private int PushChunkRead(bool firstChunk)
{
Chunk chunk;
int err;
byte[] buffer;
var top = GetCurrentContext();
if (top == null && !firstChunk)
{
return((int)ParserStatus.EndOfFile);
}
var type = top != null ? top.Type : 0;
if (firstChunk)
{
buffer = new byte[Marshal.SizeOf <SmallChunk>()];
err = _streamOperations.Read(_ioContext, buffer, 0, buffer.Length);
if (err != Marshal.SizeOf <SmallChunk>())
{
if (err >= 0)
{
err = (int)ParserStatus.NotIFF;
}
return(err);
}
var smallChunk = Marshal.BytesToStruct <SmallChunk>(buffer);
chunk.Id = smallChunk.Id;
chunk.Size = smallChunk.Size;
if (chunk.Size == (ulong)ChunkSize.Known64Bit)
{
buffer = new byte[chunk.Size];
err = _streamOperations.Read(_ioContext, buffer, 0, buffer.Length);
if ((ulong)err != chunk.Size)
{
if (err >= 0)
{
err = (int)ParserStatus.NotIFF;
}
return(err);
}
chunk.Size = BitConverter.ToUInt32(buffer, 0);
}
else if (chunk.Size >= (ulong)ChunkSize.Reserved)
{
return((int)ParserStatus.Mangled);
}
}
else
{
/* Using ReadChunk() causes these bytes to go into the
* parent's scan count
*/
buffer = new byte[Marshal.SizeOf <SmallChunk>()];
err = ReadChunk(buffer, 0, buffer.Length);
if (err != Marshal.SizeOf <SmallChunk>())
{
if (err >= 0)
{
err = (int)ParserStatus.PrematureEndOfFile;
}
return(err);
}
var smallChunk = Marshal.BytesToStruct <SmallChunk>(buffer);
chunk.Id = smallChunk.Id;
chunk.Size = smallChunk.Size;
if (chunk.Size == (ulong)ChunkSize.Known64Bit)
{
buffer = new byte[chunk.Size];
err = _streamOperations.Read(_ioContext, buffer, 0, buffer.Length);
if ((ulong)err != chunk.Size)
{
if (err >= 0)
{
err = (int)ParserStatus.NotIFF;
}
return(err);
}
chunk.Size = BitConverter.ToUInt32(buffer, 0);
}
else if (chunk.Size >= (ulong)ChunkSize.Reserved)
{
return((int)ParserStatus.Mangled);
}
if (chunk.Size > (top.Size - top.Offset))
{
return((int)ParserStatus.Mangled);
}
}
if (IdUtility.IsGoodId(chunk.Id))
{
try {
var contextNode = new ContextNode(chunk.Id, type);
contextNode.Size = chunk.Size;
contextNode.Offset = 0;
contextNode.CurrentSize = chunk.Size;
_stack.AddHead(contextNode);
return(0);
} catch (OutOfMemoryException) {
return((int)ParserStatus.OutOfMemory);
}
}
if (this._newIO)
{
return((int)ParserStatus.NotIFF);
}
return((int)ParserStatus.SyntaxError);
}