无法通过调用 JNI 在 Java 中设置 seteuid

Question

我的应用程序需要以非 root 用户身份运行，但需要切换到其他用户来执行一些命令。我尝试过了：写一个 JNI，JNIEXPORT void JNICALL Java_SetUIDJNI_setuid(JNIEnv *env, jobject thisObj,jstring uname) {    const char *name = jstringTostring(env,uname);    int pid;    struct passwd *p;    show_ids();    if ((p = getpwnam(name)) == NULL) {        perror(name);        exit(EXIT_FAILURE);    }    pid = (int) p->pw_uid;    printf("pid=%d\n",pid);    if (seteuid (pid) < 0) {        perror ("setuid");        exit (EXIT_FAILURE);    }    show_ids();}以root和chmod u+s构建它-rwsr-xr-x 1 root root  76155 Aug  7 16:56 libsetuid.so*在java中调用它api = new SetUIDJNI();  // invoke the native methodapi.setuid("slurm");但是如果以非root身份运行它，它就不起作用/opt/jdk1.8/jre/bin/java -Djava.library.path=../jni HelloJNI The real user ID is: 1000 The effective user ID is :1000   <= which expected is 0 setuid: Operation not permitted但如果 runner 是 root 则它有效The real user ID is: 0The effective user ID is :0pid=1002The real user ID is: 0The effective user ID is :1002这里有什么问题吗？