////------------------------------------------------------------------------------------------------------------------------------
private static void ValidateHeader(ApeHeader header, ApeHeader footer)
{
#if DEBUG
if (header != null && footer != null)
{
if (header.Version != footer.Version)
{
throw new System.IO.InvalidDataException(
String.Format("The APE header version {0} does not match footer version {1}.", header.Version, footer.Version));
}
if (header.Size != footer.Size)
throw new System.IO.InvalidDataException(String.Format("The APE header tag has a different size {0} than the footer size {1}", header.Size, footer.Size));
}
if ((header != null) && (header.Version >= ApeVersion.Version2))
{
//if (!header.IsHeader)
// throw new System.IO.InvalidDataException("The APE header tag is claiming to be the footer!");
// This is valid it seems.
//if (header.UseHeader)
// throw new System.IO.InvalidDataException("The APE header tag is claiming there's a header!");
//if ((footer == null) && header.UseFooter)
// throw new System.IO.InvalidDataException("The APE header tag is claiming there's a footer when there isn't!");
//if (!System.Linq.Enumerable.All(header.ReservedBytes, b => b == 0x00))
//{
// throw new System.IO.InvalidDataException(
// String.Format(
// "The APE header tag's \"reserved\" field contains non-null bytes: {0}",
// String.Join(" ", System.Linq.Enumerable.Select(header.ReservedBytes, b => "0x" + b.ToString("X2")))));
//}
}
if ((footer != null) && (footer.Version >= ApeVersion.Version2))
{
//if (footer.IsHeader)
// throw new System.IO.InvalidDataException("The APE footer tag is claiming to be the header!");
//if ((header == null) && footer.UseHeader)
// throw new System.IO.InvalidDataException("The APE header tag is claiming there's a header when there isn't!");
// This is valid it seems.
//if (footer.UseFooter)
// throw new System.IO.InvalidDataException("The APE footer tag is claiming there's a footer!");
//if (!System.Linq.Enumerable.All(footer.ReservedBytes, b => b == 0x00))
//{
// throw new System.IO.InvalidDataException(
// String.Format(
// "The APE footer tag's \"reserved\" field contains non-null bytes: {0}",
// String.Join(" ", System.Linq.Enumerable.Select(footer.ReservedBytes, b => "0x" + b.ToString("X2")))));
//}
}
#else
return;
#endif
}
////------------------------------------------------------------------------------------------------------------------------------
/// <summary>
/// Gets a value indicating whether the tag is valid or not.
/// </summary>
/// <param name="header">The header.</param>
/// <returns>
/// <c>true</c> if it is valid; otherwise, <c>false</c>.
/// </returns>
/// <exception cref="System.ArgumentNullException">header</exception>
private static bool IsValidTag(ApeHeader header)
{
if (header == null)
throw new ArgumentNullException("header");
// Validity check - only version 2.0+ may have a header.
return header.FrameCount <= ApeTag.MaxAllowedFields && (header.Size - ApeTag.FooterSize) <= ApeTag.MaxAllowedSize
&& ((header.Flags == 0) || (header.Version >= ApeVersion.Version2));
}
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;
}
