/// <summary>Processes a TIFF data sequence.</summary>
/// <param name="reader">
/// the
/// <see cref="Com.Drew.Lang.RandomAccessReader"/>
/// from which the data should be read
/// </param>
/// <param name="handler">
/// the
/// <see cref="TiffHandler"/>
/// that will coordinate processing and accept read values
/// </param>
/// <param name="tiffHeaderOffset">the offset within <code>reader</code> at which the TIFF header starts</param>
/// <exception cref="TiffProcessingException">
/// if an error occurred during the processing of TIFF data that could not be
/// ignored or recovered from
/// </exception>
/// <exception cref="System.IO.IOException">an error occurred while accessing the required data</exception>
/// <exception cref="Com.Drew.Imaging.Tiff.TiffProcessingException"/>
public virtual void ProcessTiff(RandomAccessReader reader, TiffHandler handler, int tiffHeaderOffset)
{
// This must be either "MM" or "II".
short byteOrderIdentifier = reader.GetInt16(tiffHeaderOffset);
if (byteOrderIdentifier == unchecked ((int)(0x4d4d)))
{
// "MM"
reader.SetMotorolaByteOrder(true);
}
else
{
if (byteOrderIdentifier == unchecked ((int)(0x4949)))
{
// "II"
reader.SetMotorolaByteOrder(false);
}
else
{
throw new TiffProcessingException("Unclear distinction between Motorola/Intel byte ordering: " + byteOrderIdentifier);
}
}
// Check the next two values for correctness.
int tiffMarker = reader.GetUInt16(2 + tiffHeaderOffset);
handler.SetTiffMarker(tiffMarker);
int firstIfdOffset = reader.GetInt32(4 + tiffHeaderOffset) + tiffHeaderOffset;
// David Ekholm sent a digital camera image that has this problem
// TODO getLength should be avoided as it causes RandomAccessStreamReader to read to the end of the stream
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;
}
ICollection <int> processedIfdOffsets = new HashSet <int>();
ProcessIfd(handler, reader, processedIfdOffsets, firstIfdOffset, tiffHeaderOffset);
handler.Completed(reader, tiffHeaderOffset);
}
/// <summary>Processes a TIFF data sequence.</summary>
/// <param name="reader">
/// the
/// <see cref="Com.Drew.Lang.RandomAccessReader"/>
/// from which the data should be read
/// </param>
/// <param name="handler">
/// the
/// <see cref="TiffHandler"/>
/// that will coordinate processing and accept read values
/// </param>
/// <param name="tiffHeaderOffset">the offset within <code>reader</code> at which the TIFF header starts</param>
/// <exception cref="TiffProcessingException">
/// if an error occurred during the processing of TIFF data that could not be
/// ignored or recovered from
/// </exception>
/// <exception cref="System.IO.IOException">an error occurred while accessing the required data</exception>
/// <exception cref="Com.Drew.Imaging.Tiff.TiffProcessingException"/>
public virtual void ProcessTiff(RandomAccessReader reader, TiffHandler handler, int tiffHeaderOffset)
{
// This must be either "MM" or "II".
short byteOrderIdentifier = reader.GetInt16(tiffHeaderOffset);
if (byteOrderIdentifier == unchecked((int)(0x4d4d)))
{
// "MM"
reader.SetMotorolaByteOrder(true);
}
else
{
if (byteOrderIdentifier == unchecked((int)(0x4949)))
{
// "II"
reader.SetMotorolaByteOrder(false);
}
else
{
throw new TiffProcessingException("Unclear distinction between Motorola/Intel byte ordering: " + byteOrderIdentifier);
}
}
// Check the next two values for correctness.
