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private static ApeItem ReadItem(ApeVersion version, StreamBuffer sb, long maximumItemSize)
{
if (sb == null)
throw new ArgumentNullException("sb");
// Find the item.
long startPosition = sb.Position;
long bytesToSkip = GetBytesUntilNextItem(version, sb, maximumItemSize);
// Not found; return null.
if (bytesToSkip == -1)
return null;
// Move the stream position to the start of the frame.
sb.Position = startPosition + bytesToSkip;
int valueSize = sb.ReadLittleEndianInt32();
if ((valueSize <= 0) || (valueSize > ApeTag.MaxAllowedSize))
return null;
int flags = sb.ReadLittleEndianInt32();
maximumItemSize -= 8;
int itemKeyLengthBytes = 0;
long maximumBytesToRead = maximumItemSize;
if (maximumBytesToRead > 0)
{
for (int y = 0; y < maximumBytesToRead; y++)
{
int character = sb.ReadByte();
if (character == 0x00) // 0x00 byte - string terminator.
break;
itemKeyLengthBytes++;
}
}
// Name
sb.Seek(-(itemKeyLengthBytes + 1), SeekOrigin.Current);
string key = sb.ReadString(itemKeyLengthBytes, Encoding.UTF8);
if ((key.Length < MinKeyLengthCharacters) || (itemKeyLengthBytes > MaxKeyLengthBytes))
return null;
// Skip Item key terminator (0x00 byte)
int keyTerminator = sb.ReadByte();
if (keyTerminator != 0x00)
return null;
ApeItem item = GetItem(version, key, flags);
return item.ReadItem(version, valueSize, sb, maximumItemSize) ? item : null;
}
private static ApeHeader ReadHeader(StreamBuffer stream, long startHeaderPosition, long endHeaderPosition)
{
if (stream == null)
throw new ArgumentNullException("stream");
stream.Position = startHeaderPosition;
while (startHeaderPosition < endHeaderPosition)
{
int y = 0;
while (stream.ReadByte() == TagIdentifierBytes[y++])
{
startHeaderPosition++;
if (y != TagIdentifierBytes.Length)
continue;
ApeHeader hdr = new ApeHeader
{
Position = stream.Position - TagIdentifierBytes.Length,
Version = (ApeVersion)(stream.ReadLittleEndianInt32() / 1000),
Size = stream.ReadLittleEndianInt32(),
FrameCount = stream.ReadLittleEndianInt32(),
Flags = stream.ReadLittleEndianInt32(),
ReservedBytes = new byte[8]
};
stream.Read(hdr.ReservedBytes, 8);
if (IsValidTag(hdr))
return hdr;
startHeaderPosition -= ApeTag.HeaderSize;
stream.Position = startHeaderPosition + 1;
break;
}
startHeaderPosition++;
}
return null;
}
public void ReadLittleEndianInt32Test()
{
const int Value = 0x12345678;
const int Expected = 0x12345678;
StreamBuffer target = new StreamBuffer(BitConverter.GetBytes(Value)) { Position = 0 };
int actual = target.ReadLittleEndianInt32();
Assert.AreEqual(Expected, actual);
}