C++ errExit函数代码示例

int
main(int argc, char *argv[])
{
    struct sigevent sev;
    mqd_t mqd;
    struct mq_attr attr;
    void *buffer;
    ssize_t numRead;
    sigset_t blockMask;
    siginfo_t si;

    if (argc != 2 || strcmp(argv[1], "--help") == 0)
        usageErr("%s mq-name\n", argv[0]);

    mqd = mq_open(argv[1], O_RDONLY | O_NONBLOCK);
    if (mqd == (mqd_t) -1)
        errExit("mq_open");

    /* Determine mq_msgsize for message queue, and allocate an input buffer
       of that size */

    if (mq_getattr(mqd, &attr) == -1)
        errExit("mq_getattr");
    buffer = malloc(attr.mq_msgsize);
    if (buffer == NULL)
        errExit("malloc");

    /* Block the signal that we'll accept using sigwaitinfo() */

    sigemptyset(&blockMask);
    sigaddset(&blockMask, NOTIFY_SIG);
    if (sigprocmask(SIG_BLOCK, &blockMask, NULL) == -1)
        errExit("sigprocmask");

    /* Set up message notification using the signal NOTIFY_SIG */

    sev.sigev_notify = SIGEV_SIGNAL;
    sev.sigev_signo = NOTIFY_SIG;
    sev.sigev_value.sival_ptr = &mqd;
    /* This allows us to obtain a pointer to 'mqd' in the
       siginfo_t structure returned by sigwaitinfo() */

    if (mq_notify(mqd, &sev) == -1)
        errExit("mq_notify");

    for (;;) {

        /* Wait for a signal; when it is received, display associated
           information */

        if (sigwaitinfo(&blockMask, &si) == -1)errExit("sigwaitinfo");

        printf("Accepted signal:\n");
        printf("        si_signo   = %d\n", si.si_signo);
        printf("        si_pid     = %ld\n", (long) si.si_pid);
        printf("        si_uid     = %ld\n", (long) si.si_uid);
        printf("        si_code    = %d (%s)\n", si.si_code,
               (si.si_code == SI_MESGQ) ? "SI_MESGQ" : "???");
        printf("        *sival_ptr = %p\n\n", si.si_value.sival_ptr);

        /* Reestablish message notification */

        if (mq_notify(mqd, &sev) == -1)
            errExit("mq_notify");

        /* Although only one signal might have been queued (if NOTIFY_SIG
           is a standard signal) we might have received multiple messages,
           so use nonblocking mq_receive() calls inside a loop to read
           as many messages as possible. */

        while ((numRead = mq_receive(mqd, buffer, attr.mq_msgsize, NULL)) >= 0)
            printf("Read %ld bytes\n", (long) numRead);

        if (errno != EAGAIN)            /* Unexpected error */
            errExit("mq_receive");
    }
}

int
main(int argc, char *argv[])
{
    sigset_t pending, blocked;
    const int numSecs = 5;
    struct sigaction sa;

    /* Set up a handler for SIGINT */

    printf("Setting up handler for SIGINT\n");
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sa.sa_handler = handler;
    if (sigaction(SIGINT, &sa, NULL) == -1)
        errExit("sigaction");

    /* Block SIGINT for a while */

    sigemptyset(&blocked);
    sigaddset(&blocked, SIGINT);
    if (sigprocmask(SIG_SETMASK, &blocked, NULL) == -1)
        errExit("sigprocmask");

    printf("BLOCKING SIGINT for %d seconds\n", numSecs);
    sleep(numSecs);

    /* Display mask of pending signals */

    if (sigpending(&pending) == -1)
        errExit("sigpending");
    printf("PENDING signals are: \n");
    printSigset(stdout, "\t\t", &pending);

    /* Now ignore SIGINT */

    sleep(2);
    printf("Ignoring SIGINT\n");
    if (signal(SIGINT, SIG_IGN) == SIG_ERR)     errExit("signal");

    /* Redisplay mask of pending signals */

    if (sigpending(&pending) == -1)
        errExit("sigpending");
    if (sigismember(&pending, SIGINT)) {
        printf("SIGINT is now pending\n");
    } else {
        printf("PENDING signals are: \n");
        printSigset(stdout, "\t\t", &pending);
    }
    sleep(2);

