1 files changed, 155 insertions, 0 deletions
diff --git a/dom/file/ipc/RemoteLazyInputStream.h b/dom/file/ipc/RemoteLazyInputStream.h
new file mode 100644
index 0000000000..08bb168e27
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+++ b/dom/file/ipc/RemoteLazyInputStream.h
@@ -0,0 +1,155 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_RemoteLazyInputStream_h
+#define mozilla_RemoteLazyInputStream_h
+
+#include "chrome/common/ipc_message_utils.h"
+#include "mozilla/Mutex.h"
+#include "mozIRemoteLazyInputStream.h"
+#include "nsIAsyncInputStream.h"
+#include "nsICloneableInputStream.h"
+#include "nsIFileStreams.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "nsIInputStreamLength.h"
+#include "nsCOMPtr.h"
+
+namespace mozilla {
+
+class RemoteLazyInputStreamChild;
+
+class RemoteLazyInputStream final : public nsIAsyncInputStream,
+                                    public nsIInputStreamCallback,
+                                    public nsICloneableInputStreamWithRange,
+                                    public nsIIPCSerializableInputStream,
+                                    public nsIAsyncFileMetadata,
+                                    public nsIInputStreamLength,
+                                    public nsIAsyncInputStreamLength,
+                                    public mozIRemoteLazyInputStream {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+  NS_DECL_NSIINPUTSTREAMCALLBACK
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAMWITHRANGE
+  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
+  NS_DECL_NSIFILEMETADATA
+  NS_DECL_NSIASYNCFILEMETADATA
+  NS_DECL_NSIINPUTSTREAMLENGTH
+  NS_DECL_NSIASYNCINPUTSTREAMLENGTH
+
+  // Create a new lazy RemoteLazyInputStream, and move the provided aInputStream
+  // into storage as referenced by it. May only be called in processes with
+  // RemoteLazyInputStreamStorage.
+  static already_AddRefed<RemoteLazyInputStream> WrapStream(
+      nsIInputStream* aInputStream);
+
+  // mozIRemoteLazyInputStream
+  NS_IMETHOD TakeInternalStream(nsIInputStream** aStream) override;
+  NS_IMETHOD GetInternalStreamID(nsID& aID) override;
+
+ private:
+  friend struct IPC::ParamTraits<mozilla::RemoteLazyInputStream*>;
+
+  // Constructor for an already-closed RemoteLazyInputStream.
+  RemoteLazyInputStream() = default;
+
+  explicit RemoteLazyInputStream(RemoteLazyInputStreamChild* aActor,
+                                 uint64_t aStart = 0,
+                                 uint64_t aLength = UINT64_MAX);
+
+  explicit RemoteLazyInputStream(nsIInputStream* aStream);
+
+  ~RemoteLazyInputStream();
+
+  void StreamNeeded() MOZ_REQUIRES(mMutex);
+
+  // Upon receiving the stream from our actor, we will not wrap it into an async
+  // stream until needed. This allows callers to get access to the underlying
+  // potentially-sync stream using `TakeInternalStream` before reading.
+  nsresult EnsureAsyncRemoteStream() MOZ_REQUIRES(mMutex);
+
+  // Note that data has been read from our input stream, and disconnect from our
+  // remote actor.
+  void MarkConsumed();
+
+  void IPCWrite(IPC::MessageWriter* aWriter);
+  static already_AddRefed<RemoteLazyInputStream> IPCRead(
+      IPC::MessageReader* aReader);
+
+  // Helper method to generate a description of a stream for use in loggging.
+  nsCString Describe() MOZ_REQUIRES(mMutex);
+
+  // Start and length of the slice to apply on this RemoteLazyInputStream when
+  // fetching the underlying stream with `SendStreamNeeded`.
+  const uint64_t mStart = 0;
+  const uint64_t mLength = UINT64_MAX;
+
+  // Any non-const member of this class is protected by mutex because it is
+  // touched on multiple threads.
+  Mutex mMutex{"RemoteLazyInputStream::mMutex"};
+
+  // This is the list of possible states.
+  enum {
+    // The initial state. Only ::Available() can be used without receiving an
+    // error. The available size is known by the actor.
+    eInit,
+
+    // AsyncWait() has been called for the first time. SendStreamNeeded() has
+    // been called and we are waiting for the 'real' inputStream.
+    ePending,
+
+    // When the child receives the stream from the parent, we move to this
+    // state. The received stream is stored in mInnerStream. From now on, any
+    // method call will be forwared to mInnerStream or mAsyncInnerStream.
+    eRunning,
+
+    // If Close() or CloseWithStatus() is called, we move to this state.
+    // mInnerStream is released and any method will return
+    // NS_BASE_STREAM_CLOSED.
+    eClosed,
+  } mState MOZ_GUARDED_BY(mMutex) = eClosed;
+
+  // The actor which will be used to provide the underlying stream or length
+  // information when needed, as well as to efficiently allow transferring the
+  // stream over IPC.
+  //
+  // The connection to our actor will be cleared once the stream has been closed
+  // or has started reading, at which point this stream will be serialized and
+  // cloned as-if it was the underlying stream.
+  RefPtr<RemoteLazyInputStreamChild> mActor MOZ_GUARDED_BY(mMutex);
+
+  nsCOMPtr<nsIInputStream> mInnerStream MOZ_GUARDED_BY(mMutex);
+  nsCOMPtr<nsIAsyncInputStream> mAsyncInnerStream MOZ_GUARDED_BY(mMutex);
+
+  // These 2 values are set only if mState is ePending or eRunning.
+  // RefPtr is used instead of nsCOMPtr to avoid invoking QueryInterface when
+  // assigning in debug builds, as `mInputStreamCallback` may not be threadsafe.
+  RefPtr<nsIInputStreamCallback> mInputStreamCallback MOZ_GUARDED_BY(mMutex);
+  nsCOMPtr<nsIEventTarget> mInputStreamCallbackEventTarget
+      MOZ_GUARDED_BY(mMutex);
+  uint32_t mInputStreamCallbackFlags MOZ_GUARDED_BY(mMutex) = 0;
+  uint32_t mInputStreamCallbackRequestedCount MOZ_GUARDED_BY(mMutex) = 0;
+
+  // These 2 values are set only if mState is ePending.
+  nsCOMPtr<nsIFileMetadataCallback> mFileMetadataCallback
+      MOZ_GUARDED_BY(mMutex);
+  nsCOMPtr<nsIEventTarget> mFileMetadataCallbackEventTarget
+      MOZ_GUARDED_BY(mMutex);
+};
+
+}  // namespace mozilla
+
+template <>
+struct IPC::ParamTraits<mozilla::RemoteLazyInputStream*> {
+  static void Write(IPC::MessageWriter* aWriter,
+                    mozilla::RemoteLazyInputStream* aParam);
+  static bool Read(IPC::MessageReader* aReader,
+                   RefPtr<mozilla::RemoteLazyInputStream>* aResult);
+};
+
+#endif  // mozilla_RemoteLazyInputStream_h