Bug 818672 - Implement BufferMediaResource; r=cpearce,roc

content/media/BufferMediaResource.h

@@ -0,0 +1,144 @@
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#if !defined(BufferMediaResource_h_)
+#define BufferMediaResource_h_
+
+#include "MediaResource.h"
+#include "nsISeekableStream.h"
+#include "nsIPrincipal.h"
+#include <algorithm>
+
+namespace mozilla {
+
+// A simple MediaResource based on an in memory buffer.  This class accepts
+// the address and the length of the buffer, and simulates a read/seek API
+// on top of it.  The Read implementation involves copying memory, which is
+// unfortunate, but the MediaResource interface mandates that.
+class BufferMediaResource : public MediaResource
+{
+public:
+  BufferMediaResource(const uint8_t* aBuffer,
+                      uint32_t aLength,
+                      nsIPrincipal* aPrincipal) :
+    mBuffer(aBuffer),
+    mLength(aLength),
+    mOffset(0),
+    mPrincipal(aPrincipal)
+  {
+    MOZ_COUNT_CTOR(BufferMediaResource);
+  }
+
+  virtual ~BufferMediaResource()
+  {
+    MOZ_COUNT_DTOR(BufferMediaResource);
+  }
+
+  virtual nsresult Close() { return NS_OK; }
+  virtual void Suspend(bool aCloseImmediately) {}
+  virtual void Resume() {}
+  // Get the current principal for the channel
+  virtual already_AddRefed<nsIPrincipal> GetCurrentPrincipal()
+  {
+    nsCOMPtr<nsIPrincipal> principal = mPrincipal;
+    return principal.forget();
+  }
+  virtual bool CanClone() { return false; }
+  virtual MediaResource* CloneData(MediaDecoder* aDecoder)
+  {
+    return nullptr;
+  }
+
+  // These methods are called off the main thread.
+  // The mode is initially MODE_PLAYBACK.
+  virtual void SetReadMode(MediaCacheStream::ReadMode aMode) {}
+  virtual void SetPlaybackRate(uint32_t aBytesPerSecond) {}
+  virtual nsresult Read(char* aBuffer, uint32_t aCount, uint32_t* aBytes)
+  {
+    *aBytes = std::min(mLength - mOffset, aCount);
+    memcpy(aBuffer, mBuffer + mOffset, *aBytes);
+    mOffset += *aBytes;
+    MOZ_ASSERT(mOffset <= mLength);
+    return NS_OK;
+  }
+  virtual nsresult Seek(int32_t aWhence, int64_t aOffset)
+  {
+    MOZ_ASSERT(aOffset <= UINT32_MAX);
+    switch (aWhence) {
+    case nsISeekableStream::NS_SEEK_SET:
+      if (aOffset < 0 || aOffset > mLength) {
+        return NS_ERROR_FAILURE;
+      }
+      mOffset = static_cast<uint32_t> (aOffset);
+      break;
+    case nsISeekableStream::NS_SEEK_CUR:
+      if (aOffset >= mLength - mOffset) {
+        return NS_ERROR_FAILURE;
+      }
+      mOffset += static_cast<uint32_t> (aOffset);
+      break;
+    case nsISeekableStream::NS_SEEK_END:
+      if (aOffset < 0 || aOffset > mLength) {
+        return NS_ERROR_FAILURE;
+      }
+      mOffset = mLength - aOffset;
+      break;
+    }
+
+    return NS_OK;
+  }
+  virtual void StartSeekingForMetadata() {}
+  virtual void EndSeekingForMetadata() {}
+  virtual int64_t Tell() { return mOffset; }
+
+  virtual void Pin() {}
+  virtual void Unpin() {}
+  virtual double GetDownloadRate(bool* aIsReliable) { return 0.; }
+  virtual int64_t GetLength() { return mLength; }
+  virtual int64_t GetNextCachedData(int64_t aOffset) { return aOffset; }
+  virtual int64_t GetCachedDataEnd(int64_t aOffset) { return mLength; }
+  virtual bool IsDataCachedToEndOfResource(int64_t aOffset) { return true; }
+  virtual bool IsSuspendedByCache(MediaResource** aActiveResource) { return false; }
+  virtual bool IsSuspended() { return false; }
+  virtual nsresult ReadFromCache(char* aBuffer,
+                                 int64_t aOffset,
+                                 uint32_t aCount)
+  {
+    if (aOffset < 0) {
+      return NS_ERROR_FAILURE;
+    }
+
+    uint32_t bytes = std::min(mLength - static_cast<uint32_t>(aOffset), aCount);
+    memcpy(aBuffer, mBuffer + aOffset, bytes);
+    return NS_OK;
+  }
+
+  virtual nsresult Open(nsIStreamListener** aStreamListener)
+  {
+    return NS_ERROR_FAILURE;
+  }
+
+  virtual nsresult OpenByteRange(nsIStreamListener** aStreamListener,
+                                 MediaByteRange const &aByteRange)
+  {
+    return NS_ERROR_FAILURE;
+  }
+
+  virtual nsresult GetCachedRanges(nsTArray<MediaByteRange>& aRanges)
+  {
+    aRanges.AppendElement(MediaByteRange(0, mLength));
+    return NS_OK;
+  }
+
+private:
+  const uint8_t * mBuffer;
+  uint32_t mLength;
+  uint32_t mOffset;
+  nsCOMPtr<nsIPrincipal> mPrincipal;
+};
+
+}
+
+#endif

content/media/Makefile.in

@@ -18,6 +18,7 @@ EXPORTS = \
   AbstractMediaDecoder.h \
   AudioSampleFormat.h \
   AudioSegment.h \
+  BufferMediaResource.h \
   DecoderTraits.h \
   FileBlockCache.h \
   MediaDecoderOwner.h \