    /* Reestablish SIGINT handler */

    printf("Reestablishing handler for SIGINT\n");
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sa.sa_handler = handler;
    if (sigaction(SIGINT, &sa, NULL) == -1)
        errExit("sigaction");

    sleep(2);

    /* And unblock SIGINT */

    printf("UNBLOCKING SIGINT\n");
    sigemptyset(&blocked);
    if (sigprocmask(SIG_SETMASK, &blocked, NULL) == -1)
        errExit("sigprocmask");

    exit(EXIT_SUCCESS);
}

int
main(int argc, char *argv[])
{
    struct utmpx ut;
    char *devName;

    if (argc < 2 || strcmp(argv[1], "--help") == 0)
        usageErr("%s username [sleep-time]\n", argv[0]);

    /* Initialize login record for utmp and wtmp files */

    memset(&ut, 0, sizeof(struct utmpx));
    ut.ut_type = USER_PROCESS;          /* This is a user login */
    strncpy(ut.ut_user, argv[1], sizeof(ut.ut_user));
    if (time((time_t *) &ut.ut_tv.tv_sec) == -1)
        errExit("time");                /* Stamp with current time */
    ut.ut_pid = getpid();

    /* Set ut_line and ut_id based on the terminal associated with
       'stdin'. This code assumes terminals named "/dev/[pt]t[sy]*".
       The "/dev/" dirname is 5 characters; the "[pt]t[sy]" filename
       prefix is 3 characters (making 8 characters in all). */

    devName = ttyname(STDIN_FILENO);
    if (devName == NULL)
        errExit("ttyname");
    if (strlen(devName) <= 8)           /* Should never happen */
        fatal("Terminal name is too short: %s", devName);

    strncpy(ut.ut_line, devName + 5, sizeof(ut.ut_line));
    strncpy(ut.ut_id, devName + 8, sizeof(ut.ut_id));

    printf("Creating login entries in utmp and wtmp\n");
    printf("        using pid %ld, line %.*s, id %.*s\n",
            (long) ut.ut_pid, (int) sizeof(ut.ut_line), ut.ut_line,
            (int) sizeof(ut.ut_id), ut.ut_id);

    setutxent();                        /* Rewind to start of utmp file */
    if (pututxline(&ut) == NULL)        /* Write login record to utmp */
        errExit("pututxline");
    updwtmpx(_PATH_WTMP, &ut);          /* Append login record to wtmp */

    /* Sleep a while, so we can examine utmp and wtmp files */

    sleep((argc > 2) ? getInt(argv[2], GN_NONNEG, "sleep-time") : 15);

    /* Now do a "logout"; use values from previously initialized 'ut',
       except for changes below */

    ut.ut_type = DEAD_PROCESS;          /* Required for logout record */
    time((time_t *) &ut.ut_tv.tv_sec);  /* Stamp with logout time */
    memset(&ut.ut_user, 0, sizeof(ut.ut_user));
                                        /* Logout record has null username */

    printf("Creating logout entries in utmp and wtmp\n");
    setutxent();                        /* Rewind to start of utmp file */
    if (pututxline(&ut) == NULL)        /* Overwrite previous utmp record */
        errExit("pututxline");
    updwtmpx(_PATH_WTMP, &ut);          /* Append logout record to wtmp */

    endutxent();
    exit(EXIT_SUCCESS);
}

// mon_pid: pid of sandbox to be monitored, 0 if all sandboxes are included
void pid_read(pid_t mon_pid) {
	if (pids == NULL) {
		FILE *fp = fopen("/proc/sys/kernel/pid_max", "r");
		if (fp) {
			int val;
			if (fscanf(fp, "%d", &val) == 1) {
				if (val >= max_pids)
					max_pids = val + 1;
			}
			fclose(fp);
		}
		pids = malloc(sizeof(Process) * max_pids);
		if (pids == NULL)
			errExit("malloc");
	}
	memset(pids, 0, sizeof(Process) * max_pids);
	pid_t mypid = getpid();

