src/Test-LinkCapability.ps1
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#!/usr/bin/env pwsh $ErrorActionPreference = "Stop" Set-StrictMode -Version Latest <# .SYNOPSIS Tests which filesystem link capabilities are supported by the current session. .OUTPUTS System.Management.Automation.PSCustomObject If the current session supports filesystem links, returns an object with the following properties: HardLinks: An array of strings indicating which types of hard links are supported. Junctions: An array of strings indicating which types of junctions are supported. SymbolicLinks: An array of strings indicating which types of symbolic links are supported. If the current session does not support filesystem links, returns $false. .NOTES See: https://docs.microsoft.com/en-us/windows/win32/fileio/hard-links-and-junctions #> function Test-LinkCapability() { param ( [Parameter(Mandatory = $false)] [switch] $NoCache ) [PSCustomObject] $cached_result = Get-Variable -Name "Test-LinkCapability" -Scope Global -ErrorAction SilentlyContinue | Select-Object -ExpandProperty Value if (-not $NoCache -and $cached_result) { return $cached_result } elseif ($cached_result) { Remove-Variable -Name "Test-LinkCapability" -Scope Global -ErrorAction SilentlyContinue } [hashtable] $capabilities = @{ "HardLinks" = $null "Junctions" = $null "SymbolicLinks" = $null } $testFile = Join-Path -Path $env:TEMP -ChildPath "test-file" $testDir = Join-Path -Path $env:TEMP -ChildPath "test-dir" $testJunctionFile = Join-Path -Path $env:TEMP -ChildPath "test-junction-file" $testJunctionDir = Join-Path -Path $env:TEMP -ChildPath "test-junction-dir" $testSymlinkFile = Join-Path -Path $env:TEMP -ChildPath "test-symlink-file" $testSymlinkDir = Join-Path -Path $env:TEMP -ChildPath "test-symlink-dir" $testHardLinkFile = Join-Path -Path $env:TEMP -ChildPath "test-hardlink-file" $testHardLinkDir = Join-Path -Path $env:TEMP -ChildPath "test-hardlink-dir" [string[]] $allPossibleArtifacts = @( $testFile, $testDir, $testJunctionFile, $testJunctionDir, $testSymlinkFile, $testSymlinkDir, $testHardLinkFile, $testHardLinkDir ) $allPossibleArtifacts | ForEach-Object { if (Test-Path -Path $_ -ErrorAction SilentlyContinue) { Remove-Item -Path $_ -Force } } try { New-Item -Path $testFile -ItemType File -ErrorAction Stop | Out-Null New-Item -Path $testDir -ItemType Directory -ErrorAction Stop | Out-Null try { New-Item -Path $testJunctionDir -ItemType Junction -Target $testDir -ErrorAction Stop | Out-Null $capabilities["Junctions"] = ($capabilities["Junctions"] ?? @()) + @("Directories") } catch { # Ignore } try { New-Item -Path $testSymlinkDir -ItemType SymbolicLink -Target $testDir -ErrorAction Stop | Out-Null $capabilities["SymbolicLinks"] = ($capabilities["SymbolicLinks"] ?? @()) + @("Directories") } catch { # Ignore } try { New-Item -Path $testHardLinkDir -ItemType HardLink -Target $testDir -ErrorAction Stop | Out-Null $capabilities["HardLinks"] = ($capabilities["HardLinks"] ?? @()) + @("Directories") } catch { # Ignore } try { New-Item -Path $testJunctionFile -ItemType Junction -Target $testFile -ErrorAction Stop | Out-Null $capabilities["Junctions"] = ($capabilities["Junctions"] ?? @()) + @("Files") } catch { # Ignore } try { New-Item -Path $testSymlinkFile -ItemType SymbolicLink -Target $testFile -ErrorAction Stop | Out-Null $capabilities["SymbolicLinks"] = ($capabilities["SymbolicLinks"] ?? @()) + @("Files") } catch { # Ignore } try { New-Item -Path $testHardLinkFile -ItemType HardLink -Target $testFile -ErrorAction Stop | Out-Null $capabilities["HardLinks"] = ($capabilities["HardLinks"] ?? @()) + @("Files") } catch { # Ignore } [PSCustomObject] $result = [PSCustomObject]$capabilities # If all members are empty, convert to false. if (($null -eq $result.PSObject.Properties.Value) -or ($result.PSObject.Properties.Value -eq @())) { $result = $false } if (-not $NoCache) { Set-Variable -Name "Test-LinkCapability" -Value $result -Scope Global -Option Constant -ErrorAction SilentlyContinue } return $result } finally { $allPossibleArtifacts | ForEach-Object { if (Test-Path -Path $_ -ErrorAction SilentlyContinue) { Remove-Item -Path $_ -Force -ErrorAction Continue } } } } |