ZwOpenProcess如何使用？

ZwOpenProcess（OUT PHANDLE ProcessHandle,
         IN ACCESS_MASK DesiredAccess,
         IN POBJECT_ATTRIBUTES ObjectAttributes,
         IN PCLIENT_ID ClientId OPTIONAL);
的后2个参数是什么？先谢了。

ZwOpenProcess（OUT PHANDLE ProcessHandle,
         IN ACCESS_MASK DesiredAccess,
         IN POBJECT_ATTRIBUTES ObjectAttributes,
         IN PCLIENT_ID ClientId OPTIONAL);
的后2个参数是什么？先谢了。

typedef struct _CLIENT_ID {
    HANDLE UniqueProcess;
    HANDLE UniqueThread;
} CLIENT_ID;
typedef CLIENT_ID *PCLIENT_ID;

typedef struct _OBJECT_ATTRIBUTES {
    ULONG Length;
    HANDLE RootDirectory;
    PUNICODE_STRING ObjectName;
    ULONG Attributes;
    PVOID SecurityDescriptor;        // Points to type SECURITY_DESCRIPTOR
    PVOID SecurityQualityOfService;  // Points to type SECURITY_QUALITY_OF_SERVICE
} OBJECT_ATTRIBUTES;
typedef OBJECT_ATTRIBUTES *POBJECT_ATTRIBUTES;

谢谢AllenZh，第三个参数这么复杂，仅有processid能通过这个函数得到process handle吗？第三个参数怎么设啊？


[编辑 -  12/14/04 by  one]

有点复杂