/// <summary>
/// Reads a single exception handler from the provided input stream.
/// </summary>
/// <param name="body">The method body containing the exception handler.</param>
/// <param name="reader">The input stream.</param>
/// <param name="isFat"><c>true</c> if the fat format should be used, <c>false</c> otherwise.</param>
/// <returns>The exception handler.</returns>
public static CilExceptionHandler FromReader(CilMethodBody body, IBinaryStreamReader reader, bool isFat)
{
CilExceptionHandlerType handlerType;
int tryStartOffset;
int tryEndOffset;
int handlerStartOffset;
int handlerEndOffset;
// Read raw structure.
if (isFat)
{
handlerType = (CilExceptionHandlerType)reader.ReadUInt32();
tryStartOffset = reader.ReadInt32();
tryEndOffset = tryStartOffset + reader.ReadInt32();
handlerStartOffset = reader.ReadInt32();
handlerEndOffset = handlerStartOffset + reader.ReadInt32();
}
else
{
handlerType = (CilExceptionHandlerType)reader.ReadUInt16();
tryStartOffset = reader.ReadUInt16();
tryEndOffset = tryStartOffset + reader.ReadByte();
handlerStartOffset = reader.ReadUInt16();
handlerEndOffset = handlerStartOffset + reader.ReadByte();
}
int exceptionTokenOrFilterStart = reader.ReadInt32();
// Create handler.
var handler = new CilExceptionHandler
{
HandlerType = handlerType,
TryStart = body.Instructions.GetByOffset(tryStartOffset)?.CreateLabel() ??
new CilOffsetLabel(tryStartOffset),
TryEnd = body.Instructions.GetByOffset(tryEndOffset)?.CreateLabel() ?? new CilOffsetLabel(tryEndOffset),
HandlerStart = body.Instructions.GetByOffset(handlerStartOffset)?.CreateLabel() ??
new CilOffsetLabel(handlerStartOffset),
HandlerEnd = body.Instructions.GetByOffset(handlerEndOffset)?.CreateLabel() ??
new CilOffsetLabel(handlerEndOffset),
};
// Interpret last field.
switch (handler.HandlerType)
{
case CilExceptionHandlerType.Exception when body.Owner.Module.TryLookupMember(exceptionTokenOrFilterStart, out var member):
handler.ExceptionType = member as ITypeDefOrRef;
break;
case CilExceptionHandlerType.Filter:
handler.FilterStart = body.Instructions.GetByOffset(exceptionTokenOrFilterStart)?.CreateLabel()
?? new CilOffsetLabel(exceptionTokenOrFilterStart);
break;;
}
return(handler);
}
private static void ReadExceptionHandlers(CilRawFatMethodBody fatBody, CilMethodBody result)
{
foreach (var section in fatBody.ExtraSections)
{
if (section.IsEHTable)
{
var reader = new ByteArrayReader(section.Data);
int size = section.IsFat
? CilExceptionHandler.FatExceptionHandlerSize
: CilExceptionHandler.TinyExceptionHandlerSize;
while (reader.CanRead(size))
result.ExceptionHandlers.Add(CilExceptionHandler.FromReader(result, reader, section.IsFat));
}
}
}
private void WriteExceptionHandler(MethodBodySerializationContext context, IBinaryStreamWriter writer, CilExceptionHandler handler, bool useFatFormat)
{
if (handler.IsFat && !useFatFormat)
{
throw new InvalidOperationException("Can only serialize fat exception handlers in fat format.");
}
// Write handler type and boundaries.
if (useFatFormat)
{
writer.WriteUInt32((uint)handler.HandlerType);
writer.WriteUInt32((uint)handler.TryStart.Offset);
writer.WriteUInt32((uint)(handler.TryEnd.Offset - handler.TryStart.Offset));
writer.WriteUInt32((uint)handler.HandlerStart.Offset);
writer.WriteUInt32((uint)(handler.HandlerEnd.Offset - handler.HandlerStart.Offset));
}
else
{
writer.WriteUInt16((ushort)handler.HandlerType);
writer.WriteUInt16((ushort)handler.TryStart.Offset);
writer.WriteByte((byte)(handler.TryEnd.Offset - handler.TryStart.Offset));
writer.WriteUInt16((ushort)handler.HandlerStart.Offset);
writer.WriteByte((byte)(handler.HandlerEnd.Offset - handler.HandlerStart.Offset));
}
// Write handler type or filter start.
switch (handler.HandlerType)
{
case CilExceptionHandlerType.Exception:
{
var provider = context.TokenProvider;
var token = handler.ExceptionType switch
{
TypeReference typeReference => provider.GetTypeReferenceToken(typeReference),
TypeDefinition typeDefinition => provider.GetTypeDefinitionToken(typeDefinition),
TypeSpecification typeSpecification => provider.GetTypeSpecificationToken(typeSpecification),
_ => context.DiagnosticBag.RegisterExceptionAndReturnDefault <MetadataToken>(
new ArgumentOutOfRangeException(
$"Invalid or unsupported exception type ({handler.ExceptionType.SafeToString()})"))
};
writer.WriteUInt32(token.ToUInt32());
break;
}
case CilExceptionHandlerType.Filter:
writer.WriteUInt32((uint)handler.FilterStart.Offset);
break;
case CilExceptionHandlerType.Finally:
case CilExceptionHandlerType.Fault:
writer.WriteUInt32(0);
break;
default:
context.DiagnosticBag.RegisterException(new ArgumentOutOfRangeException(
$"Invalid or unsupported handler type ({handler.HandlerType.SafeToString()}"));
break;
}
}
private void WriteExceptionHandler(IMetadataTokenProvider provider, IBinaryStreamWriter writer, CilExceptionHandler handler, bool useFatFormat)
{
if (handler.IsFat && !useFatFormat)
{
throw new InvalidOperationException("Can only serialize fat exception handlers in fat format.");
}
// Write handler type and boundaries.
if (useFatFormat)
{
writer.WriteUInt32((uint)handler.HandlerType);
writer.WriteUInt32((uint)handler.TryStart.Offset);
writer.WriteUInt32((uint)(handler.TryEnd.Offset - handler.TryStart.Offset));
writer.WriteUInt32((uint)handler.HandlerStart.Offset);
writer.WriteUInt32((uint)(handler.HandlerEnd.Offset - handler.HandlerStart.Offset));
}
else
{
writer.WriteUInt16((ushort)handler.HandlerType);
writer.WriteUInt16((ushort)handler.TryStart.Offset);
writer.WriteByte((byte)(handler.TryEnd.Offset - handler.TryStart.Offset));
writer.WriteUInt16((ushort)handler.HandlerStart.Offset);
writer.WriteByte((byte)(handler.HandlerEnd.Offset - handler.HandlerStart.Offset));
}
// Write handler type or filter start.
switch (handler.HandlerType)
{
case CilExceptionHandlerType.Exception:
{
var token = handler.ExceptionType switch
{
TypeReference typeReference => provider.GetTypeReferenceToken(typeReference),
TypeDefinition typeDefinition => provider.GetTypeDefinitionToken(typeDefinition),
TypeSpecification typeSpecification => provider.GetTypeSpecificationToken(typeSpecification),
_ => throw new ArgumentOutOfRangeException()
};
writer.WriteUInt32(token.ToUInt32());
break;
}
case CilExceptionHandlerType.Filter:
writer.WriteUInt32((uint)handler.FilterStart.Offset);
break;
case CilExceptionHandlerType.Finally:
case CilExceptionHandlerType.Fault:
writer.WriteUInt32(0);
break;
default:
throw new ArgumentOutOfRangeException();
}
}
