Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 676 insertions, 0 deletions

diff --git a/dom/media/webm/WebMBufferedParser.cpp b/dom/media/webm/WebMBufferedParser.cpp
new file mode 100644
index 0000000000..114fd7df89
--- /dev/null
+++ b/dom/media/webm/WebMBufferedParser.cpp
@@ -0,0 +1,676 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#include "WebMBufferedParser.h"
+
+#include <algorithm>
+
+#include "mozilla/CheckedInt.h"
+#include "nsAlgorithm.h"
+#include "nsThreadUtils.h"
+
+extern mozilla::LazyLogModule gMediaDemuxerLog;
+#define WEBM_DEBUG(arg, ...)                          \
+  MOZ_LOG(gMediaDemuxerLog, mozilla::LogLevel::Debug, \
+          ("WebMBufferedParser(%p)::%s: " arg, this, __func__, ##__VA_ARGS__))
+
+namespace mozilla {
+
+static uint32_t VIntLength(unsigned char aFirstByte, uint32_t* aMask) {
+  uint32_t count = 1;
+  uint32_t mask = 1 << 7;
+  while (count < 8) {
+    if ((aFirstByte & mask) != 0) {
+      break;
+    }
+    mask >>= 1;
+    count += 1;
+  }
+  if (aMask) {
+    *aMask = mask;
+  }
+  NS_ASSERTION(count >= 1 && count <= 8, "Insane VInt length.");
+  return count;
+}
+
+constexpr uint8_t EBML_MAX_ID_LENGTH_DEFAULT = 4;
+constexpr uint8_t EBML_MAX_SIZE_LENGTH_DEFAULT = 8;
+
+WebMBufferedParser::WebMBufferedParser(int64_t aOffset)
+    : mStartOffset(aOffset),
+      mCurrentOffset(aOffset),
+      mInitEndOffset(-1),
+      mBlockEndOffset(-1),
+      mState(READ_ELEMENT_ID),
+      mNextState(READ_ELEMENT_ID),
+      mVIntRaw(false),
+      mLastInitStartOffset(-1),
+      mLastInitSize(0),
+      mEBMLMaxIdLength(EBML_MAX_ID_LENGTH_DEFAULT),
+      mEBMLMaxSizeLength(EBML_MAX_SIZE_LENGTH_DEFAULT),
+      mClusterSyncPos(0),
+      mVIntLeft(0),
+      mBlockSize(0),
+      mClusterTimecode(0),
+      mClusterOffset(-1),
+      mClusterEndOffset(-1),
+      mBlockOffset(0),
+      mBlockTimecode(0),
+      mBlockTimecodeLength(0),
+      mSkipBytes(0),
+      mTimecodeScale(1000000),
+      mGotTimecodeScale(false),
+      mGotClusterTimecode(false) {
+  if (mStartOffset != 0) {
+    mState = FIND_CLUSTER_SYNC;
+  }
+}
+
+MediaResult WebMBufferedParser::Append(const unsigned char* aBuffer,
+                                       uint32_t aLength,
+                                       nsTArray<WebMTimeDataOffset>& aMapping) {
+  static const uint32_t EBML_ID = 0x1a45dfa3;
+  static const uint32_t SEGMENT_ID = 0x18538067;
+  static const uint32_t SEGINFO_ID = 0x1549a966;
+  static const uint32_t TRACKS_ID = 0x1654AE6B;
+  static const uint32_t CLUSTER_ID = 0x1f43b675;
+  static const uint32_t TIMECODESCALE_ID = 0x2ad7b1;
+  static const unsigned char TIMECODE_ID = 0xe7;
+  static const unsigned char BLOCKGROUP_ID = 0xa0;
+  static const unsigned char BLOCK_ID = 0xa1;
+  static const unsigned char SIMPLEBLOCK_ID = 0xa3;
+  static const uint16_t EBML_MAX_ID_LENGTH_ID = 0x42f2;
+  static const uint16_t EBML_MAX_SIZE_LENGTH_ID = 0x42f3;
+  static const uint32_t BLOCK_TIMECODE_LENGTH = 2;
+
+  static const unsigned char CLUSTER_SYNC_ID[] = {0x1f, 0x43, 0xb6, 0x75};
+
+  const unsigned char* p = aBuffer;
+
+  // Parse each byte in aBuffer one-by-one, producing timecodes and updating
+  // aMapping as we go.  Parser pauses at end of stream (which may be at any
+  // point within the parse) and resumes parsing the next time Append is
+  // called with new data.
