Displaying the build date

Question

I currently have an app displaying the build number in its title window. That's well and good except it means nothing to most of the users, who want to know if they have the latest build - they tend to refer to it as "last Thursday's" rather than build 1.0.8.4321.

The plan is to put the build date there instead - So "App built on 21/10/2009" for example.

I'm struggling to find a programmatic way to pull the build date out as a text string for use like this.

For the build number, I used:

Assembly.GetExecutingAssembly().GetName().Version.ToString()

after defining how those came up.

I'd like something like that for the compile date (and time, for bonus points).

Pointers here much appreciated (excuse pun if appropriate), or neater solutions...

Answer 1

For .NET Core projects, I adapted Postlagerkarte's answer to update the assembly Copyright field with the build date.

Directly Edit csproj

The following can be added directly to the first PropertyGroup in the csproj:

<Copyright>Copyright © $([System.DateTime]::UtcNow.Year) Travis Troyer ($([System.DateTime]::UtcNow.ToString("s")))</Copyright>

Alternative: Visual Studio Project Properties

Or paste the inner expression directly into the Copyright field in the Package section of the project properties in Visual Studio:

Copyright © $([System.DateTime]::UtcNow.Year) Travis Troyer ($([System.DateTime]::UtcNow.ToString("s")))

This can be a little confusing, because Visual Studio will evaluate the expression and display the current value in the window, but it will also update the project file appropriately behind the scenes.

Solution-wide via Directory.Build.props

You can plop the <Copyright> element above into a Directory.Build.props file in your solution root, and have it automatically applied to all projects within the directory, assuming each project does not supply its own Copyright value.

<Project>
 <PropertyGroup>
   <Copyright>Copyright © $([System.DateTime]::UtcNow.Year) Travis Troyer ($([System.DateTime]::UtcNow.ToString("s")))</Copyright>
 </PropertyGroup>
</Project>

Directory.Build.props: Customize your build

Output

The example expression will give you a copyright like this:

Copyright © 2018 Travis Troyer (2018-05-30T14:46:23)

Retrieval

You can view the copyright information from the file properties in Windows, or grab it at runtime:

var version = FileVersionInfo.GetVersionInfo(Assembly.GetEntryAssembly().Location);

Console.WriteLine(version.LegalCopyright);

Answer 2

One approach which I'm amazed no-one has mentioned yet is to use T4 Text Templates for code generation.

<#@ template debug="false" hostspecific="true" language="C#" #>
<#@ assembly name="System.Core" #>
<#@ import namespace="System" #>
<#@ output extension=".g.cs" #>
namespace Foo.Bar
{
    public static partial class Constants
    {
        public static DateTime CompilationTimestampUtc { get { return new DateTime(<# Write(DateTime.UtcNow.Ticks); #>L, DateTimeKind.Utc); } }
    }
}

Pros:

• Locale-independent
• Allows a lot more than just the time of compilation

Cons:

• Only applicable to libraries where you control the source
• Requires configuring your project (and build server, if that doesn't pick it up) to execute the template in a pre-build step. (See also T4 without VS).

Answer 3

The above method can be tweaked for assemblies already loaded within the process by using the file's image in memory (as opposed to re-reading it from storage):

using System;
using System.Runtime.InteropServices;
using Assembly = System.Reflection.Assembly;

static class Utils
{
    public static DateTime GetLinkerDateTime(this Assembly assembly, TimeZoneInfo tzi = null)
    {
        // Constants related to the Windows PE file format.
        const int PE_HEADER_OFFSET = 60;
        const int LINKER_TIMESTAMP_OFFSET = 8;

        // Discover the base memory address where our assembly is loaded
        var entryModule = assembly.ManifestModule;
        var hMod = Marshal.GetHINSTANCE(entryModule);
        if (hMod == IntPtr.Zero - 1) throw new Exception("Failed to get HINSTANCE.");

        // Read the linker timestamp
        var offset = Marshal.ReadInt32(hMod, PE_HEADER_OFFSET);
        var secondsSince1970 = Marshal.ReadInt32(hMod, offset + LINKER_TIMESTAMP_OFFSET);

        // Convert the timestamp to a DateTime
        var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
        var linkTimeUtc = epoch.AddSeconds(secondsSince1970);
        var dt = TimeZoneInfo.ConvertTimeFromUtc(linkTimeUtc, tzi ?? TimeZoneInfo.Local);
        return dt;
    }
}

Answer 4

I'm not sure, but maybe the Build Incrementer helps.

