clipboard_writer.h | Explore in Territory

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_CLIPBOARD_CLIPBOARD_WRITER_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_CLIPBOARD_CLIPBOARD_WRITER_H_

#include "base/sequence_checker.h"
#include "base/task/single_thread_task_runner.h"
#include "third_party/blink/renderer/core/fileapi/blob.h"
#include "third_party/blink/renderer/core/fileapi/file_reader_client.h"
#include "third_party/blink/renderer/modules/clipboard/clipboard_promise.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/heap/self_keep_alive.h"
#include "third_party/skia/include/core/SkImage.h"

namespace blink {

class FileReaderLoader;
class SystemClipboard;

// Interface for writing an individual Clipboard API format as a Blob to the
// System Clipboard, safely and asynchronously.
//
// ClipboardWriter takes as input a ClipboardPromise, which manages writing
// multiple formats and passes in unsanitized clipboard payloads.
// ClipboardWriter then sanitizes a Blob payload and writes it onto the
// underlying system clipboard. All System Clipboard operations should be
// called from the main thread.
//
// Writing a Blob's data to the system clipboard is accomplished by:
// (1) Reading - the Blob's contents using a FileReaderLoader.
// (2) Decoding - or sanitizing the Blob's contents to avoid RCE in native
//     applications that may take advantage of vulnerabilities in their
//     decoders, whenever possible. Decoding may be time-consuming, so it
//     is done on a background thread whenever possible. An example where
//     decoding is done on the main thread is HTML, where Blink's HTML decoder
//     can only be used on the main thread.
// (3) Writing - the Blob's decoded contents to the system clipboard.
//
// Subclasses of ClipboardWriter should be implemented for each supported
// format. Subclasses should:
// (1) Begin execution by implementing ClipboardWriter::StartWrite().
// (2) Decode the payload on a background thread (if possible) by implementing
//     a static DecodeOnBackgroundThread() function. This function is called by
//     StartWrite() via worker_pool::PostTask().
// (3) Write the decoded content to the system clipboard by implementing
//     ClipboardWriter::Write();
//
// ClipboardWriter is owned only by itself and ClipboardPromise. It keeps
// itself alive for the duration of FileReaderLoader's async operations using
// SelfKeepAlive, and keeps itself alive afterwards during cross-thread
// operations by using WrapCrossThreadPersistent.
class ClipboardWriter : public GarbageCollected<ClipboardWriter>,
                        public FileReaderAccumulator { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_MODULES_CLIPBOARD_CLIPBOARD_WRITER_H_
chromium/third_party/blink/renderer/modules/clipboard/clipboard_writer.h
