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MSBuild: Reliably Retrieving the Assembly Version (without locking the file!)

, 28 Jun 2010 CPOL
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I’ve recently had to look at dynamically assigning an assembly versions based in part on the date of compilation and the version of a compiled 3rd Party library. This looked like a simple job for the MSBuild.ExtensionPack.Framework.Assembly task in the MSBuild Extension Pack.  However, this had a s

I’ve recently had to look at dynamically assigning an assembly versions based in part on the date of compilation and the version of a compiled 3rd Party library.

This looked like a simple job for the MSBuild.ExtensionPack.Framework.Assembly task in the MSBuild Extension Pack.  However, this had a serious downside it locked the Assembly for the duration of the build!. 

Erkk.

This is the Devil Line that causes the problem:

   1: protected override void InternalExecute()
   2: {; 
   3:     // Implementation ommitted
   4:     this.assembly = Assembly.LoadFrom(this.NetAssembly.GetMetadata("FullPath"));; 
   5:     // Implementation ommitted
   6: }; 
   7: /* Taken From MSBuild.ExtensionPack.Framework.Assembly using Reflector
   8: protected override void InternalExecute();; 
   9:  
   10: Declaring Type: MSBuild.ExtensionPack.Framework.Assembly
   11: Assembly: MSBuild.ExtensionPack, Version=3.5.0.0 
   12: */;

It looks innocent enough, but it loads the assembly into the current AppDomain (MSBuild’s build process) which then prevents any other process from accessing the file – even the build process itself. 

Fail.

The Workaround

To get around this, I knocked up a quick custom MSBuild Task:

   1: using System;
   2: using System.Linq;; 
   3: using System.Reflection;
   4: using Microsoft.Build.Framework;; 
   5: using Microsoft.Build.Utilities;
   6:    
   7: namespace MartinOnDotNet.MSBuild.Tasks
   8: {; 
   9:     /// <span class="code-SummaryComment"><summary>
</span>  10:     /// This task takes a four section version number 8.0.0.128 and returns an abbreviated version number; 
  11:     /// based on the  first three parts (800).  This can then be used to distinguish depended versions.
  12:     /// <span class="code-SummaryComment"></summary>; 
</span>  13:     public class AbbreviateVersionTask : Task
  14:     {; 
  15:  
  16:         /// <span class="code-SummaryComment"><summary>; 
</span>  17:         /// Executes this instance.
  18:         /// <span class="code-SummaryComment"></summary>; 
</span>  19:         /// <span class="code-SummaryComment"><returns></returns>
</span>  20:         public override bool Execute(); 
  21:         {
  22: #if DEBUG; 
  23:             if (Properties.Settings.Default.LaunchDebugger
  24:                 && !System.Diagnostics.Debugger.IsAttached) System.Diagnostics.Debugger.Launch();; 
  25: #endif
  26:             if (AbbreviatedVersionParts <= 0 || AbbreviatedVersionParts > 4) AbbreviatedVersionParts = 3;; 
  27:             AssemblyName assname = AssemblyName.GetAssemblyName(NetAssembly.GetMetadata("FullPath"));
  28:             Version v = assname.Version;; 
  29:             AssemblyVersion = v.ToString();
  30:             string[] parts = v.ToString(AbbreviatedVersionParts).Split(new char[] { '.' }, 
                      StringSplitOptions.RemoveEmptyEntries);; 
  31:             AbbreviatedVersion = string.Concat(parts.ToArray());>  32:             Major = v.Major;; 
  33:             Minor = v.Minor;
  34:             Build = v.Build;; 
  35:             Revision = v.Revision;
  36:             return true;; 
  37:         }
  38: 
  39:         /// <span class="code-SummaryComment"><summary>
</span>  40:         /// Gets or sets the assembly version.; 
  41:         /// <span class="code-SummaryComment"></summary>
</span>  42:         /// <span class="code-SummaryComment"><value>The assembly version.</value>; 
</span>  43:         [Output]
  44:         public string AssemblyVersion { get; set; }; 
  45:  
  46:         /// <span class="code-SummaryComment"><summary>; 
</span>  47:         /// Gets or sets the abbreviated version pats.
  48:         /// <span class="code-SummaryComment"></summary>; 
</span>  49:         /// <span class="code-SummaryComment"><value>The abbreviated version pats.</value>
</span>  50:         public int AbbreviatedVersionParts { get; set; }; 
  51:
  52:         /// <span class="code-SummaryComment"><summary>; 
</span>  53:         /// Gets or sets the assembly.
  54:         /// <span class="code-SummaryComment"></summary>; 
</span>  55:         /// <span class="code-SummaryComment"><value>The assembly.</value>
</span>  56:         [Required]; 
  57:         public ITaskItem NetAssembly { get; set; }
  58:   59:         /// <span class="code-SummaryComment"><summary>
</span>  60:         /// Gets or sets the abbreviated version.; 
  61:         /// <span class="code-SummaryComment"></summary>
</span>  62:         /// <span class="code-SummaryComment"><value>The abbreviated version.</value>; 
</span>  63:         [Output]
  64:         public string AbbreviatedVersion { get; set; }; 
  65:  
  66:         /// <span class="code-SummaryComment"><summary>; 
</span>  67:         /// Gets or sets the major.
  68:         /// <span class="code-SummaryComment"></summary>; 
</span>  69:         /// <span class="code-SummaryComment"><value>The major.</value>
</span>  70:         [Output]; 
  71:         public int Major { get; set; }
  72:         /// <span class="code-SummaryComment"><summary>; 
</span>  73:         /// Gets or sets the minor.
  74:         /// <span class="code-SummaryComment"></summary>; 
</span>  75:         /// <span class="code-SummaryComment"><value>The minor.</value>
</span>  76:         [Output]; 
  77:         public int Minor { get; set; }
  78:         /// <span class="code-SummaryComment"><summary>; 
</span>  79:         /// Gets or sets the build.
  80:         /// <span class="code-SummaryComment"></summary>; 
</span>  81:         /// <span class="code-SummaryComment"><value>The build.</value>
</span>  82:         [Output]; 
  83:         public int Build { get; set; }
  84:         /// <span class="code-SummaryComment"><summary>; 
</span>  85:         /// Gets or sets the revision.
  86:         /// <span class="code-SummaryComment"></summary>; 
</span>  87:         /// <span class="code-SummaryComment"><value>The revision.</value>
</span>  88:         [Output]; 
  89:         public int Revision { get; set; }
  90:   
  91:  
  92:     }; 
  93: };