	DIR *dir;
	if (!(dir = opendir("/proc"))) {
		// sleep 2 seconds and try again
		sleep(2);
		if (!(dir = opendir("/proc"))) {
			fprintf(stderr, "Error: cannot open /proc directory\n");
			exit(1);
		}
	}
	
	pid_t child = -1;
	struct dirent *entry;
	char *end;
	while (child < 0 && (entry = readdir(dir))) {
		pid_t pid = strtol(entry->d_name, &end, 10);
		pid %= max_pids;
		if (end == entry->d_name || *end)
			continue;
		if (pid == mypid)
			continue;
		
		// open stat file
		char *file;
		if (asprintf(&file, "/proc/%u/status", pid) == -1) {
			perror("asprintf");
			exit(1);
		}
		FILE *fp = fopen(file, "r");
		if (!fp) {
			free(file);
			continue;
		}

		// look for firejail executable name
		char buf[PIDS_BUFLEN];
		while (fgets(buf, PIDS_BUFLEN - 1, fp)) {
			if (strncmp(buf, "Name:", 5) == 0) {
				char *ptr = buf + 5;
				while (*ptr != '\0' && (*ptr == ' ' || *ptr == '\t')) {
					ptr++;
				}
				if (*ptr == '\0') {
					fprintf(stderr, "Error: cannot read /proc file\n");
					exit(1);
				}

				if (mon_pid == 0 && strncmp(ptr, "firejail", 8) == 0) {
					pids[pid].level = 1;
				}
				else if (mon_pid == pid && strncmp(ptr, "firejail", 8) == 0) {
					pids[pid].level = 1;
				}
//				else if (mon_pid == 0 && strncmp(ptr, "lxc-execute", 11) == 0) {
//					pids[pid].level = 1;
//				}
//				else if (mon_pid == pid && strncmp(ptr, "lxc-execute", 11) == 0) {
//					pids[pid].level = 1;
//				}
				else
					pids[pid].level = -1;
			}
			if (strncmp(buf, "State:", 6) == 0) {
				if (strstr(buf, "(zombie)"))
					pids[pid].zombie = 1;
			}
			else if (strncmp(buf, "PPid:", 5) == 0) {
				char *ptr = buf + 5;
				while (*ptr != '\0' && (*ptr == ' ' || *ptr == '\t')) {
					ptr++;
				}
				if (*ptr == '\0') {
					fprintf(stderr, "Error: cannot read /proc file\n");
					exit(1);
				}
				unsigned parent = atoi(ptr);
				parent %= max_pids;
				if (pids[parent].level > 0) {
					pids[pid].level = pids[parent].level + 1;
				}
				pids[pid].parent = parent;
			}
//.........这里部分代码省略.........

int main(int argc,char *argv[])
{
    char cmd[CMD_SIZE];
    pid_t childPid;
    sigset_t blockMask,emptyMask;
    struct sigaction sa;

    setbuf(stdout,NULL);    /* Disable buffering of stdout */

    memset(cmd,0,CMD_SIZE);
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sa.sa_handler = sigHandler;
    if (sigaction(SIGCHLD,&sa,NULL) == -1)
    {
        errExit("sigaction");
    }

    /* Block SIGCHLD to prevent its delivery if a child terminates
       before the parent commences the sigsupsend() */
    sigemptyset(&blockMask);
    sigaddset(&blockMask,SIGCHLD);
    if (sigprocmask(SIG_SETMASK,&blockMask,NULL) == -1)
    {
        errExit("sigprocmask");
    }
    
    printf("Parent PID=%ld\n",(long)getpid());

    switch(childPid = fork())
    {
    case -1:
        errExit("fork");
    case 0:   /* Child: immediately exits to become zombie */
        printf("Child (PID=%ld) exiting\n",(long)getpid());
        _exit(EXIT_SUCCESS);
    default:  /* Parent */

        sigemptyset(&emptyMask);
        if (sigsuspend(&emptyMask) == -1 && errno != EINTR)
        {
            errExit("sigsuspend");
        }
        
        snprintf(cmd,CMD_SIZE,"ps -c | grep %s",basename(argv[0]));
        cmd[CMD_SIZE - 1] = '\0';   /* Ensure string is null-terminated */
        system(cmd);               /* View zombie child */
        
