camera/exif/ExifParser.java

/*
 * Copyright (C) 2012 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 com.android.dialer.callcomposer.camera.exif;

import android.annotation.SuppressLint;
import com.android.dialer.common.LogUtil;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteOrder;
import java.nio.charset.Charset;
import java.util.Map.Entry;
import java.util.TreeMap;

/**
 * This class provides a low-level EXIF parsing API. Given a JPEG format InputStream, the caller can
 * request which IFD's to read via {@link #parse(java.io.InputStream, int)} with given options.
 *
 * <p>Below is an example of getting EXIF data from IFD 0 and EXIF IFD using the parser.
 *
 * <pre>
 * void parse() {
 *     ExifParser parser = ExifParser.parse(mImageInputStream,
 *             ExifParser.OPTION_IFD_0 | ExifParser.OPTIONS_IFD_EXIF);
 *     int event = parser.next();
 *     while (event != ExifParser.EVENT_END) {
 *         switch (event) {
 *             case ExifParser.EVENT_START_OF_IFD:
 *                 break;
 *             case ExifParser.EVENT_NEW_TAG:
 *                 ExifTag tag = parser.getTag();
 *                 if (!tag.hasValue()) {
 *                     parser.registerForTagValue(tag);
 *                 } else {
 *                     processTag(tag);
 *                 }
 *                 break;
 *             case ExifParser.EVENT_VALUE_OF_REGISTERED_TAG:
 *                 tag = parser.getTag();
 *                 if (tag.getDataType() != ExifTag.TYPE_UNDEFINED) {
 *                     processTag(tag);
 *                 }
 *                 break;
 *         }
 *         event = parser.next();
 *     }
 * }
 *
 * void processTag(ExifTag tag) {
 *     // process the tag as you like.
 * }
 * </pre>
 */
public class ExifParser {
  private static final boolean LOGV = false;
  /**
   * When the parser reaches a new IFD area. Call {@link #getCurrentIfd()} to know which IFD we are
   * in.
   */
  static final int EVENT_START_OF_IFD = 0;
  /** When the parser reaches a new tag. Call {@link #getTag()}to get the corresponding tag. */
  static final int EVENT_NEW_TAG = 1;
  /**
   * When the parser reaches the value area of tag that is registered by {@link
   * #registerForTagValue(ExifTag)} previously. Call {@link #getTag()} to get the corresponding tag.
   */
  static final int EVENT_VALUE_OF_REGISTERED_TAG = 2;

  /** When the parser reaches the compressed image area. */
  static final int EVENT_COMPRESSED_IMAGE = 3;
  /**
   * When the parser reaches the uncompressed image strip. Call {@link #getStripIndex()} to get the
   * index of the strip.
   *
   * @see #getStripIndex()
   */
  static final int EVENT_UNCOMPRESSED_STRIP = 4;
  /** When there is nothing more to parse. */
  static final int EVENT_END = 5;

  /** Option bit to request to parse IFD0. */
  private static final int OPTION_IFD_0 = 1;
  /** Option bit to request to parse IFD1. */
  private static final int OPTION_IFD_1 = 1 << 1;
  /** Option bit to request to parse Exif-IFD. */
  private static final int OPTION_IFD_EXIF = 1 << 2;
  /** Option bit to request to parse GPS-IFD. */
  private static final int OPTION_IFD_GPS = 1 << 3;
  /** Option bit to request to parse Interoperability-IFD. */
  private static final int OPTION_IFD_INTEROPERABILITY = 1 << 4;
  /** Option bit to request to parse thumbnail. */
  private static final int OPTION_THUMBNAIL = 1 << 5;

  private static final int EXIF_HEADER = 0x45786966; // EXIF header "Exif"
  private static final short EXIF_HEADER_TAIL = (short) 0x0000; // EXIF header in APP1