int tiffMarker = reader.GetUInt16(2 + tiffHeaderOffset);
handler.SetTiffMarker(tiffMarker);
int firstIfdOffset = reader.GetInt32(4 + tiffHeaderOffset) + tiffHeaderOffset;
// David Ekholm sent a digital camera image that has this problem
// TODO getLength should be avoided as it causes RandomAccessStreamReader to read to the end of the stream
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;
}
ICollection<int> processedIfdOffsets = new HashSet<int>();
ProcessIfd(handler, reader, processedIfdOffsets, firstIfdOffset, tiffHeaderOffset);
handler.Completed(reader, tiffHeaderOffset);
}
/// <exception cref="System.IO.IOException"/>
private static void ProcessTag(TiffHandler handler, int tagId, int tagValueOffset, int componentCount, int formatCode, RandomAccessReader reader)
{
switch (formatCode)
{
case TiffDataFormat.CodeUndefined:
{
// this includes exif user comments
handler.SetByteArray(tagId, reader.GetBytes(tagValueOffset, componentCount));
break;
}
case TiffDataFormat.CodeString:
{
handler.SetString(tagId, reader.GetNullTerminatedString(tagValueOffset, componentCount));
break;
}
case TiffDataFormat.CodeRationalS:
{
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.CodeRationalU:
{
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.CodeSingle:
{
if (componentCount == 1)
{
handler.SetFloat(tagId, reader.GetFloat32(tagValueOffset));
}
else
{
float[] array = new float[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetFloat32(tagValueOffset + (i * 4));
}
handler.SetFloatArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeDouble:
{
if (componentCount == 1)
{
handler.SetDouble(tagId, reader.GetDouble64(tagValueOffset));
}
else
{
double[] array = new double[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetDouble64(tagValueOffset + (i * 4));
}
handler.SetDoubleArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt8S:
{
if (componentCount == 1)
{
handler.SetInt8s(tagId, reader.GetInt8(tagValueOffset));
}
else
{
sbyte[] array = new sbyte[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetInt8(tagValueOffset + i);
}
handler.SetInt8sArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt8U:
{
if (componentCount == 1)
{
handler.SetInt8u(tagId, reader.GetUInt8(tagValueOffset));
}
else
{
short[] array = new short[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetUInt8(tagValueOffset + i);
}
handler.SetInt8uArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt16S:
{
if (componentCount == 1)
{
handler.SetInt16s(tagId, (int)reader.GetInt16(tagValueOffset));
}
else
{
short[] array = new short[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetInt16(tagValueOffset + (i * 2));
}
handler.SetInt16sArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt16U:
{
if (componentCount == 1)
{
handler.SetInt16u(tagId, reader.GetUInt16(tagValueOffset));
}
else
{
int[] array = new int[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetUInt16(tagValueOffset + (i * 2));
}
handler.SetInt16uArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt32S:
{
// NOTE 'long' in this case means 32 bit, not 64
if (componentCount == 1)
{
handler.SetInt32s(tagId, reader.GetInt32(tagValueOffset));
}
else
{
int[] array = new int[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetInt32(tagValueOffset + (i * 4));
}
handler.SetInt32sArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt32U:
{
// NOTE 'long' in this case means 32 bit, not 64
if (componentCount == 1)
{
handler.SetInt32u(tagId, reader.GetUInt32(tagValueOffset));
}
else
{
long[] array = new long[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetUInt32(tagValueOffset + (i * 4));
}
handler.SetInt32uArray(tagId, array);
}
break;
}
default:
{
handler.Error(Sharpen.Extensions.StringFormat("Unknown format code %d for tag %d", formatCode, tagId));
break;
}
}
}
/// <summary>Processes a TIFF IFD.</summary>
/// <remarks>
/// Processes a TIFF IFD.
/// <p/>
/// IFD Header:
/// <ul>
/// <li><b>2 bytes</b> number of tags</li>
/// </ul>
/// Tag structure:
/// <ul>
/// <li><b>2 bytes</b> tag type</li>
/// <li><b>2 bytes</b> format code (values 1 to 12, inclusive)</li>
/// <li><b>4 bytes</b> component count</li>
/// <li><b>4 bytes</b> inline value, or offset pointer if too large to fit in four bytes</li>
/// </ul>
/// </remarks>
/// <param name="handler">
/// the
/// <see cref="TiffHandler"/>
/// that will coordinate processing and accept read values
/// </param>
/// <param name="reader">
/// the
/// <see cref="Com.Drew.Lang.RandomAccessReader"/>
/// from which the data should be read
/// </param>
/// <param name="processedIfdOffsets">the set of visited IFD offsets, to avoid revisiting the same IFD in an endless loop</param>
/// <param name="ifdOffset">the offset within <code>reader</code> at which the IFD data starts</param>
/// <param name="tiffHeaderOffset">the offset within <code>reader</code> at which the TIFF header starts</param>
/// <exception cref="System.IO.IOException">an error occurred while accessing the required data</exception>
public static void ProcessIfd(TiffHandler handler, RandomAccessReader reader, ICollection <int> processedIfdOffsets, int ifdOffset, int tiffHeaderOffset)
{
try
{
// check for directories we've already visited to avoid stack overflows when recursive/cyclic directory structures exist
if (processedIfdOffsets.Contains(Sharpen.Extensions.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
//
for (int tagNumber = 0; tagNumber < dirTagCount; tagNumber++)
{
int tagOffset = CalculateTagOffset(ifdOffset, tagNumber);
// 2 bytes for the tag id
int tagId = reader.GetUInt16(tagOffset);
// 2 bytes for the format code
int formatCode = reader.GetUInt16(tagOffset + 2);
TiffDataFormat format = TiffDataFormat.FromTiffFormatCode(formatCode);
if (format == null)
{
// 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). Exit now.