        /* Now send the "sure kill" signal to the zombie */

        if (kill(childPid,SIGKILL) == -1)
        {
            errMsg("kill");
        }

        sleep(10);   /* Give child a chance to react to signal */
        printf("After sending SIGKILL to zombie (PID=%ld):\n",(long)childPid);
        system(cmd);   /* View zombie child again */
        
        exit(EXIT_SUCCESS);
    }
}

int
main(int argc, char *argv[])
{
    char buf[BUF_SIZE];
    int outbound[2];            /* Pipe to send data from parent to child */
    int inbound[2];             /* Pipe to send data from child to parent */
    int j;
    ssize_t cnt;

    if (pipe(outbound) == -1)
        errExit("pipe");
    if (pipe(inbound) == -1)
        errExit("pipe");

    switch (fork()) {
    case -1:
        errExit("fork");

    case 0: /* Child */

        /* Close unused pipe descriptors */

        if (close(outbound[1]) == -1)
            errExit("close");
        if (close(inbound[0]) == -1)
            errExit("close");

        /* Read data from outbound pipe, convert to uppercase,
           and send back to parent on inbound pipe */

        while ((cnt = read(outbound[0], buf, BUF_SIZE)) > 0) {
            for (j = 0; j < cnt; j++)
                buf[j] = toupper((unsigned char) buf[j]);
            if (write(inbound[1], buf, cnt) == -1)
                errExit("write");
        }

        if (cnt == -1)
            errExit("read");
        _exit(EXIT_SUCCESS);

    default:

        /* Close unused pipe descriptors */

        if (close(outbound[0]) == -1)
            errExit("close");
        if (close(inbound[1]) == -1)
            errExit("close");

        /* Read data from stdin, send to the child via the
           outbound pipe, read the results back from the child
           on the inbound pipe, and print them on stdout */

        while ((cnt = read(STDIN_FILENO, buf, BUF_SIZE)) > 0) {
            if (write(outbound[1], buf, cnt) == -1)
                errExit("write");

            cnt = read(inbound[0], buf, BUF_SIZE);
            if (cnt == -1)
                errExit("read");
            if (cnt > 0)
                if (write(STDOUT_FILENO, buf, cnt) == -1)
                    errExit("write");
        }

        if (cnt == -1)
            errExit("read");

        /* Exiting will close write end of outbound pipe, so that
           child see EOF */

        exit(EXIT_SUCCESS);
    }
}

int
main(int argc, char *argv[])
{
	int epfd,ready,fd,s,j,numOpenFds;
	struct epoll_event ev;
	struct epoll_event evlist[MAX_EVENTS];
	char buf[MAX_BUF];
	
	//使用说明
	if(argc < 2|| strcmp(argv[1], "--help") == 0)
		usageErr("%s file ..\n",argv[0]);

	epfd = epoll_create(argc - 1);
	if(epfd==-1)
		errExit("epoll_create");

	//open each file on command line, and add it to the "interest list" for the epoll instance
	for(j = 1;j<argc; ++j)
	{
		fd = open(argv[j],O_RDONLY);
		if(fd == -1)
			errExit("open");
		printf("Opened \"%s\" on fd %d\n",argv[j],fd);

		ev.events = EPOLLIN; //Only interested in input events
		ev.data.fd = fd;
		if(epoll_ctl(epfd,EPOLL_CTL_ADD,fd,&ev) == -1)
			errExit("epoll_ctl");
	}

	numOpenFds = argc -1;
	while(numOpenFds > 0)
	{
		//fetch up to MAX_EVENTS items from the ready list
		printf("About to epoll_wait()\n");
		ready = epoll_wait(epfd,evlist,MAX_EVENTS, -1);
		if(ready == -1)
		{
			if(errno == EINTR)
				continue;
			else
				errExit("epoll_wait");
		}


		printf("Ready: %d\n",ready);