  // TIFF header
  private static final short LITTLE_ENDIAN_TAG = (short) 0x4949; // "II"
  private static final short BIG_ENDIAN_TAG = (short) 0x4d4d; // "MM"
  private static final short TIFF_HEADER_TAIL = 0x002A;

  private static final int TAG_SIZE = 12;
  private static final int OFFSET_SIZE = 2;

  private static final Charset US_ASCII = Charset.forName("US-ASCII");

  private static final int DEFAULT_IFD0_OFFSET = 8;

  private final CountedDataInputStream tiffStream;
  private final int options;
  private int ifdStartOffset = 0;
  private int numOfTagInIfd = 0;
  private int ifdType;
  private ExifTag tag;
  private ImageEvent imageEvent;
  private ExifTag stripSizeTag;
  private ExifTag jpegSizeTag;
  private boolean needToParseOffsetsInCurrentIfd;
  private boolean containExifData = false;
  private int app1End;
  private byte[] dataAboveIfd0;
  private int ifd0Position;
  private final ExifInterface mInterface;

  private static final short TAG_EXIF_IFD = ExifInterface.getTrueTagKey(ExifInterface.TAG_EXIF_IFD);
  private static final short TAG_GPS_IFD = ExifInterface.getTrueTagKey(ExifInterface.TAG_GPS_IFD);
  private static final short TAG_INTEROPERABILITY_IFD =
      ExifInterface.getTrueTagKey(ExifInterface.TAG_INTEROPERABILITY_IFD);
  private static final short TAG_JPEG_INTERCHANGE_FORMAT =
      ExifInterface.getTrueTagKey(ExifInterface.TAG_JPEG_INTERCHANGE_FORMAT);
  private static final short TAG_JPEG_INTERCHANGE_FORMAT_LENGTH =
      ExifInterface.getTrueTagKey(ExifInterface.TAG_JPEG_INTERCHANGE_FORMAT_LENGTH);
  private static final short TAG_STRIP_OFFSETS =
      ExifInterface.getTrueTagKey(ExifInterface.TAG_STRIP_OFFSETS);
  private static final short TAG_STRIP_BYTE_COUNTS =
      ExifInterface.getTrueTagKey(ExifInterface.TAG_STRIP_BYTE_COUNTS);

  private final TreeMap<Integer, Object> correspondingEvent = new TreeMap<>();

  private boolean isIfdRequested(int ifdType) {
    switch (ifdType) {
      case IfdId.TYPE_IFD_0:
        return (options & OPTION_IFD_0) != 0;
      case IfdId.TYPE_IFD_1:
        return (options & OPTION_IFD_1) != 0;
      case IfdId.TYPE_IFD_EXIF:
        return (options & OPTION_IFD_EXIF) != 0;
      case IfdId.TYPE_IFD_GPS:
        return (options & OPTION_IFD_GPS) != 0;
      case IfdId.TYPE_IFD_INTEROPERABILITY:
        return (options & OPTION_IFD_INTEROPERABILITY) != 0;
    }
    return false;
  }

  private boolean isThumbnailRequested() {
    return (options & OPTION_THUMBNAIL) != 0;
  }

  private ExifParser(InputStream inputStream, int options, ExifInterface iRef)
      throws IOException, ExifInvalidFormatException {
    if (inputStream == null) {
      throw new IOException("Null argument inputStream to ExifParser");
    }
    if (LOGV) {
      LogUtil.v("ExifParser.ExifParser", "Reading exif...");
    }
    mInterface = iRef;
    containExifData = seekTiffData(inputStream);
    tiffStream = new CountedDataInputStream(inputStream);
    this.options = options;
    if (!containExifData) {
      return;
    }

    parseTiffHeader();
    long offset = tiffStream.readUnsignedInt();
    if (offset > Integer.MAX_VALUE) {
      throw new ExifInvalidFormatException("Invalid offset " + offset);
    }
    ifd0Position = (int) offset;
    ifdType = IfdId.TYPE_IFD_0;
    if (isIfdRequested(IfdId.TYPE_IFD_0) || needToParseOffsetsInCurrentIfd()) {
      registerIfd(IfdId.TYPE_IFD_0, offset);
      if (offset != DEFAULT_IFD0_OFFSET) {
        dataAboveIfd0 = new byte[(int) offset - DEFAULT_IFD0_OFFSET];
        read(dataAboveIfd0);
      }
    }
  }