The main different between my implementation and the MSBuild Extension Pack task is this line:

   1: AssemblyName assname = AssemblyName.GetAssemblyName(NetAssembly.GetMetadata("FullPath"));;

This line retrieves the assemblies name object (version, public key, etc, etc) without actually loading the assembly into the AppDomain, hence – no locking!  Sweet.

This can now be referenced in your build scripts, like so:

   1: <!-- Register Task -->
   2: <UsingTask AssemblyFile="..\3rd Party\MartinOnDotNet Build Tasks\MartinOnDotNet.MSBuild.Tasks.dll"; 
   3:                      TaskName="MartinOnDotNet.MSBuild.Tasks.AbbreviateVersionTask" />
   4:    
   5: <!-- And Now Use in Build Target -->
   6: <Target Name="MergeVersions">; 
   7:     <!-- Implementation Ommitted -->
   8:       
   9:     <MartinOnDotNet.MSBuild.Tasks.AbbreviateVersionTask NetAssembly="$(HelpersLibrary)">
  10:         <Output TaskParameter="AssemblyVersion"; 
  11:                         PropertyName="HelpersAssemblyVersion" />
  12:         <Output TaskParameter="Major"; 
  13:                         PropertyName="HelpersMajor" />
  14:         <Output TaskParameter="Major"; 
  15:                         PropertyName="HelpersMajor" />
  16:         <Output TaskParameter="Minor"; 
  17:                         PropertyName="HelpersMinor" />
  18:         <Output TaskParameter="Build"; 
  19:                         PropertyName="HelpersBuild" />
  20:         <Output TaskParameter="Revision"; 
  21:                         PropertyName="HelpersRevision" />
  22:     </MartinOnDotNet.MSBuild.Tasks.AbbreviateVersionTask>; 
  23:     <Message Text="Helpers Version: $(HelpersAssemblyVersion)"
  24:                      Importance="high" />; 
  25:     <ItemGroup>
  26:         <AssemblyInfoFiles Include="..\Freestyle.Helpers.Ektron\Properties\AssemblyInfo.cs"/>; 
  27:     </ItemGroup>
  28:      
  29:     <Message Text="Assembly Info File: %(AssemblyInfoFiles.FullPath)"
  30:                      Importance="high" />; 
  31:     <MSBuild.ExtensionPack.Framework.AssemblyInfo AssemblyInfoFiles="@(AssemblyInfoFiles)"
  32:                      AssemblyFileMajorVersion="$(HelpersMajor)"; 
  33:                      AssemblyFileMinorVersion="$(AbbreviatedVersion)"
  34:                      AssemblyFileBuildNumberType="NoIncrement"; 
  35:                      AssemblyFileBuildNumber="$(HelpersBuild)"
  36:                      AssemblyFileRevisionType="NoIncrement"; 
  37:                      AssemblyFileRevision="$(HelpersRevision)"
  38:                      AssemblyMajorVersion="$(HelpersMajor)"; 
  39:                      AssemblyMinorVersion="$(AbbreviatedVersion)"
  40:                      AssemblyBuildNumberType="NoIncrement"; 
  41:                      AssemblyBuildNumber="$(HelpersBuild)"
  42:                      AssemblyRevisionType="NoIncrement"; 
  43:                      AssemblyRevision="$(HelpersRevision)"
  44:                      SkipVersioning="false"/>; 
  45:     
  46: </target>;

The above example makes use the AssemblyInfo task in the MSBuild Extension Pack to explicitly set the version number for my assembly.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Martin Jarvis
Software Developer (Senior) Freestyle Interactive Ltd
United Kingdom United Kingdom
I'm a lead developer for Freestyle Interactive Ltd where we create many wonderful websites built on Microsofts ASP.Net and Ektron CMS.
 
I've been developing .Net applications (both Windows and Web) since 2002.
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Comments and Discussions

 
GeneralThe problem has been fixed in the later versions PinmemberMartin Jarvis28-Jun-10 11:42 

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