		//deal with returned list of events

		for(j=0;j<ready;++j)
		{
			printf("   fd=%d;events: %s%s%s\n",evlist[j].data.fd,
					(evlist[j].events & EPOLLIN) ? "EPOLLIN" :"",
					(evlist[j].events & EPOLLHUP)? "EPOLLHUP":"",
					(evlist[j].events & EPOLLERR)? "EPOLLERR":"");

			if(evlist[j].events & EPOLLIN)
			{
				s = read(evlist[j].data.fd, buf ,MAX_BUF);
				if(s == -1)
					errExit("read");
				printf("   read %d bytes:%.*s\n",s,s,buf);
			}
			else if(evlist[j].events & (EPOLLHUP | EPOLLERR))
			{
				/*if EPOLLIN and EPOLLHUP were both set,
				then there might be more than MAX_BUF bytes to read.
				Therefore, we close the file descriptor only if EPOLLIN wsa not set.
				We'll read further bytes after the next epoll_wait().*/

				printf("   closing fd %d\n",evlist[j].data.fd);
				if(close(evlist[j].data.fd) == -1)
					errExit("close");
				numOpenFds--;
			}
		}
	}

	printf("All file descriptors closed,bye!\n");
	exit(EXIT_SUCCESS);
}

static void sanitize_group(void) {
	struct stat s;
	if (stat("/etc/group", &s) == -1)
		return;
	assert(gid_min);
	if (arg_debug)
		printf("Sanitizing /etc/group, GID_MIN %d\n", gid_min);
	if (is_link("/etc/group")) {
		fprintf(stderr, "Error: invalid /etc/group\n");
		exit(1);
	}

	FILE *fpin = NULL;
	FILE *fpout = NULL;

	// open files
	/* coverity[toctou] */
	fpin = fopen("/etc/group", "r");
	if (!fpin)
		goto errout;
	fpout = fopen(RUN_GROUP_FILE, "w");
	if (!fpout)
		goto errout;

	// read the file line by line
	char buf[MAXBUF];
	gid_t mygid = getgid();
	while (fgets(buf, MAXBUF, fpin)) {
		// comments and empty lines
		if (*buf == '\0' || *buf == '#')
			continue;

		// sample line:
		// 	pulse:x:115:netblue,bingo
		// drop lines with uid > 1000 and not the current user group
		char *ptr = buf;

		// advance to uid
		while (*ptr != ':' && *ptr != '\0')
			ptr++;
		if (*ptr == '\0')
			goto errout;
		ptr++;
		while (*ptr != ':' && *ptr != '\0')
			ptr++;
		if (*ptr == '\0')
			goto errout;
		ptr++;
		if (*ptr == '\0')
			goto errout;

		// process uid
		int gid;
		int rv = sscanf(ptr, "%d:", &gid);
		if (rv == 0 || gid < 0)
			goto errout;
		assert(gid_min);
		if (gid < gid_min || gid == 65534) { // on Debian platforms 65534 is group nogroup
			if (copy_line(fpout, buf, ptr))
				goto errout;
			continue;
		}
		if ((gid_t) gid != mygid) {
			continue; // skip line
		}
		if (copy_line(fpout, buf, ptr))
			goto errout;
	}
	fclose(fpin);
	SET_PERMS_STREAM(fpout, 0, 0, 0644);
	fclose(fpout);

	// mount-bind tne new group file
	if (mount(RUN_GROUP_FILE, "/etc/group", "none", MS_BIND, "mode=400,gid=0") < 0)
		errExit("mount");
	fs_logger("create /etc/group");

	return;

errout:
	fwarning("failed to clean up /etc/group\n");
	if (fpin)
		fclose(fpin);
	if (fpout)
		fclose(fpout);
}

static void
processInotifyEvents(int *inotifyFd)
{
    char buf[INOTIFY_READ_BUF_LEN]
        __attribute__ ((aligned(__alignof__(struct inotify_event))));
    ssize_t numRead, nr;
    char *evp;
    size_t cnt;
    int evLen;
    int firstTry;
    int j;
    struct sigaction sa;

