1. Problem
I have a complicated batch file where some parts need to run with elevated/admin rights (e.g. interacting with Windows services) and I found a Powershell way to do that:
powershell.exe -command "try {$proc = start-process -wait -Verb runas -filepath '%~nx0' -ArgumentList '<arguments>'; exit $proc.ExitCode} catch {write-host $Error; exit -10}"
But there's a huge caveat! The elevated instance of my script (%~nx0
) starts with a fresh copy of environment variables and everything I set "var=content"
before is unavailable.
2. What I've tried so far
This Powershell script doesn't help either because Verb = "RunAs"
requires UseShellExecute = $true
which in turn is mutually exclusive to/with StartInfo.EnvironmentVariables.Add()
$p = New-Object System.Diagnostics.Process
$p.StartInfo.FileName = "cmd.exe";
$p.StartInfo.Arguments = '/k set blasfg'
$p.StartInfo.UseShellExecute = $true;
$p.StartInfo.Verb = "RunAs";
$p.StartInfo.EnvironmentVariables.Add("blasfg", "C:\\Temp")
$p.Start() | Out-Null
$p.WaitForExit()
exit $p.ExitCode
And even if that would work I'd still need to transfer dozens of variables...
3. unappealing semi-solutions
because circumventing the problem is no proper solution.
- helper tools like hstart - because I can't relay on external tools. Only CMD, Powershell and maybe VBscript (but it looks like
runas
pluswait
anderrorlevel/ExitCode
processing isn't possible with/in vbs). - passing (only required) variables as arguments - because I need dozens and escaping them is an ugly chore (both the result and doing it).
- restarting the whole script - because it's inefficient with all the parsing, checking processing and other tasks happening again (and again and ...). I'd like to keep the elevated parts to a minimum and some actions can later be run as a normal user (e.g service start/stop).
- Writing the environment to a file and rereading it in the elevated instance - because it's an ugly hack and I'd hope there's a cleaner option out there. And writing possibly sensitive information to a file is even worse than storing it temporarily in an environment variable.
CodePudding user response:
Here's a proof of concept that uses the following approach:
Make the
powershell
call invoke another, aux.powershell
instance as the elevated target process.This allows the outer
powershell
instance to "bake"Set-Item
statements that re-create the caller's environment variables (which the outer instance inherited, and which can therefore be enumerated withGet-ChilItem Env:
) into the-command
string passed to the aux. instance, followed by a re-invocation of the original batch file.
Caveat: This solution blindly recreates all environment variables defined in the caller's process in the elevated process - consider pre-filtering, possibly by name patterns, such as by a shared prefix; e.g., to limit variable re-creation to those whose names start with foo
, replace Get-ChildItem Env:
with Get-ChildItem Env:foo*
in the command below.
@echo off & setlocal
:: Test if elevated.
net session 1>NUL 2>NUL && goto :ELEVATED
:: Set sample env. vars. to pass to the elevated re-invocation.
set foo1=bar
set "foo2=none done"
set foo3=3" of snow
:: " dummy comment to fix syntax highlighting
:: Re-invoke with elevation, synchronously, reporting the exit
:: code of the elevated run.
powershell -noprofile -command ^
exit ( ^
Start-Process -Wait -PassThru -Verb RunAs powershell ^
"\" -noprofile -command `\" $(Get-ChildItem Env: | ForEach-Object { 'Set-Item \\\"env:' $_.Name '\\\" \\\"' $($_.Value -replace '\""', '`\\\""') '\\\"; ' }) cmd /c `\"%~f0`\" ... ``& exit; exit `$LASTEXITCODE`\" \"" ^
).ExitCode
echo -- Elevated re-invocation exited with %ERRORLEVEL%.
:: End of non-elevated part.
exit /b
:ELEVATED
echo Now running elevated...
echo -- Arguments received:
echo [%*]
echo -- Env. vars. whose names start with "foo":
set foo
:: Determine the exit code to report.
set ec=5
echo -- Exiting with exit code