从 LUID 检索权限名称

问题描述

我正在编写一种方法来找出与给定 LUID 关联的权限名称。以下是相同的代码：

private string PrivilegeName(LUID luid)
{
    StringBuilder sbuilder = new StringBuilder();
    int nameLength = 0;
    IntPtr ptrToLuid = Marshal.AllocHGlobal(Marshal.SizeOf(luid));
    Marshal.StructuretoPtr(luid,ptrToLuid,true);
    if(!InvokeAPI.LookupPrivilegeName(null,null,ref nameLength))
    {
        Console.WriteLine("Unable to lookup value.");
        Console.WriteLine(Marshal.GetLastWin32Error());
        Marshal.FreeHGlobal(ptrToLuid);
        return null;
    }
    sbuilder.EnsureCapacity(nameLength + 1);

    InvokeAPI.LookupPrivilegeName(null,sbuilder,ref nameLength);
    Marshal.FreeHGlobal(ptrToLuid);

    return sbuilder.ToString();
}

作为参考，我的 LUID 结构如下

[StructLayout(LayoutKind.Sequential)]
public struct LUID
{
    public UInt32 LowPart;
    public Int32 HighPart;
}

在执行此代码时，我得到一个 ERROR_INSUFFICIENT_BUFFER (122) 而不是与 LUID 关联的权限名称。

有人能帮我解决上面代码中我缺少的阻止我检索权限名称的内容吗？

解决方法

写“更好”的pinvoke，在评论中写下对错误的解释。写在内部评论 LookupPrivilegeName 长度的有趣处理。

// https://www.pinvoke.net/default.aspx/advapi32.lookupprivilegename
[DllImport("advapi32.dll",SetLastError = true,CharSet = CharSet.Auto)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool LookupPrivilegeName(
    string lpSystemName,ref LUID lpLuid,StringBuilder lpName,ref int cchName);

private static string PrivilegeName(LUID luid)
{
    StringBuilder sbuilder = new StringBuilder();
    int nameLength = 0;

    LookupPrivilegeName(null,ref luid,sbuilder,ref nameLength);

    // Will always fail with nameLength == 0. We simply check that nameLength != 0
    if (nameLength == 0)
    {
        Console.WriteLine("Unable to lookup value.");
        Console.WriteLine(Marshal.GetLastWin32Error());
        return null;
    }

    // On "failure" (that is really a success,only we get 
    // just the length),nameLength is the length required 
    // for the buffer,including the \0
    sbuilder.EnsureCapacity(nameLength);

    // On a success of this second call,nameLength is the 
    // "real" length of the name,excluding the \0
    // so on a success,now nameLength = oldNameLength - 1
    // Don't ask,it is absurd... Classical case where the 
    // Windows API are quite random in their handling of 
    // buffer lengths
    if (!LookupPrivilegeName(null,ref nameLength))
    {
        Console.WriteLine("Unable to lookup value.");
        Console.WriteLine(Marshal.GetLastWin32Error());
        return null;
    }

    return sbuilder.ToString();
}