    /* SIGALRM handler is designed simply to interrupt read() */

    sigemptyset(&sa.sa_mask);
    sa.sa_handler = alarmHandler;
    sa.sa_flags = 0;
    if (sigaction(SIGALRM, &sa, NULL) == -1)
        errExit("sigaction");

    firstTry = 1;

    /* Read some events from inotify file descriptor */

    cnt = (readBufferSize > 0) ? readBufferSize : INOTIFY_READ_BUF_LEN;
    numRead = read(*inotifyFd, buf, cnt);
    if (numRead == -1)
        errExit("read");
    if (numRead == 0) {
        fprintf(stderr, "read() from inotify fd returned 0!");
        exit(EXIT_FAILURE);
    }

    inotifyReadCnt++;

    logMessage(VB_NOISY,
               "\n==========> Read %d: got %zd bytes\n",
               inotifyReadCnt, numRead);

    /* Process each event in the buffer returned by read() */

    for (evp = buf; evp < buf + numRead; ) {
        evLen = processNextInotifyEvent(inotifyFd, evp,
                                 buf + numRead - evp, firstTry);

        if (evLen > 0) {
            evp += evLen;
            firstTry = 1;
        } else {

            /* We got here because an IN_MOVED_FROM event was found at
               the end of a previously read buffer and that event may be
               part of an "intra-tree" rename(), meaning that we should
               check if there is a subsequent IN_MOVED_TO event with the
               same cookie value. We left that event unprocessed and we
               will now try to read some more events, delaying for a
               short time, to give the associated IN_MOVED_IN event (if
               there is one) a chance to arrive. However, we only want
               to do this once: if the read() below fails to gather
               further events, then when we reprocess the IN_MOVED_FROM
               we should treat it as though this is an out-of-tree
               rename(). Thus, we set 'firstTry' to 0 for the next
               processNextInotifyEvent() call. */

            struct sigaction sa;
            int savedErrno;

            firstTry = 0;

            numRead = buf + numRead - evp;

            /* Shuffle remaining bytes to start of buffer */

            for (j = 0; j < numRead; j++)
                buf[j] = evp[j];

            /* Do a read with timeout, to allow next events
               (if any) to arrive */

            sa.sa_flags = 0;
            sigemptyset(&sa.sa_mask);
            sa.sa_handler = alarmHandler;

            /* Set a timeout for read(). Some rough testing suggests
               that a 2-millisecond timeout is sufficient to ensure
               that, in around 99.8% of cases, we get the IN_MOVED_TO
               event (if there is one) that matched an IN_MOVED_FROM
               event, even in a highly dynamic directory tree. This
               number may, of course, warrant tuning on different
               hardware and in environments with different filesystem
               activity levels. */

            ualarm(2000, 0);

            nr = read(*inotifyFd, buf + numRead,
                      INOTIFY_READ_BUF_LEN - numRead);

            savedErrno = errno; /* In case ualarm() should change errno */
            ualarm(0, 0);       /* Cancel alarm */
//.........这里部分代码省略.........

