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Building .NET Coverage Tool

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25 Aug 2009MIT8 min read 85.5K   2.3K   109  
This article is a walkthrough for building a .NET coverage tool
 
//
// ImageReader.cs
//
// Author:
//   Jb Evain (jbevain@gmail.com)
//
// (C) 2005 - 2007 Jb Evain
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

namespace Mono.Cecil.Binary {

	using System;
	using System.IO;
	using System.Text;

	using Mono.Cecil.Metadata;

	sealed class ImageReader : BaseImageVisitor {

		MetadataReader m_mdReader;
		BinaryReader m_binaryReader;
		Image m_image;

		public MetadataReader MetadataReader {
			get { return m_mdReader; }
		}

		public Image Image {
			get { return m_image; }
		}

		ImageReader (Image img, BinaryReader reader)
		{
			m_image = img;
			m_binaryReader = reader;
		}

		static ImageReader Read (Image img, Stream stream)
		{
			ImageReader reader = new ImageReader (img, new BinaryReader (stream));
			img.Accept (reader);
			return reader;
		}

		public static ImageReader Read (string file)
		{
			if (file == null)
				throw new ArgumentNullException ("file");

			FileInfo fi = new FileInfo (file);
			if (!File.Exists (fi.FullName))
			#if CF_1_0 || CF_2_0
				throw new FileNotFoundException (fi.FullName);
			#else
				throw new FileNotFoundException (string.Format ("File '{0}' not found.", fi.FullName), fi.FullName);
			#endif

			FileStream stream = null;
			try {
				stream = new FileStream (fi.FullName, FileMode.Open, FileAccess.Read, FileShare.Read);
				return Read (new Image (fi), stream);
			} catch (Exception e) {
				if (stream != null)
					stream.Close ();
#if CF_1_0 || CF_2_0
				throw new BadImageFormatException ("Invalid PE file: " + file, e);
#else
				throw new BadImageFormatException ("Invalid PE file", file, e);
#endif
			}
		}

		public static ImageReader Read (byte [] image)
		{
			if (image == null)
				throw new ArgumentNullException ("image");

			if (image.Length == 0)
				throw new ArgumentException ("Empty image array");

			return Read (new Image (), new MemoryStream (image));
		}

		public static ImageReader Read (Stream stream)
		{
			if (stream == null)
				throw new ArgumentNullException ("stream");

			if (!stream.CanRead)
				throw new ArgumentException ("Can not read from stream");

			return Read (new Image (), stream);
		}

		public BinaryReader GetReader ()
		{
			return m_binaryReader;
		}

		public override void VisitImage (Image img)
		{
			m_mdReader = new MetadataReader (this);
		}

		void SetPositionToAddress (RVA address)
		{
			m_binaryReader.BaseStream.Position = m_image.ResolveVirtualAddress (address);
		}

		public override void VisitDOSHeader (DOSHeader header)
		{
			header.Start = m_binaryReader.ReadBytes (60);
			header.Lfanew = m_binaryReader.ReadUInt32 ();
			header.End = m_binaryReader.ReadBytes (64);

			m_binaryReader.BaseStream.Position = header.Lfanew;

			if (m_binaryReader.ReadUInt16 () != 0x4550 ||
				m_binaryReader.ReadUInt16 () != 0)

				throw new ImageFormatException ("Invalid PE File Signature");
		}

		public override void VisitPEFileHeader (PEFileHeader header)
		{
			header.Machine = m_binaryReader.ReadUInt16 ();
			header.NumberOfSections = m_binaryReader.ReadUInt16 ();
			header.TimeDateStamp = m_binaryReader.ReadUInt32 ();
			header.PointerToSymbolTable = m_binaryReader.ReadUInt32 ();
			header.NumberOfSymbols = m_binaryReader.ReadUInt32 ();
			header.OptionalHeaderSize = m_binaryReader.ReadUInt16 ();
			header.Characteristics = (ImageCharacteristics) m_binaryReader.ReadUInt16 ();
		}

		ulong ReadIntOrLong ()
		{
			return m_image.PEOptionalHeader.StandardFields.IsPE64 ?
				m_binaryReader.ReadUInt64 () :
				m_binaryReader.ReadUInt32 ();
		}

