TiffIFD parseDngPrivateData(TiffEntry t)
{
/*
1. Six bytes containing the zero-terminated string "Adobe". (The DNG specification calls for the DNGPrivateData tag to start with an ASCII string identifying the creator/format).
2. 4 bytes: an ASCII string ("MakN" for a Makernote), indicating what sort of data is being stored here. Note that this is not zero-terminated.
3. A four-byte count (number of data bytes following); this is the length of the original MakerNote data. (This is always in "most significant byte first" format).
4. 2 bytes: the byte-order indicator from the original file (the usual 'MM'/4D4D or 'II'/4949).
5. 4 bytes: the original file offset for the MakerNote tag data (stored according to the byte order given above).
6. The contents of the MakerNote tag. This is a simple byte-for-byte copy, with no modification.
*/
UInt32 size = t.count;
byte[] data = t.getData();
string id((char*) data);
if (0 != id.compare("Adobe"))
TiffParsingException.ThrowTPE("Not Adobe Private data");
data += 6;
if (!(data[0] == 'M' && data[1] == 'a' && data[2] == 'k' && data[3] == 'N'))
ThrowTPE("Not Makernote");
data += 4;
UInt32 count;
if (Endianness.big == Common.getHostEndianness())
count = *(UInt32*)data;
else
count = (unsigned int)data[0] << 24 | (unsigned int)data[1] << 16 | (unsigned int)data[2] << 8 | (unsigned int)data[3];
data += 4;
if (count > size)
ThrowTPE("Error reading TIFF structure (invalid size). File Corrupt");
Endianness makernote_endian = unknown;
if (data[0] == 0x49 && data[1] == 0x49)
makernote_endian = little;
else if (data[0] == 0x4D && data[1] == 0x4D)
makernote_endian = big;
else
ThrowTPE("Cannot determine endianess of DNG makernote");
data += 2;
UInt32 org_offset;
if (big == getHostEndianness())
org_offset = *(UInt32*)data;
else
org_offset = (unsigned int)data[0] << 24 | (unsigned int)data[1] << 16 | (unsigned int)data[2] << 8 | (unsigned int)data[3];
data += 4;
/* We don't parse original makernotes that are placed after 300MB mark in the original file */
if (org_offset + count > 300 * 1024 * 1024)
ThrowTPE("Adobe Private data: original offset of makernote is past 300MB offset");
/* Create fake tiff with original offsets */
byte[] maker_data = new byte8[org_offset + count];
memcpy(&maker_data[org_offset], data, count);
FileMap* maker_map = new FileMap(maker_data, org_offset + count);
TiffIFD* maker_ifd;
try
{
maker_ifd = parseMakerNote(maker_map, org_offset, makernote_endian);
}
catch (TiffParserException &e) {
delete[] maker_data;
delete maker_map;
throw e;
}
delete[] maker_data;
delete maker_map;
return maker_ifd;
}