  /**
   * Parses the the given InputStream with the given options
   *
   * @exception java.io.IOException
   * @exception ExifInvalidFormatException
   */
  protected static ExifParser parse(InputStream inputStream, int options, ExifInterface iRef)
      throws IOException, ExifInvalidFormatException {
    return new ExifParser(inputStream, options, iRef);
  }

  /**
   * Parses the the given InputStream with default options; that is, every IFD and thumbnaill will
   * be parsed.
   *
   * @exception java.io.IOException
   * @exception ExifInvalidFormatException
   * @see #parse(java.io.InputStream, int, ExifInterface)
   */
  protected static ExifParser parse(InputStream inputStream, ExifInterface iRef)
      throws IOException, ExifInvalidFormatException {
    return new ExifParser(
        inputStream,
        OPTION_IFD_0
            | OPTION_IFD_1
            | OPTION_IFD_EXIF
            | OPTION_IFD_GPS
            | OPTION_IFD_INTEROPERABILITY
            | OPTION_THUMBNAIL,
        iRef);
  }

  /**
   * Moves the parser forward and returns the next parsing event
   *
   * @exception java.io.IOException
   * @exception ExifInvalidFormatException
   * @see #EVENT_START_OF_IFD
   * @see #EVENT_NEW_TAG
   * @see #EVENT_VALUE_OF_REGISTERED_TAG
   * @see #EVENT_COMPRESSED_IMAGE
   * @see #EVENT_UNCOMPRESSED_STRIP
   * @see #EVENT_END
   */
  protected int next() throws IOException, ExifInvalidFormatException {
    if (!containExifData) {
      return EVENT_END;
    }
    int offset = tiffStream.getReadByteCount();
    int endOfTags = ifdStartOffset + OFFSET_SIZE + TAG_SIZE * numOfTagInIfd;
    if (offset < endOfTags) {
      tag = readTag();
      if (tag == null) {
        return next();
      }
      if (needToParseOffsetsInCurrentIfd) {
        checkOffsetOrImageTag(tag);
      }
      return EVENT_NEW_TAG;
    } else if (offset == endOfTags) {
      // There is a link to ifd1 at the end of ifd0
      if (ifdType == IfdId.TYPE_IFD_0) {
        long ifdOffset = readUnsignedLong();
        if (isIfdRequested(IfdId.TYPE_IFD_1) || isThumbnailRequested()) {
          if (ifdOffset != 0) {
            registerIfd(IfdId.TYPE_IFD_1, ifdOffset);
          }
        }
      } else {
        int offsetSize = 4;
        // Some camera models use invalid length of the offset
        if (correspondingEvent.size() > 0) {
          offsetSize = correspondingEvent.firstEntry().getKey() - tiffStream.getReadByteCount();
        }
        if (offsetSize < 4) {
          LogUtil.i("ExifParser.next", "Invalid size of link to next IFD: " + offsetSize);
        } else {
          long ifdOffset = readUnsignedLong();
          if (ifdOffset != 0) {
            LogUtil.i("ExifParser.next", "Invalid link to next IFD: " + ifdOffset);
          }
        }
      }
    }
    while (correspondingEvent.size() != 0) {
      Entry<Integer, Object> entry = correspondingEvent.pollFirstEntry();
      Object event = entry.getValue();
      try {
        skipTo(entry.getKey());
      } catch (IOException e) {
        LogUtil.i(
            "ExifParser.next",
            "Failed to skip to data at: "
                + entry.getKey()
                + " for "
                + event.getClass().getName()
                + ", the file may be broken.");
        continue;
      }
      if (event instanceof IfdEvent) {
        ifdType = ((IfdEvent) event).ifd;
        numOfTagInIfd = tiffStream.readUnsignedShort();
        ifdStartOffset = entry.getKey();

        if (numOfTagInIfd * TAG_SIZE + ifdStartOffset + OFFSET_SIZE > app1End) {
          LogUtil.i("ExifParser.next", "Invalid size of IFD " + ifdType);
          return EVENT_END;
        }