+  while (p < aBuffer + aLength) {
+    switch (mState) {
+      case READ_ELEMENT_ID:
+        mVIntRaw = true;
+        mState = READ_VINT;
+        mNextState = READ_ELEMENT_SIZE;
+        break;
+      case READ_ELEMENT_SIZE:
+        if (mVInt.mLength > mEBMLMaxIdLength) {
+          nsPrintfCString detail("Invalid element id of length %" PRIu64,
+                                 mVInt.mLength);
+          WEBM_DEBUG("%s", detail.get());
+          return MediaResult(NS_ERROR_FAILURE, detail);
+        }
+        mVIntRaw = false;
+        mElement.mID = mVInt;
+        mState = READ_VINT;
+        mNextState = PARSE_ELEMENT;
+        break;
+      case FIND_CLUSTER_SYNC:
+        if (*p++ == CLUSTER_SYNC_ID[mClusterSyncPos]) {
+          mClusterSyncPos += 1;
+        } else {
+          mClusterSyncPos = 0;
+        }
+        if (mClusterSyncPos == sizeof(CLUSTER_SYNC_ID)) {
+          mVInt.mValue = CLUSTER_ID;
+          mVInt.mLength = sizeof(CLUSTER_SYNC_ID);
+          mState = READ_ELEMENT_SIZE;
+        }
+        break;
+      case PARSE_ELEMENT:
+        if (mVInt.mLength > mEBMLMaxSizeLength) {
+          nsPrintfCString detail("Invalid element size of length %" PRIu64,
+                                 mVInt.mLength);
+          WEBM_DEBUG("%s", detail.get());
+          return MediaResult(NS_ERROR_FAILURE, detail);
+        }
+        mElement.mSize = mVInt;
+        switch (mElement.mID.mValue) {
+          case SEGMENT_ID:
+            mState = READ_ELEMENT_ID;
+            break;
+          case SEGINFO_ID:
+            mGotTimecodeScale = true;
+            mState = READ_ELEMENT_ID;
+            break;
+          case TIMECODE_ID:
+            mVInt = VInt();
+            mVIntLeft = mElement.mSize.mValue;
+            mState = READ_VINT_REST;
+            mNextState = READ_CLUSTER_TIMECODE;
+            break;
+          case TIMECODESCALE_ID:
+            mVInt = VInt();
+            mVIntLeft = mElement.mSize.mValue;
+            mState = READ_VINT_REST;
+            mNextState = READ_TIMECODESCALE;
+            break;
+          case CLUSTER_ID:
+            mClusterOffset = mCurrentOffset + (p - aBuffer) -
+                             (mElement.mID.mLength + mElement.mSize.mLength);
+            // Handle "unknown" length;
+            if (mElement.mSize.mValue + 1 !=
+                uint64_t(1) << (mElement.mSize.mLength * 7)) {
+              mClusterEndOffset = mClusterOffset + mElement.mID.mLength +
+                                  mElement.mSize.mLength +
+                                  mElement.mSize.mValue;
+            } else {
+              mClusterEndOffset = -1;
+            }
+            mGotClusterTimecode = false;
+            mState = READ_ELEMENT_ID;
+            break;
+          case BLOCKGROUP_ID:
+            mState = READ_ELEMENT_ID;
+            break;
+          case SIMPLEBLOCK_ID:
+            /* FALLTHROUGH */
+          case BLOCK_ID:
+            if (!mGotClusterTimecode) {
+              WEBM_DEBUG(
+                  "The Timecode element must appear before any Block or "
+                  "SimpleBlock elements in a Cluster");
+              return MediaResult(
+                  NS_ERROR_FAILURE,
+                  "The Timecode element must appear before any Block or "
+                  "SimpleBlock elements in a Cluster");
+            }
+            mBlockSize = mElement.mSize.mValue;
+            mBlockTimecode = 0;
+            mBlockTimecodeLength = BLOCK_TIMECODE_LENGTH;
+            mBlockOffset = mCurrentOffset + (p - aBuffer) -
+                           (mElement.mID.mLength + mElement.mSize.mLength);
+            mState = READ_VINT;
+            mNextState = READ_BLOCK_TIMECODE;
