internal static AssemblyMetadata ReadAssemblyMetadata(Stream stream, AssemblyMetadataFields fields)
{
long length = stream.Length;
if (length < 0x40)
{
return(null);
}
BinaryReader reader = new BinaryReader(stream);
// Read the pointer to the PE header.
stream.Position = 0x3c;
uint peHeaderPtr = reader.ReadUInt32();
if (peHeaderPtr == 0)
{
peHeaderPtr = 0x80;
}
// Ensure there is at least enough room for the following structures:
// 24 byte PE Signature & Header
// 28 byte Standard Fields (24 bytes for PE32+)
// 68 byte NT Fields (88 bytes for PE32+)
// >= 128 byte Data Dictionary Table
if (peHeaderPtr > length - 256)
{
return(null);
}
// Check the PE signature. Should equal 'PE\0\0'.
stream.Position = peHeaderPtr;
uint peSignature = reader.ReadUInt32();
if (peSignature != 0x00004550)
{
return(null);
}
// Read PE header fields.
ushort machine = reader.ReadUInt16();
ushort numberOfSections = reader.ReadUInt16();
uint timeStamp = reader.ReadUInt32();
uint symbolTablePtr = reader.ReadUInt32();
uint numberOfSymbols = reader.ReadUInt32();
ushort optionalHeaderSize = reader.ReadUInt16();
ushort characteristics = reader.ReadUInt16();
// Read PE magic number from Standard Fields to determine format.
PEFormat peFormat = (PEFormat)reader.ReadUInt16();
if (peFormat != PEFormat.PE32 && peFormat != PEFormat.PE32Plus)
{
return(null);
}
// Read the 15th Data Dictionary RVA field which contains the CLI header RVA.
// When this is non-zero then the file contains CLI data otherwise not.
stream.Position = peHeaderPtr + (peFormat == PEFormat.PE32 ? 232 : 248);
uint cliHeaderRva = reader.ReadUInt32();
if (cliHeaderRva == 0)
{
return(null);
}
// Read section headers. Each one is 40 bytes.
// 8 byte Name
// 4 byte Virtual Size
// 4 byte Virtual Address
// 4 byte Data Size
// 4 byte Data Pointer
// ... total of 40 bytes
uint sectionTablePtr = peHeaderPtr + 24 + optionalHeaderSize;
Section[] sections = new Section[numberOfSections];
for (int i = 0; i < numberOfSections; i++)
{
stream.Position = sectionTablePtr + i * 40 + 8;
Section section = new Section();
section.VirtualSize = reader.ReadUInt32();
section.VirtualAddress = reader.ReadUInt32();
reader.ReadUInt32();
section.Pointer = reader.ReadUInt32();
sections[i] = section;
}
// Read parts of the CLI header.
uint cliHeaderPtr = ResolveRva(sections, cliHeaderRva);
if (cliHeaderPtr == 0)
{
return(null);
}
stream.Position = cliHeaderPtr + 4;
ushort majorRuntimeVersion = reader.ReadUInt16();
ushort minorRuntimeVersion = reader.ReadUInt16();
uint metadataRva = reader.ReadUInt32();
uint metadataSize = reader.ReadUInt32();
CorFlags corflags = (CorFlags)reader.ReadUInt32();
// Read optional fields.
AssemblyName assemblyName = null;
IList <AssemblyName> assemblyReferences = null;
string runtimeVersion = null;
if ((fields & AssemblyMetadataFields.RuntimeVersion) != 0)
{
uint metadataPtr = ResolveRva(sections, metadataRva);
stream.Position = metadataPtr + 12;
int paddedRuntimeVersionLength = reader.ReadInt32();
byte[] runtimeVersionBytes = reader.ReadBytes(paddedRuntimeVersionLength);
int runtimeVersionLength = 0;
while (runtimeVersionLength < paddedRuntimeVersionLength &&
runtimeVersionBytes[runtimeVersionLength] != 0)
{
runtimeVersionLength += 1;
}
runtimeVersion = Encoding.UTF8.GetString(runtimeVersionBytes, 0, runtimeVersionLength);
}
if ((fields & (AssemblyMetadataFields.AssemblyName | AssemblyMetadataFields.AssemblyReferences)) != 0)
{
// Using Cecil.
stream.Position = 0;
var imageReader = new ImageReader(stream);
if ((fields & AssemblyMetadataFields.AssemblyName) != 0)
{
assemblyName = imageReader.GetAssemblyName();
}
if ((fields & AssemblyMetadataFields.AssemblyReferences) != 0)
{
assemblyReferences = imageReader.GetAssemblyReferences();
}
}
// Done.
return(new AssemblyMetadata(majorRuntimeVersion, minorRuntimeVersion, corflags, peFormat,
assemblyName, assemblyReferences, runtimeVersion));
}
