Unable to pass null as lpCommandLine parameter to CreateProcess()

[skst]

Actual behavior

Generated code:

internal static unsafe winmdroot.Foundation.BOOL CreateProcess(string lpApplicationName, ref Span<char>lpCommandLine, winmdroot.Security.SECURITY_ATTRIBUTES? lpProcessAttributes, winmdroot.Security.SECURITY_ATTRIBUTES? lpThreadAttributes, winmdroot.Foundation.BOOL bInheritHandles, winmdroot.System.Threading.PROCESS_CREATION_FLAGS dwCreationFlags, void* lpEnvironment, string lpCurrentDirectory, in winmdroot.System.Threading.STARTUPINFOW lpStartupInfo, out winmdroot.System.Threading.PROCESS_INFORMATION lpProcessInformation)
		{
			if (lpCommandLine.LastIndexOf('\0') == -1)throw new ArgumentException("Required null terminator missing.", "lpCommandLine");

Expected behavior

CreateProcess

"The lpCommandLine parameter can be NULL. In that case, the function uses the string pointed to by lpApplicationName as the command line."

Repro steps

1. NativeMethods.txt content:

CreateProcess
PROCESS_CREATION_FLAGS

3. Any of your own code that should be shared?

	Span<char> spanCmdLine = new(null);
	bool ok = PInvoke.CreateProcess(path, ref spanCmdLine, lpProcessAttributes: null, lpThreadAttributes: null, bInheritHandles: false,
												Windows.Win32.System.Threading.PROCESS_CREATION_FLAGS.CREATE_SUSPENDED,
												lpEnvironment: null, lpCurrentDirectory: wd, startupInfo, out process);

System.ArgumentException
  HResult=0x80070057
  Message=Required null terminator missing. (Parameter 'lpCommandLine')

Context

• CsWin32 version: 0.2.188-beta
• Win32Metadata version (if explicitly set by project):
• Target Framework: .NET 7
• LangVersion (if explicitly set by project): latest (C# 11)

[AArnott]

It seems our null termination check should include a null span check first. Something like this:

-if (lpCommandLine.LastIndexOf('\0') == -1)
+if (lpCommandLine != null && lpCommandLine.LastIndexOf('\0') == -1)