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Add handling of generic attributes to CustomAttributeDecoder #57466

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Add handling of generic attributes to CustomAttributeDecoder #57466

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5204378
Add handling of generic attributes to CustomAttributeDecoder
MichalStrehovsky Aug 16, 2021
878d9ae
Update CustomAttributeDecoder.cs
MichalStrehovsky Aug 16, 2021
52b4270
Update CustomAttributeDecoder.cs
MichalStrehovsky Aug 17, 2021
e60bc79
Update CustomAttributeDecoder.cs
MichalStrehovsky Aug 17, 2021
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144 changes: 139 additions & 5 deletions ...stem.Reflection.Metadata/src/System/Reflection/Metadata/Ecma335/CustomAttributeDecoder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ public CustomAttributeDecoder(ICustomAttributeTypeProvider<TType> provider, Meta
public CustomAttributeValue<TType> DecodeValue(EntityHandle constructor, BlobHandle value)
{
BlobHandle signature;
BlobHandle attributeOwningTypeSpec = default;
switch (constructor.Kind)
{
case HandleKind.MethodDefinition:
Expand All @@ -32,6 +33,13 @@ public CustomAttributeValue<TType> DecodeValue(EntityHandle constructor, BlobHan
case HandleKind.MemberReference:
MemberReference reference = _reader.GetMemberReference((MemberReferenceHandle)constructor);
signature = reference.Signature;

// If this is a generic attribute, we'll need its instantiation to decode the signatures
if (reference.Parent.Kind == HandleKind.TypeSpecification)
{
TypeSpecification genericOwner = _reader.GetTypeSpecification((TypeSpecificationHandle)reference.Parent);
attributeOwningTypeSpec = genericOwner.Signature;
}
break;

default:
Expand Down Expand Up @@ -60,12 +68,32 @@ public CustomAttributeValue<TType> DecodeValue(EntityHandle constructor, BlobHan
throw new BadImageFormatException();
}

ImmutableArray<CustomAttributeTypedArgument<TType>> fixedArguments = DecodeFixedArguments(ref signatureReader, ref valueReader, parameterCount);
BlobReader genericContextReader = default;
if (!attributeOwningTypeSpec.IsNil)
{
// If this is a generic attribute, grab the instantiation arguments so that we can
// interpret the constructor signature, should it refer to the generic context.
genericContextReader = _reader.GetBlobReader(attributeOwningTypeSpec);
if (genericContextReader.ReadSignatureTypeCode() == SignatureTypeCode.GenericTypeInstance)
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{
int kind = genericContextReader.ReadCompressedInteger();
if (kind != (int)SignatureTypeKind.Class && kind != (int)SignatureTypeKind.ValueType)
{
throw new BadImageFormatException();
}

genericContextReader.ReadTypeHandle();

// At this point, the reader points to the "GenArgCount Type Type*" part of the signature.
}
}

ImmutableArray<CustomAttributeTypedArgument<TType>> fixedArguments = DecodeFixedArguments(ref signatureReader, ref valueReader, parameterCount, genericContextReader);
ImmutableArray<CustomAttributeNamedArgument<TType>> namedArguments = DecodeNamedArguments(ref valueReader);
return new CustomAttributeValue<TType>(fixedArguments, namedArguments);
}

private ImmutableArray<CustomAttributeTypedArgument<TType>> DecodeFixedArguments(ref BlobReader signatureReader, ref BlobReader valueReader, int count)
private ImmutableArray<CustomAttributeTypedArgument<TType>> DecodeFixedArguments(ref BlobReader signatureReader, ref BlobReader valueReader, int count, BlobReader genericContextReader)
{
if (count == 0)
{
Expand All @@ -76,7 +104,7 @@ private ImmutableArray<CustomAttributeTypedArgument<TType>> DecodeFixedArguments

for (int i = 0; i < count; i++)
{
ArgumentTypeInfo info = DecodeFixedArgumentType(ref signatureReader);
ArgumentTypeInfo info = DecodeFixedArgumentType(ref signatureReader, genericContextReader);
arguments.Add(DecodeArgument(ref valueReader, info));
}

Expand Down Expand Up @@ -124,7 +152,7 @@ private struct ArgumentTypeInfo
// better perf-wise, but even more important is that we can't actually reason about
// a method signature with opaque TType values without adding some unnecessary chatter
// with the provider.
private ArgumentTypeInfo DecodeFixedArgumentType(ref BlobReader signatureReader, bool isElementType = false)
private ArgumentTypeInfo DecodeFixedArgumentType(ref BlobReader signatureReader, BlobReader genericContextReader, bool isElementType = false)
{
SignatureTypeCode signatureTypeCode = signatureReader.ReadSignatureTypeCode();

