private IFDEntry ParseMakernote(ushort tag, ushort type, uint count, long base_offset, uint offset)
{
long makernote_offset = base_offset + offset;
IFDStructure ifd_structure = new IFDStructure();
// This is the minimum size a makernote should have
// The shortest header is PENTAX_HEADER (4)
// + IFD entry count (2)
// + at least one IFD etry (12)
// + next IFD pointer (4)
// = 22 ....
// we use this number to read a header which is big used
// to identify the makernote types
int header_size = 18;
long length = 0;
try {
length = file.Length;
} catch (Exception) {
// Use a safety-value of 4 gigabyte.
length = 1073741824L * 4;
}
if (makernote_offset > length)
{
file.MarkAsCorrupt("offset to makernote is beyond file size");
return(null);
}
if (makernote_offset + header_size > length)
{
file.MarkAsCorrupt("data is to short to contain a maker note ifd");
return(null);
}
// read header
file.Seek(makernote_offset, SeekOrigin.Begin);
ByteVector header = file.ReadBlock(header_size);
if (header.StartsWith(PANASONIC_HEADER))
{
IFDReader reader =
new IFDReader(file, is_bigendian, ifd_structure, base_offset, offset + 12, max_offset);
reader.ReadIFD(base_offset, offset + 12, max_offset);
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Panasonic, PANASONIC_HEADER, 12, true, null));
}
if (header.StartsWith(PENTAX_HEADER))
{
IFDReader reader =
new IFDReader(file, is_bigendian, ifd_structure, base_offset, offset + 6, max_offset);
reader.ReadIFD(base_offset, offset + 6, max_offset);
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Pentax, header.Mid(0, 6), 6, true, null));
}
if (header.StartsWith(OLYMPUS1_HEADER))
{
IFDReader reader =
new IFDReader(file, is_bigendian, ifd_structure, base_offset, offset + 8, max_offset);
reader.Read();
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Olympus1, header.Mid(0, 8), 8, true, null));
}
if (header.StartsWith(OLYMPUS2_HEADER))
{
IFDReader reader =
new IFDReader(file, is_bigendian, ifd_structure, makernote_offset, 12, count);
reader.Read();
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Olympus2, header.Mid(0, 12), 12, false, null));
}
if (header.StartsWith(SONY_HEADER))
{
IFDReader reader =
new IFDReader(file, is_bigendian, ifd_structure, base_offset, offset + 12, max_offset);
reader.ReadIFD(base_offset, offset + 12, max_offset);
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Sony, SONY_HEADER, 12, true, null));
}
if (header.StartsWith(NIKON_HEADER))
{
ByteVector endian_bytes = header.Mid(10, 2);
if (endian_bytes.ToString() == "II" || endian_bytes.ToString() == "MM")
{
bool makernote_endian = endian_bytes.ToString().Equals("MM");
ushort magic = header.Mid(12, 2).ToUShort(is_bigendian);
if (magic == 42)
{
// TODO: the max_offset value is not correct here. However, some nikon files have offsets to a sub-ifd
// (preview image) which are not stored with the other makernote data. Therfore, we keep the max_offset
// for now. (It is just an upper bound for some checks. So if it is too big, it doesn't matter)
var reader =
new Nikon3MakernoteReader(file, makernote_endian, ifd_structure, makernote_offset + 10, 8, max_offset - offset - 10);
reader.Read();
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Nikon3, header.Mid(0, 18), 8, false, makernote_endian));
}
}
}
if (header.StartsWith(LEICA_HEADER))
{
IFDReader reader = new IFDReader(file, is_bigendian, ifd_structure, makernote_offset, 8, count);
reader.Read();
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Leica, header.Mid(0, 8), 10, false, null));
}
try {
IFDReader reader =
new IFDReader(file, is_bigendian, ifd_structure, base_offset, offset, max_offset);
reader.Read();
return(new MakernoteIFDEntry(tag, ifd_structure, MakernoteType.Canon));
} catch {
return(null);
}
}
/// <summary>
/// Try to parse the given IFD entry, used to discover format-specific entries.
/// </summary>
/// <param name="tag">
/// A <see cref="System.UInt16"/> with the tag of the entry.
/// </param>
/// <param name="type">
/// A <see cref="System.UInt16"/> with the type of the entry.
/// </param>
/// <param name="count">
/// A <see cref="System.UInt32"/> with the data count of the entry.
/// </param>
/// <param name="base_offset">
/// A <see cref="System.Int64"/> with the base offset which every offsets in the
/// IFD are relative to.
/// </param>
/// <param name="offset">
/// A <see cref="System.UInt32"/> with the offset of the entry.
/// </param>
/// <returns>
/// A <see cref="IFDEntry"/> with the given parameters, or null if none was parsed, after
/// which the normal TIFF parsing is used.
/// </returns>
protected virtual IFDEntry ParseIFDEntry(ushort tag, ushort type, uint count, long base_offset, uint offset)
{
if (tag == (ushort)ExifEntryTag.MakerNote && parse_makernote)
{
return(ParseMakernote(tag, type, count, base_offset, offset));
}
if (tag == (ushort)IFDEntryTag.SubIFDs)
{
var entries = new List <IFDStructure> ();
uint [] data;
if (count >= 2)
{
// This is impossible right?
if (base_offset + offset > file.Length)
{
file.MarkAsCorrupt("Length of SubIFD is too long");
return(null);
}
file.Seek(base_offset + offset, SeekOrigin.Begin);
data = ReadUIntArray(count);
}
else
{
data = new uint [] { offset };
}
foreach (var sub_offset in data)
{
var sub_structure = new IFDStructure();
var sub_reader = CreateSubIFDReader(file, is_bigendian, sub_structure, base_offset, sub_offset, max_offset);
sub_reader.Read();
entries.Add(sub_structure);
}
return(new SubIFDArrayEntry(tag, entries));
}
IFDStructure ifd_structure = new IFDStructure();
IFDReader reader = CreateSubIFDReader(file, is_bigendian, ifd_structure, base_offset, offset, max_offset);
// Sub IFDs are either identified by the IFD-type ...
if (type == (ushort)IFDEntryType.IFD)
{
reader.Read();
return(new SubIFDEntry(tag, type, (uint)ifd_structure.Directories.Length, ifd_structure));
}
// ... or by one of the following tags
switch (tag)
{
case (ushort)IFDEntryTag.ExifIFD:
case (ushort)IFDEntryTag.InteroperabilityIFD:
case (ushort)IFDEntryTag.GPSIFD:
reader.Read();
return(new SubIFDEntry(tag, (ushort)IFDEntryType.Long, 1, ifd_structure));
default:
return(null);
}
}