How do I get the version of an assembly without loading it?

Question

One small function of a large program examines assemblies in a folder and replaces out-of-date assemblies with the latest versions. To accomplish this, it needs to read the version numbers of the existing assembly files without actually loading those assemblies into the executing process.

Answer 1

I found the following in this article.

using System.Reflection;
using System.IO;

...

// Get current and updated assemblies
AssemblyName currentAssemblyName = AssemblyName.GetAssemblyName(currentAssemblyPath);
AssemblyName updatedAssemblyName = AssemblyName.GetAssemblyName(updatedAssemblyPath);

// Compare both versions
if (updatedAssemblyName.Version.CompareTo(currentAssemblyName.Version) <= 0)
{
    // There's nothing to update
    return;
}

// Update older version
File.Copy(updatedAssemblyPath, currentAssemblyPath, true);

Answer 2

Depending on the files, one option might be FileVersionInfo - i.e.

FileVersionInfo fvi = FileVersionInfo.GetVersionInfo(path)
string ver = fvi.FileVersion;

The problem is that this depends on the code having the [AssemblyFileVersion] attribute, and it matching the [AssemblyVersion] attribute.

I think I'd look at the AssemblyName options suggested by others first, though.

Answer 3

Use AssemblyName.GetAssemblyName("assembly.dll");, then parse the name. According to MSDN:

This will only work if the file contains an assembly manifest. This method causes the file to be opened and closed, but the assembly is not added to this domain.

Answer 4

Just for the record: Here's how to get the file version in C#.NET Compact Framework. It's basically from OpenNETCF but quite shorter and exctacted so it can by copy'n'pasted. Hope it'll help...

public static Version GetFileVersionCe(string fileName)
{
    int handle = 0;
    int length = GetFileVersionInfoSize(fileName, ref handle);
    Version v = null;
    if (length > 0)
    {
        IntPtr buffer = System.Runtime.InteropServices.Marshal.AllocHGlobal(length);
        if (GetFileVersionInfo(fileName, handle, length, buffer))
        {
            IntPtr fixedbuffer = IntPtr.Zero;
            int fixedlen = 0;
            if (VerQueryValue(buffer, "\\", ref fixedbuffer, ref fixedlen))
            {
                byte[] fixedversioninfo = new byte[fixedlen];
                System.Runtime.InteropServices.Marshal.Copy(fixedbuffer, fixedversioninfo, 0, fixedlen);
                v = new Version(
                    BitConverter.ToInt16(fixedversioninfo, 10), 
                    BitConverter.ToInt16(fixedversioninfo,  8), 
                    BitConverter.ToInt16(fixedversioninfo, 14),
                    BitConverter.ToInt16(fixedversioninfo, 12));
            }
        }
        Marshal.FreeHGlobal(buffer);
    }
    return v;
}

[DllImport("coredll", EntryPoint = "GetFileVersionInfo", SetLastError = true)]
private static extern bool GetFileVersionInfo(string filename, int handle, int len, IntPtr buffer);
[DllImport("coredll", EntryPoint = "GetFileVersionInfoSize", SetLastError = true)]
private static extern int GetFileVersionInfoSize(string filename, ref int handle);
[DllImport("coredll", EntryPoint = "VerQueryValue", SetLastError = true)]
private static extern bool VerQueryValue(IntPtr buffer, string subblock, ref IntPtr blockbuffer, ref int len);