		RVA ReadRVA ()
		{
			return m_binaryReader.ReadUInt32 ();
		}

		DataDirectory ReadDataDirectory ()
		{
			return new DataDirectory (ReadRVA (), m_binaryReader.ReadUInt32 ());
		}

		public override void VisitNTSpecificFieldsHeader (PEOptionalHeader.NTSpecificFieldsHeader header)
		{
			header.ImageBase = ReadIntOrLong ();
			header.SectionAlignment = m_binaryReader.ReadUInt32 ();
			header.FileAlignment = m_binaryReader.ReadUInt32 ();
			header.OSMajor = m_binaryReader.ReadUInt16 ();
			header.OSMinor = m_binaryReader.ReadUInt16 ();
			header.UserMajor = m_binaryReader.ReadUInt16 ();
			header.UserMinor = m_binaryReader.ReadUInt16 ();
			header.SubSysMajor = m_binaryReader.ReadUInt16 ();
			header.SubSysMinor = m_binaryReader.ReadUInt16 ();
			header.Reserved = m_binaryReader.ReadUInt32 ();
			header.ImageSize = m_binaryReader.ReadUInt32 ();
			header.HeaderSize = m_binaryReader.ReadUInt32 ();
			header.FileChecksum = m_binaryReader.ReadUInt32 ();
			header.SubSystem = (SubSystem) m_binaryReader.ReadUInt16 ();
			header.DLLFlags = m_binaryReader.ReadUInt16 ();
			header.StackReserveSize = ReadIntOrLong ();
			header.StackCommitSize = ReadIntOrLong ();
			header.HeapReserveSize = ReadIntOrLong ();
			header.HeapCommitSize = ReadIntOrLong ();
			header.LoaderFlags = m_binaryReader.ReadUInt32 ();
			header.NumberOfDataDir = m_binaryReader.ReadUInt32 ();
		}

		public override void VisitStandardFieldsHeader (PEOptionalHeader.StandardFieldsHeader header)
		{
			header.Magic = m_binaryReader.ReadUInt16 ();
			header.LMajor = m_binaryReader.ReadByte ();
			header.LMinor = m_binaryReader.ReadByte ();
			header.CodeSize = m_binaryReader.ReadUInt32 ();
			header.InitializedDataSize = m_binaryReader.ReadUInt32 ();
			header.UninitializedDataSize = m_binaryReader.ReadUInt32 ();
			header.EntryPointRVA = ReadRVA ();
			header.BaseOfCode = ReadRVA ();
			if (!header.IsPE64)
				header.BaseOfData = ReadRVA ();
		}

		public override void VisitDataDirectoriesHeader (PEOptionalHeader.DataDirectoriesHeader header)
		{
			header.ExportTable = ReadDataDirectory ();
			header.ImportTable = ReadDataDirectory ();
			header.ResourceTable = ReadDataDirectory ();
			header.ExceptionTable = ReadDataDirectory ();
			header.CertificateTable = ReadDataDirectory ();
			header.BaseRelocationTable = ReadDataDirectory ();
			header.Debug = ReadDataDirectory ();
			header.Copyright = ReadDataDirectory ();
			header.GlobalPtr = ReadDataDirectory ();
			header.TLSTable = ReadDataDirectory ();
			header.LoadConfigTable = ReadDataDirectory ();
			header.BoundImport = ReadDataDirectory ();
			header.IAT = ReadDataDirectory ();
			header.DelayImportDescriptor = ReadDataDirectory ();
			header.CLIHeader = ReadDataDirectory ();
			header.Reserved = ReadDataDirectory ();

			if (header.CLIHeader != DataDirectory.Zero)
				m_image.CLIHeader = new CLIHeader ();
			if (header.ExportTable != DataDirectory.Zero)
				m_image.ExportTable = new ExportTable ();
		}

		public override void VisitSectionCollection (SectionCollection coll)
		{
			for (int i = 0; i < m_image.PEFileHeader.NumberOfSections; i++)
				coll.Add (new Section ());
		}

		public override void VisitSection (Section sect)
		{
			char [] buffer = new char [8];
			int read = 0;
			while (read < 8) {
				char cur = (char) m_binaryReader.ReadSByte ();
				if (cur == '\0') {
					m_binaryReader.BaseStream.Position += 8 - read - 1;
					break;
				}
				buffer [read++] = cur;
			}
			sect.Name = read == 0 ? string.Empty : new string (buffer, 0, read);
			if (sect.Name == Section.Text)
				m_image.TextSection = sect;

			sect.VirtualSize = m_binaryReader.ReadUInt32 ();
			sect.VirtualAddress = ReadRVA ();
			sect.SizeOfRawData = m_binaryReader.ReadUInt32 ();
			sect.PointerToRawData = ReadRVA ();
			sect.PointerToRelocations = ReadRVA ();
			sect.PointerToLineNumbers = ReadRVA ();
			sect.NumberOfRelocations = m_binaryReader.ReadUInt16 ();
			sect.NumberOfLineNumbers = m_binaryReader.ReadUInt16 ();
			sect.Characteristics = (SectionCharacteristics) m_binaryReader.ReadUInt32 ();

			long pos = m_binaryReader.BaseStream.Position;
			m_binaryReader.BaseStream.Position = sect.PointerToRawData;
			sect.Data = m_binaryReader.ReadBytes ((int) sect.SizeOfRawData);
			m_binaryReader.BaseStream.Position = pos;
		}

		public override void VisitImportAddressTable (ImportAddressTable iat)
		{
			if (m_image.PEOptionalHeader.DataDirectories.IAT.VirtualAddress == RVA.Zero)
				return;

