bool dng_info::ValidateIFD (dng_stream &stream,
uint64 ifdOffset,
int64 offsetDelta)
{
// Make sure we have a count.
if (ifdOffset + 2 > stream.Length ())
{
return false;
}
// Get entry count.
stream.SetReadPosition (ifdOffset);
uint32 ifdEntries = stream.Get_uint16 ();
if (ifdEntries < 1)
{
return false;
}
// Make sure we have room for all entries and next IFD link.
if (ifdOffset + 2 + ifdEntries * 12 + 4 > stream.Length ())
{
return false;
}
// Check each entry.
for (uint32 tag_index = 0; tag_index < ifdEntries; tag_index++)
{
stream.SetReadPosition (ifdOffset + 2 + tag_index * 12);
stream.Skip (2); // Ignore tag code.
uint32 tagType = stream.Get_uint16 ();
uint32 tagCount = stream.Get_uint32 ();
uint32 tag_type_size = TagTypeSize (tagType);
if (tag_type_size == 0)
{
return false;
}
uint32 tag_data_size = tagCount * tag_type_size;
if (tag_data_size > 4)
{
uint64 tagOffset = stream.Get_uint32 ();
tagOffset += offsetDelta;
if (tagOffset + tag_data_size > stream.Length ())
{
return false;
}
}
}
return true;
}
bool dng_camera_profile_info::ParseExtended (dng_stream &stream)
{
try
{
// Offsets are relative to the start of this structure, not the entire file.
uint64 startPosition = stream.Position ();
// Read header. Like a TIFF header, but with different magic number
// Plus all offsets are relative to the start of the IFD, not to the
// stream or file.
uint16 byteOrder = stream.Get_uint16 ();
if (byteOrder == byteOrderMM)
fBigEndian = true;
else if (byteOrder == byteOrderII)
fBigEndian = false;
else
return false;
TempBigEndian setEndianness (stream, fBigEndian);
uint16 magicNumber = stream.Get_uint16 ();
if (magicNumber != magicExtendedProfile)
{
return false;
}
uint32 offset = stream.Get_uint32 ();
stream.Skip (offset - 8);
// Start on IFD entries.
uint32 ifdEntries = stream.Get_uint16 ();
if (ifdEntries < 1)
{
return false;
}
for (uint32 tag_index = 0; tag_index < ifdEntries; tag_index++)
{
stream.SetReadPosition (startPosition + 8 + 2 + tag_index * 12);
uint16 tagCode = stream.Get_uint16 ();
uint32 tagType = stream.Get_uint16 ();
uint32 tagCount = stream.Get_uint32 ();
uint64 tagOffset = stream.Position ();
if (TagTypeSize (tagType) * tagCount > 4)
{
tagOffset = startPosition + stream.Get_uint32 ();
stream.SetReadPosition (tagOffset);
}
if (!ParseTag (stream,
0,
tagCode,
tagType,
tagCount,
tagOffset))
{
#if qDNGValidate
if (gVerbose)
{
stream.SetReadPosition (tagOffset);
printf ("*");
DumpTagValues (stream,
LookupTagType (tagType),
0,
tagCode,
tagType,
tagCount);
}
#endif
}
}
return true;
}
catch (...)
{
// Eat parsing errors.
}
return false;
}