dlwyatt / powershellloggingmodule Goto Github PK

Dear All

When trying to use the module in PowerShell 7 I get the following error.

C:\> import-module PowerShellLogging
C:\> Enable-LogFile -Path "c:\temp\test.txt"

ErrorCallback Path             Streams DateTimeFormat
------------- ----             ------- --------------
              C:\temp\test.txt     All r
Enable-LogFile: Object reference not set to an instance of an object.

Thank you very much.
Marc

$PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.0.0
PSEdition                      Core
GitCommitId                    7.0.0
OS                             Microsoft Windows 10.0.18363
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

get-module -Name PowerShellLogging
                                                                                
ModuleType Version    PreRelease Name                                ExportedCom
---------- -------    ---------- ----                                -----------
Script     1.3.0                 PowerShellLogging                   {Disable-Lo

When inside one of the script blocks, something will be written to the console, then this is also captured. Initially it sounds reasonable but there is a danger here.

$onWriteDebugBlock={
    param(
        [string]$Message
    )
    Write-Host "[OnWriteDebug] $Message"
}
$onWriteVerboseBlock={
    param(
        [string]$Message
    )
    Write-Host "[OnWriteVerbose] $Message"
}
$onWriteErrorBlock={
    param(
        [string]$Message
    )
    Write-Host "[OnWriteError] $Message"
}
$onWriteWarningBlock={
    param(
        [string]$Message
    )
    Write-Host "[OnWriteWarning] $Message"
}
$onWriteOutputBlock={
    param(
        [string]$Message
    )
    Write-Host "[OnWriteOutput] $Message"
}

$splat=@{
    OnWriteDebug=$onWriteDebugBlock
    OnWriteVerbose=$onWriteVerboseBlock
    OnWriteError=$onWriteErrorBlock
    OnWriteOutput=$onWriteOutputBlock
    OnWriteWarning=$onWriteWarningBlock
}

$outputSubscriber=Enable-OutputSubscriber @splat

Write-Error "An error message"

The Write-Error "An error message" will be captured by onWriteErrorBlock and written to the host as [OnWriteError] An error message which in turn will be captured by onWriteOutputBlock and written to the host as [OnWriteError] [OnWriteError] An error message. This flow is recursive.

The danger here is not only with the error or output but also with debug. Imagine using in the OnWriteDebug block a cmdlet that outputs debug messages.

The module is very cool but have you considered this flow?

Adding some examples to the ReadMe showing how to use it (not just install it) and what that looks like would be helpful. I (and I imagine others) don't even bother trying out modules/packages when there's no docs showing how to use it. Thanks!

We're using this module in some of our modules, and now someone's tried to call our module from C# with a PowerShell.Create (no host).

We expected the logs would still show up, but instead PowerShellLogging throws on any output.

A quick review of source shows that (almost) all the output methods are deliberately throwing when the host is null (as it is, presumably, in the case where we're using PowerShell.Create).

Proposal: (I will implement, if you're OK with this). I think that simply changing the methods to use the null check just to skip calling the host (rather than throwing) would:

• Avoid breaking PowerShell when there's no host
• Allow logging even when there's no a host

The commands all use a static HostIOInterceptor.Instance

When AttachToHost is called on that static instance (from any command) the current InternalHost shim (the one that's active in the current runspace) gets attached. It's only detached when the module is unloaded -- so there can only ever be one logged runspace per process.

In a parallel runspace scenario (like ThreadJob or PoshRSJob) each runspace has it's own InternalHost` shim (even though none of them have an actual host).

With many InternalHosts, and only one Interceptor, only the first one to Attach actually gets logged, and the rest silently fail to log with no errors! The Attach simply returns and only the first runspace in a process logs properly -- unless the module is unloaded from that runspace before the registration of listeners in the second runspace.

To fix this we'd have to cache the attached hosts somehow (probably by creating a HostIOInterceptor per host).

We could try using a caching Factory pattern to have a static HostIOInterceptor HostIOInterceptor.GetInterceptor(PSHost Host) which would keep a collection of active interceptors and return the right one for the given host.

So for instance, Enable-LogFile could call:

HostIOInterceptor.GetInstance(Host).AddSubscriber();

Instead of:

HostIOInterceptor.Instance.AttachToHost(Host);
HostIOInterceptor.Instance.AddSubscriber(logFile);

I believe this would require a change to the LogFile as well (in order to be able to pause logging when it's writing exceptions). It would need to either store a reference to the HostIOInterceptor which it was created for, or a pointer to the Paused property, or a callback/event for pausing and unpausing.

I'm using the logging module in a script and it works fine when ran from the IDE. Not when called from CLI. powershell -file "path". I'm sure it's something simple but I havent been able to find it with google.

Thanks,
Levi