//.........这里部分代码省略.........
	}
	else if (strcmp(ptr, "private-dev") == 0) {
		arg_private_dev = 1;
		return 0;
	}
	else if (strcmp(ptr, "private-tmp") == 0) {
		arg_private_tmp = 1;
		return 0;
	}
	else if (strcmp(ptr, "nogroups") == 0) {
		arg_nogroups = 1;
		return 0;
	}
	else if (strcmp(ptr, "nosound") == 0) {
		arg_nosound = 1;
		arg_private_dev = 1;
		return 0;
	}
	else if (strcmp(ptr, "netfilter") == 0) {
#ifdef HAVE_NETWORK
		if (checkcfg(CFG_NETWORK))
			arg_netfilter = 1;
		else
			fprintf(stderr, "Warning: networking features are disabled in Firejail configuration file\n");
#endif
		return 0;
	}
	else if (strncmp(ptr, "netfilter ", 10) == 0) {
#ifdef HAVE_NETWORK
		if (checkcfg(CFG_NETWORK)) {
			arg_netfilter = 1;
			arg_netfilter_file = strdup(ptr + 10);
			if (!arg_netfilter_file)
				errExit("strdup");
			check_netfilter_file(arg_netfilter_file);
		}
		else
			fprintf(stderr, "Warning: networking features are disabled in Firejail configuration file\n");
#endif
		return 0;
	}
	else if (strncmp(ptr, "netfilter6 ", 11) == 0) {
#ifdef HAVE_NETWORK
		if (checkcfg(CFG_NETWORK)) {
			arg_netfilter6 = 1;
			arg_netfilter6_file = strdup(ptr + 11);
			if (!arg_netfilter6_file)
				errExit("strdup");
			check_netfilter_file(arg_netfilter6_file);
		}
		else
			fprintf(stderr, "Warning: networking features are disabled in Firejail configuration file\n");
#endif
		return 0;
	}
	else if (strcmp(ptr, "net none") == 0) {
#ifdef HAVE_NETWORK
		if (checkcfg(CFG_NETWORK)) {
			arg_nonetwork  = 1;
			cfg.bridge0.configured = 0;
			cfg.bridge1.configured = 0;
			cfg.bridge2.configured = 0;
			cfg.bridge3.configured = 0;
			cfg.interface0.configured = 0;
			cfg.interface1.configured = 0;
			cfg.interface2.configured = 0;

static void sanitize_passwd(void) {
	struct stat s;
	if (stat("/etc/passwd", &s) == -1)
		return;
	assert(uid_min);
	if (arg_debug)
		printf("Sanitizing /etc/passwd, UID_MIN %d\n", uid_min);
	if (is_link("/etc/passwd")) {
		fprintf(stderr, "Error: invalid /etc/passwd\n");
		exit(1);
	}

	FILE *fpin = NULL;
	FILE *fpout = NULL;

	// open files
	/* coverity[toctou] */
	fpin = fopen("/etc/passwd", "r");
	if (!fpin)
		goto errout;
	fpout = fopen(RUN_PASSWD_FILE, "w");
	if (!fpout)
		goto errout;

	// read the file line by line
	char buf[MAXBUF];
	uid_t myuid = getuid();
	while (fgets(buf, MAXBUF, fpin)) {
		// comments and empty lines
		if (*buf == '\0' || *buf == '#')
			continue;

		// sample line:
		// 	www-data:x:33:33:www-data:/var/www:/bin/sh
		// drop lines with uid > 1000 and not the current user
		char *ptr = buf;

		// advance to uid
		while (*ptr != ':' && *ptr != '\0')
			ptr++;
		if (*ptr == '\0')
			goto errout;
		char *ptr1 = ptr;
		ptr++;
		while (*ptr != ':' && *ptr != '\0')
			ptr++;
		if (*ptr == '\0')
			goto errout;
		ptr++;
		if (*ptr == '\0')
			goto errout;

		// process uid
		int uid;
		int rv = sscanf(ptr, "%d:", &uid);
		if (rv == 0 || uid < 0)
			goto errout;
		assert(uid_min);
		if (uid < uid_min || uid == 65534) { // on Debian platforms user nobody is 65534
			fprintf(fpout, "%s", buf);
			continue;
		}
		if ((uid_t) uid != myuid) {
			// store user name - necessary to process /etc/group
			*ptr1 = '\0';
			char *user = strdup(buf);
			if (!user)
				errExit("malloc");
			ulist_add(user);
			continue; // skip line
		}
		fprintf(fpout, "%s", buf);
	}
	fclose(fpin);
	SET_PERMS_STREAM(fpout, 0, 0, 0644);
	fclose(fpout);

	// mount-bind tne new password file
	if (mount(RUN_PASSWD_FILE, "/etc/passwd", "none", MS_BIND, "mode=400,gid=0") < 0)
		errExit("mount");
	fs_logger("create /etc/passwd");

	return;

errout:
	fwarning("failed to clean up /etc/passwd\n");
	if (fpin)
		fclose(fpin);
	if (fpout)
		fclose(fpout);
}

int
main(int argc, char *argv[])
{
    struct timeval start, finish;
    struct timespec request, remain;
    struct sigaction sa;
    int s, flags;

    if (argc < 3 || strcmp(argv[1], "--help") == 0)
        usageErr("%s secs nanosecs [a]\n", argv[0]);

