Private/Import-FluenceLibrary.ps1
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<# Copyright (c) 2026, Dan Cunningham. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #> function Import-FluenceLibrary { <# .SYNOPSIS Loads Fluence.Wpf.dll for the current edition into the process, once. .DESCRIPTION When a host has already loaded Fluence.Wpf, reuse that assembly rather than loading a second copy. that copy is reused, because the CLR will not load a second assembly with the same identity into the same context. If the module's staged build is newer than the copy in memory a warning names both versions, since a cmdlet may then rely on a type or member the older library does not have. Otherwise the sibling assemblies and Fluence.Wpf.dll are loaded from the module's lib folder for this edition. .PARAMETER ModuleRoot The module root folder that contains lib/<tfm>/Fluence.Wpf.dll. .NOTES Does not require a host application. #> [CmdletBinding()] [OutputType([void])] param ( [Parameter(Mandatory = $true)] [string]$ModuleRoot ) $already = [System.AppDomain]::CurrentDomain.GetAssemblies() | Where-Object { $_.GetName().Name -eq 'Fluence.Wpf' } | Select-Object -First 1 if ($null -ne $already) { Write-Verbose "Fluence.Wpf already loaded from: $($already.Location)" # Compare against the staged build when one is present. A hosted module may ship without a # lib folder at all, in which case there is nothing to compare and no warning to raise. $staged = $null try { $staged = Get-FluenceLibraryPath -ModuleRoot $ModuleRoot } catch { Write-Verbose "No staged Fluence.Wpf to compare against: $($_.Exception.Message)" } if ($null -ne $staged) { $loadedVersion = $already.GetName().Version $stagedVersion = [System.Reflection.AssemblyName]::GetAssemblyName($staged).Version if ($loadedVersion -lt $stagedVersion) { Write-Warning ("The host has already loaded Fluence.Wpf $loadedVersion from '$($already.Location)', " + "which is older than the $stagedVersion build staged with this module. The module will use the " + "host's copy; cmdlets that rely on newer library members may fail.") } } return } $dll = Get-FluenceLibraryPath -ModuleRoot $ModuleRoot $libDir = [System.IO.Path]::GetDirectoryName($dll) # Load the sibling dependencies (the net8 WinRT projections) eagerly from the lib folder. # # This deliberately does NOT register an AppDomain.AssemblyResolve handler. A PowerShell # scriptblock can never be used safely as a ResolveEventHandler: the CLR raises # AssemblyResolve on whatever thread triggered the load, and when that thread has no # PowerShell execution context, ScriptBlock.GetContextFromTLS builds an ErrorRecord before # the scriptblock body runs. Formatting that record reads a resource string, which probes a # satellite assembly, which raises AssemblyResolve again: unbounded recursion ending in # STATUS_STACK_OVERFLOW (0xC00000FD), a hard process kill with no catchable exception. Because # the recursion happens *before* the body executes, no guard inside the body can prevent it. # # Reproduction of the old behaviour: import the module, then open any runspace # ([runspacefactory]::CreateRunspace().Open()). Provider initialisation reads a resource # string and the process dies. tests/Close-FluenceUiRunspace.Tests.ps1 covers it. # # Eager loading is also strictly more predictable: LoadFrom on Fluence.Wpf.dll already probes # its own directory for dependencies, so the handler only ever mattered for assemblies the # LoadFrom context missed. Loading them up front costs one directory enumeration and removes # a process-wide, never-unregistered hook. foreach ($sibling in [System.IO.Directory]::GetFiles($libDir, '*.dll')) { if ([System.IO.Path]::GetFileName($sibling) -eq 'Fluence.Wpf.dll') { continue } try { $null = [System.Reflection.Assembly]::LoadFrom($sibling) } catch { # A sibling that will not load is not fatal: Fluence.Wpf may not need it on this # edition, and if it does the LoadFrom below fails with a far clearer error. Write-Verbose "Skipped sibling assembly '$sibling': $($_.Exception.Message)" } } $null = [System.Reflection.Assembly]::LoadFrom($dll) } |