ExternalCommand.psm1

<#
.SYNOPSIS
This is a helper function that runs a external executable binary and checks
exit code for success to see if an error occurred. If an non 0 exit code is
detected then an exception is thrown by default. It also properly creates
and escapes arguments supplied via Arguments array parameter. Supports UTF8
and whitespace in the argument values.
.PARAMETER Command
Executable name/command to run. Must be available at PATH env var or you can specify full path to the binary.
.PARAMETER Arguments
Arguments string array to path to Command as arguments
.PARAMETER HideArguments
List indexes (starting with 0) of arguments you would like to obscure in the message that command and its
arguments that being executed.
.PARAMETER OutVarStdout
Provide variable name that will be used to save STDOUT output of the command execution.
.PARAMETER OutVarStderr
Provide variable name that will be used to save STDERR output of the command execution.
.PARAMETER OutVarCode
Provide variable name that will be used to save process exit code.
.PARAMETER Return
By default this function returns $null, if specified you will get this object:
@{Stdout="Contains Stdout",Stderr="Contains Stderr",All="Stdout and Stderr output as it was generated",Code="Int from process exit code"}
Stdout output sequence order is guaranteed, while Stderr lines sequence might be out of order (eventing nature?).
.PARAMETER IgnoreExitCode
Specify if you expect non 0 exit code from the Command and would like to avoid non 0 exit code exception.
.PARAMETER HideStdout
Specify if don't want STDOUT to be written to the host
.PARAMETER HideStderr
Specify if don't want STDERR to be written to the host
# .EXAMPLE
➜ Invoke-ExternalCommand -Command git -Arguments version
Running command [ C:\Program Files\Git\cmd\git.exe ] with arguments: "version"
git version 2.20.1.windows.1

➜ Invoke-ExternalCommand -Command helm -Arguments version,--client
Running command [ C:\ProgramData\chocolatey\bin\helm.exe ] with arguments: "version" "--client"
Client: &version.Version{SemVer:"v2.12.2", GitCommit:"7d2b0c73d734f6586ed222a567c5d103fed435be", GitTreeState:"clean"}

➜ Invoke-ExternalCommand -Command helm -Arguments versiondd,--client
Running command [ C:\ProgramData\chocolatey\bin\helm.exe ] with arguments: "versiondd" "--client"
Error: unknown command "versiondd" for "helm"
Did you mean this?


        version
Run 'helm --help' for usage.

Command returned non zero exit code of '1'. Command: helm
At C:\Users\apopovich\dev\ps-modules\Igloo.Powershell.ExternalCommand\Igloo.Powershell.ExternalCommand.psm1:237 char:9
+ throw ([string]::Format("Command returned non zero exit code ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo : OperationStopped: (Command returne.... Command: helm:String) [], RuntimeException
    + FullyQualifiedErrorId : Command returned non zero exit code of '1'. Command: helm


#>

function Invoke-ExternalCommand
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param (
        [Parameter(Mandatory = 1)][string]$Command,
        [string[]]$Arguments = @(),
        [int[]]$HideArguments = @(),
        [string]$OutVarStdout = $null,
        [string]$OutVarStderr = $null,
        [string]$OutVarCode = $null,
        [switch]$Return,
        [switch]$IgnoreExitCode,
        [switch]$HideStdout,
        [switch]$HideStderr
    )
    # setting desired $ErrorActionPreference, backup old one
    $OldErrorActionPreference = $ErrorActionPreference
    $ErrorActionPreference = "Stop"

    $CommandObject = (Get-Command $Command -CommandType Application -ErrorAction Ignore | Select-Object -First 1)
    if (! $CommandObject)
    {
        throw "Invalid application name\path provided (Cmdlets not supported): $Command"
    }

    # for debug info hiding args
    # looping through all arguments
    $ArgsToShow = New-Object System.Collections.Generic.List[String]

    for ($i = 0; $i -lt $Arguments.length; $i++)
    {
        # replacing sensitive arguments with "<sensitive>"
        if ($HideArguments -contains $i)
        {
            $ArgsToShow.Add("<sensitive>")
        }
        else
        {
            $ArgsToShow.Add($Arguments[$i])
        }
    }
    if ($ArgsToShow.Length -gt 0)
    {
        $ArgsToShow = (EscapeArguments($ArgsToShow))
    }
    # Displaying what will be executed
    Write-Host -Object "Running command [", $CommandObject.Source, "] with arguments:", $ArgsToShow -ForegroundColor Yellow

    $pinfo = New-Object System.Diagnostics.ProcessStartInfo
    # Full pth to the binary
    $pinfo.FileName = $CommandObject.Source
    # enable UTF-8 Support and redirecting STDERR and STDOUT
    $pinfo.StandardOutputEncoding = New-Object System.Text.UTF8Encoding $false
    $pinfo.StandardErrorEncoding = New-Object System.Text.UTF8Encoding $false
    $pinfo.RedirectStandardError = $true
    $pinfo.RedirectStandardOutput = $true