        needToParseOffsetsInCurrentIfd = needToParseOffsetsInCurrentIfd();
        if (((IfdEvent) event).isRequested) {
          return EVENT_START_OF_IFD;
        } else {
          skipRemainingTagsInCurrentIfd();
        }
      } else if (event instanceof ImageEvent) {
        imageEvent = (ImageEvent) event;
        return imageEvent.type;
      } else {
        ExifTagEvent tagEvent = (ExifTagEvent) event;
        tag = tagEvent.tag;
        if (tag.getDataType() != ExifTag.TYPE_UNDEFINED) {
          readFullTagValue(tag);
          checkOffsetOrImageTag(tag);
        }
        if (tagEvent.isRequested) {
          return EVENT_VALUE_OF_REGISTERED_TAG;
        }
      }
    }
    return EVENT_END;
  }

  /**
   * Skips the tags area of current IFD, if the parser is not in the tag area, nothing will happen.
   *
   * @throws java.io.IOException
   * @throws ExifInvalidFormatException
   */
  private void skipRemainingTagsInCurrentIfd() throws IOException, ExifInvalidFormatException {
    int endOfTags = ifdStartOffset + OFFSET_SIZE + TAG_SIZE * numOfTagInIfd;
    int offset = tiffStream.getReadByteCount();
    if (offset > endOfTags) {
      return;
    }
    if (needToParseOffsetsInCurrentIfd) {
      while (offset < endOfTags) {
        tag = readTag();
        offset += TAG_SIZE;
        if (tag == null) {
          continue;
        }
        checkOffsetOrImageTag(tag);
      }
    } else {
      skipTo(endOfTags);
    }
    long ifdOffset = readUnsignedLong();
    // For ifd0, there is a link to ifd1 in the end of all tags
    if (ifdType == IfdId.TYPE_IFD_0
        && (isIfdRequested(IfdId.TYPE_IFD_1) || isThumbnailRequested())) {
      if (ifdOffset > 0) {
        registerIfd(IfdId.TYPE_IFD_1, ifdOffset);
      }
    }
  }

  private boolean needToParseOffsetsInCurrentIfd() {
    switch (ifdType) {
      case IfdId.TYPE_IFD_0:
        return isIfdRequested(IfdId.TYPE_IFD_EXIF)
            || isIfdRequested(IfdId.TYPE_IFD_GPS)
            || isIfdRequested(IfdId.TYPE_IFD_INTEROPERABILITY)
            || isIfdRequested(IfdId.TYPE_IFD_1);
      case IfdId.TYPE_IFD_1:
        return isThumbnailRequested();
      case IfdId.TYPE_IFD_EXIF:
        // The offset to interoperability IFD is located in Exif IFD
        return isIfdRequested(IfdId.TYPE_IFD_INTEROPERABILITY);
      default:
        return false;
    }
  }

  /**
   * If {@link #next()} return {@link #EVENT_NEW_TAG} or {@link #EVENT_VALUE_OF_REGISTERED_TAG},
   * call this function to get the corresponding tag.
   *
   * <p>For {@link #EVENT_NEW_TAG}, the tag may not contain the value if the size of the value is
   * greater than 4 bytes. One should call {@link ExifTag#hasValue()} to check if the tag contains
   * value. If there is no value,call {@link #registerForTagValue(ExifTag)} to have the parser emit
   * {@link #EVENT_VALUE_OF_REGISTERED_TAG} when it reaches the area pointed by the offset.
   *
   * <p>When {@link #EVENT_VALUE_OF_REGISTERED_TAG} is emitted, the value of the tag will have
   * already been read except for tags of undefined type. For tags of undefined type, call one of
   * the read methods to get the value.
   *
   * @see #registerForTagValue(ExifTag)
   * @see #read(byte[])
   * @see #read(byte[], int, int)
   * @see #readLong()
   * @see #readRational()
   * @see #readString(int)
   * @see #readString(int, java.nio.charset.Charset)
   */
  protected ExifTag getTag() {
    return tag;
  }

  /**
   * Gets the ID of current IFD.
   *
   * @see IfdId#TYPE_IFD_0
   * @see IfdId#TYPE_IFD_1
   * @see IfdId#TYPE_IFD_GPS
   * @see IfdId#TYPE_IFD_INTEROPERABILITY
   * @see IfdId#TYPE_IFD_EXIF
   */
  int getCurrentIfd() {
    return ifdType;
  }