			SetPositionToAddress (m_image.PEOptionalHeader.DataDirectories.IAT.VirtualAddress);

			iat.HintNameTableRVA = ReadRVA ();
		}

		public override void VisitCLIHeader (CLIHeader header)
		{
			if (m_image.PEOptionalHeader.DataDirectories.Debug != DataDirectory.Zero) {
				m_image.DebugHeader = new DebugHeader ();
				VisitDebugHeader (m_image.DebugHeader);
			}

			SetPositionToAddress (m_image.PEOptionalHeader.DataDirectories.CLIHeader.VirtualAddress);
			header.Cb = m_binaryReader.ReadUInt32 ();
			header.MajorRuntimeVersion = m_binaryReader.ReadUInt16 ();
			header.MinorRuntimeVersion = m_binaryReader.ReadUInt16 ();
			header.Metadata = ReadDataDirectory ();
			header.Flags = (RuntimeImage) m_binaryReader.ReadUInt32 ();
			header.EntryPointToken = m_binaryReader.ReadUInt32 ();
			header.Resources = ReadDataDirectory ();
			header.StrongNameSignature = ReadDataDirectory ();
			header.CodeManagerTable = ReadDataDirectory ();
			header.VTableFixups = ReadDataDirectory ();
			header.ExportAddressTableJumps = ReadDataDirectory ();
			header.ManagedNativeHeader = ReadDataDirectory ();

			if (header.StrongNameSignature != DataDirectory.Zero) {
				SetPositionToAddress (header.StrongNameSignature.VirtualAddress);
				header.ImageHash = m_binaryReader.ReadBytes ((int) header.StrongNameSignature.Size);
			} else
				header.ImageHash = new byte [0];

			SetPositionToAddress (m_image.CLIHeader.Metadata.VirtualAddress);
			m_image.MetadataRoot.Accept (m_mdReader);
		}

		public override void VisitDebugHeader (DebugHeader header)
		{
			if (m_image.PEOptionalHeader.DataDirectories.Debug == DataDirectory.Zero)
				return;

			long pos = m_binaryReader.BaseStream.Position;

			SetPositionToAddress (m_image.PEOptionalHeader.DataDirectories.Debug.VirtualAddress);
			header.Characteristics = m_binaryReader.ReadUInt32 ();
			header.TimeDateStamp = m_binaryReader.ReadUInt32 ();
			header.MajorVersion = m_binaryReader.ReadUInt16 ();
			header.MinorVersion = m_binaryReader.ReadUInt16 ();
			header.Type = (DebugStoreType) m_binaryReader.ReadUInt32 ();
			header.SizeOfData = m_binaryReader.ReadUInt32 ();
			header.AddressOfRawData = ReadRVA ();
			header.PointerToRawData = m_binaryReader.ReadUInt32 ();

			m_binaryReader.BaseStream.Position = header.PointerToRawData;

			header.Magic = m_binaryReader.ReadUInt32 ();
			header.Signature = new Guid (m_binaryReader.ReadBytes (16));
			header.Age = m_binaryReader.ReadUInt32 ();
			header.FileName = ReadZeroTerminatedString ();

			m_binaryReader.BaseStream.Position = pos;
		}

		string ReadZeroTerminatedString ()
		{
			StringBuilder sb = new StringBuilder ();
			while (true) {
				byte chr = m_binaryReader.ReadByte ();
				if (chr == 0)
					break;
				sb.Append ((char) chr);
			}
			return sb.ToString ();
		}

		public override void VisitImportTable (ImportTable it)
		{
			if (m_image.PEOptionalHeader.DataDirectories.ImportTable.VirtualAddress == RVA.Zero)
				return;

			SetPositionToAddress (m_image.PEOptionalHeader.DataDirectories.ImportTable.VirtualAddress);

			it.ImportLookupTable = ReadRVA ();
			it.DateTimeStamp = m_binaryReader.ReadUInt32 ();
			it.ForwardChain = m_binaryReader.ReadUInt32 ();
			it.Name = ReadRVA ();
			it.ImportAddressTable = ReadRVA ();
		}

		public override void VisitImportLookupTable (ImportLookupTable ilt)
		{
			if (m_image.ImportTable.ImportLookupTable == RVA.Zero)
				return;

