check if unmanaged dll is 32-bit or 64-bit?

Question

How can I programmatically tell in C# if an unmanaged dll is x86 or x64?

Answer 1

Check this out: How to find if native dll is compiled as x64 or x86?

Answer 2

Lazarus, thanks for link, it pointed me to the specs I needed. In case others are looking, here's a basic implementation:

public static MachineType GetDllMachineType(string dllPath)
    {
      //see http://www.microsoft.com/whdc/system/platform/firmware/PECOFF.mspx
      //offset to PE header is always at 0x3C
      //PE header starts with "PE\0\0" =  0x50 0x45 0x00 0x00
      //followed by 2-byte machine type field (see document above for enum)
      FileStream fs = new FileStream(dllPath, FileMode.Open);
      BinaryReader br = new BinaryReader(fs);
      fs.Seek(0x3c, SeekOrigin.Begin);
      Int32 peOffset = br.ReadInt32();
      fs.Seek(peOffset, SeekOrigin.Begin);
      UInt32 peHead = br.ReadUInt32();
      if(peHead!=0x00004550) // "PE\0\0", little-endian
        throw new Exception("Can't find PE header");       
      MachineType machineType = (MachineType) br.ReadUInt16();
      br.Close();
      fs.Close();
      return machineType;
    }

The MachineType enum is defined as:

public enum MachineType : ushort
{
  IMAGE_FILE_MACHINE_UNKNOWN = 0x0,
  IMAGE_FILE_MACHINE_AM33 = 0x1d3,
  IMAGE_FILE_MACHINE_AMD64 = 0x8664,
  IMAGE_FILE_MACHINE_ARM = 0x1c0,
  IMAGE_FILE_MACHINE_EBC = 0xebc,
  IMAGE_FILE_MACHINE_I386 = 0x14c,
  IMAGE_FILE_MACHINE_IA64 = 0x200,
  IMAGE_FILE_MACHINE_M32R = 0x9041,
  IMAGE_FILE_MACHINE_MIPS16 = 0x266,
  IMAGE_FILE_MACHINE_MIPSFPU = 0x366,
  IMAGE_FILE_MACHINE_MIPSFPU16 = 0x466,
  IMAGE_FILE_MACHINE_POWERPC = 0x1f0,
  IMAGE_FILE_MACHINE_POWERPCFP = 0x1f1,
  IMAGE_FILE_MACHINE_R4000 = 0x166,
  IMAGE_FILE_MACHINE_SH3 = 0x1a2,
  IMAGE_FILE_MACHINE_SH3DSP = 0x1a3,
  IMAGE_FILE_MACHINE_SH4 = 0x1a6,
  IMAGE_FILE_MACHINE_SH5 = 0x1a8,
  IMAGE_FILE_MACHINE_THUMB = 0x1c2,
  IMAGE_FILE_MACHINE_WCEMIPSV2 = 0x169,
}

I only needed three of these, but I included them all for completeness. Final 64-bit check:

// returns true if the dll is 64-bit, false if 32-bit, and null if unknown
public static bool? UnmanagedDllIs64Bit(string dllPath)
{
  switch (GetDllMachineType(dllPath))
  {
    case MachineType.IMAGE_FILE_MACHINE_AMD64:
    case MachineType.IMAGE_FILE_MACHINE_IA64:
      return true;
    case MachineType.IMAGE_FILE_MACHINE_I386:
      return false;
    default:
      return null;
  }
}

Answer 3

Even easier: check out the System.Reflection.Module class. It includes the GetPEKind method, which returns 2 enums that describe the type of code and the CPU target. No more hex!

(the rest of this very informative post was copied shamelessly from http://www.developersdex.com/vb/message.asp?p=2924&r=6413567)

Sample code:

Assembly assembly = assembly.loadfile(@"<assembly Path>");
PortableExecutableKinds kinds;
ImageFileMachine imgFileMachine;
assembly.ManifestModule.GetPEKind(out kinds, out imgFileMachine);

PortableExecutableKinds can be used to check what kind of the assembly. It has 5 values:

ILOnly: The executable contains only Microsoft intermediate language (MSIL), and is therefore neutral with respect to 32-bit or 64-bit platforms.

NotAPortableExecutableImage: The file is not in portable executable (PE) file format.

PE32Plus: The executable requires a 64-bit platform.

Required32Bit: The executable can be run on a 32-bit platform, or in the 32-bit Windows on Windows (WOW) environment on a 64-bit platform.

Unmanaged32Bit: The executable contains pure unmanaged code.

Following are the links:

Module.GetPEKind Method: http://msdn.microsoft.com/en-us/library/system.reflection.module.getpekind.a spx

PortableExecutableKinds Enumeration: http://msdn.microsoft.com/en-us/library/system.reflection.portableexecutable kinds(VS.80).aspx

ImageFileMachine Enumeration: http://msdn.microsoft.com/en-us/library/system.reflection.imagefilemachine.a spx

Answer 4

Hi All,

I am getting exception on the below line when i am trying to find whether the lib is x86 or x64... UInt32 peHead = br.ReadUInt32();

Is i need to do some chnages for the library files

Answer 5

Using a Visual Studio command prompt, dumpbin /headers dllname.dll works too. On my machine the beginning of the output stated:

FILE HEADER VALUES
8664 machine (x64)
5 number of sections
47591774 time date stamp Fri Dec 07 03:50:44 2007