代码之家 › 专栏 › 技术社区 › Tim Lovell-Smith

P/invoke函数获取指向结构[duplicate]的指针

pinvoke interop winapi c#

Tim Lovell-Smith · 技术社区 · 14 年前

功能,如 CreateProcess 让签名指向结构。在C中,我只想通过 NULL

在C#中,我将其声明为(p/invoke)

[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public static extern bool CreateProcess(
            string lpApplicationName,
            string lpCommandLine,
            ref SECURITY_ATTRIBUTES lpProcessAttributes,
            ref SECURITY_ATTRIBUTES lpThreadAttributes,
            bool bInheritHandles,
            CreateProcessFlags dwProcessCreationFlags,
            IntPtr lpEnvironment,
            string lpCurrentDirectory,
            ref STARTUPINFO lpStartupInfo,
            ref PROCESS_INFORMATION lpProcessInformation);

null 对于 lpProcessAttributes lpThreadAttributes

调试.Wrappers.SECURITY\u属性

如何修改上面的函数签名以便我可以通过

2 回复 | 直到 6 年前

Mark H 14 年前

null 仅对.Net中的引用类型有效。你的安全属性是 struct ,这是一个 ValueType . 您需要传递一个空的安全属性结构,而不是传递null(就说吧 new SECURITY_ATTRIBUTES()

一个更干净的方法是向结构中添加一个静态空属性,然后只传递 SECURITY_ATTRIBUTES.Empty

[StructLayout(LayoutKind.Sequential)]
public struct SECURITY_ATTRIBUTES {
    public int nLength;
    public IntPtr lpSecurityDescriptor;
    public int bInheritHandle;

    public static SECURITY_ATTRIBUTES Empty {
        get {
            return new SECURITY_ATTRIBUTES {
                nLength = sizeof(int)*2 + IntPtr.Size,
                lpSecurityDescriptor = IntPtr.Zero,
                bInheritHandle = 0,
            };
        }
    }
}

或者更好的方法是,与其使用P/Invoke来创建流程,不如检查 System.Diagnostics.Process

Tim Lovell-Smith 14 年前

好吧,我终于(!)找到了更好的方法:

将SECURITY\u属性声明为class而不是struct,并且不要通过ref传递它:-)

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool CreateProcess(
        string lpApplicationName,
        StringBuilder lpCommandLine,
        SECURITY_ATTRIBUTES lpProcessAttributes,
        SECURITY_ATTRIBUTES lpThreadAttributes,
        bool bInheritHandles,
        CreateProcessFlags dwCreationFlags,
        IntPtr lpEnvironment,
        string lpCurrentDirectory,
        STARTUPINFO lpStartupInfo, /// Required
        PROCESS_INFORMATION lpProcessInformation //Returns information about the created process
        );

/// <summary>
/// See http://msdn.microsoft.com/en-us/library/aa379560(v=VS.85).aspx
/// </summary>
[StructLayout(LayoutKind.Sequential)]
public class SECURITY_ATTRIBUTES
{
    public uint nLength;
    public IntPtr lpSecurityDescriptor;
    [MarshalAs(UnmanagedType.Bool)] public bool bInheritHandle;
}

好处:这还允许您在初始化nLength的SECURITY\u属性上声明一个像样的构造函数。