+            break;
+          case TRACKS_ID:
+            mSkipBytes = mElement.mSize.mValue;
+            mState = CHECK_INIT_FOUND;
+            break;
+          case EBML_MAX_ID_LENGTH_ID:
+          case EBML_MAX_SIZE_LENGTH_ID:
+            if (int64_t currentOffset = mCurrentOffset + (p - aBuffer);
+                currentOffset < mLastInitStartOffset ||
+                currentOffset >= mLastInitStartOffset + mLastInitSize) {
+              nsPrintfCString str("Unexpected %s outside init segment",
+                                  mElement.mID.mValue == EBML_MAX_ID_LENGTH_ID
+                                      ? "EBMLMaxIdLength"
+                                      : "EBMLMaxSizeLength");
+              WEBM_DEBUG("%s", str.get());
+              return MediaResult(NS_ERROR_FAILURE, str);
+            }
+            if (mElement.mSize.mValue > 8) {
+              // https://www.rfc-editor.org/rfc/rfc8794.html (EBML):
+              //   An Unsigned Integer Element MUST declare a length from zero
+              //   to eight octets.
+              nsPrintfCString str("Bad length of %s size",
+                                  mElement.mID.mValue == EBML_MAX_ID_LENGTH_ID
+                                      ? "EBMLMaxIdLength"
+                                      : "EBMLMaxSizeLength");
+              WEBM_DEBUG("%s", str.get());
+              return MediaResult(NS_ERROR_FAILURE, str);
+            }
+            mVInt = VInt();
+            mVIntLeft = mElement.mSize.mValue;
+            mState = READ_VINT_REST;
+            mNextState = mElement.mID.mValue == EBML_MAX_ID_LENGTH_ID
+                             ? READ_EBML_MAX_ID_LENGTH
+                             : READ_EBML_MAX_SIZE_LENGTH;
+            break;
+          case EBML_ID:
+            mLastInitStartOffset =
+                mCurrentOffset + (p - aBuffer) -
+                (mElement.mID.mLength + mElement.mSize.mLength);
+            mLastInitSize = mElement.mSize.mValue;
+            mEBMLMaxIdLength = EBML_MAX_ID_LENGTH_DEFAULT;
+            mEBMLMaxSizeLength = EBML_MAX_SIZE_LENGTH_DEFAULT;
+            mState = READ_ELEMENT_ID;
+            break;
+          default:
+            mSkipBytes = mElement.mSize.mValue;
+            mState = SKIP_DATA;
+            mNextState = READ_ELEMENT_ID;
+            break;
+        }
+        break;
+      case READ_VINT: {
+        unsigned char c = *p++;
+        uint32_t mask;
+        mVInt.mLength = VIntLength(c, &mask);
+        mVIntLeft = mVInt.mLength - 1;
+        mVInt.mValue = mVIntRaw ? c : c & ~mask;
+        mState = READ_VINT_REST;
+        break;
+      }
+      case READ_VINT_REST:
+        if (mVIntLeft) {
+          mVInt.mValue <<= 8;
+          mVInt.mValue |= *p++;
+          mVIntLeft -= 1;
+        } else {
+          mState = mNextState;
+        }
+        break;
+      case READ_TIMECODESCALE:
+        if (!mGotTimecodeScale) {
+          WEBM_DEBUG("Should get the SegmentInfo first");
+          return MediaResult(NS_ERROR_FAILURE,
+                             "TimecodeScale appeared before SegmentInfo");
+        }
+        mTimecodeScale = mVInt.mValue;
+        mState = READ_ELEMENT_ID;
+        break;
+      case READ_CLUSTER_TIMECODE:
+        mClusterTimecode = mVInt.mValue;
+        mGotClusterTimecode = true;
+        mState = READ_ELEMENT_ID;
+        break;
+      case READ_BLOCK_TIMECODE:
+        if (mBlockTimecodeLength) {
+          mBlockTimecode <<= 8;
+          mBlockTimecode |= *p++;
+          mBlockTimecodeLength -= 1;
+        } else {
+          // It's possible we've parsed this data before, so avoid inserting
+          // duplicate WebMTimeDataOffset entries.
