/// <summary>Processes a TIFF data sequence.</summary>
/// <param name="reader">the <see cref="IndexedReader"/> from which the data should be read</param>
/// <param name="handler">the <see cref="ITiffHandler"/> that will coordinate processing and accept read values</param>
/// <param name="tiffHeaderOffset">the offset within <c>reader</c> 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="TiffProcessingException"/>
public static void ProcessTiff([NotNull] IndexedReader reader, [NotNull] ITiffHandler handler, int tiffHeaderOffset = 0)
{
// Read byte order.
switch (reader.GetInt16(tiffHeaderOffset))
{
case 0x4d4d: // MM
reader.IsMotorolaByteOrder = true;
break;
case 0x4949: // II
reader.IsMotorolaByteOrder = false;
break;
default:
throw new TiffProcessingException("Unclear distinction between Motorola/Intel byte ordering: " + reader.GetInt16(tiffHeaderOffset));
}
// Check the next two values for correctness.
int tiffMarker = reader.GetUInt16(2 + tiffHeaderOffset);
handler.SetTiffMarker(tiffMarker);
var firstIfdOffset = reader.GetInt32(4 + tiffHeaderOffset) + tiffHeaderOffset;
// David Ekholm sent a digital camera image that has this problem
// TODO calling Length should be avoided as it causes IndexedCapturingReader to read to the end of the stream
if (firstIfdOffset >= reader.Length - 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;
}
var processedIfdOffsets = new HashSet <int>();
ProcessIfd(handler, reader, processedIfdOffsets, firstIfdOffset, tiffHeaderOffset);
handler.Completed(reader, tiffHeaderOffset);
}
Extract(IndexedReader reader, int readerOffset = 0)
{
var directories = new List <Directory>();
try
{
// Read the TIFF-formatted Exif data
TiffReader.ProcessTiff(reader, new ExifTiffHandler(directories, StoreThumbnailBytes), readerOffset);
}
catch (TiffProcessingException e)
{
// TODO what do to with this error state?
Console.Error.WriteLine(e);
}
catch (IOException e)
{
// TODO what do to with this error state?
Console.Error.WriteLine(e);
}
return(directories);
}
/// <exception cref="System.IO.IOException"/>
private bool ProcessMakernote(int makernoteOffset, [NotNull] ICollection <int> processedIfdOffsets, [NotNull] IndexedReader reader)
{
Debug.Assert(makernoteOffset >= 0, "makernoteOffset >= 0");
var cameraMake = Directories.OfType <ExifIfd0Directory>().FirstOrDefault()?.GetString(ExifDirectoryBase.TagMake);
var firstTwoChars = reader.GetString(makernoteOffset, 2, Encoding.UTF8);
var firstThreeChars = reader.GetString(makernoteOffset, 3, Encoding.UTF8);
var firstFourChars = reader.GetString(makernoteOffset, 4, Encoding.UTF8);
var firstFiveChars = reader.GetString(makernoteOffset, 5, Encoding.UTF8);
var firstSixChars = reader.GetString(makernoteOffset, 6, Encoding.UTF8);
var firstSevenChars = reader.GetString(makernoteOffset, 7, Encoding.UTF8);
var firstEightChars = reader.GetString(makernoteOffset, 8, Encoding.UTF8);
var firstTenChars = reader.GetString(makernoteOffset, 10, Encoding.UTF8);
var firstTwelveChars = reader.GetString(makernoteOffset, 12, Encoding.UTF8);
if (string.Equals("OLYMP\0", firstSixChars, StringComparison.Ordinal) ||
string.Equals("EPSON", firstFiveChars, StringComparison.Ordinal) ||
string.Equals("AGFA", firstFourChars, StringComparison.Ordinal))
{
// Olympus Makernote
// Epson and Agfa use Olympus makernote standard: http://www.ozhiker.com/electronics/pjmt/jpeg_info/
PushDirectory(new OlympusMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset + 8);
}
else if (string.Equals("OLYMPUS\0II", firstTenChars, StringComparison.Ordinal))
{
// Olympus Makernote (alternate)
// Note that data is relative to the beginning of the makernote
// http://exiv2.org/makernote.html
PushDirectory(new OlympusMakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithShiftedBaseOffset(makernoteOffset), processedIfdOffsets, 12);
}
else if (cameraMake != null && cameraMake.StartsWith("MINOLTA", StringComparison.OrdinalIgnoreCase))
{
// Cases seen with the model starting with MINOLTA in capitals seem to have a valid Olympus makernote
// area that commences immediately.