  /**
   * When receiving {@link #EVENT_UNCOMPRESSED_STRIP}, call this function to get the index of this
   * strip.
   */
  int getStripIndex() {
    return imageEvent.stripIndex;
  }

  /** When receiving {@link #EVENT_UNCOMPRESSED_STRIP}, call this function to get the strip size. */
  int getStripSize() {
    if (stripSizeTag == null) {
      return 0;
    }
    return (int) stripSizeTag.getValueAt(0);
  }

  /**
   * When receiving {@link #EVENT_COMPRESSED_IMAGE}, call this function to get the image data size.
   */
  int getCompressedImageSize() {
    if (jpegSizeTag == null) {
      return 0;
    }
    return (int) jpegSizeTag.getValueAt(0);
  }

  private void skipTo(int offset) throws IOException {
    tiffStream.skipTo(offset);
    while (!correspondingEvent.isEmpty() && correspondingEvent.firstKey() < offset) {
      correspondingEvent.pollFirstEntry();
    }
  }

  /**
   * When getting {@link #EVENT_NEW_TAG} in the tag area of IFD, the tag may not contain the value
   * if the size of the value is greater than 4 bytes. When the value is not available here, call
   * this method so that the parser will emit {@link #EVENT_VALUE_OF_REGISTERED_TAG} when it reaches
   * the area where the value is located.
   *
   * @see #EVENT_VALUE_OF_REGISTERED_TAG
   */
  void registerForTagValue(ExifTag tag) {
    if (tag.getOffset() >= tiffStream.getReadByteCount()) {
      correspondingEvent.put(tag.getOffset(), new ExifTagEvent(tag, true));
    }
  }

  private void registerIfd(int ifdType, long offset) {
    // Cast unsigned int to int since the offset is always smaller
    // than the size of APP1 (65536)
    correspondingEvent.put((int) offset, new IfdEvent(ifdType, isIfdRequested(ifdType)));
  }

  private void registerCompressedImage(long offset) {
    correspondingEvent.put((int) offset, new ImageEvent(EVENT_COMPRESSED_IMAGE));
  }

  private void registerUncompressedStrip(int stripIndex, long offset) {
    correspondingEvent.put((int) offset, new ImageEvent(EVENT_UNCOMPRESSED_STRIP, stripIndex));
  }

  @SuppressLint("DefaultLocale")
  private ExifTag readTag() throws IOException, ExifInvalidFormatException {
    short tagId = tiffStream.readShort();
    short dataFormat = tiffStream.readShort();
    long numOfComp = tiffStream.readUnsignedInt();
    if (numOfComp > Integer.MAX_VALUE) {
      throw new ExifInvalidFormatException("Number of component is larger then Integer.MAX_VALUE");
    }
    // Some invalid image file contains invalid data type. Ignore those tags
    if (!ExifTag.isValidType(dataFormat)) {
      LogUtil.i("ExifParser.readTag", "Tag %04x: Invalid data type %d", tagId, dataFormat);
      tiffStream.skip(4);
      return null;
    }
    // TODO(blemmon): handle numOfComp overflow
    ExifTag tag =
        new ExifTag(
            tagId,
            dataFormat,
            (int) numOfComp,
            ifdType,
            ((int) numOfComp) != ExifTag.SIZE_UNDEFINED);
    int dataSize = tag.getDataSize();
    if (dataSize > 4) {
      long offset = tiffStream.readUnsignedInt();
      if (offset > Integer.MAX_VALUE) {
        throw new ExifInvalidFormatException("offset is larger then Integer.MAX_VALUE");
      }
      // Some invalid images put some undefined data before IFD0.
      // Read the data here.
      if ((offset < ifd0Position) && (dataFormat == ExifTag.TYPE_UNDEFINED)) {
        byte[] buf = new byte[(int) numOfComp];
        System.arraycopy(
            dataAboveIfd0, (int) offset - DEFAULT_IFD0_OFFSET, buf, 0, (int) numOfComp);
        tag.setValue(buf);
      } else {
        tag.setOffset((int) offset);
      }
    } else {
      boolean defCount = tag.hasDefinedCount();
      // Set defined count to 0 so we can add \0 to non-terminated strings
      tag.setHasDefinedCount(false);
      // Read value
      readFullTagValue(tag);
      tag.setHasDefinedCount(defCount);
      tiffStream.skip(4 - dataSize);
      // Set the offset to the position of value.
      tag.setOffset(tiffStream.getReadByteCount() - 4);
    }
    return tag;
  }

