facebookincubator / TTPForge / 10495847045

64%

main: 67%

Pull #509

github

Properly process powershell nested scripts as TTP steps (#509)

Summary:
Pull Request resolved: https://github.com/facebookincubator/TTPForge/pull/509

## Problem scope
Let's test with the following simple powershell script
```
% cat nested.ps
echo "start"
if ($true) {
  echo "nested"
}
echo "stop"
```

Here is results of running this script differently
```
% pwsh -File nested.ps
start
nested
stop
% pwsh nested.ps
start
nested
stop
% cat nested.ps | pwsh -File -
PS /data/users/nesusvet/fbsource/fbcode> echo "start"
start
PS /data/users/nesusvet/fbsource/fbcode> if ($true) {
>>   echo "nested"
>> }
>> echo "stop"
>> %
% cat nested.ps | pwsh -Command -
start
```

## Initial proposal
Instead of writing the TTP step body to power shell process stdin, we might rely on a new temp file to hold the body of TTP step to pass it to PowerShell as only argument.  This produces the best results.

### Limitations
Runtime environment where standard golang library call to `os.CreateTemp` fails or the file created is not writable.

## Can We Do Better?

Actually **yes** when we better understand the way PowerShell processes scripts from stdin.
It is expected to wrap your commands into `&{}` block before passing it to PowerShell's stdin.
See [documentation](https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_pwsh?view=powershell-7.4#-command---c) on `-Command` param for details.

Resolves https://github.com/facebookincubator/TTPForge/issues/481

Reviewed By: CrimsonK1ng

Differential Revision: D61387125

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