handler.Error("Invalid TIFF tag format code: " + formatCode);
return;
}
// 4 bytes dictate the number of components in this tag's data
int componentCount = reader.GetInt32(tagOffset + 4);
if (componentCount < 0)
{
handler.Error("Negative TIFF tag component count");
continue;
}
int byteCount = componentCount * format.GetComponentSizeBytes();
int tagValueOffset;
if (byteCount > 4)
{
// If it's bigger than 4 bytes, the dir entry contains an offset.
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(tagId))
{
int subDirOffset = tiffHeaderOffset + reader.GetInt32(tagValueOffset);
ProcessIfd(handler, reader, processedIfdOffsets, subDirOffset, tiffHeaderOffset);
}
else
{
if (!handler.CustomProcessTag(tagValueOffset, processedIfdOffsets, tiffHeaderOffset, reader, tagId, byteCount))
{
ProcessTag(handler, tagId, tagValueOffset, componentCount, formatCode, reader);
}
}
}
// at the end of each IFD is an optional link to the next IFD
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)
{
// TODO is this a valid restriction?
// Last 4 bytes of IFD reference another IFD with an address that is before the start of this directory
return;
}
}
if (handler.HasFollowerIfd())
{
ProcessIfd(handler, reader, processedIfdOffsets, nextIfdOffset, tiffHeaderOffset);
}
}
}
finally
{
handler.EndingIFD();
}
}
/// <exception cref="System.IO.IOException"/>
private static void ProcessTag(TiffHandler handler, int tagId, int tagValueOffset, int componentCount, int formatCode, RandomAccessReader reader)
{
switch (formatCode)
{
case TiffDataFormat.CodeUndefined:
{
// this includes exif user comments
handler.SetByteArray(tagId, reader.GetBytes(tagValueOffset, componentCount));
break;
}
case TiffDataFormat.CodeString:
{
handler.SetString(tagId, reader.GetNullTerminatedString(tagValueOffset, componentCount));
break;
}
case TiffDataFormat.CodeRationalS:
{
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.CodeRationalU:
{
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.CodeSingle:
{
if (componentCount == 1)
{
handler.SetFloat(tagId, reader.GetFloat32(tagValueOffset));
}
else
{
float[] array = new float[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetFloat32(tagValueOffset + (i * 4));
}
handler.SetFloatArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeDouble:
{
if (componentCount == 1)
{
handler.SetDouble(tagId, reader.GetDouble64(tagValueOffset));
}
else
{
double[] array = new double[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetDouble64(tagValueOffset + (i * 4));
}
handler.SetDoubleArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt8S:
{
if (componentCount == 1)
{
handler.SetInt8s(tagId, reader.GetInt8(tagValueOffset));
}
else
{
sbyte[] array = new sbyte[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetInt8(tagValueOffset + i);
}
handler.SetInt8sArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt8U:
{
if (componentCount == 1)
{
handler.SetInt8u(tagId, reader.GetUInt8(tagValueOffset));
}
else
{
short[] array = new short[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetUInt8(tagValueOffset + i);
}
handler.SetInt8uArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt16S:
{
if (componentCount == 1)
{
handler.SetInt16s(tagId, (int)reader.GetInt16(tagValueOffset));
}
else
{
short[] array = new short[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetInt16(tagValueOffset + (i * 2));
}
handler.SetInt16sArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt16U:
{
if (componentCount == 1)
{
handler.SetInt16u(tagId, reader.GetUInt16(tagValueOffset));
}
else
{
int[] array = new int[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetUInt16(tagValueOffset + (i * 2));
}
handler.SetInt16uArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt32S:
{
// NOTE 'long' in this case means 32 bit, not 64
if (componentCount == 1)
{
handler.SetInt32s(tagId, reader.GetInt32(tagValueOffset));
}
else
{
int[] array = new int[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetInt32(tagValueOffset + (i * 4));
}
handler.SetInt32sArray(tagId, array);
}
break;
}
case TiffDataFormat.CodeInt32U:
{
// NOTE 'long' in this case means 32 bit, not 64
if (componentCount == 1)
{
handler.SetInt32u(tagId, reader.GetUInt32(tagValueOffset));
}
else
{
long[] array = new long[componentCount];
for (int i = 0; i < componentCount; i++)
{
array[i] = reader.GetUInt32(tagValueOffset + (i * 4));
}
handler.SetInt32uArray(tagId, array);
}
break;
}
default:
{
handler.Error(Sharpen.Extensions.StringFormat("Unknown format code %d for tag %d", formatCode, tagId));
break;
}
}
}
/// <summary>Processes a TIFF IFD.</summary>
/// <remarks>
/// Processes a TIFF IFD.