  /**
   * Check the if the tag is one of the offset tag that points to the IFD or image the caller is
   * interested in, register the IFD or image.
   */
  private void checkOffsetOrImageTag(ExifTag tag) {
    // Some invalid formattd image contains tag with 0 size.
    if (tag.getComponentCount() == 0) {
      return;
    }
    short tid = tag.getTagId();
    int ifd = tag.getIfd();
    if (tid == TAG_EXIF_IFD && checkAllowed(ifd, ExifInterface.TAG_EXIF_IFD)) {
      if (isIfdRequested(IfdId.TYPE_IFD_EXIF) || isIfdRequested(IfdId.TYPE_IFD_INTEROPERABILITY)) {
        registerIfd(IfdId.TYPE_IFD_EXIF, tag.getValueAt(0));
      }
    } else if (tid == TAG_GPS_IFD && checkAllowed(ifd, ExifInterface.TAG_GPS_IFD)) {
      if (isIfdRequested(IfdId.TYPE_IFD_GPS)) {
        registerIfd(IfdId.TYPE_IFD_GPS, tag.getValueAt(0));
      }
    } else if (tid == TAG_INTEROPERABILITY_IFD
        && checkAllowed(ifd, ExifInterface.TAG_INTEROPERABILITY_IFD)) {
      if (isIfdRequested(IfdId.TYPE_IFD_INTEROPERABILITY)) {
        registerIfd(IfdId.TYPE_IFD_INTEROPERABILITY, tag.getValueAt(0));
      }
    } else if (tid == TAG_JPEG_INTERCHANGE_FORMAT
        && checkAllowed(ifd, ExifInterface.TAG_JPEG_INTERCHANGE_FORMAT)) {
      if (isThumbnailRequested()) {
        registerCompressedImage(tag.getValueAt(0));
      }
    } else if (tid == TAG_JPEG_INTERCHANGE_FORMAT_LENGTH
        && checkAllowed(ifd, ExifInterface.TAG_JPEG_INTERCHANGE_FORMAT_LENGTH)) {
      if (isThumbnailRequested()) {
        jpegSizeTag = tag;
      }
    } else if (tid == TAG_STRIP_OFFSETS && checkAllowed(ifd, ExifInterface.TAG_STRIP_OFFSETS)) {
      if (isThumbnailRequested()) {
        if (tag.hasValue()) {
          for (int i = 0; i < tag.getComponentCount(); i++) {
            if (tag.getDataType() == ExifTag.TYPE_UNSIGNED_SHORT) {
              registerUncompressedStrip(i, tag.getValueAt(i));
            } else {
              registerUncompressedStrip(i, tag.getValueAt(i));
            }
          }
        } else {
          correspondingEvent.put(tag.getOffset(), new ExifTagEvent(tag, false));
        }
      }
    } else if (tid == TAG_STRIP_BYTE_COUNTS
        && checkAllowed(ifd, ExifInterface.TAG_STRIP_BYTE_COUNTS)
        && isThumbnailRequested()
        && tag.hasValue()) {
      stripSizeTag = tag;
    }
  }

  private boolean checkAllowed(int ifd, int tagId) {
    int info = mInterface.getTagInfo().get(tagId);
    return info != ExifInterface.DEFINITION_NULL && ExifInterface.isIfdAllowed(info, ifd);
  }