+          {
+            int64_t endOffset = mBlockOffset + mBlockSize +
+                                mElement.mID.mLength + mElement.mSize.mLength;
+            uint32_t idx = aMapping.IndexOfFirstElementGt(endOffset);
+            if (idx == 0 || aMapping[idx - 1] != endOffset) {
+              // Don't insert invalid negative timecodes.
+              if (mBlockTimecode >= 0 ||
+                  mClusterTimecode >= uint16_t(abs(mBlockTimecode))) {
+                if (!mGotTimecodeScale) {
+                  WEBM_DEBUG("Should get the TimecodeScale first");
+                  return MediaResult(NS_ERROR_FAILURE,
+                                     "Timecode appeared before SegmentInfo");
+                }
+                uint64_t absTimecode = mClusterTimecode + mBlockTimecode;
+                absTimecode *= mTimecodeScale;
+                // Avoid creating an entry if the timecode is out of order
+                // (invalid according to the WebM specification) so that
+                // ordering invariants of aMapping are not violated.
+                if (idx == 0 || aMapping[idx - 1].mTimecode <= absTimecode ||
+                    (idx + 1 < aMapping.Length() &&
+                     aMapping[idx + 1].mTimecode >= absTimecode)) {
+                  WebMTimeDataOffset entry(endOffset, absTimecode,
+                                           mLastInitStartOffset, mClusterOffset,
+                                           mClusterEndOffset);
+                  aMapping.InsertElementAt(idx, entry);
+                } else {
+                  WEBM_DEBUG("Out of order timecode %" PRIu64
+                             " in Cluster at %" PRId64 " ignored",
+                             absTimecode, mClusterOffset);
+                }
+              }
+            }
+          }
+
+          // Skip rest of block header and the block's payload.
+          mBlockSize -= mVInt.mLength;
+          mBlockSize -= BLOCK_TIMECODE_LENGTH;
+          mSkipBytes = uint32_t(mBlockSize);
+          mState = SKIP_DATA;
+          mNextState = READ_ELEMENT_ID;
+        }
+        break;
+      case READ_EBML_MAX_ID_LENGTH:
+        if (mElement.mSize.mLength == 0) {
+          // https://www.rfc-editor.org/rfc/rfc8794.html (EBML):
+          //   If an Empty Element has a default value declared, then the EBML
+          //   Reader MUST interpret the value of the Empty Element as the
+          //   default value.
+          mVInt.mValue = EBML_MAX_ID_LENGTH_DEFAULT;
+        }
+        if (mVInt.mValue < 4 || mVInt.mValue > 5) {
+          // https://www.ietf.org/archive/id/draft-ietf-cellar-matroska-13.html
+          // (Matroska):
+          //   The EBMLMaxIDLength of the EBML Header MUST be "4".
+          //
+          // Also Matroska:
+          //   Element IDs are encoded using the VINT mechanism described in
+          //   Section 4 of [RFC8794] and can be between one and five octets
+          //   long. Five-octet-long Element IDs are possible only if declared
+          //   in the EBML header.
+          nsPrintfCString detail("Invalid EMBLMaxIdLength %" PRIu64,
+                                 mVInt.mValue);
+          WEBM_DEBUG("%s", detail.get());
+          return MediaResult(NS_ERROR_FAILURE, detail);
+        }
+        mEBMLMaxIdLength = mVInt.mValue;
+        mState = READ_ELEMENT_ID;
+        break;
+      case READ_EBML_MAX_SIZE_LENGTH:
+        if (mElement.mSize.mLength == 0) {
+          // https://www.rfc-editor.org/rfc/rfc8794.html (EBML):
+          //   If an Empty Element has a default value declared, then the EBML
+          //   Reader MUST interpret the value of the Empty Element as the
+          //   default value.
+          mVInt.mValue = EBML_MAX_SIZE_LENGTH_DEFAULT;
+        }
+        if (mVInt.mValue < 1 || mVInt.mValue > 8) {
+          // https://www.ietf.org/archive/id/draft-ietf-cellar-matroska-13.html
+          // (Matroska):
+          //   The EBMLMaxSizeLength of the EBML Header MUST be between "1" and
+          //   "8" inclusive.