    # please no shell
    $pinfo.UseShellExecute = $false

    # set process working directory
    $pinfo.WorkingDirectory = (Get-Location).Path

    # adding arguments if needed
    if ($Arguments.Length -gt 0)
    {
        $pinfo.Arguments = (EscapeArguments($Arguments))
    }

    # Creating process
    $p = New-Object System.Diagnostics.Process
    $p.StartInfo = $pinfo

    # https://xiaalex.wordpress.com/2013/05/03/use-asynchronous-read-on-standard-output-of-a-process/

    # object in which we will capture STDOUT and STDERR
    $Results = @{
        Stderr = ""
        Stdout = ""
        All    = ""
        Code   = 0
    }

    # Event handler for STDERR lines
    # Additional output handler to print STDERR into console realtime and capture it into var
    $ErrAction = {
        $EventData = $Event.SourceEventArgs.Data
        if (![String]::IsNullOrWhiteSpace($EventData))
        {
            $Event.MessageData.Stderr += "$EventData`n"
            $Event.MessageData.All += "$EventData`n"
            if (!$HideStderr)
            {
                Write-Host $EventData -ForegroundColor Gray
            }
        }
    }

    # STDERR might get captured out of sequence
    $ErrEvent = Register-ObjectEvent -InputObject $p -EventName ErrorDataReceived -Action $ErrAction -MessageData $Results
    # Start command process
    $p.Start() | Out-Null

    # Start triggering events for STDERR
    $p.BeginErrorReadLine();

    # running until process have exited and ErrorDataReceived events are done and no more data in StandardOutput stream
    do
    {
        # capturing STDOUT this way guaranties sequence of lines (important)
        $StdoutLine = $p.StandardOutput.ReadLine()
        if ($null -ne $StdoutLine)
        {
            if (!$HideStdout)
            {
                Write-Host $StdoutLine -ForegroundColor Green
            }
            $Results.Stdout += $StdoutLine
            $Results.All += $StdoutLine
            if (!$p.StandardOutput.EndOfStream)
            {
                # dont add new line at the end
                $Results.Stdout += "`n"
                $Results.All += "`n"
            }
        }
    } while (!$p.HasExited -or !$ErrEvent.HasMoreData -or !$p.StandardOutput.EndOfStream)
    Unregister-Event -SourceIdentifier $ErrEvent.Name

    # Some Trimming
    $Results.Stderr = $Results.Stderr.TrimEnd("`n")
    $Results.All = $Results.All.TrimEnd("`n")

    # Saving exit code
    $Results.Code = $p.ExitCode

    # Exit code check if not asked to ignore it
    if ( ($Results.Code -ne 0) -and !$IgnoreExitCode)
    {
        throw ([string]::Format("Command returned non zero exit code of '{0}'. Command: {1}`nSTDERR: {2}", $p.ExitCode, $Command, $Results.Stderr))
    }

    # Setting OutVarCode variable if requested
    if ($OutVarCode)
    {
        $PSCmdlet.SessionState.PSVariable.Set($OutVarCode, $Results.Code)
    }

    # Setting OutVarStderr variable if requested
    if ($OutVarStderr)
    {
        $PSCmdlet.SessionState.PSVariable.Set($OutVarStderr, $Results.Stderr)
    }

    # Setting OutVarStdout variable if requested
    if ($OutVarStdout)
    {
        $PSCmdlet.SessionState.PSVariable.Set($OutVarStdout, $Results.Stdout)
    }

    # Restoring $ErrorActionPreference on success
    $ErrorActionPreference = $OldErrorActionPreference

    # Returning if requested
    if ($Return)
    {
        return $Results
    }
    return $null
}

<#
.SYNOPSIS
Utility function to convert list of arguments from array of string to properly escaped string of arguments
.PARAMETER Arguments
Array of stings with arguments values
#>

function EscapeArguments
{
    param (
        [string[]]$Arguments
    )
    $EscapedArguments = New-Object System.Collections.Generic.List[String]
    foreach ($EscapedArg in $Arguments)
    {
        # https://docs.microsoft.com/en-gb/windows/desktop/api/shellapi/nf-shellapi-commandlinetoargvw
        # https://stackoverflow.com/questions/21314633/how-do-i-pass-a-literal-double-quote-from-powershell-to-a-native-command
        
        # stdlib Rules:
        # 2N backslashes + " ==> N backslashes and begin/end quote
        # 2N+1 backslashes + " ==> N backslashes + literal "
        # N backslashes ==> N backslashes
        
        # escaping each slash
        $EscapedArg = $EscapedArg.Replace('\','\\')
        # escaping double quotes as we use them to indicate start/end of argument
        $EscapedArg = $EscapedArg.Replace('"','\"')
        # wrapping argument
        $EscapedArg = "`"$EscapedArg`""
        # appending to result
        $EscapedArguments.Add($EscapedArg)
        Write-Verbose "Escaped Arguments: $EscapedArg"

    }
    return $EscapedArguments -join " "
}