PushDirectory(new OlympusMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset);
}
else if (cameraMake != null && cameraMake.TrimStart().StartsWith("NIKON", StringComparison.OrdinalIgnoreCase))
{
if (string.Equals("Nikon", firstFiveChars, StringComparison.Ordinal))
{
switch (reader.GetByte(makernoteOffset + 6))
{
case 1:
{
/* There are two scenarios here:
* Type 1: **
* :0000: 4E 69 6B 6F 6E 00 01 00-05 00 02 00 02 00 06 00 Nikon...........
* :0010: 00 00 EC 02 00 00 03 00-03 00 01 00 00 00 06 00 ................
* Type 3: **
* :0000: 4E 69 6B 6F 6E 00 02 00-00 00 4D 4D 00 2A 00 00 Nikon....MM.*...
* :0010: 00 08 00 1E 00 01 00 07-00 00 00 04 30 32 30 30 ............0200
*/
PushDirectory(new NikonType1MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset + 8);
break;
}
case 2:
{
PushDirectory(new NikonType2MakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithShiftedBaseOffset(makernoteOffset + 10), processedIfdOffsets, 8);
break;
}
default:
{
Error("Unsupported Nikon makernote data ignored.");
break;
}
}
}
else
{
// The IFD begins with the first Makernote byte (no ASCII name). This occurs with CoolPix 775, E990 and D1 models.
PushDirectory(new NikonType2MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset);
}
}
else if (string.Equals("SONY CAM", firstEightChars, StringComparison.Ordinal) ||
string.Equals("SONY DSC", firstEightChars, StringComparison.Ordinal))
{
PushDirectory(new SonyType1MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset + 12);
}
// Do this check LAST after most other Sony checks
else if (cameraMake != null && cameraMake.StartsWith("SONY", StringComparison.Ordinal) &&
reader.GetBytes(makernoteOffset, 2) != new byte[] { 0x01, 0x00 })
{
// The IFD begins with the first Makernote byte (no ASCII name). Used in SR2 and ARW images
PushDirectory(new SonyType1MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset);
}
else if (string.Equals("SEMC MS\u0000\u0000\u0000\u0000\u0000", firstTwelveChars, StringComparison.Ordinal))
{
// Force Motorola byte order for this directory
// skip 12 byte header + 2 for "MM" + 6
PushDirectory(new SonyType6MakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithByteOrder(isMotorolaByteOrder: true), processedIfdOffsets, makernoteOffset + 20);
}
else if (string.Equals("SIGMA\u0000\u0000\u0000", firstEightChars, StringComparison.Ordinal) ||
string.Equals("FOVEON\u0000\u0000", firstEightChars, StringComparison.Ordinal))
{
PushDirectory(new SigmaMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset + 10);
}
else if (string.Equals("KDK", firstThreeChars, StringComparison.Ordinal))
{
var directory = new KodakMakernoteDirectory();
Directories.Add(directory);
ProcessKodakMakernote(directory, makernoteOffset, reader.WithByteOrder(isMotorolaByteOrder: firstSevenChars == "KDK INFO"));
}
else if ("CANON".Equals(cameraMake, StringComparison.OrdinalIgnoreCase))
{
PushDirectory(new CanonMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset);
}
else if (cameraMake != null && cameraMake.StartsWith("CASIO", StringComparison.OrdinalIgnoreCase))
{
if (string.Equals("QVC\u0000\u0000\u0000", firstSixChars, StringComparison.Ordinal))
{
PushDirectory(new CasioType2MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset + 6);
}
else
{
PushDirectory(new CasioType1MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset);
}
}
else if (string.Equals("FUJIFILM", firstEightChars, StringComparison.Ordinal) ||
string.Equals("FUJIFILM", cameraMake, StringComparison.OrdinalIgnoreCase))
{
// Note that this also applies to certain Leica cameras, such as the Digilux-4.3.
// The 4 bytes after "FUJIFILM" in the makernote point to the start of the makernote
// IFD, though the offset is relative to the start of the makernote, not the TIFF header
var makernoteReader = reader.WithShiftedBaseOffset(makernoteOffset).WithByteOrder(isMotorolaByteOrder: false);
var ifdStart = makernoteReader.GetInt32(8);
PushDirectory(new FujifilmMakernoteDirectory());
TiffReader.ProcessIfd(this, makernoteReader, processedIfdOffsets, ifdStart);
}
else if (string.Equals("KYOCERA", firstSevenChars, StringComparison.Ordinal))
{
// http://www.ozhiker.com/electronics/pjmt/jpeg_info/kyocera_mn.html
PushDirectory(new KyoceraMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset + 22);
}
else if (string.Equals("LEICA", firstFiveChars, StringComparison.Ordinal))
{
// used by the X1/X2/X VARIO/T
// (X1 starts with "LEICA\0\x01\0", Make is "LEICA CAMERA AG")
// (X2 starts with "LEICA\0\x05\0", Make is "LEICA CAMERA AG")
// (X VARIO starts with "LEICA\0\x04\0", Make is "LEICA CAMERA AG")
// (T (Typ 701) starts with "LEICA\0\0x6", Make is "LEICA CAMERA AG")
// (X (Typ 113) starts with "LEICA\0\0x7", Make is "LEICA CAMERA AG")
if (string.Equals("LEICA\0\x1\0", firstEightChars, StringComparison.Ordinal) ||
string.Equals("LEICA\0\x4\0", firstEightChars, StringComparison.Ordinal) ||
string.Equals("LEICA\0\x5\0", firstEightChars, StringComparison.Ordinal) ||
string.Equals("LEICA\0\x6\0", firstEightChars, StringComparison.Ordinal) ||
string.Equals("LEICA\0\x7\0", firstEightChars, StringComparison.Ordinal))
{
PushDirectory(new LeicaType5MakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithShiftedBaseOffset(makernoteOffset), processedIfdOffsets, 8);
}
else if (string.Equals("Leica Camera AG", cameraMake, StringComparison.Ordinal))
{
PushDirectory(new LeicaMakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithByteOrder(isMotorolaByteOrder: false), processedIfdOffsets, makernoteOffset + 8);
}
else if (string.Equals("LEICA", cameraMake, StringComparison.Ordinal))
{
// Some Leica cameras use Panasonic makernote tags
PushDirectory(new PanasonicMakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithByteOrder(isMotorolaByteOrder: false), processedIfdOffsets, makernoteOffset + 8);
}
else
{
return(false);
}
}
else if (string.Equals("Panasonic\u0000\u0000\u0000", firstTwelveChars, StringComparison.Ordinal))
{
// NON-Standard TIFF IFD Data using Panasonic Tags. There is no Next-IFD pointer after the IFD
// Offsets are relative to the start of the TIFF header at the beginning of the EXIF segment
// more information here: http://www.ozhiker.com/electronics/pjmt/jpeg_info/panasonic_mn.html
PushDirectory(new PanasonicMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset + 12);
}
else if (string.Equals("AOC\u0000", firstFourChars, StringComparison.Ordinal))
{
// NON-Standard TIFF IFD Data using Casio Type 2 Tags
// IFD has no Next-IFD pointer at end of IFD, and
// Offsets are relative to the start of the current IFD tag, not the TIFF header
// Observed for:
// - Pentax ist D
PushDirectory(new CasioType2MakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithShiftedBaseOffset(makernoteOffset), processedIfdOffsets, 6);
}
else if (cameraMake != null && (cameraMake.StartsWith("PENTAX", StringComparison.OrdinalIgnoreCase) || cameraMake.StartsWith("ASAHI", StringComparison.OrdinalIgnoreCase)))
{
// NON-Standard TIFF IFD Data using Pentax Tags
// IFD has no Next-IFD pointer at end of IFD, and
// Offsets are relative to the start of the current IFD tag, not the TIFF header
// Observed for:
// - PENTAX Optio 330
// - PENTAX Optio 430
PushDirectory(new PentaxMakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithShiftedBaseOffset(makernoteOffset), processedIfdOffsets, 0);
}
// else if ("KC" == firstTwoChars || "MINOL" == firstFiveChars || "MLY" == firstThreeChars || "+M+M+M+M" == firstEightChars)
// {
// // This Konica data is not understood. Header identified in accordance with information at this site:
// // http://www.ozhiker.com/electronics/pjmt/jpeg_info/minolta_mn.html
// // TODO add support for minolta/konica cameras
// exifDirectory.addError("Unsupported Konica/Minolta data ignored.");
// }
else if (string.Equals("SANYO\x0\x1\x0", firstEightChars, StringComparison.Ordinal))
{
PushDirectory(new SanyoMakernoteDirectory());
TiffReader.ProcessIfd(this, reader.WithShiftedBaseOffset(makernoteOffset), processedIfdOffsets, 8);
}
else if (cameraMake != null && cameraMake.StartsWith("RICOH", StringComparison.OrdinalIgnoreCase))
{
if (string.Equals(firstTwoChars, "Rv", StringComparison.Ordinal) ||
string.Equals(firstThreeChars, "Rev", StringComparison.Ordinal))
{
// This is a textual format, where the makernote bytes look like:
// Rv0103;Rg1C;Bg18;Ll0;Ld0;Aj0000;Bn0473800;Fp2E00:������������������������������
// Rv0103;Rg1C;Bg18;Ll0;Ld0;Aj0000;Bn0473800;Fp2D05:������������������������������
// Rv0207;Sf6C84;Rg76;Bg60;Gg42;Ll0;Ld0;Aj0004;Bn0B02900;Fp10B8;Md6700;Ln116900086D27;Sv263:0000000000000000000000��
// This format is currently unsupported
return(false);
}
if (firstFiveChars.Equals("RICOH", StringComparison.OrdinalIgnoreCase))
{
PushDirectory(new RicohMakernoteDirectory());
// Always in Motorola byte order
TiffReader.ProcessIfd(this, reader.WithByteOrder(isMotorolaByteOrder: true).WithShiftedBaseOffset(makernoteOffset), processedIfdOffsets, 8);
}
}
else if (string.Equals(firstTenChars, "Apple iOS\0", StringComparison.Ordinal))
{
PushDirectory(new AppleMakernoteDirectory());
// Always in Motorola byte order
TiffReader.ProcessIfd(this, reader.WithByteOrder(isMotorolaByteOrder: true).WithShiftedBaseOffset(makernoteOffset), processedIfdOffsets, 14);
}
else if (string.Equals("RECONYX", cameraMake, StringComparison.OrdinalIgnoreCase) ||
reader.GetUInt16(makernoteOffset) == ReconyxMakernoteDirectory.HyperFireMakernoteVersion)
{
var directory = new ReconyxMakernoteDirectory();
Directories.Add(directory);
ProcessReconyxMakernote(directory, makernoteOffset, reader);
}
else if (string.Equals("SAMSUNG", cameraMake, StringComparison.Ordinal))
{
// Only handles Type2 notes correctly. Others aren't implemented, and it's complex to determine which ones to use
PushDirectory(new SamsungType2MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, makernoteOffset);
}
else
{
// The makernote is not comprehended by this library.
// If you are reading this and believe a particular camera's image should be processed, get in touch.
return(false);
}
return(true);
}
public override bool CustomProcessTag(int tagOffset, ICollection <int> processedIfdOffsets, IndexedReader reader, int tagId, int byteCount)
{
// Some 0x0000 tags have a 0 byteCount. Determine whether it's bad.
if (tagId == 0)
{
if (CurrentDirectory.ContainsTag(tagId))
{
// Let it go through for now. Some directories handle it, some don't.
return(false);
}
// Skip over 0x0000 tags that don't have any associated bytes. No idea what it contains in this case, if anything.
if (byteCount == 0)
{
return(true);
}
}
// Custom processing for the Makernote tag
if (tagId == ExifDirectoryBase.TagMakernote && CurrentDirectory is ExifSubIfdDirectory)
{
return(ProcessMakernote(tagOffset, processedIfdOffsets, reader));
}
// Custom processing for embedded IPTC data
if (tagId == ExifDirectoryBase.TagIptcNaa && CurrentDirectory is ExifIfd0Directory)
{
// NOTE Adobe sets type 4 for IPTC instead of 7
if (reader.GetSByte(tagOffset) == 0x1c)
{
var iptcBytes = reader.GetBytes(tagOffset, byteCount);
var iptcDirectory = new IptcReader().Extract(new SequentialByteArrayReader(iptcBytes), iptcBytes.Length);
iptcDirectory.Parent = CurrentDirectory;
Directories.Add(iptcDirectory);
return(true);
}
return(false);
}
// Custom processing for embedded XMP data
if (tagId == ExifDirectoryBase.TagApplicationNotes && CurrentDirectory is ExifIfd0Directory)
{
var xmpDirectory = new XmpReader().Extract(reader.GetNullTerminatedBytes(tagOffset, byteCount));
xmpDirectory.Parent = CurrentDirectory;
Directories.Add(xmpDirectory);
return(true);
}
if (HandlePrintIM(CurrentDirectory, tagId))
{
var dirPrintIm = new PrintIMDirectory();
dirPrintIm.Parent = CurrentDirectory;
Directories.Add(dirPrintIm);
ProcessPrintIM(dirPrintIm, tagOffset, reader, byteCount);
return(true);
}
// Note: these also appear in TryEnterSubIfd because some are IFD pointers while others begin immediately
// for the same directories
if (CurrentDirectory is OlympusMakernoteDirectory)
{
switch (tagId)
{
case OlympusMakernoteDirectory.TagEquipment:
PushDirectory(new OlympusEquipmentMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
case OlympusMakernoteDirectory.TagCameraSettings:
PushDirectory(new OlympusCameraSettingsMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
case OlympusMakernoteDirectory.TagRawDevelopment:
PushDirectory(new OlympusRawDevelopmentMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
case OlympusMakernoteDirectory.TagRawDevelopment2:
PushDirectory(new OlympusRawDevelopment2MakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
case OlympusMakernoteDirectory.TagImageProcessing:
PushDirectory(new OlympusImageProcessingMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
case OlympusMakernoteDirectory.TagFocusInfo:
PushDirectory(new OlympusFocusInfoMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
case OlympusMakernoteDirectory.TagRawInfo:
PushDirectory(new OlympusRawInfoMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
case OlympusMakernoteDirectory.TagMainInfo:
PushDirectory(new OlympusMakernoteDirectory());
TiffReader.ProcessIfd(this, reader, processedIfdOffsets, tagOffset);
return(true);
}
}
if (CurrentDirectory is PanasonicRawIfd0Directory)
{
// these contain binary data with specific offsets, and can't be processed as regular ifd's.
// The binary data is broken into 'fake' tags and there is a pattern.
switch (tagId)
{
case PanasonicRawIfd0Directory.TagWbInfo:
var dirWbInfo = new PanasonicRawWbInfoDirectory();
dirWbInfo.Parent = CurrentDirectory;
Directories.Add(dirWbInfo);
ProcessBinary(dirWbInfo, tagOffset, reader, byteCount, false, 2);
return(true);
case PanasonicRawIfd0Directory.TagWbInfo2:
var dirWbInfo2 = new PanasonicRawWbInfo2Directory();
dirWbInfo2.Parent = CurrentDirectory;
Directories.Add(dirWbInfo2);
ProcessBinary(dirWbInfo2, tagOffset, reader, byteCount, false, 3);
return(true);
case PanasonicRawIfd0Directory.TagDistortionInfo:
var dirDistort = new PanasonicRawDistortionDirectory();
dirDistort.Parent = CurrentDirectory;
Directories.Add(dirDistort);
ProcessBinary(dirDistort, tagOffset, reader, byteCount);
return(true);
}
}
// Panasonic RAW sometimes contains an embedded version of the data as a JPG file.
if (tagId == PanasonicRawIfd0Directory.TagJpgFromRaw && CurrentDirectory is PanasonicRawIfd0Directory)
{
var jpegrawbytes = reader.GetBytes(tagOffset, byteCount);
// Extract information from embedded image since it is metadata-rich
var jpegmem = new MemoryStream(jpegrawbytes);
var jpegDirectory = Jpeg.JpegMetadataReader.ReadMetadata(jpegmem);
foreach (var dir in jpegDirectory)
{
dir.Parent = CurrentDirectory;
Directories.Add(dir);
}
return(true);
}
return(false);
}
/// <summary>Processes a TIFF IFD.</summary>
/// <remarks>
/// IFD Header:
/// <list type="bullet">
/// <item><b>2 bytes</b> number of tags</item>
/// </list>
/// Tag structure:
/// <list type="bullet">
/// <item><b>2 bytes</b> tag type</item>
/// <item><b>2 bytes</b> format code (values 1 to 12, inclusive)</item>
/// <item><b>4 bytes</b> component count</item>
/// <item><b>4 bytes</b> inline value, or offset pointer if too large to fit in four bytes</item>
/// </list>
/// </remarks>
/// <param name="handler">the <see cref="ITiffHandler"/> that will coordinate processing and accept read values</param>
/// <param name="reader">the <see cref="IndexedReader"/> 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 <c>reader</c> at which the IFD data starts</param>
/// <param name="tiffHeaderOffset">the offset within <c>reader</c> 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([NotNull] ITiffHandler handler, [NotNull] IndexedReader reader, [NotNull] 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(ifdOffset))
{
return;
}
// remember that we've visited this directory so that we don't visit it again later
processedIfdOffsets.Add(ifdOffset);
if (ifdOffset >= reader.Length || 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);
var dirLength = (2 + (12 * dirTagCount) + 4);
if (dirLength + ifdOffset > reader.Length)
{
handler.Error("Illegally sized IFD");
return;
}
//
// Handle each tag in this directory
//
var invalidTiffFormatCodeCount = 0;
for (var tagNumber = 0; tagNumber < dirTagCount; tagNumber++)
{
var tagOffset = CalculateTagOffset(ifdOffset, tagNumber);
// 2 bytes for the tag id
int tagId = reader.GetUInt16(tagOffset);
// 2 bytes for the format code
var formatCode = (TiffDataFormatCode)reader.GetUInt16(tagOffset + 2);
var 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);
// TODO specify threshold as a parameter, or provide some other external control over this behaviour
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
var componentCount = reader.GetInt32(tagOffset + 4);
if (componentCount < 0)
{
handler.Error("Negative TIFF tag component count");
continue;
}
var byteCount = componentCount * format.ComponentSizeBytes;
int tagValueOffset;
if (byteCount > 4)
{
// If it's bigger than 4 bytes, the dir entry contains an offset.
var offsetVal = reader.GetInt32(tagOffset + 8);
if (offsetVal + byteCount > reader.Length)
{
// 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.Length)
{
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.Length)
{
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))
{
var 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
var finalTagOffset = CalculateTagOffset(ifdOffset, dirTagCount);
var nextIfdOffset = reader.GetInt32(finalTagOffset);
if (nextIfdOffset != 0)
{
nextIfdOffset += tiffHeaderOffset;
if (nextIfdOffset >= reader.Length)
{
// 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();
}
}
public override bool CustomProcessTag(int tagOffset, ICollection <int> processedIfdOffsets, IndexedReader reader, int tagId, int byteCount)
{
switch (tagId)
{
case TagXmp:
Directories.Add(new XmpReader().Extract(reader.GetBytes(tagOffset, byteCount)));
return(true);
case TagPhotoshopImageResources:
Directories.AddRange(new PhotoshopReader().Extract(new SequentialByteArrayReader(reader.GetBytes(tagOffset, byteCount)), byteCount));
return(true);
case TagIccProfiles:
Directories.Add(new IccReader().Extract(new ByteArrayReader(reader.GetBytes(tagOffset, byteCount))));
return(true);
}
return(base.CustomProcessTag(tagOffset, processedIfdOffsets, reader, tagId, byteCount));
}
public abstract void Completed(IndexedReader reader, int tiffHeaderOffset);