+          nsPrintfCString detail("Invalid EMBLMaxSizeLength %" PRIu64,
+                                 mVInt.mValue);
+          WEBM_DEBUG("%s", detail.get());
+          return MediaResult(NS_ERROR_FAILURE, detail);
+        }
+        mEBMLMaxSizeLength = mVInt.mValue;
+        mState = READ_ELEMENT_ID;
+        break;
+      case SKIP_DATA:
+        if (mSkipBytes) {
+          uint32_t left = aLength - (p - aBuffer);
+          left = std::min(left, mSkipBytes);
+          p += left;
+          mSkipBytes -= left;
+        }
+        if (!mSkipBytes) {
+          mBlockEndOffset = mCurrentOffset + (p - aBuffer);
+          mState = mNextState;
+        }
+        break;
+      case CHECK_INIT_FOUND:
+        if (mSkipBytes) {
+          uint32_t left = aLength - (p - aBuffer);
+          left = std::min(left, mSkipBytes);
+          p += left;
+          mSkipBytes -= left;
+        }
+        if (!mSkipBytes) {
+          if (mInitEndOffset < 0) {
+            mInitEndOffset = mCurrentOffset + (p - aBuffer);
+            mBlockEndOffset = mCurrentOffset + (p - aBuffer);
+          }
+          mState = READ_ELEMENT_ID;
+        }
+        break;
+    }
+  }
+
+  NS_ASSERTION(p == aBuffer + aLength, "Must have parsed to end of data.");
+  mCurrentOffset += aLength;
+
+  return NS_OK;
+}
+
+int64_t WebMBufferedParser::EndSegmentOffset(int64_t aOffset) {
+  if (mLastInitStartOffset > aOffset || mClusterOffset > aOffset) {
+    return std::min(
+        mLastInitStartOffset >= 0 ? mLastInitStartOffset : INT64_MAX,
+        mClusterOffset >= 0 ? mClusterOffset : INT64_MAX);
+  }
+  return mBlockEndOffset;
+}
+
+int64_t WebMBufferedParser::GetClusterOffset() const { return mClusterOffset; }
+
+// SyncOffsetComparator and TimeComparator are slightly confusing, in that
+// the nsTArray they're used with (mTimeMapping) is sorted by mEndOffset and
+// these comparators are used on the other fields of WebMTimeDataOffset.
+// This is only valid because timecodes are required to be monotonically
+// increasing within a file (thus establishing an ordering relationship with
+// mTimecode), and mEndOffset is derived from mSyncOffset.
+struct SyncOffsetComparator {
+  bool Equals(const WebMTimeDataOffset& a, const int64_t& b) const {
+    return a.mSyncOffset == b;
+  }
+
+  bool LessThan(const WebMTimeDataOffset& a, const int64_t& b) const {
+    return a.mSyncOffset < b;
+  }
+};
+
+struct TimeComparator {
+  bool Equals(const WebMTimeDataOffset& a, const uint64_t& b) const {
+    return a.mTimecode == b;
+  }
+
+  bool LessThan(const WebMTimeDataOffset& a, const uint64_t& b) const {
+    return a.mTimecode < b;
+  }
+};
+
+bool WebMBufferedState::CalculateBufferedForRange(int64_t aStartOffset,
+                                                  int64_t aEndOffset,
+                                                  uint64_t* aStartTime,
+                                                  uint64_t* aEndTime) {
+  MutexAutoLock lock(mMutex);
+
+  // Find the first WebMTimeDataOffset at or after aStartOffset.
+  uint32_t start = mTimeMapping.IndexOfFirstElementGt(aStartOffset - 1,
+                                                      SyncOffsetComparator());
+  if (start == mTimeMapping.Length()) {
+    return false;
+  }
+
+  // Find the first WebMTimeDataOffset at or before aEndOffset.
+  uint32_t end = mTimeMapping.IndexOfFirstElementGt(aEndOffset);
+  if (end > 0) {
+    end -= 1;
+  }
+
+  // Range is empty.