			SetPositionToAddress (m_image.ImportTable.ImportLookupTable);

			ilt.HintNameRVA = ReadRVA ();
		}

		public override void VisitHintNameTable (HintNameTable hnt)
		{
			if (m_image.ImportAddressTable.HintNameTableRVA == RVA.Zero)
				return;

			if ((m_image.ImportAddressTable.HintNameTableRVA & 0x80000000) != 0)
				return;

			SetPositionToAddress (m_image.ImportAddressTable.HintNameTableRVA);

			hnt.Hint = m_binaryReader.ReadUInt16 ();

			byte [] bytes = m_binaryReader.ReadBytes (11);
			hnt.RuntimeMain = Encoding.ASCII.GetString (bytes, 0, bytes.Length);

			SetPositionToAddress (m_image.ImportTable.Name);

			bytes = m_binaryReader.ReadBytes (11);
			hnt.RuntimeLibrary = Encoding.ASCII.GetString (bytes, 0, bytes.Length);

			SetPositionToAddress (m_image.PEOptionalHeader.StandardFields.EntryPointRVA);
			hnt.EntryPoint = m_binaryReader.ReadUInt16 ();
			hnt.RVA = ReadRVA ();
		}

		public override void VisitExportTable (ExportTable et)
		{
			SetPositionToAddress (m_image.PEOptionalHeader.DataDirectories.ExportTable.VirtualAddress);

			et.Characteristics = m_binaryReader.ReadUInt32 ();
			et.TimeDateStamp = m_binaryReader.ReadUInt32 ();
			et.MajorVersion = m_binaryReader.ReadUInt16 ();
			et.MinorVersion = m_binaryReader.ReadUInt16 ();

			//et.Name =
			m_binaryReader.ReadUInt32 ();

			et.Base = m_binaryReader.ReadUInt32 ();
			et.NumberOfFunctions = m_binaryReader.ReadUInt32 ();
			et.NumberOfNames = m_binaryReader.ReadUInt32 ();
			et.AddressOfFunctions = m_binaryReader.ReadUInt32 ();
			et.AddressOfNames = m_binaryReader.ReadUInt32 ();
			et.AddressOfNameOrdinals = m_binaryReader.ReadUInt32 ();

			et.AddressesOfFunctions = ReadArrayOfRVA (et.AddressOfFunctions, et.NumberOfFunctions);
			et.AddressesOfNames = ReadArrayOfRVA (et.AddressOfNames, et.NumberOfNames);
			et.NameOrdinals = ReadArrayOfUInt16 (et.AddressOfNameOrdinals, et.NumberOfNames);
			et.Names = new string [et.NumberOfFunctions];

			for (int i = 0; i < et.NumberOfFunctions; i++) {
				if (et.AddressesOfFunctions [i] == 0)
					continue;

				et.Names [i] = ReadFunctionName (et, i);
			}
		}

		string ReadFunctionName (ExportTable et, int index)
		{
			for (int i = 0; i < et.NumberOfNames; i++) {
				if (et.NameOrdinals [i] != index)
					continue;

				SetPositionToAddress (et.AddressesOfNames [i]);
				return ReadZeroTerminatedString ();
			}

			return string.Empty;
		}

		ushort [] ReadArrayOfUInt16 (RVA position, uint length)
		{
			if (position == RVA.Zero)
				return new ushort [0];

			SetPositionToAddress (position);
			ushort [] array = new ushort [length];
			for (int i = 0; i < length; i++)
				array [i] = m_binaryReader.ReadUInt16 ();

			return array;
		}

		RVA [] ReadArrayOfRVA (RVA position, uint length)
		{
			if (position == RVA.Zero)
				return new RVA [0];

			SetPositionToAddress (position);
			RVA [] addresses = new RVA [length];
			for (int i = 0; i < length; i++)
				addresses [i] = m_binaryReader.ReadUInt32 ();

			return addresses;
		}

		public override void TerminateImage(Image img)
		{
			m_binaryReader.Close ();

			try {
				ResourceReader resReader = new ResourceReader (img);
				img.ResourceDirectoryRoot = resReader.Read ();
			} catch {
				img.ResourceDirectoryRoot = null;
			}
		}
	}
}

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License

This article, along with any associated source code and files, is licensed under The MIT License


Written By
Sergiy Sakharov
Software Developer (Senior)
United Kingdom United Kingdom
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

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Posted 24 Aug 2009

Article Copyright 2009 by Sergiy Sakharov
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