  void readFullTagValue(ExifTag tag) throws IOException {
    // Some invalid images contains tags with wrong size, check it here
    short type = tag.getDataType();
    if (type == ExifTag.TYPE_ASCII
        || type == ExifTag.TYPE_UNDEFINED
        || type == ExifTag.TYPE_UNSIGNED_BYTE) {
      int size = tag.getComponentCount();
      if (correspondingEvent.size() > 0) {
        if (correspondingEvent.firstEntry().getKey() < tiffStream.getReadByteCount() + size) {
          Object event = correspondingEvent.firstEntry().getValue();
          if (event instanceof ImageEvent) {
            // Tag value overlaps thumbnail, ignore thumbnail.
            LogUtil.i(
                "ExifParser.readFullTagValue",
                "Thumbnail overlaps value for tag: \n" + tag.toString());
            Entry<Integer, Object> entry = correspondingEvent.pollFirstEntry();
            LogUtil.i("ExifParser.readFullTagValue", "Invalid thumbnail offset: " + entry.getKey());
          } else {
            // Tag value overlaps another shorten count
            if (event instanceof IfdEvent) {
              LogUtil.i(
                  "ExifParser.readFullTagValue",
                  "Ifd " + ((IfdEvent) event).ifd + " overlaps value for tag: \n" + tag.toString());
            } else if (event instanceof ExifTagEvent) {
              LogUtil.i(
                  "ExifParser.readFullTagValue",
                  "Tag value for tag: \n"
                      + ((ExifTagEvent) event).tag.toString()
                      + " overlaps value for tag: \n"
                      + tag.toString());
            }
            size = correspondingEvent.firstEntry().getKey() - tiffStream.getReadByteCount();
            LogUtil.i(
                "ExifParser.readFullTagValue",
                "Invalid size of tag: \n" + tag.toString() + " setting count to: " + size);
            tag.forceSetComponentCount(size);
          }
        }
      }
    }
    switch (tag.getDataType()) {
      case ExifTag.TYPE_UNSIGNED_BYTE:
      case ExifTag.TYPE_UNDEFINED:
        {
          byte[] buf = new byte[tag.getComponentCount()];
          read(buf);
          tag.setValue(buf);
        }
        break;
      case ExifTag.TYPE_ASCII:
        tag.setValue(readString(tag.getComponentCount()));
        break;
      case ExifTag.TYPE_UNSIGNED_LONG:
        {
          long[] value = new long[tag.getComponentCount()];
          for (int i = 0, n = value.length; i < n; i++) {
            value[i] = readUnsignedLong();
          }
          tag.setValue(value);
        }
        break;
      case ExifTag.TYPE_UNSIGNED_RATIONAL:
        {
          Rational[] value = new Rational[tag.getComponentCount()];
          for (int i = 0, n = value.length; i < n; i++) {
            value[i] = readUnsignedRational();
          }
          tag.setValue(value);
        }
        break;
      case ExifTag.TYPE_UNSIGNED_SHORT:
        {
          int[] value = new int[tag.getComponentCount()];
          for (int i = 0, n = value.length; i < n; i++) {
            value[i] = readUnsignedShort();
          }
          tag.setValue(value);
        }
        break;
      case ExifTag.TYPE_LONG:
        {
          int[] value = new int[tag.getComponentCount()];
          for (int i = 0, n = value.length; i < n; i++) {
            value[i] = readLong();
          }
          tag.setValue(value);
        }
        break;
      case ExifTag.TYPE_RATIONAL:
        {
          Rational[] value = new Rational[tag.getComponentCount()];
          for (int i = 0, n = value.length; i < n; i++) {
            value[i] = readRational();
          }
          tag.setValue(value);
        }
        break;
    }
    if (LOGV) {
      LogUtil.v("ExifParser.readFullTagValue", "\n" + tag.toString());
    }
  }

  private void parseTiffHeader() throws IOException, ExifInvalidFormatException {
    short byteOrder = tiffStream.readShort();
    if (LITTLE_ENDIAN_TAG == byteOrder) {
      tiffStream.setByteOrder(ByteOrder.LITTLE_ENDIAN);
    } else if (BIG_ENDIAN_TAG == byteOrder) {
      tiffStream.setByteOrder(ByteOrder.BIG_ENDIAN);
    } else {
      throw new ExifInvalidFormatException("Invalid TIFF header");
    }

    if (tiffStream.readShort() != TIFF_HEADER_TAIL) {
      throw new ExifInvalidFormatException("Invalid TIFF header");
    }
  }

