Functions/Resolve-RelativePath.ps1
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# Copyright 2012 Aaron Jensen # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. function Resolve-RelativePath { <# .SYNOPSIS Converts a path to a relative path from a given source. .DESCRIPTION The .NET framework doesn't expose an API for getting a relative path to an item. This function uses Win32 APIs to call [PathRelativePathTo](http://msdn.microsoft.com/en-us/library/windows/desktop/bb773740.aspx). Neither the `From` or `To` paths need to exist. .EXAMPLE Resolve-RelativePath -Path 'C:\Program Files' -FromDirectory 'C:\Windows\system32' Returns `..\..\Program Files`. .EXAMPLE Get-ChildItem * | Resolve-RelativePath -FromDirectory 'C:\Windows\system32' Returns the relative path from the `C:\Windows\system32` directory to the current directory. .EXAMPLE Resolve-RelativePath -Path 'C:\I\do\not\exist\either' -FromDirectory 'C:\I\do\not\exist' Returns `.\either`. .EXAMPLE Resolve-RelativePath -Path 'C:\I\do\not\exist\either' -FromFile 'C:\I\do\not\exist_file' Treats `C:\I\do\not\exist_file` as a file, so returns a relative path of `.\exist\either`. .LINK http://msdn.microsoft.com/en-us/library/windows/desktop/bb773740.aspx #> [CmdletBinding()] param( [Parameter(ValueFromPipelineByPropertyName=$true)] [string] # The path to convert to a relative path. It will be relative to the value of the From parameter. [Alias('FullName')] $Path, [Parameter(Mandatory=$true,ParameterSetName='FromDirectory')] [string] # The source directory from which the relative path will be calculated. Can be a string or an file system object. $FromDirectory, [Parameter(Mandatory=$true,ParameterSetName='FromFile')] [string] # The source directory from which the relative path will be calculated. Can be a string or an file system object. $FromFile ) begin { Set-StrictMode -Version 'Latest' Use-CallerPreference -Cmdlet $PSCmdlet -Session $ExecutionContext.SessionState } process { $relativePath = New-Object System.Text.StringBuilder 260 switch( $pscmdlet.ParameterSetName ) { 'FromFile' { $fromAttr = [IO.FileAttributes]::Normal $fromPath = $FromFile } 'FromDirectory' { $fromAttr = [IO.FileAttributes]::Directory $fromPath = $FromDirectory } } $toPath = $Path if( $Path | Get-Member -Name 'FullName' ) { $toPath = $Path.FullName } $toAttr = [IO.FileAttributes]::Normal $converted = [Carbon.IO.Path]::PathRelativePathTo( $relativePath, $fromPath, $fromAttr, $toPath, $toAttr ) $result = if( $converted ) { $relativePath.ToString() } else { $null } return $result } } |