/// <p/>
/// IFD Header:
/// <ul>
/// <li><b>2 bytes</b> number of tags</li>
/// </ul>
/// Tag structure:
/// <ul>
/// <li><b>2 bytes</b> tag type</li>
/// <li><b>2 bytes</b> format code (values 1 to 12, inclusive)</li>
/// <li><b>4 bytes</b> component count</li>
/// <li><b>4 bytes</b> inline value, or offset pointer if too large to fit in four bytes</li>
/// </ul>
/// </remarks>
/// <param name="handler">
/// the
/// <see cref="TiffHandler"/>
/// that will coordinate processing and accept read values
/// </param>
/// <param name="reader">
/// the
/// <see cref="Com.Drew.Lang.RandomAccessReader"/>
/// from which the data should be read
/// </param>
/// <param name="processedIfdOffsets">the set of visited IFD offsets, to avoid revisiting the same IFD in an endless loop</param>
/// <param name="ifdOffset">the offset within <code>reader</code> at which the IFD data starts</param>
/// <param name="tiffHeaderOffset">the offset within <code>reader</code> at which the TIFF header starts</param>
/// <exception cref="System.IO.IOException">an error occurred while accessing the required data</exception>
public static void ProcessIfd(TiffHandler handler, RandomAccessReader reader, ICollection<int> processedIfdOffsets, int ifdOffset, int tiffHeaderOffset)
{
try
{
// check for directories we've already visited to avoid stack overflows when recursive/cyclic directory structures exist
if (processedIfdOffsets.Contains(Sharpen.Extensions.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
//
for (int tagNumber = 0; tagNumber < dirTagCount; tagNumber++)
{
int tagOffset = CalculateTagOffset(ifdOffset, tagNumber);
// 2 bytes for the tag id
int tagId = reader.GetUInt16(tagOffset);
// 2 bytes for the format code
int formatCode = reader.GetUInt16(tagOffset + 2);
TiffDataFormat format = TiffDataFormat.FromTiffFormatCode(formatCode);
if (format == null)
{
// 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). Exit now.
handler.Error("Invalid TIFF tag format code: " + formatCode);
return;
}
// 4 bytes dictate the number of components in this tag's data
int componentCount = reader.GetInt32(tagOffset + 4);
if (componentCount < 0)
{
handler.Error("Negative TIFF tag component count");
continue;
}
int byteCount = componentCount * format.GetComponentSizeBytes();
int tagValueOffset;
if (byteCount > 4)
{
// If it's bigger than 4 bytes, the dir entry contains an offset.
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(tagId))
{
int subDirOffset = tiffHeaderOffset + reader.GetInt32(tagValueOffset);
ProcessIfd(handler, reader, processedIfdOffsets, subDirOffset, tiffHeaderOffset);
}
else
{
if (!handler.CustomProcessTag(tagValueOffset, processedIfdOffsets, tiffHeaderOffset, reader, tagId, byteCount))
{
ProcessTag(handler, tagId, tagValueOffset, componentCount, formatCode, reader);
}
}
}
// at the end of each IFD is an optional link to the next IFD
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)
{
// TODO is this a valid restriction?
// Last 4 bytes of IFD reference another IFD with an address that is before the start of this directory
return;
}
}
if (handler.HasFollowerIfd())
{
ProcessIfd(handler, reader, processedIfdOffsets, nextIfdOffset, tiffHeaderOffset);
}
}
}
finally
{
handler.EndingIFD();
}
}