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[cDAC] Alternative fix for handling non-mapped images #114742

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[cDAC] Alternative fix for handling non-mapped images #114742

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9 changes: 8 additions & 1 deletion ...cdacreader/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/EcmaMetadata_1.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,9 +16,16 @@ internal sealed class EcmaMetadata_1(Target target) : IEcmaMetadata

public TargetSpan GetReadOnlyMetadataAddress(ModuleHandle handle)
{
ILoader loader = target.Contracts.Loader;
Data.Module module = target.ProcessedData.GetOrAdd<Data.Module>(handle.Address);

TargetPointer baseAddress = module.GetLoadedMetadata(out ulong size);
if (!loader.TryGetLoadedImageContents(handle, out _, out _, out uint imageFlags))
{
throw new InvalidOperationException("Module is not loaded.");
}

bool isMapped = (imageFlags & 0x1) != 0; // FLAG_MAPPED = 0x1
TargetPointer baseAddress = module.GetLoadedMetadata(isMapped, out ulong size);

return new TargetSpan(baseAddress, size);
}
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59 changes: 53 additions & 6 deletions ...tive/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Module.cs
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Expand Up @@ -58,28 +58,59 @@ public Module(Target target, TargetPointer address)

private TargetPointer _metadataStart = TargetPointer.Null;
private ulong _metadataSize;
public TargetPointer GetLoadedMetadata(out ulong size)
public TargetPointer GetLoadedMetadata(bool isMapped, out ulong size)
{
if (Base != TargetPointer.Null && _metadataStart == TargetPointer.Null && _metadataSize == 0)
{
int peSignatureOffset = _target.Read<int>(Base + PEFormat.DosStub.PESignatureOffset);
ulong headerOffset = Base + (ulong)peSignatureOffset;
ushort magic = _target.Read<ushort>(headerOffset + PEFormat.PEHeader.MagicOffset);
ulong clrHeaderOffset = magic == (ushort)PEMagic.PE32
? PEFormat.PEHeader.CLRRuntimeHeader32Offset
: PEFormat.PEHeader.CLRRuntimeHeader32PlusOffset;
bool is64Bit = magic == (ushort)PEMagic.PE32Plus;
ulong clrHeaderOffset = is64Bit
? PEFormat.PEHeader.CLRRuntimeHeader32PlusOffset
: PEFormat.PEHeader.CLRRuntimeHeader32Offset;
int corHeaderRva = _target.Read<int>(headerOffset + clrHeaderOffset);
ulong corHeaderOffset = isMapped ? (ulong)corHeaderRva : RVAToOffset((ulong)corHeaderRva, headerOffset, is64Bit);

// Read RVA and size of the metadata
ulong metadataDirectoryAddress = Base + (ulong)corHeaderRva + PEFormat.CorHeader.MetadataOffset;
_metadataStart = Base + (ulong)_target.Read<int>(metadataDirectoryAddress);
ulong metadataDirectoryAddress = Base + corHeaderOffset + PEFormat.CorHeader.MetadataOffset;
ulong metadataRVA = (ulong)_target.Read<int>(metadataDirectoryAddress);
ulong offset = isMapped ? metadataRVA : RVAToOffset(metadataRVA, headerOffset, is64Bit);
_metadataStart = Base + offset;
_metadataSize = (ulong)_target.Read<int>(metadataDirectoryAddress + sizeof(int));
}

size = _metadataSize;
return _metadataStart;
}

private ulong RVAToOffset(ulong rva, ulong headerOffset, bool is64Bit)
{
uint numberOfSections = _target.Read<uint>(headerOffset + PEFormat.CoffHeader.NumberOSectionsOffset);
uint sectionAlignment = _target.Read<uint>(headerOffset + PEFormat.PEHeader.SectionAlignmentOffset);
ulong sectionsStartOffset = headerOffset + (is64Bit ? PEFormat.PEHeader.SectionHeader32PlusOffset : PEFormat.PEHeader.SectionHeader32Offset);
for (uint i = 0; i < numberOfSections; i++)
{
ulong sectionHeaderOffset = sectionsStartOffset + (i * PEFormat.SectionHeader.Size);
PEFormat.SectionHeader sectionHeader = new(_target, sectionHeaderOffset);
if (rva < sectionHeader.VirtualAddress + AlignUp(sectionHeader.VirtualSize, sectionAlignment))
{
if (rva < sectionHeader.VirtualAddress)
{
return 0;
}
else
{
return rva - sectionHeader.VirtualAddress + sectionHeader.PointerToRawData;
}
}
}

return 0;
}

private static ulong AlignUp(ulong value, ulong alignment) => (value + alignment - 1) & ~(alignment - 1);

// https://learn.microsoft.com/windows/win32/debug/pe-format
private static class PEFormat
{
Expand All @@ -91,12 +122,28 @@ public static class DosStub
public const int PESignatureOffset = 0x3c;
}

public static class CoffHeader
{
public const ulong NumberOSectionsOffset = PESignatureSize + 2;
}

public static class PEHeader
{
private const ulong OptionalHeaderOffset = PESignatureSize + CoffHeaderSize;
public const ulong MagicOffset = OptionalHeaderOffset;
public const ulong SectionAlignmentOffset = OptionalHeaderOffset + 32;
public const ulong CLRRuntimeHeader32Offset = OptionalHeaderOffset + 208;
public const ulong CLRRuntimeHeader32PlusOffset = OptionalHeaderOffset + 224;
public const ulong SectionHeader32Offset = OptionalHeaderOffset + 224;
public const ulong SectionHeader32PlusOffset = OptionalHeaderOffset + 240;
}

public class SectionHeader(Target target, TargetPointer address)
{
public const int Size = 40;
public uint VirtualSize { get; init; } = target.Read<uint>(address + 8);
public uint VirtualAddress { get; init; } = target.Read<uint>(address + 12);
public uint PointerToRawData { get; init; } = target.Read<uint>(address + 20);
}

// See ECMA-335 II.25.3.3 CLI Header
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