    /* Allow SIGINT handler to interrupt clock_nanosleep() */

    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sa.sa_handler = sigintHandler;
    if (sigaction(SIGINT, &sa, NULL) == -1)
        errExit("sigaction");

    /* If more than three command-line arguments, use TIMER_ABSTIME flag */

    flags = (argc > 3) ? TIMER_ABSTIME : 0;

    if (flags == TIMER_ABSTIME) {
        if (clock_gettime(CLOCK_REALTIME, &request) == -1)
            errExit("clock_gettime");
        printf("Initial CLOCK_REALTIME value: %ld.%09ld\n",
                (long) request.tv_sec, (long) request.tv_nsec);

        request.tv_sec  += getLong(argv[1], 0, "secs");
        request.tv_nsec += getLong(argv[2], 0, "nanosecs");
        if (request.tv_nsec >= 1000000000) {
            request.tv_sec += request.tv_nsec / 1000000000;
            request.tv_nsec %= 1000000000;
        }

    } else {                    /* Relative sleep */
        request.tv_sec  = getLong(argv[1], 0, "secs");
        request.tv_nsec = getLong(argv[2], 0, "nanosecs");
    }

    if (gettimeofday(&start, NULL) == -1)
        errExit("gettimeofday");

    for (;;) {
        s = clock_nanosleep(CLOCK_REALTIME, flags, &request, &remain);
        if (s != 0 && s != EINTR)
            errExitEN(s, "clock_nanosleep");

        if (s == EINTR)
            printf("Interrupted... ");

        if (gettimeofday(&finish, NULL) == -1)
            errExit("gettimeofday");
        printf("Slept: %.6f secs", finish.tv_sec - start.tv_sec +
                        (finish.tv_usec - start.tv_usec) / 1000000.0);

        if (s == 0)
            break;                      /* sleep completed */

        if (flags != TIMER_ABSTIME) {
            printf("... Remaining: %ld.%09ld",
                    (long) remain.tv_sec, remain.tv_nsec);

            request = remain;
        }

        printf("... Restarting\n");
    }

    printf("\nSleep complete\n");
    exit(EXIT_SUCCESS);
}

int
main(int argc, char *argv[])
{
    char *username, *password, *encrypted, *p;
    struct passwd *pwd;
    struct spwd *spwd;
    Boolean authOk;
    size_t len;
    long lnmax;

    /* Determine size of buffer required for a username, and allocate it */

    lnmax = sysconf(_SC_LOGIN_NAME_MAX);
    if (lnmax == -1)                    /* If limit is indeterminate */
        lnmax = 256;                    /* make a guess */

    username = malloc(lnmax);
    if (username == NULL)
        errExit("malloc");

    printf("Username: ");
    fflush(stdout);
    if (fgets(username, lnmax, stdin) == NULL)
        exit(EXIT_FAILURE);             /* Exit on EOF */

    len = strlen(username);
    if (username[len - 1] == '\n')
        username[len - 1] = '\0';       /* Remove trailing '\n' */

    /* Look up password and shadow password records for username */

    pwd = getpwnam(username);
    if (pwd == NULL)
        fatal("couldn't get password record");
    spwd = getspnam(username);
    if (spwd == NULL && errno == EACCES)
        fatal("no permission to read shadow password file");

    if (spwd != NULL)           /* If there is a shadow password record */
        pwd->pw_passwd = spwd->sp_pwdp;     /* Use the shadow password */

    password = getpass("Password: ");

    /* Encrypt password and erase cleartext version immediately */

    encrypted = crypt(password, pwd->pw_passwd);
    for (p = password; *p != '\0'; )
        *p++ = '\0';

    if (encrypted == NULL)
        errExit("crypt");

    authOk = strcmp(encrypted, pwd->pw_passwd) == 0;
    if (!authOk) {
        printf("Incorrect password\n");
        exit(EXIT_FAILURE);
    }

    printf("Successfully authenticated: UID=%ld\n", (long) pwd->pw_uid);

    /* