/*! \note The value of "Size" does not include the size of any filler before
* the primer, but the return value does
* \return The number of bytes read (<b>including</b> any preceeding filler)
*/
Length mxflib::Partition::ReadMetadata(MXFFilePtr File, Length Size)
{
Length Bytes = 0;
Length FillerBytes = 0;
// Clear any existing metadata, including the primer
ClearMetadata(false);
// Quick return for NULL metadata
if(Size == 0) return 0;
// Record the position of the current item
Position Location = File->Tell();
// Check for a leading filler item
{
ULPtr FirstUL = File->ReadKey();
if(!FirstUL)
{
error("Error reading first KLV after %s at 0x%s in %s\n", FullName().c_str(),
Int64toHexString(GetLocation(),8).c_str(), GetSource().c_str());
return 0;
}
if(FirstUL->Matches(KLVFill_UL))
{
// Skip over the filler, recording how far we went
Position NewLocation = File->ReadBER();
NewLocation += File->Tell();
FillerBytes = NewLocation - Location;
Location = NewLocation;
}
}
// Sanity check the size for this platform
// TODO: Should we fix this so that we can read larger metadata - but if so where in memory would we put it if its > 4GB on a 32-bit machine?
if((sizeof(size_t) < 8) && Size > 0xffffffff)
{
error("Maximum read size on this platform is 4Gbytes - However, requested to read metadata at 0x%s which has size of 0x%s\n",
Int64toHexString(Location,8).c_str(), Int64toHexString(Size,8).c_str());
return 0;
}
// Read enough bytes for the metadata
File->Seek(Location);
DataChunkPtr Data = File->Read(static_cast<size_t>(Size));
if(Data->Size != static_cast<size_t>(Size))
{
error("Header Metadata starting at 0x%s should contain 0x%s bytes, but only 0x%s could be read\n",
Int64toHexString(Location,8).c_str(), Int64toHexString(Size,8).c_str(), Int64toHexString(Data->Size,8).c_str());
Size = static_cast<Length>(Data->Size);
}
// Start of data buffer
const UInt8 *BuffPtr = Data->Data;
while(Size)
{
Length BytesAtItemStart = Bytes;
if(Size < 16)
{
error("Less than 16-bytes of header metadata available after reading 0x%s bytes at 0x%s in file \"%s\"\n",
Int64toHexString(Bytes, 8).c_str(), Int64toHexString(File->Tell(),8).c_str(), File->Name.c_str() );
break;
}
/* // Sanity check the keys
if((BuffPtr[0] != 6) || (BuffPtr[1] != 0x0e))
{
error("Invalid KLV key found at 0x%s in file \"%s\"\n", Int64toHexString(File->Tell(),8).c_str(), File->Name.c_str() );
break;
}
*/
// Build an object (it may come back as an "unknown")
ULPtr NewUL = new UL(BuffPtr);
/* If we are loading metadictionaries, we do so when we first read the Preface key */
if(Feature(FeatureLoadMetadict))
{
if(NewUL->Matches(Preface_UL))
{
LoadMetadict();
}
}
MDObjectPtr NewItem = new MDObject(NewUL);
mxflib_assert(NewItem);
BuffPtr += 16;
Size -= 16;
Bytes += 16;
if(Size < 1)
{
error("Incomplete BER length at 0x%s in file \"%s\"\n", Int64toHexString(File->Tell(),8).c_str(), File->Name.c_str() );
break;
}
Length Len = *BuffPtr++;
Size--;
Bytes++;
if(Len >= 0x80)
{
UInt32 i = (UInt32)Len & 0x7f;
if(Size < i)
{
error("Incomplete BER length at 0x%s in \"%s\"\n", Int64toHexString(File->Tell(),8).c_str(), File->Name.c_str() );
break;
}
Len = 0;
while(i--)
{
Len = ((Len<<8) + *(BuffPtr++));
Size--;
Bytes++;
}
}
// DRAGONS: KLV Size limit!!
if(Len > 0xffffffff)
{
error("Current implementation KLV size limit of 0xffffffff bytes exceeded at 0x%s in file \"%s\"\n",
Int64toHexString(Location + Bytes,8).c_str(), File->Name.c_str() );
break;
}
if(Size < Len)
{
error("KLV length is %s but available data size is only %s after reading 0x%s of header metadata at 0x%s in \"%s\"\n",
UInt64toString(Len).c_str(), UInt64toString(Size).c_str(), Int64toHexString(Bytes, 8).c_str(),
Int64toHexString(Location + Bytes,8).c_str(), File->Name.c_str() );
// Try reading what we have
Len = Size;
}
// Check for the primer until we have found it
if(!PartitionPrimer)
{
if(NewItem->IsA(Primer_UL))
{
PartitionPrimer = new Primer;
UInt32 ThisBytes = PartitionPrimer->ReadValue(BuffPtr, (UInt32)Len);
Size -= ThisBytes;
Bytes += ThisBytes;
BuffPtr += ThisBytes;
// Skip further processing for the primer
continue;
}
}
// Skip any filler items
if(NewItem->IsA(KLVFill_UL))
{
Size -= Len;
Bytes += Len;
BuffPtr += Len;
// Don't add the filler
continue;
}
if(Len)
{
NewItem->SetParent(File, BytesAtItemStart + Location,(UInt32)( Bytes - BytesAtItemStart));
NewItem->ReadValue(BuffPtr,(UInt32) Len, PartitionPrimer);
// Skip total length, not just the length actually consumed
Size -= Len;
Bytes += Len;
BuffPtr += Len;
}
AddMetadata(NewItem);
}
return Bytes + FillerBytes;
}
