BuildCommon.targets

<?xml version="1.0" encoding="utf-8"?>
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
    <PropertyGroup>
    <CompileDependsOn>
        CommonBuildDefineModifiedAssemblyVersion;
        $(CompileDependsOn);
    </CompileDependsOn>
</PropertyGroup>
<Target Name="CommonBuildDefineModifiedAssemblyVersion" Condition="'$(GitCommit)' != ''">
    <!-- Find AssemblyInfo.cs or AssemblyInfo.vb in the "Compile" Items. Remove it from "Compile" Items because we will use a modified version instead. -->
    <ItemGroup>
        <OriginalAssemblyInfo Include="@(Compile)" Condition="%(Filename) == 'AssemblyInfo' And (%(Extension) == '.vb' Or %(Extension) == '.cs')" />
        <Compile Remove="**/AssemblyInfo.vb" />
        <Compile Remove="**/AssemblyInfo.cs" />
    </ItemGroup>
    <!-- Copy the original AssemblyInfo.cs/.vb to obj\ folder, i.e. $(IntermediateOutputPath). The copied filepath is saved into @(ModifiedAssemblyInfo) Item. -->
    <Copy SourceFiles="@(OriginalAssemblyInfo)"
          DestinationFiles="@(OriginalAssemblyInfo->'$(IntermediateOutputPath)%(Identity)')">
        <Output TaskParameter="DestinationFiles" ItemName="ModifiedAssemblyInfo"/>
    </Copy>
    <!-- Replace the version bit (in AssemblyVersion and AssemblyFileVersion attributes) using regular expression. Use the defined property: $(GitCommit). -->
    <Message Text="Setting GitCommit to $(GitCommit)" />
    <AppendFile Files="@(ModifiedAssemblyInfo)"
                GitHash="$(GitCommit)"
                />
    <!-- Include the modified AssemblyInfo.cs/.vb file in "Compile" items (instead of the original). -->
    <ItemGroup>
        <Compile Include="@(ModifiedAssemblyInfo)" />
    </ItemGroup>
</Target>

<UsingTask TaskName="AppendFile" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll">
    <ParameterGroup>
        <Files ParameterType="Microsoft.Build.Framework.ITaskItem[]" Required="true" />
        <GitHash ParameterType="System.String" Required="true" />
    </ParameterGroup>
    <Task>
        <Reference Include="System.Core" />
        <Using Namespace="System" />
        <Using Namespace="System.IO" />
        <Using Namespace="Microsoft.Build.Framework" />
        <Using Namespace="Microsoft.Build.Utilities" />
        <Code Type="Fragment" Language="cs">
            <![CDATA[
            try {
                for (int i = 0; i < Files.Length; ++i)
                {
                    var path = Files[i].GetMetadata("FullPath");
                    if (!File.Exists(path)) continue;

                    using (StreamWriter sw = File.AppendText(path)) 
                    {
                      var text = $"[assembly: AssemblyGitCommit(\"{GitHash}\")]";
                      Log.LogMessage(text);
                      sw.WriteLine(text);
                    } 
                }
                return true;
            }
            catch (Exception ex) {
                Log.LogErrorFromException(ex);
                return false;
            }
        ]]>
        </Code>
    </Task>
</UsingTask>

</Project>