/*
* Copyright 2002-2015 Drew Noakes
*
* More information about this project is available at:
*
* https://drewnoakes.com/code/exif/
* https://github.com/drewnoakes/metadata-extractor
*/
package tim.prune.jpeg.drew;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
import tim.prune.jpeg.JpegData;
/**
* Processes TIFF-formatted data, using an ExifTiffHandler
*
* @author Drew Noakes https://drewnoakes.com
*/
public class TiffProcessor
{
/**
* Processes a TIFF data sequence.
*
* @param reader the {@link RandomAccessReader} from which the data should be read
* @param jpegData the data to populate
* @param tiffHeaderOffset the offset within reader
at which the TIFF header starts
* @throws ExifException if an error occurred during the processing of TIFF data that could
* not be ignored or recovered from
* @throws IOException an error occurred while accessing the required data
*/
public static void processTiff(final ByteArrayReader reader, JpegData jpegData,
final int tiffHeaderOffset) throws ExifException, IOException
{
// This must be either "MM" or "II".
short byteOrderIdentifier = reader.getInt16(tiffHeaderOffset);
if (byteOrderIdentifier == 0x4d4d) { // "MM"
reader.setMotorolaByteOrder(true);
} else if (byteOrderIdentifier == 0x4949) { // "II"
reader.setMotorolaByteOrder(false);
} else {
throw new ExifException("Unclear distinction between Motorola/Intel byte ordering: " + byteOrderIdentifier);
}
int firstIfdOffset = reader.getInt32(4 + tiffHeaderOffset) + tiffHeaderOffset;
// David Ekholm sent a digital camera image that has this problem
if (firstIfdOffset >= reader.getLength() - 1) {
//handler.warn("First IFD offset is beyond the end of the TIFF data segment -- trying default offset");
// First directory normally starts immediately after the offset bytes, so try that
firstIfdOffset = tiffHeaderOffset + 2 + 2 + 4;
}
// Make a handler object to use for the processing
ExifTiffHandler handler = new ExifTiffHandler(jpegData);
Set processedIfdOffsets = new HashSet();
processDirectory(handler, reader, processedIfdOffsets, firstIfdOffset, tiffHeaderOffset, 0);
handler.completed(reader, tiffHeaderOffset);
}
/**
* Processes a TIFF IFD.
*
* IFD Header:
*
* - 2 bytes number of tags
*
* Tag structure:
*
* - 2 bytes tag type
* - 2 bytes format code (values 1 to 12, inclusive)
* - 4 bytes component count
* - 4 bytes inline value, or offset pointer if too large to fit in four bytes
*
*
* @param handler the {@link ExifTiffHandler} that will coordinate processing and accept read values
* @param reader the byte reader from which the data should be read
* @param processedIfdOffsets the set of visited IFD offsets, to avoid revisiting the same IFD in an endless loop
* @param ifdOffset the offset within reader
at which the IFD data starts
* @param tiffHeaderOffset the offset within reader
at which the TIFF header starts
* @param inDirectoryId directory id
* @throws IOException an error occurred while accessing the required data
*/
private static void processDirectory(final ExifTiffHandler handler,
final ByteArrayReader reader, final Set processedIfdOffsets,
final int ifdOffset, final int tiffHeaderOffset, int inDirectoryId) throws ExifException
{
// check for directories we've already visited to avoid stack overflows when recursive/cyclic directory structures exist
if (processedIfdOffsets.contains(Integer.valueOf(ifdOffset))) {
return;
}
// remember that we've visited this directory so that we don't visit it again later
processedIfdOffsets.add(ifdOffset);
if (ifdOffset >= reader.getLength() || ifdOffset < 0) {
//handler.error("Ignored IFD marked to start outside data segment");
return;
}
// First two bytes in the IFD are the number of tags in this directory
int dirTagCount = reader.getUInt16(ifdOffset);
int dirLength = (2 + (12 * dirTagCount) + 4);
if (dirLength + ifdOffset > reader.getLength()) {
//handler.error("Illegally sized IFD");
return;
}
// Handle each tag in this directory
//
int invalidTiffFormatCodeCount = 0;
for (int tagNumber = 0; tagNumber < dirTagCount; tagNumber++)
{
final int tagOffset = calculateTagOffset(ifdOffset, tagNumber);
// 2 bytes for the tag id
final int childTagId = reader.getUInt16(tagOffset);
// 2 bytes for the format code
final int formatCode = reader.getUInt16(tagOffset + 2);
final int componentSizeInBytes = TiffDataFormat.getComponentSize(formatCode);
if (componentSizeInBytes == 0)
{
// This error suggests that we are processing at an incorrect index and will generate
// rubbish until we go out of bounds (which may be a while).
if (++invalidTiffFormatCodeCount > 5) {
//handler.error("Stopping processing as too many errors seen in TIFF IFD");
return;
}
continue;
}
// 4 bytes dictate the number of components in this tag's data
final int componentCount = reader.getInt32(tagOffset + 4);
if (componentCount < 0) {
//handler.error("Negative TIFF tag component count");
continue;
}
final int byteCount = componentCount * componentSizeInBytes;
final int tagValueOffset;
if (byteCount > 4)
{
// If it's bigger than 4 bytes, the dir entry contains an offset.
final int offsetVal = reader.getInt32(tagOffset + 8);
if (offsetVal + byteCount > reader.getLength()) {
// Bogus pointer offset and / or byteCount value
//handler.error("Illegal TIFF tag pointer offset");
continue;
}
tagValueOffset = tiffHeaderOffset + offsetVal;
}
else {
// 4 bytes or less and value is in the dir entry itself.
tagValueOffset = tagOffset + 8;
}
if (tagValueOffset < 0 || tagValueOffset > reader.getLength()) {
//handler.error("Illegal TIFF tag pointer offset");
continue;
}
// Check that this tag isn't going to allocate outside the bounds of the data array.