+  if (end <= start) {
+    return false;
+  }
+
+  NS_ASSERTION(mTimeMapping[start].mSyncOffset >= aStartOffset &&
+                   mTimeMapping[end].mEndOffset <= aEndOffset,
+               "Computed time range must lie within data range.");
+  if (start > 0) {
+    NS_ASSERTION(mTimeMapping[start - 1].mSyncOffset < aStartOffset,
+                 "Must have found least WebMTimeDataOffset for start");
+  }
+  if (end < mTimeMapping.Length() - 1) {
+    NS_ASSERTION(mTimeMapping[end + 1].mEndOffset > aEndOffset,
+                 "Must have found greatest WebMTimeDataOffset for end");
+  }
+
+  MOZ_ASSERT(mTimeMapping[end].mTimecode >= mTimeMapping[end - 1].mTimecode);
+  uint64_t frameDuration =
+      mTimeMapping[end].mTimecode - mTimeMapping[end - 1].mTimecode;
+  *aStartTime = mTimeMapping[start].mTimecode;
+  CheckedUint64 endTime{mTimeMapping[end].mTimecode};
+  endTime += frameDuration;
+  if (!endTime.isValid()) {
+    WEBM_DEBUG("End time overflow during CalculateBufferedForRange.");
+    return false;
+  }
+  *aEndTime = endTime.value();
+  return true;
+}
+
+bool WebMBufferedState::GetOffsetForTime(uint64_t aTime, int64_t* aOffset) {
+  MutexAutoLock lock(mMutex);
+
+  if (mTimeMapping.IsEmpty()) {
+    return false;
+  }
+
+  uint64_t time = aTime;
+  if (time > 0) {
+    time = time - 1;
+  }
+  uint32_t idx = mTimeMapping.IndexOfFirstElementGt(time, TimeComparator());
+  if (idx == mTimeMapping.Length()) {
+    // Clamp to end
+    *aOffset = mTimeMapping[mTimeMapping.Length() - 1].mSyncOffset;
+  } else {
+    // Idx is within array or has been clamped to start
+    *aOffset = mTimeMapping[idx].mSyncOffset;
+  }
+  return true;
+}
+
+void WebMBufferedState::NotifyDataArrived(const unsigned char* aBuffer,
+                                          uint32_t aLength, int64_t aOffset) {
+  uint32_t idx = mRangeParsers.IndexOfFirstElementGt(aOffset - 1);
+  if (idx == 0 || !(mRangeParsers[idx - 1] == aOffset)) {
+    // If the incoming data overlaps an already parsed range, adjust the
+    // buffer so that we only reparse the new data.  It's also possible to
+    // have an overlap where the end of the incoming data is within an
+    // already parsed range, but we don't bother handling that other than by
+    // avoiding storing duplicate timecodes when the parser runs.
+    if (idx != mRangeParsers.Length() &&
+        mRangeParsers[idx].mStartOffset <= aOffset) {
+      // Complete overlap, skip parsing.
+      if (aOffset + aLength <= mRangeParsers[idx].mCurrentOffset) {
+        return;
+      }
+
+      // Partial overlap, adjust the buffer to parse only the new data.
+      int64_t adjust = mRangeParsers[idx].mCurrentOffset - aOffset;
+      NS_ASSERTION(adjust >= 0, "Overlap detection bug.");
+      aBuffer += adjust;
+      aLength -= uint32_t(adjust);
+    } else {
+      mRangeParsers.InsertElementAt(idx, WebMBufferedParser(aOffset));
+      if (idx != 0) {
+        mRangeParsers[idx].SetTimecodeScale(
+            mRangeParsers[0].GetTimecodeScale());
+      }
+    }
+  }
+
+  {
+    MutexAutoLock lock(mMutex);
+    mRangeParsers[idx].Append(aBuffer, aLength, mTimeMapping);
+  }
+
+  // Merge parsers with overlapping regions and clean up the remnants.
