PowerShell/docs/building/internals.md

Internals of build process

The purpose of this document is to explain build process internals with subtle nuances. This document is not by any means complete. The ultimate source of truth is the code in .\build.psm1 that's getting executed on the corresponding CI system.

This document assumes that you can successfully build PowerShell from sources for your platform.

Top directory

We are calling dotnet tool build for $Top directory

• src\powershell-win-core for CoreCLR on Windows.
• src\powershell-unix for CoreCLR on Linux and macOS.

Dummy dependencies

We use dummy dependencies between projects to leverage dotnet build functionality. For example, src\powershell-win-core\powershell-win-core.csproj has dependency on Microsoft.PowerShell.PSReadLine, but in reality, there is no build dependency.

Dummy dependencies allows us to build just $Top folder, instead of building several folders.

Dummy dependencies rules

If assembly is part of CoreCLR build, it should be listed as a dependency for $Top folder (src\powershell-unix or src\powershell-win-core)

Preliminary steps

ResGen

Until the .NET CLI dotnet-resgen tool supports the generation of strongly typed classes, we run our own tool C# ResGen tool. While the Start-PSBuild command runs this automatically via the Start-ResGen function, it does not require PowerShell. The same command can be run manually:

cd src/ResGen
dotnet restore
dotnet run

Running the program does everything else:

• For each project, given a resources folder, create a gen folder.
• For each *.resx file from the resources folder, fill in a strongly typed C# class, and write it out to the corresponding *.cs file in the gen folder.

These files are not automatically updated on each build, as the project lacks the ability to detect changes. Thus, running it for every build would break incremental recompilation.

If you pull new commits and get an error about missing strings, you likely need to delete the gen folders and re-run the tool.

Type Catalog

A pre-generated catalog of C# types is used in PowerShell to help type resolution. Generating this catalog is a pre-build step that is run via Start-TypeGen, which Start-PSBuild calls. Again, however, PowerShell is not required. The necessary steps can be run manually:

cd ../TypeCatalogGen
dotnet restore
dotnet run ../System.Management.Automation/CoreCLR/CorePsTypeCatalog.cs powershell.inc

The file powershell.inc is generated by running a custom MSBuild target, which can be set-up by navigating to the src directory and running the following commands:

targetFile="Microsoft.PowerShell.SDK/obj/Microsoft.PowerShell.SDK.csproj.TypeCatalog.targets"
cat > $targetFile <<-"EOF"
<Project>
  <Target Name="_GetDependencies"
          DependsOnTargets="ResolveAssemblyReferencesDesignTime">
    <ItemGroup>
      <_RefAssemblyPath Include="%(_ReferencesFromRAR.ResolvedPath)%3B" Condition=" '%(_ReferencesFromRAR.Type)' == 'assembly' And '%(_ReferencesFromRAR.PackageName)' != 'Microsoft.Management.Infrastructure' " />
    </ItemGroup>
    <WriteLinesToFile File="$(_DependencyFile)" Lines="@(_RefAssemblyPath)" Overwrite="true" />
  </Target>
</Project>
EOF
dotnet msbuild Microsoft.PowerShell.SDK/Microsoft.PowerShell.SDK.csproj /t:_GetDependencies "/property:DesignTimeBuild=true;_DependencyFile=$(pwd)/src/TypeCatalogGen/powershell.inc" /nologo

powershell.inc contains the resolved paths to the DLLs of each dependency of PowerShell, and is taken as input to the TypeCatalogGen tool, which generates a source file CorePsTypeCatalog.cs for the Microsoft.PowerShell.CoreCLR.AssemblyLoadContext project.

The error The name 'InitializeTypeCatalog' does not exist in the current context indicates that the CorePsTypeCatalog.cs source file does not exist, so follow the steps to generate it.

Native Components

On Windows, PowerShell Core depends on the WinRM plugin pwrshplugin.dll to enable remoting over WinRM. On Linux/macOS, PowerShell Core depends on the binary libpsl-native.so/libpsl-native.dylib to provide some necessary supports.

Building those native components requires setting up additional dependencies, which could be a burden to those who don't seek to make changes to the native components. At the meantime, the native component code seldom changes, so it doesn't make sense to always build them with Start-PSBuild. Therefore, we decided to wrap the native components into NuGet packages, so that we only need to build them once when changes are made, and then reuse the produced binaries for many builds subsequently.

The NuGet package for pwrshplugin.dll is psrp.windows, and the NuGet package for libpsl-native is libpsl.

psrp.windows

To build pwrshplugin.dll, you need to install Visual Studio 2015 and run Start-PSBootstrap -BuildWindowsNative to install the prerequisites. Then run Start-BuildNativeWindowsBinaries to build the binary. For example, the following builds the release flavor of the binary targeting x64 architecture.

Start-BuildNativeWindowsBinaries -Configuration Release -Arch x64

After that, the binary pwrshplugin.dll and its PDB file will be placed under 'src/powershell-win-core'.

To create a new NuGet package for pwrshplugin.dll, first you need to get the psrp.windows.nuspec from an existing psrp.windows package. You can find it at ~/.nuget/packages/psrp.windows on your windows machine if you have recently built PowerShell on it. Or you can download the existing package from powershell-core feed. Once you get psrp.windows.nuspec, copy it to an empty folder.

Then you need to build pwrshplugin.dll targeting both win-x64 and win-x86 on Windows 10. After building successfully, copy the produced files to the same folder, and create the same layout of files as in the existing package. The layout of files should look like this:

\---runtimes
    +---win-x64
    |   \---native
    |           pwrshplugin.dll
    |           pwrshplugin.pdb
    |
    \---win-x86
        \---native
                pwrshplugin.dll
                pwrshplugin.pdb

Lastly, run nuget pack . from within the folder. Note that you may need the latest nuget.exe.

libpsl

For linux-arm, you need to run Start-PSBootstrap -BuildLinuxArm to install additional prerequisites to build libpsl-native. Note that currently you can build linux-arm only on a Ubuntu machine.

For linux-x64 and macOS, the initial run of Start-PSBootstrap would be enough -- no additional prerequisite required.

After making sure the prerequisites are met, run Start-BuildNativeUnixBinaries to build the binary:

## Build targeting linux-x64 or macOS
Start-BuildNativeUnixBinaries

## Build targeting linux-arm
Start-BuildNativeUnixBinaries -BuildLinuxArm

After the build succeeds, the binary libpsl-native.so (libpsl-native.dylib on macOS) will be placed under src/powershell-unix.

To create a new NuGet package for libpsl-native, first you need to get the libpsl.nuspec from an existing libpsl package. You can find it at ~/.nuget/packages/libpsl on your Linux or macOS machine if you have recently built PowerShell on it. Or you can download the existing package from powershell-core feed. Once you get psrp.windows.nuspec, copy it to an empty folder on your Windows machine.

Then you need to build three binaries of libpsl-native targeting linux-x64, linux-arm and osx respectively. Please note that, in order for the linux-x64 binary libpsl-native.so to be portable to all other Linux distributions, the linux-x64 binary needs to be built on CentOS 7 (.NET Core Linux native binaries are also built on CentOS 7 to ensure that they don't depend on newer glibc).

After building successfully, copy those three binaries to the same folder, and create the same layout of files as in the existing package. The layout of files should look like this:

└── runtimes
    ├── linux-arm
    │   └── native
    │       └── libpsl-native.so
    ├── linux-x64
    │   └── native
    │       └── libpsl-native.so
    └── osx
        └── native
            └── libpsl-native.dylib

Lastly, run nuget pack . from within the folder. Note that you may need the latest nuget.exe.