CA1839: Use Environment.ProcessPath instead of Process.GetCurrentProcess().MainModule.FileName

#Cause

Using Process.GetCurrentProcess().MainModule.FileName for getting the path to the file that launched the process instead of System.Environment.ProcessPath.

#Rule description

System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName is expensive:

• It allocates a System.Diagnostics.Process and System.Diagnostics.ProcessModule instance, usually just to get the FileName.
• The System.Diagnostics.Process instance needs to be disposed, which has a performance impact.
• It's easy to forget to call System.Diagnostics.Process.Dispose on the System.Diagnostics.Process instance.
• If nothing else besides FileName uses the Process instance, then the linked size grows unnecessarily by increasing the graph of types referenced.
• It is somewhat difficult to discover or find this API.

System.Environment.ProcessPath avoids all of these downsides and produces the same information.

#How to fix violations

The violation can either be fixed manually, or, in some cases, using Quick Actions to fix code in Visual Studio.

The following two code snippets show a violation of the rule and how to fix it:

using System.Diagnostics;

class MyClass
{
    void MyMethod()
    {
        string path = Process.GetCurrentProcess().MainModule.FileName; // Violation occurs
    }
}

Imports System.Diagnostics

Class MyClass
    Private Sub MyMethod()
        Dim path As String = Process.GetCurrentProcess().MainModule.FileName ' Violation occurs.
    End Function
End Class

using System.Diagnostics;

class MyClass
{
    void MyMethod()
    {
        string path = System.Environment.ProcessPath; // Violation fixed
    }
}

Imports System.Diagnostics

Class MyClass
    Private Sub MyMethod()
        Dim path As String = System.Environment.ProcessPath ' Violation fixed.
    End Function
End Class

#When to suppress warnings

It's safe to suppress a violation of this rule if you're not concerned about the performance impact from unnecessary allocation and eventual disposal of the System.Diagnostics.Process and System.Diagnostics.ProcessModule instances.

#Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA1839
// The code that's violating the rule is on this line.
#pragma warning restore CA1839

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.CA1839.severity = none

For more information, see How to suppress code analysis warnings.

#See also

• Performance rules
• Use 'Environment.ProcessId' instead of 'Process.GetCurrentProcess().Id'
• Use 'Environment.CurrentManagedThreadId' instead of 'Thread.CurrentThread.ManagedThreadId'