1 files changed, 260 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java
new file mode 100644
index 0000000000..b4e160fa74
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/mkv/DefaultEbmlReader.java
@@ -0,0 +1,260 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.mkv;
+
+import androidx.annotation.IntDef;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.ParserException;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ExtractorInput;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Assertions;
+import java.io.EOFException;
+import java.io.IOException;
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.ArrayDeque;
+
+/**
+ * Default implementation of {@link EbmlReader}.
+ */
+/* package */ final class DefaultEbmlReader implements EbmlReader {
+
+  @Documented
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({ELEMENT_STATE_READ_ID, ELEMENT_STATE_READ_CONTENT_SIZE, ELEMENT_STATE_READ_CONTENT})
+  private @interface ElementState {}
+
+  private static final int ELEMENT_STATE_READ_ID = 0;
+  private static final int ELEMENT_STATE_READ_CONTENT_SIZE = 1;
+  private static final int ELEMENT_STATE_READ_CONTENT = 2;
+
+  private static final int MAX_ID_BYTES = 4;
+  private static final int MAX_LENGTH_BYTES = 8;
+
+  private static final int MAX_INTEGER_ELEMENT_SIZE_BYTES = 8;
+  private static final int VALID_FLOAT32_ELEMENT_SIZE_BYTES = 4;
+  private static final int VALID_FLOAT64_ELEMENT_SIZE_BYTES = 8;
+
+  private final byte[] scratch;
+  private final ArrayDeque<MasterElement> masterElementsStack;
+  private final VarintReader varintReader;
+
+  private EbmlProcessor processor;
+  private @ElementState int elementState;
+  private int elementId;
+  private long elementContentSize;
+
+  public DefaultEbmlReader() {
+    scratch = new byte[8];
+    masterElementsStack = new ArrayDeque<>();
+    varintReader = new VarintReader();
+  }
+
+  @Override
+  public void init(EbmlProcessor processor) {
+    this.processor = processor;
+  }
+
+  @Override
+  public void reset() {
+    elementState = ELEMENT_STATE_READ_ID;
+    masterElementsStack.clear();
+    varintReader.reset();
+  }
+
+  @Override
+  public boolean read(ExtractorInput input) throws IOException, InterruptedException {
+    Assertions.checkNotNull(processor);
+    while (true) {
+      if (!masterElementsStack.isEmpty()
+          && input.getPosition() >= masterElementsStack.peek().elementEndPosition) {
+        processor.endMasterElement(masterElementsStack.pop().elementId);
+        return true;
+      }
+
+      if (elementState == ELEMENT_STATE_READ_ID) {
+        long result = varintReader.readUnsignedVarint(input, true, false, MAX_ID_BYTES);
+        if (result == C.RESULT_MAX_LENGTH_EXCEEDED) {
+          result = maybeResyncToNextLevel1Element(input);
+        }
+        if (result == C.RESULT_END_OF_INPUT) {
+          return false;
+        }
+        // Element IDs are at most 4 bytes, so we can cast to integers.
+        elementId = (int) result;
+        elementState = ELEMENT_STATE_READ_CONTENT_SIZE;
+      }
+
+      if (elementState == ELEMENT_STATE_READ_CONTENT_SIZE) {
+        elementContentSize = varintReader.readUnsignedVarint(input, false, true, MAX_LENGTH_BYTES);
+        elementState = ELEMENT_STATE_READ_CONTENT;
+      }
+
+      @EbmlProcessor.ElementType int type = processor.getElementType(elementId);
+      switch (type) {
+        case EbmlProcessor.ELEMENT_TYPE_MASTER:
+          long elementContentPosition = input.getPosition();
+          long elementEndPosition = elementContentPosition + elementContentSize;
+          masterElementsStack.push(new MasterElement(elementId, elementEndPosition));
+          processor.startMasterElement(elementId, elementContentPosition, elementContentSize);
+          elementState = ELEMENT_STATE_READ_ID;
+          return true;
+        case EbmlProcessor.ELEMENT_TYPE_UNSIGNED_INT:
+          if (elementContentSize > MAX_INTEGER_ELEMENT_SIZE_BYTES) {
+            throw new ParserException("Invalid integer size: " + elementContentSize);
+          }
+          processor.integerElement(elementId, readInteger(input, (int) elementContentSize));
+          elementState = ELEMENT_STATE_READ_ID;
+          return true;
+        case EbmlProcessor.ELEMENT_TYPE_FLOAT:
+          if (elementContentSize != VALID_FLOAT32_ELEMENT_SIZE_BYTES
+              && elementContentSize != VALID_FLOAT64_ELEMENT_SIZE_BYTES) {
+            throw new ParserException("Invalid float size: " + elementContentSize);
+          }
+          processor.floatElement(elementId, readFloat(input, (int) elementContentSize));
+          elementState = ELEMENT_STATE_READ_ID;
+          return true;
+        case EbmlProcessor.ELEMENT_TYPE_STRING:
+          if (elementContentSize > Integer.MAX_VALUE) {
+            throw new ParserException("String element size: " + elementContentSize);
+          }
+          processor.stringElement(elementId, readString(input, (int) elementContentSize));
+          elementState = ELEMENT_STATE_READ_ID;
+          return true;
+        case EbmlProcessor.ELEMENT_TYPE_BINARY:
+          processor.binaryElement(elementId, (int) elementContentSize, input);
+          elementState = ELEMENT_STATE_READ_ID;
+          return true;
+        case EbmlProcessor.ELEMENT_TYPE_UNKNOWN:
+          input.skipFully((int) elementContentSize);
+          elementState = ELEMENT_STATE_READ_ID;
+          break;
+        default:
+          throw new ParserException("Invalid element type " + type);
+      }
+    }
+  }
+
+  /**
+   * Does a byte by byte search to try and find the next level 1 element. This method is called if
+   * some invalid data is encountered in the parser.
