Public/File/Save-RandomDataToFile.ps1
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function Save-RandomDataToFile { [CmdletBinding()] param ( [Parameter(Mandatory, ValueFromPipeline)] [String] $OutputPath, [Parameter(Mandatory, ValueFromPipelineByPropertyName)] [Decimal] $Filesize, [Parameter(Mandatory, ValueFromPipelineByPropertyName)] [ValidateSet('Bytes', 'KB', 'MB', 'GB', 'TB', IgnoreCase = $true)] [String] $Unit, [Parameter(Mandatory = $false, ValueFromPipelineByPropertyName)] [String] $FileExtension = 'txt', [Parameter(Mandatory = $false, ValueFromPipelineByPropertyName)] [Int32] $FilenameLength = 16 ) process { # Gather parameters and rope them into useable values # Extension / Filename / Full Path $DestExtension = $FileExtension $RandomString = $(Get-RandomAlphanumericString -Length $FilenameLength) + '.' + $DestExtension $DestFullPath = Join-Path $OutputPath $RandomString Write-Host "`$DestFullPath:" $DestFullPath -ForegroundColor Green # We need to convert the input filesize from whatever units specified to bytes $IntendedFilesize = (Format-FileSize -Value $Filesize -From $Unit -To Bytes) # If we are creating a file less than ~2.1474GB, we can use a faster # method for writing random data. For some reason this technique is quicker # than the alternative of writing data in chunks to a temp file. if ($IntendedFilesize -lt 2147483500) { # Create our file to match the target filesize and place it in destination. $Buffer = [System.Byte[]]::CreateInstance([System.Byte], $IntendedFilesize) (New-Object Random).NextBytes($Buffer) [IO.File]::WriteAllBytes($DestFullPath, $Buffer) } else { # This method is only used for files over ~2.1474GB. Arrays in .NET cannot exceed # 2^31-1 items in length (2,147,483,647 Bytes). This is because the index value # used for arrays is [int]. So we fall back to writing the file in 4KB chunks. # Create a new byte array instance, as well as our RNG provider. $Buffer = [System.Byte[]]::CreateInstance([System.Byte], 4KB) $RNG = [System.Security.Cryptography.RNGCryptoServiceProvider]::Create() # Create a temp file and open it for streaming. $TempFile = [System.IO.Path]::GetTempFileName() | Get-Item $FileStream = $TempFile.OpenWrite() do { # Write random data to our temp file in 4KB chunks. $RNG.GetBytes($Buffer) $FileStream.Write($Buffer, 0, $Buffer.Length) # We're finished when the filesize hits IntendedFilesize } while ($FileStream.Length -lt $IntendedFilesize) # Cleanup $FileStream.Dispose() $RNG.Dispose() # Move and Rename the temp file to match our function's parameters. Move-Item $TempFile.FullName -Destination $OutputPath $NewFullName = [System.IO.Path]::Combine($OutputPath, $TempFile.Name) Rename-Item -Path $NewFullName -NewName $DestFilename } } } |