DeclSecurityTableReader.cs

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using System.Reflection.Internal;
 
namespace System.Reflection.Metadata.Ecma335;
 
internal readonly struct DeclSecurityTableReader
{
    internal readonly int NumberOfRows;
 
    private readonly bool _IsHasDeclSecurityRefSizeSmall;
 
    private readonly bool _IsBlobHeapRefSizeSmall;
 
    private readonly int _ActionOffset;
 
    private readonly int _ParentOffset;
 
    private readonly int _PermissionSetOffset;
 
    internal readonly int RowSize;
 
    internal readonly MemoryBlock Block;
 
    internal DeclSecurityTableReader(int numberOfRows, bool declaredSorted, int hasDeclSecurityRefSize, int blobHeapRefSize, MemoryBlock containingBlock, int containingBlockOffset)
    {
        NumberOfRows = numberOfRows;
        _IsHasDeclSecurityRefSizeSmall = hasDeclSecurityRefSize == 2;
        _IsBlobHeapRefSizeSmall = blobHeapRefSize == 2;
        _ActionOffset = 0;
        _ParentOffset = _ActionOffset + 2;
        _PermissionSetOffset = _ParentOffset + hasDeclSecurityRefSize;
        RowSize = _PermissionSetOffset + blobHeapRefSize;
        Block = containingBlock.GetMemoryBlockAt(containingBlockOffset, RowSize * numberOfRows);
        if (!declaredSorted && !CheckSorted())
        {
            Throw.TableNotSorted(TableIndex.DeclSecurity);
        }
    }
 
    internal DeclarativeSecurityAction GetAction(int rowId)
    {
        int num = (rowId - 1) * RowSize;
        return (DeclarativeSecurityAction)Block.PeekUInt16(num + _ActionOffset);
    }
 
    internal EntityHandle GetParent(int rowId)
    {
        int num = (rowId - 1) * RowSize;
        return HasDeclSecurityTag.ConvertToHandle(Block.PeekTaggedReference(num + _ParentOffset, _IsHasDeclSecurityRefSizeSmall));
    }
 
    internal BlobHandle GetPermissionSet(int rowId)
    {
        int num = (rowId - 1) * RowSize;
        return BlobHandle.FromOffset(Block.PeekHeapReference(num + _PermissionSetOffset, _IsBlobHeapRefSizeSmall));
    }
 
    internal void GetAttributeRange(EntityHandle parentToken, out int firstImplRowId, out int lastImplRowId)
    {
        Block.BinarySearchReferenceRange(NumberOfRows, RowSize, _ParentOffset, HasDeclSecurityTag.ConvertToTag(parentToken), _IsHasDeclSecurityRefSizeSmall, out var startRowNumber, out var endRowNumber);
        if (startRowNumber == -1)
        {
            firstImplRowId = 1;
            lastImplRowId = 0;
        }
        else
        {
            firstImplRowId = startRowNumber + 1;
            lastImplRowId = endRowNumber + 1;
        }
    }
 
    private bool CheckSorted()
    {
        return Block.IsOrderedByReferenceAscending(RowSize, _ParentOffset, _IsHasDeclSecurityRefSizeSmall);
    }
}