Expand Down Expand Up @@ -170,12 +198,28 @@ private ArgumentTypeInfo DecodeFixedArgumentType(ref BlobReader signatureReader,
throw new BadImageFormatException();
}

var elementInfo = DecodeFixedArgumentType(ref signatureReader, isElementType: true);
var elementInfo = DecodeFixedArgumentType(ref signatureReader, genericContextReader, isElementType: true);
info.ElementType = elementInfo.Type;
info.ElementTypeCode = elementInfo.TypeCode;
info.Type = _provider.GetSZArrayType(info.ElementType);
break;

case SignatureTypeCode.GenericTypeParameter:
int parameterIndex = signatureReader.ReadCompressedInteger();
int numGenericParameters = genericContextReader.ReadCompressedInteger();
if (parameterIndex >= numGenericParameters)
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@krwq krwq Aug 24, 2021 •
edited
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consider also checking for negative parameterIndex and numGenericParameters

{
throw new BadImageFormatException();
}

while (parameterIndex > 0)
{
SkipType(ref genericContextReader);
parameterIndex--;
}

return DecodeFixedArgumentType(ref genericContextReader, default, isElementType);

default:
throw new BadImageFormatException();
}
Expand Down Expand Up @@ -363,5 +407,95 @@ private TType GetTypeFromHandle(EntityHandle handle) =>
HandleKind.TypeReference => _provider.GetTypeFromReference(_reader, (TypeReferenceHandle)handle, 0),
_ => throw new BadImageFormatException(SR.NotTypeDefOrRefHandle),
};

private static void SkipType(ref BlobReader blobReader)
{
int typeCode = blobReader.ReadCompressedInteger();

switch (typeCode)
{
case (int)SignatureTypeCode.Boolean:
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isn't there any existing subroutine for checking simple types?

case (int)SignatureTypeCode.Char:
case (int)SignatureTypeCode.SByte:
case (int)SignatureTypeCode.Byte:
case (int)SignatureTypeCode.Int16:
case (int)SignatureTypeCode.UInt16:
case (int)SignatureTypeCode.Int32:
case (int)SignatureTypeCode.UInt32:
case (int)SignatureTypeCode.Int64:
case (int)SignatureTypeCode.UInt64:
case (int)SignatureTypeCode.Single:
case (int)SignatureTypeCode.Double:
case (int)SignatureTypeCode.IntPtr:
case (int)SignatureTypeCode.UIntPtr:
case (int)SignatureTypeCode.Object:
case (int)SignatureTypeCode.String:
case (int)SignatureTypeCode.Void:
case (int)SignatureTypeCode.TypedReference:
return;

case (int)SignatureTypeCode.Pointer:
case (int)SignatureTypeCode.ByReference:
case (int)SignatureTypeCode.Pinned:
case (int)SignatureTypeCode.SZArray:
SkipType(ref blobReader);
return;

case (int)SignatureTypeCode.FunctionPointer:
SignatureHeader header = blobReader.ReadSignatureHeader();
if (header.IsGeneric)
{
blobReader.ReadCompressedInteger(); // arity
}

int paramCount = blobReader.ReadCompressedInteger();
SkipType(ref blobReader);
for (int i = 0; i < paramCount; i++)
SkipType(ref blobReader);
return;

case (int)SignatureTypeCode.Array:
SkipType(ref blobReader);
blobReader.ReadCompressedInteger(); // rank
int boundsCount = blobReader.ReadCompressedInteger();
for (int i = 0; i < boundsCount; i++)
{
blobReader.ReadCompressedInteger();
}
int lowerBoundsCount = blobReader.ReadCompressedInteger();
for (int i = 0; i < lowerBoundsCount; i++)
{
blobReader.ReadCompressedSignedInteger();
}
return;

case (int)SignatureTypeCode.RequiredModifier:
case (int)SignatureTypeCode.OptionalModifier:
blobReader.ReadTypeHandle();
SkipType(ref blobReader);
return;

case (int)SignatureTypeCode.GenericTypeInstance:
SkipType(ref blobReader);
int count = blobReader.ReadCompressedInteger();
for (int i = 0; i < count; i++)
{
SkipType(ref blobReader);
}
return;

case (int)SignatureTypeCode.GenericTypeParameter:
blobReader.ReadCompressedInteger();
return;

case (int)SignatureTypeKind.Class:
case (int)SignatureTypeKind.ValueType:
SkipType(ref blobReader);
break;

default:
throw new BadImageFormatException();
}
}
}
}