+   *
+   * @param input The {@link ExtractorInput} from which data has to be read.
+   * @return id of the next level 1 element that has been found.
+   * @throws EOFException If the end of input was encountered when searching for the next level 1
+   *     element.
+   * @throws IOException If an error occurs reading from the input.
+   * @throws InterruptedException If the thread is interrupted.
+   */
+  private long maybeResyncToNextLevel1Element(ExtractorInput input) throws IOException,
+      InterruptedException {
+    input.resetPeekPosition();
+    while (true) {
+      input.peekFully(scratch, 0, MAX_ID_BYTES);
+      int varintLength = VarintReader.parseUnsignedVarintLength(scratch[0]);
+      if (varintLength != C.LENGTH_UNSET && varintLength <= MAX_ID_BYTES) {
+        int potentialId = (int) VarintReader.assembleVarint(scratch, varintLength, false);
+        if (processor.isLevel1Element(potentialId)) {
+          input.skipFully(varintLength);
+          return potentialId;
+        }
+      }
+      input.skipFully(1);
+    }
+  }
+
+  /**
+   * Reads and returns an integer of length {@code byteLength} from the {@link ExtractorInput}.
+   *
+   * @param input The {@link ExtractorInput} from which to read.
+   * @param byteLength The length of the integer being read.
+   * @return The read integer value.
+   * @throws IOException If an error occurs reading from the input.
+   * @throws InterruptedException If the thread is interrupted.
+   */
+  private long readInteger(ExtractorInput input, int byteLength)
+      throws IOException, InterruptedException {
+    input.readFully(scratch, 0, byteLength);
+    long value = 0;
+    for (int i = 0; i < byteLength; i++) {
+      value = (value << 8) | (scratch[i] & 0xFF);
+    }
+    return value;
+  }
+
+  /**
+   * Reads and returns a float of length {@code byteLength} from the {@link ExtractorInput}.
+   *
+   * @param input The {@link ExtractorInput} from which to read.
+   * @param byteLength The length of the float being read.
+   * @return The read float value.
+   * @throws IOException If an error occurs reading from the input.
+   * @throws InterruptedException If the thread is interrupted.
+   */
+  private double readFloat(ExtractorInput input, int byteLength)
+      throws IOException, InterruptedException {
+    long integerValue = readInteger(input, byteLength);
+    double floatValue;
+    if (byteLength == VALID_FLOAT32_ELEMENT_SIZE_BYTES) {
+      floatValue = Float.intBitsToFloat((int) integerValue);
+    } else {
+      floatValue = Double.longBitsToDouble(integerValue);
+    }
+    return floatValue;
+  }
+
+  /**
+   * Reads a string of length {@code byteLength} from the {@link ExtractorInput}. Zero padding is
+   * removed, so the returned string may be shorter than {@code byteLength}.
+   *
+   * @param input The {@link ExtractorInput} from which to read.
+   * @param byteLength The length of the string being read, including zero padding.
+   * @return The read string value.
+   * @throws IOException If an error occurs reading from the input.
+   * @throws InterruptedException If the thread is interrupted.
+   */
+  private String readString(ExtractorInput input, int byteLength)
+      throws IOException, InterruptedException {
+    if (byteLength == 0) {
+      return "";
+    }
+    byte[] stringBytes = new byte[byteLength];
+    input.readFully(stringBytes, 0, byteLength);
+    // Remove zero padding.
+    int trimmedLength = byteLength;
+    while (trimmedLength > 0 && stringBytes[trimmedLength - 1] == 0) {
+      trimmedLength--;
+    }
+    return new String(stringBytes, 0, trimmedLength);
+  }
+
+  /**
+   * Used in {@link #masterElementsStack} to track when the current master element ends, so that
+   * {@link EbmlProcessor#endMasterElement(int)} can be called.
+   */
+  private static final class MasterElement {
+
+    private final int elementId;
+    private final long elementEndPosition;
+
+    private MasterElement(int elementId, long elementEndPosition) {
+      this.elementId = elementId;
+      this.elementEndPosition = elementEndPosition;
+    }
+
+  }
+
+}