  private boolean seekTiffData(InputStream inputStream)
      throws IOException, ExifInvalidFormatException {
    CountedDataInputStream dataStream = new CountedDataInputStream(inputStream);
    if (dataStream.readShort() != JpegHeader.SOI) {
      throw new ExifInvalidFormatException("Invalid JPEG format");
    }

    short marker = dataStream.readShort();
    while (marker != JpegHeader.EOI && !JpegHeader.isSofMarker(marker)) {
      int length = dataStream.readUnsignedShort();
      // Some invalid formatted image contains multiple APP1,
      // try to find the one with Exif data.
      if (marker == JpegHeader.APP1) {
        int header;
        short headerTail;
        if (length >= 8) {
          header = dataStream.readInt();
          headerTail = dataStream.readShort();
          length -= 6;
          if (header == EXIF_HEADER && headerTail == EXIF_HEADER_TAIL) {
            app1End = length;
            return true;
          }
        }
      }
      if (length < 2 || (length - 2) != dataStream.skip(length - 2)) {
        LogUtil.i("ExifParser.seekTiffData", "Invalid JPEG format.");
        return false;
      }
      marker = dataStream.readShort();
    }
    return false;
  }

  /** Reads bytes from the InputStream. */
  protected int read(byte[] buffer, int offset, int length) throws IOException {
    return tiffStream.read(buffer, offset, length);
  }

  /** Equivalent to read(buffer, 0, buffer.length). */
  protected int read(byte[] buffer) throws IOException {
    return tiffStream.read(buffer);
  }

  /**
   * Reads a String from the InputStream with US-ASCII charset. The parser will read n bytes and
   * convert it to ascii string. This is used for reading values of type {@link ExifTag#TYPE_ASCII}.
   */
  private String readString(int n) throws IOException {
    return readString(n, US_ASCII);
  }

  /**
   * Reads a String from the InputStream with the given charset. The parser will read n bytes and
   * convert it to string. This is used for reading values of type {@link ExifTag#TYPE_ASCII}.
   */
  private String readString(int n, Charset charset) throws IOException {
    if (n > 0) {
      return tiffStream.readString(n, charset);
    } else {
      return "";
    }
  }

  /** Reads value of type {@link ExifTag#TYPE_UNSIGNED_SHORT} from the InputStream. */
  private int readUnsignedShort() throws IOException {
    return tiffStream.readShort() & 0xffff;
  }

  /** Reads value of type {@link ExifTag#TYPE_UNSIGNED_LONG} from the InputStream. */
  private long readUnsignedLong() throws IOException {
    return readLong() & 0xffffffffL;
  }

  /** Reads value of type {@link ExifTag#TYPE_UNSIGNED_RATIONAL} from the InputStream. */
  private Rational readUnsignedRational() throws IOException {
    long nomi = readUnsignedLong();
    long denomi = readUnsignedLong();
    return new Rational(nomi, denomi);
  }

  /** Reads value of type {@link ExifTag#TYPE_LONG} from the InputStream. */
  private int readLong() throws IOException {
    return tiffStream.readInt();
  }

  /** Reads value of type {@link ExifTag#TYPE_RATIONAL} from the InputStream. */
  private Rational readRational() throws IOException {
    int nomi = readLong();
    int denomi = readLong();
    return new Rational(nomi, denomi);
  }

  private static class ImageEvent {
    int stripIndex;
    int type;

    ImageEvent(int type) {
      this.stripIndex = 0;
      this.type = type;
    }

    ImageEvent(int type, int stripIndex) {
      this.type = type;
      this.stripIndex = stripIndex;
    }
  }

  private static class IfdEvent {
    int ifd;
    boolean isRequested;

    IfdEvent(int ifd, boolean isInterestedIfd) {
      this.ifd = ifd;
      this.isRequested = isInterestedIfd;
    }
  }

  private static class ExifTagEvent {
    ExifTag tag;
    boolean isRequested;

    ExifTagEvent(ExifTag tag, boolean isRequireByUser) {
      this.tag = tag;
      this.isRequested = isRequireByUser;
    }
  }
}