// This addresses an uncommon OutOfMemoryError.
if (byteCount < 0 || tagValueOffset + byteCount > reader.getLength()) {
//handler.error("Illegal number of bytes for TIFF tag data: " + byteCount);
continue;
}
// Special handling for tags that point to other IFDs
if (byteCount == 4 && handler.isTagIfdPointer(childTagId)) {
final int subDirOffset = tiffHeaderOffset + reader.getInt32(tagValueOffset);
processDirectory(handler, reader, processedIfdOffsets, subDirOffset, tiffHeaderOffset, childTagId);
}
else if (handler.isInterestingTag(inDirectoryId, childTagId))
{
processTag(handler, childTagId, tagValueOffset, componentCount, formatCode, reader);
}
}
// at the end of each IFD is an optional link to the next IFD
final int finalTagOffset = calculateTagOffset(ifdOffset, dirTagCount);
int nextIfdOffset = reader.getInt32(finalTagOffset);
if (nextIfdOffset != 0)
{
nextIfdOffset += tiffHeaderOffset;
if (nextIfdOffset >= reader.getLength()) {
// Last 4 bytes of IFD reference another IFD with an address that is out of bounds
// Note this could have been caused by jhead 1.3 cropping too much
return;
}
else if (nextIfdOffset < ifdOffset) {
// Last 4 bytes of IFD reference another IFD with an address that is before the start of this directory
return;
}
processDirectory(handler, reader, processedIfdOffsets, nextIfdOffset, tiffHeaderOffset, inDirectoryId);
}
}
/**
* Process a single tag value
*/
private static void processTag(final ExifTiffHandler handler,
final int tagId, final int tagValueOffset,
final int componentCount, final int formatCode,
final ByteArrayReader reader) throws ExifException
{
switch (formatCode)
{
case TiffDataFormat.CODE_STRING:
handler.setString(tagId, reader.getNullTerminatedString(tagValueOffset, componentCount));
break;
case TiffDataFormat.CODE_RATIONAL_S:
if (componentCount == 1) {
handler.setRational(tagId, new Rational(reader.getInt32(tagValueOffset), reader.getInt32(tagValueOffset + 4)));
} else if (componentCount > 1) {
Rational[] array = new Rational[componentCount];
for (int i = 0; i < componentCount; i++)
array[i] = new Rational(reader.getInt32(tagValueOffset + (8 * i)), reader.getInt32(tagValueOffset + 4 + (8 * i)));
handler.setRationalArray(tagId, array);
}
break;
case TiffDataFormat.CODE_RATIONAL_U:
if (componentCount == 1) {
handler.setRational(tagId, new Rational(reader.getUInt32(tagValueOffset), reader.getUInt32(tagValueOffset + 4)));
} else if (componentCount > 1) {
Rational[] array = new Rational[componentCount];
for (int i = 0; i < componentCount; i++)
array[i] = new Rational(reader.getUInt32(tagValueOffset + (8 * i)), reader.getUInt32(tagValueOffset + 4 + (8 * i)));
handler.setRationalArray(tagId, array);
}
break;
case TiffDataFormat.CODE_INT8_S:
if (componentCount == 1) {
handler.setIntegerValue(tagId, reader.getInt8(tagValueOffset));
}
break;
case TiffDataFormat.CODE_INT8_U:
if (componentCount == 1) {
handler.setIntegerValue(tagId, reader.getUInt8(tagValueOffset));
}
break;
case TiffDataFormat.CODE_INT16_S:
if (componentCount == 1) {
handler.setIntegerValue(tagId, reader.getInt16(tagValueOffset));
}
break;
case TiffDataFormat.CODE_INT16_U:
if (componentCount == 1) {
handler.setIntegerValue(tagId, reader.getUInt16(tagValueOffset));
}
break;
case TiffDataFormat.CODE_INT32_S:
// NOTE 'long' in this case means 32 bit, not 64
if (componentCount == 1) {
handler.setIntegerValue(tagId, reader.getInt32(tagValueOffset));
}
break;
case TiffDataFormat.CODE_INT32_U:
// NOTE 'long' in this case means 32 bit, not 64
if (componentCount == 1) {
handler.setRational(tagId, new Rational(reader.getUInt32(tagValueOffset), 1L));
}
break;
case TiffDataFormat.CODE_SINGLE:
case TiffDataFormat.CODE_DOUBLE:
case TiffDataFormat.CODE_UNDEFINED:
default:
break;
}
}
/**
* Determine the offset of a given tag within the specified IFD.
*
* @param ifdStartOffset the offset at which the IFD starts
* @param entryNumber the zero-based entry number
*/
private static int calculateTagOffset(int ifdStartOffset, int entryNumber)
{
// Add 2 bytes for the tag count.
// Each entry is 12 bytes.
return ifdStartOffset + 2 + (12 * entryNumber);
}
}