1 files changed, 102 insertions, 0 deletions
diff --git a/xpcom/io/SlicedInputStream.h b/xpcom/io/SlicedInputStream.h
new file mode 100644
index 0000000000..30b6c118ab
--- /dev/null
+++ b/xpcom/io/SlicedInputStream.h
@@ -0,0 +1,102 @@
+/* -*- 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 SlicedInputStream_h
+#define SlicedInputStream_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Mutex.h"
+#include "nsCOMPtr.h"
+#include "nsIAsyncInputStream.h"
+#include "nsICloneableInputStream.h"
+#include "nsIIPCSerializableInputStream.h"
+#include "nsISeekableStream.h"
+#include "nsIInputStreamLength.h"
+
+namespace mozilla {
+
+// A wrapper for a slice of an underlying input stream.
+
+class SlicedInputStream final : public nsIAsyncInputStream,
+                                public nsICloneableInputStream,
+                                public nsIIPCSerializableInputStream,
+                                public nsISeekableStream,
+                                public nsIInputStreamCallback,
+                                public nsIInputStreamLength,
+                                public nsIAsyncInputStreamLength,
+                                public nsIInputStreamLengthCallback {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+  NS_DECL_NSICLONEABLEINPUTSTREAM
+  NS_DECL_NSIIPCSERIALIZABLEINPUTSTREAM
+  NS_DECL_NSISEEKABLESTREAM
+  NS_DECL_NSITELLABLESTREAM
+  NS_DECL_NSIINPUTSTREAMCALLBACK
+  NS_DECL_NSIINPUTSTREAMLENGTH
+  NS_DECL_NSIASYNCINPUTSTREAMLENGTH
+  NS_DECL_NSIINPUTSTREAMLENGTHCALLBACK
+
+  // Create an input stream whose data comes from a slice of aInputStream.  The
+  // slice begins at aStart bytes beyond aInputStream's current position, and
+  // extends for a maximum of aLength bytes.  If aInputStream contains fewer
+  // than aStart bytes, reading from SlicedInputStream returns no data.  If
+  // aInputStream contains more than aStart bytes, but fewer than aStart +
+  // aLength bytes, reading from SlicedInputStream returns as many bytes as can
+  // be consumed from aInputStream after reading aLength bytes.
+  //
+  // aInputStream should not be read from after constructing a
+  // SlicedInputStream wrapper around it.
+
+  SlicedInputStream(already_AddRefed<nsIInputStream> aInputStream,
+                    uint64_t aStart, uint64_t aLength);
+
+  // This CTOR is meant to be used just for IPC.
+  SlicedInputStream();
+
+ private:
+  ~SlicedInputStream();
+
+  void SetSourceStream(already_AddRefed<nsIInputStream> aInputStream);
+
+  uint64_t AdjustRange(uint64_t aRange);
+
+  nsCOMPtr<nsIInputStream> mInputStream;
+
+  // Raw pointers because these are just QI of mInputStream.
+  nsICloneableInputStream* mWeakCloneableInputStream;
+  nsIIPCSerializableInputStream* mWeakIPCSerializableInputStream;
+  nsISeekableStream* mWeakSeekableInputStream;
+  nsITellableStream* mWeakTellableInputStream;
+  nsIAsyncInputStream* mWeakAsyncInputStream;
+  nsIInputStreamLength* mWeakInputStreamLength;
+  nsIAsyncInputStreamLength* mWeakAsyncInputStreamLength;
+
+  uint64_t mStart;
+  uint64_t mLength;
+  uint64_t mCurPos;
+
+  bool mClosed;
+
+  // These four are used for AsyncWait. They are protected by mutex because
+  // touched on multiple threads.
+  nsCOMPtr<nsIInputStreamCallback> mAsyncWaitCallback MOZ_GUARDED_BY(mMutex);
+  nsCOMPtr<nsIEventTarget> mAsyncWaitEventTarget MOZ_GUARDED_BY(mMutex);
+  uint32_t mAsyncWaitFlags MOZ_GUARDED_BY(mMutex);
+  uint32_t mAsyncWaitRequestedCount MOZ_GUARDED_BY(mMutex);
+
+  // This is use for nsIAsyncInputStreamLength::AsyncWait.
+  // This is protected by mutex.
+  nsCOMPtr<nsIInputStreamLengthCallback> mAsyncWaitLengthCallback
+      MOZ_GUARDED_BY(mMutex);
+
+  Mutex mMutex;
+};
+
+}  // namespace mozilla
+
+#endif  // SlicedInputStream_h