base::Bind(&BlobURLLoader::OnResponseBodyStreamReady,
+                   base::Unretained(this)));
+
+    // Start reading...
+    ReadMore();
+  }
+
+  void ReadMore() {
+    DCHECK(!pending_write_.get());
+
+    uint32_t num_bytes;
+    // TODO: we should use the abstractions in MojoAsyncResourceHandler.
+    MojoResult result = NetToMojoPendingBuffer::BeginWrite(
+        &response_body_stream_, &pending_write_, &num_bytes);
+    if (result == MOJO_RESULT_SHOULD_WAIT) {
+      // The pipe is full. We need to wait for it to have more space.
+      writable_handle_watcher_.ArmOrNotify();
+      return;
+    } else if (result != MOJO_RESULT_OK) {
+      // The response body stream is in a bad state. Bail.
+      writable_handle_watcher_.Cancel();
+      response_body_stream_.reset();
+      NotifyCompleted(net::ERR_UNEXPECTED);

[kinuko, 2017/05/30 06:27:32]

return here

[jam, 2017/05/30 15:54:18]

Done.

+    }
+
+    CHECK_GT(static_cast<uint32_t>(std::numeric_limits<int>::max()), num_bytes);
+    scoped_refptr<net::IOBuffer> buf(
+        new NetToMojoIOBuffer(pending_write_.get()));
+    int bytes_read;
+    storage::BlobReader::Status read_status = blob_reader_->Read(
+        buf.get(), static_cast<int>(num_bytes), &bytes_read,
+        base::Bind(&BlobURLLoader::DidRead, weak_factory_.GetWeakPtr(), false));
+    switch (read_status) {
+      case storage::BlobReader::Status::NET_ERROR:
+        NotifyCompleted(blob_reader_->net_error());
+        return;
+      case storage::BlobReader::Status::IO_PENDING:
+        // Wait for DidRead.
+        return;
+      case storage::BlobReader::Status::DONE:
+        if (bytes_read > 0) {
+          DidRead(true, bytes_read);
+        } else {
+          writable_handle_watcher_.Cancel();
+          pending_write_->Complete(0);
+          pending_write_ = nullptr;  // This closes the data pipe.
+          NotifyCompleted(net::OK);
+          return;
+        }
+    }
+  }
+
+  void DidRead(bool completed_synchronously, int num_bytes) {
+    if (response_body_consumer_handle_.is_valid()) {
+      // Send the data pipe on the first OnReadCompleted call.
+      client_->OnStartLoadingResponseBody(
+          std::move(response_body_consumer_handle_));
+    }
+    response_body_stream_ = pending_write_->Complete(num_bytes);
+    pending_write_ = nullptr;
+    if (completed_synchronously) {
+      base::ThreadTaskRunnerHandle::Get()->PostTask(
+          FROM_HERE,
+          base::Bind(&BlobURLLoader::ReadMore, weak_factory_.GetWeakPtr()));
+    } else {
+      ReadMore();
+    }
+  }
+
+  void OnResponseBodyStreamClosed(MojoResult result) {
+    response_body_stream_.reset();
+    pending_write_ = nullptr;
+    DeleteIfNeeded();
+  }
+
+  void OnResponseBodyStreamReady(MojoResult result) {
+    // TODO: Handle a bad |result| value.
+    DCHECK_EQ(result, MOJO_RESULT_OK);
+    ReadMore();
+  }
+
+  void DeleteIfNeeded() {
+    bool has_data_pipe =
+        pending_write_.get() || response_body_stream_.is_valid();
+    if (!has_data_pipe)
+      delete this;
+  }
+
+  mojo::Binding<mojom::URLLoader> binding_;
+  ResourceRequest request_;
+  mojom::URLLoaderClientPtr client_;
+
+  bool byte_range_set_;
+  net::HttpByteRange byte_range_;
+
+  std::unique_ptr<storage::BlobDataHandle> blob_handle_;
+  std::unique_ptr<storage::BlobReader> blob_reader_;
+
+  // TODO(jam): share with URLLoaderImpl
+  mojo::ScopedDataPipeProducerHandle response_body_stream_;
+  mojo::ScopedDataPipeConsumerHandle response_body_consumer_handle_;
+  scoped_refptr<NetToMojoPendingBuffer> pending_write_;
+  mojo::SimpleWatcher writable_handle_watcher_;
+  mojo::SimpleWatcher peer_closed_handle_watcher_;
+
+  base::WeakPtrFactory<BlobURLLoader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlobURLLoader);
+};
+
+}  // namespace
+
+BlobURLLoaderFactory::BlobURLLoaderFactory(
+    StoragePartitionImpl* storage_partition)
+    : blob_storage_context_(ChromeBlobStorageContext::GetFor(
+          storage_partition->browser_context())),
+      file_system_context_(storage_partition->GetFileSystemContext()) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+}
+
+mojom::URLLoaderFactoryPtr BlobURLLoaderFactory::CreateFactory() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  mojom::URLLoaderFactoryPtr factory;
+  mojom::URLLoaderFactoryRequest request = mojo::MakeRequest(&factory);
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::BindOnce(&BlobURLLoaderFactory::BindOnIO, this,
+                                         std::move(request)));
+
+  return factory;
+}
+
+BlobURLLoaderFactory::~BlobURLLoaderFactory() {}
+
+void BlobURLLoaderFactory::BindOnIO(mojom::URLLoaderFactoryRequest request) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  loader_factory_bindings_.AddBinding(this, std::move(request));
+}
+
+void BlobURLLoaderFactory::CreateLoaderAndStart(
+    mojom::URLLoaderRequest loader,
+    int32_t routing_id,
+    int32_t request_id,
+    uint32_t options,
+    const ResourceRequest& request,
+    mojom::URLLoaderClientPtr client) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  new BlobURLLoader(std::move(loader), request, std::move(client),
+                    blob_storage_context_->context(),
+                    file_system_context_.get());
+}
+
+void BlobURLLoaderFactory::SyncLoad(int32_t routing_id,
+                                    int32_t request_id,
+                                    const ResourceRequest& request,
+                                    SyncLoadCallback callback) {
+  NOTREACHED();
+}
+
+}  // namespace content