+  uint32_t i = 0;
+  while (i + 1 < mRangeParsers.Length()) {
+    if (mRangeParsers[i].mCurrentOffset >= mRangeParsers[i + 1].mStartOffset) {
+      mRangeParsers[i + 1].mStartOffset = mRangeParsers[i].mStartOffset;
+      mRangeParsers[i + 1].mInitEndOffset = mRangeParsers[i].mInitEndOffset;
+      mRangeParsers.RemoveElementAt(i);
+    } else {
+      i += 1;
+    }
+  }
+
+  if (mRangeParsers.IsEmpty()) {
+    return;
+  }
+
+  MutexAutoLock lock(mMutex);
+  mLastBlockOffset = mRangeParsers.LastElement().mBlockEndOffset;
+}
+
+void WebMBufferedState::Reset() {
+  MutexAutoLock lock(mMutex);
+  mRangeParsers.Clear();
+  mTimeMapping.Clear();
+}
+
+void WebMBufferedState::UpdateIndex(const MediaByteRangeSet& aRanges,
+                                    MediaResource* aResource) {
+  for (uint32_t index = 0; index < aRanges.Length(); index++) {
+    const MediaByteRange& range = aRanges[index];
+    int64_t offset = range.mStart;
+    uint32_t length = range.mEnd - range.mStart;
+
+    uint32_t idx = mRangeParsers.IndexOfFirstElementGt(offset - 1);
+    if (!idx || !(mRangeParsers[idx - 1] == offset)) {
+      // If the incoming data overlaps an already parsed range, adjust the
+      // buffer so that we only reparse the new data.  It's also possible to
+      // have an overlap where the end of the incoming data is within an
+      // already parsed range, but we don't bother handling that other than by
+      // avoiding storing duplicate timecodes when the parser runs.
+      if (idx != mRangeParsers.Length() &&
+          mRangeParsers[idx].mStartOffset <= offset) {
+        // Complete overlap, skip parsing.
+        if (offset + length <= mRangeParsers[idx].mCurrentOffset) {
+          continue;
+        }
+
+        // Partial overlap, adjust the buffer to parse only the new data.
+        int64_t adjust = mRangeParsers[idx].mCurrentOffset - offset;
+        NS_ASSERTION(adjust >= 0, "Overlap detection bug.");
+        offset += adjust;
+        length -= uint32_t(adjust);
+      } else {
+        mRangeParsers.InsertElementAt(idx, WebMBufferedParser(offset));
+        if (idx) {
+          mRangeParsers[idx].SetTimecodeScale(
+              mRangeParsers[0].GetTimecodeScale());
+        }
+      }
+    }
+
+    MediaResourceIndex res(aResource);
+    while (length > 0) {
+      static const uint32_t BLOCK_SIZE = 1048576;
+      uint32_t block = std::min(length, BLOCK_SIZE);
+      RefPtr<MediaByteBuffer> bytes = res.CachedMediaReadAt(offset, block);
+      if (!bytes) {
+        break;
+      }
+      NotifyDataArrived(bytes->Elements(), bytes->Length(), offset);
+      length -= bytes->Length();
+      offset += bytes->Length();
+    }
+  }
+}
+
+int64_t WebMBufferedState::GetInitEndOffset() {
+  if (mRangeParsers.IsEmpty()) {
+    return -1;
+  }
+  return mRangeParsers[0].mInitEndOffset;
+}
+
+int64_t WebMBufferedState::GetLastBlockOffset() {
+  MutexAutoLock lock(mMutex);
+
+  return mLastBlockOffset;
+}
+
+bool WebMBufferedState::GetStartTime(uint64_t* aTime) {
+  MutexAutoLock lock(mMutex);
+
+  if (mTimeMapping.IsEmpty()) {
+    return false;
+  }
+
+  uint32_t idx = mTimeMapping.IndexOfFirstElementGt(0, SyncOffsetComparator());
+  if (idx == mTimeMapping.Length()) {
+    return false;
+  }
+
+  *aTime = mTimeMapping[idx].mTimecode;
+  return true;
+}
+
+bool WebMBufferedState::GetNextKeyframeTime(uint64_t aTime,
+                                            uint64_t* aKeyframeTime) {
+  MutexAutoLock lock(mMutex);
+  int64_t offset = 0;
+  bool rv = GetOffsetForTime(aTime, &offset);
+  if (!rv) {
+    return false;
+  }
+  uint32_t idx =
+      mTimeMapping.IndexOfFirstElementGt(offset, SyncOffsetComparator());
+  if (idx == mTimeMapping.Length()) {
+    return false;
+  }
+  *aKeyframeTime = mTimeMapping[idx].mTimecode;
+  return true;
+}
+}  // namespace mozilla
+
+#undef WEBM_DEBUG