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Allow opt-out of the named-pipe listener using an environment variable #26086

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Merged
daxian-dbw merged 3 commits into from
Sep 30, 2025
Merged

Allow opt-out of the named-pipe listener using an environment variable #26086

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c2f0754
Allow opt-out of the named-pipe listener using an environment variable
daxian-dbw Sep 23, 2025
700ed27
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daxian-dbw Sep 23, 2025
142cd55
Use upper case for the env variable
daxian-dbw Sep 30, 2025
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67 changes: 66 additions & 1 deletion src/System.Management.Automation/engine/Utils.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,6 @@
using System.Threading;
using Microsoft.PowerShell.Commands;
using Microsoft.Win32;
using Microsoft.Win32.SafeHandles;

using TypeTable = System.Management.Automation.Runspaces.TypeTable;

Expand Down Expand Up @@ -1548,6 +1547,72 @@ internal static bool IsSessionRestricted(ExecutionContext context)
}
return true;
}

/// <summary>
/// Determine whether the environment variable is set and how.
/// </summary>
/// <param name="name">The name of the environment variable.</param>
/// <param name="defaultValue">If the environment variable is not set, use this as the default value.</param>
/// <returns>A boolean representing the value of the environment variable.</returns>
internal static bool GetEnvironmentVariableAsBool(string name, bool defaultValue)
{
var str = Environment.GetEnvironmentVariable(name);
if (string.IsNullOrEmpty(str))
{
return defaultValue;
}

var boolStr = str.AsSpan();

if (boolStr.Length == 1)
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@jborean93 jborean93 Sep 23, 2025 •
edited
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Could you possibly use SequenceEqual possibly with or without StringComparer.OrdinalIgnoreCase to avoid the individual length and char checks. I assume .NET has all the necessary logic to make that performant and you could make this a lot simpler by doing something like

ReadOnlySpan<char> true1 = ['1'];
ReadOnlySpan<char> trueYes = ['y', 'e', 's'];
ReadOnlySpan<char> trueTrue = ['t', 'r', 'u', 'e'];

// Repeat for false checks

var boolStr = str.AsSpan()
if (boolStr.SequenceEquals(true1, StringComparer.OrdinalIgnoreCase) ||
    boolStr.SequenceEquals(trueYes, StringComparer.OrdinalIgnoreCase ||
    ...)
{
    return true;
}

// Repeat for false checks and default
...

Not sure if stackalloc'ing one big span with all the options and slicing it would be more efficient or not but that's probably in micro-optimising territory.

Edit: Ah I see this has been copied from elsewhere.

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@daxian-dbw daxian-dbw Sep 24, 2025

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Yes, this is copied from Telemetry.cs. I will keep it as is in this PR as this one will be included in the next preview and the following RC. But I will submit a separate PR to make this optimization change.

{
if (boolStr[0] == '1')
{
return true;
}

if (boolStr[0] == '0')
{
return false;
}
}

if (boolStr.Length == 3 &&
(boolStr[0] == 'y' || boolStr[0] == 'Y') &&
(boolStr[1] == 'e' || boolStr[1] == 'E') &&
(boolStr[2] == 's' || boolStr[2] == 'S'))
{
return true;
}

if (boolStr.Length == 2 &&
(boolStr[0] == 'n' || boolStr[0] == 'N') &&
(boolStr[1] == 'o' || boolStr[1] == 'O'))
{
return false;
}

if (boolStr.Length == 4 &&
(boolStr[0] == 't' || boolStr[0] == 'T') &&
(boolStr[1] == 'r' || boolStr[1] == 'R') &&
(boolStr[2] == 'u' || boolStr[2] == 'U') &&
(boolStr[3] == 'e' || boolStr[3] == 'E'))
{
return true;
}

if (boolStr.Length == 5 &&
(boolStr[0] == 'f' || boolStr[0] == 'F') &&
(boolStr[1] == 'a' || boolStr[1] == 'A') &&
(boolStr[2] == 'l' || boolStr[2] == 'L') &&
(boolStr[3] == 's' || boolStr[3] == 'S') &&
(boolStr[4] == 'e' || boolStr[4] == 'E'))
{
return false;
}

return defaultValue;
}
}
}

Expand Down
14 changes: 7 additions & 7 deletions src/System.Management.Automation/engine/remoting/common/RemoteSessionNamedPipe.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,6 @@
using System.Security.AccessControl;
using System.Security.Principal;
using System.Threading;
using System.Threading.Tasks;

using Microsoft.Win32.SafeHandles;

Expand Down Expand Up @@ -500,13 +499,14 @@ static RemoteSessionNamedPipeServer()
{
s_syncObject = new object();