Answer 5

Jeff Atwood had a few things to say about this issue in Determining Build Date the hard way.

The most reliable method turns out to be retrieving the linker timestamp from the PE header embedded in the executable file -- some C# code (by Joe Spivey) for that from the comments to Jeff's article:

public static DateTime GetLinkerTime(this Assembly assembly, TimeZoneInfo target = null)
{
    var filePath = assembly.Location;
    const int c_PeHeaderOffset = 60;
    const int c_LinkerTimestampOffset = 8;

    var buffer = new byte[2048];

    using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
        stream.Read(buffer, 0, 2048);

    var offset = BitConverter.ToInt32(buffer, c_PeHeaderOffset);
    var secondsSince1970 = BitConverter.ToInt32(buffer, offset + c_LinkerTimestampOffset);
    var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

    var linkTimeUtc = epoch.AddSeconds(secondsSince1970);

    var tz = target ?? TimeZoneInfo.Local;
    var localTime = TimeZoneInfo.ConvertTimeFromUtc(linkTimeUtc, tz);

    return localTime;
}

Usage example:

var linkTimeLocal = Assembly.GetExecutingAssembly().GetLinkerTime();

UPDATE: The method was working for .Net Core 1.0, but stopped working after .Net Core 1.1 release(gives random years in 1900-2020 range)

Answer 6

For anyone that needs to get the compile time in Windows 8 / Windows Phone 8:

    public static async Task<DateTimeOffset?> RetrieveLinkerTimestamp(Assembly assembly)
    {
        var pkg = Windows.ApplicationModel.Package.Current;
        if (null == pkg)
        {
            return null;
        }

        var assemblyFile = await pkg.InstalledLocation.GetFileAsync(assembly.ManifestModule.Name);
        if (null == assemblyFile)
        {
            return null;
        }

        using (var stream = await assemblyFile.OpenSequentialReadAsync())
        {
            using (var reader = new DataReader(stream))
            {
                const int PeHeaderOffset = 60;
                const int LinkerTimestampOffset = 8;

                //read first 2048 bytes from the assembly file.
                byte[] b = new byte[2048];
                await reader.LoadAsync((uint)b.Length);
                reader.ReadBytes(b);
                reader.DetachStream();

                //get the pe header offset
                int i = System.BitConverter.ToInt32(b, PeHeaderOffset);

                //read the linker timestamp from the PE header
                int secondsSince1970 = System.BitConverter.ToInt32(b, i + LinkerTimestampOffset);

                var dt = new DateTimeOffset(1970, 1, 1, 0, 0, 0, DateTimeOffset.Now.Offset) + DateTimeOffset.Now.Offset;
                return dt.AddSeconds(secondsSince1970);
            }
        }
    }

For anyone that needs to get the compile time in Windows Phone 7:

    public static async Task<DateTimeOffset?> RetrieveLinkerTimestampAsync(Assembly assembly)
    {
        const int PeHeaderOffset = 60;
        const int LinkerTimestampOffset = 8;            
        byte[] b = new byte[2048];

        try
        {
            var rs = Application.GetResourceStream(new Uri(assembly.ManifestModule.Name, UriKind.Relative));
            using (var s = rs.Stream)
            {
                var asyncResult = s.BeginRead(b, 0, b.Length, null, null);
                int bytesRead = await Task.Factory.FromAsync<int>(asyncResult, s.EndRead);
            }
        }
        catch (System.IO.IOException)
        {
            return null;
        }

        int i = System.BitConverter.ToInt32(b, PeHeaderOffset);
        int secondsSince1970 = System.BitConverter.ToInt32(b, i + LinkerTimestampOffset);
        var dt = new DateTimeOffset(1970, 1, 1, 0, 0, 0, DateTimeOffset.Now.Offset) + DateTimeOffset.Now.Offset;
        dt = dt.AddSeconds(secondsSince1970);
        return dt;
    }

NOTE: In all cases you're running in a sandbox, so you'll only be able to get the compile time of assemblies that you deploy with your app. (i.e. this won't work on anything in the GAC).