// All PowerShell instances will start with the named pipe
// and listener created and running.
IPCNamedPipeServerEnabled = true;

CreateIPCNamedPipeServerSingleton();
// Unless opt-out, all PowerShell instances will start with the named-pipe listener created and running.
IPCNamedPipeServerEnabled = !Utils.GetEnvironmentVariableAsBool(name: "POWERSHELL_DIAGNOSTICS_OPTOUT", defaultValue: false);

CreateProcessExitHandler();
if (IPCNamedPipeServerEnabled)
{
CreateIPCNamedPipeServerSingleton();
CreateProcessExitHandler();
}
}

#endregion
Expand Down
2 changes: 1 addition & 1 deletion src/System.Management.Automation/resources/RemotingErrorIdStrings.resx
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Original file line number Diff line number Diff line change
Expand Up @@ -1411,7 +1411,7 @@ All WinRM sessions connected to PowerShell session configurations, such as Micro
<value>Multiple processes were found with this name {0}. Use the process Id to specify a single process to enter.</value>
</data>
<data name="EnterPSHostProcessNoPowerShell" xml:space="preserve">
<value>Cannot enter process with Id '{0}' because it has not loaded the PowerShell engine.</value>
<value>Cannot enter process with Id '{0}' because it has not loaded the PowerShell engine or the named-pipe listener was disabled.</value>
</data>
<data name="EnterPSHostProcessNoProcessFoundWithId" xml:space="preserve">
<value>No process was found with Id: {0}.</value>
Expand Down
69 changes: 1 addition & 68 deletions src/System.Management.Automation/utils/Telemetry.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,6 @@
using System.Linq;
using System.Management.Automation;
using System.Runtime.InteropServices;
using System.Security.AccessControl;
using System.Threading;

using Microsoft.ApplicationInsights;
Expand Down Expand Up @@ -177,7 +176,7 @@ public static class ApplicationInsightsTelemetry
static ApplicationInsightsTelemetry()
{
// If we can't send telemetry, there's no reason to do any of this
CanSendTelemetry = !GetEnvironmentVariableAsBool(name: _telemetryOptoutEnvVar, defaultValue: false);
CanSendTelemetry = !Utils.GetEnvironmentVariableAsBool(name: _telemetryOptoutEnvVar, defaultValue: false);
if (CanSendTelemetry)
{
s_sessionId = Guid.NewGuid().ToString();
Expand Down Expand Up @@ -643,72 +642,6 @@ static ApplicationInsightsTelemetry()
}
}

/// <summary>
/// Determine whether the environment variable is set and how.
/// </summary>
/// <param name="name">The name of the environment variable.</param>
/// <param name="defaultValue">If the environment variable is not set, use this as the default value.</param>
/// <returns>A boolean representing the value of the environment variable.</returns>
private static bool GetEnvironmentVariableAsBool(string name, bool defaultValue)
{
var str = Environment.GetEnvironmentVariable(name);
if (string.IsNullOrEmpty(str))
{
return defaultValue;
}

var boolStr = str.AsSpan();

if (boolStr.Length == 1)
{
if (boolStr[0] == '1')
{
return true;
}

if (boolStr[0] == '0')
{
return false;
}
}

if (boolStr.Length == 3 &&
(boolStr[0] == 'y' || boolStr[0] == 'Y') &&
(boolStr[1] == 'e' || boolStr[1] == 'E') &&
(boolStr[2] == 's' || boolStr[2] == 'S'))
{
return true;
}

if (boolStr.Length == 2 &&
(boolStr[0] == 'n' || boolStr[0] == 'N') &&
(boolStr[1] == 'o' || boolStr[1] == 'O'))
{
return false;
}

if (boolStr.Length == 4 &&
(boolStr[0] == 't' || boolStr[0] == 'T') &&
(boolStr[1] == 'r' || boolStr[1] == 'R') &&
(boolStr[2] == 'u' || boolStr[2] == 'U') &&
(boolStr[3] == 'e' || boolStr[3] == 'E'))
{
return true;
}

if (boolStr.Length == 5 &&
(boolStr[0] == 'f' || boolStr[0] == 'F') &&
(boolStr[1] == 'a' || boolStr[1] == 'A') &&
(boolStr[2] == 'l' || boolStr[2] == 'L') &&
(boolStr[3] == 's' || boolStr[3] == 'S') &&
(boolStr[4] == 'e' || boolStr[4] == 'E'))
{
return false;
}

return defaultValue;
}

/// <summary>
/// Send module load telemetry as a metric.
/// For modules we send the module name (if allowed), and the version.
Expand Down
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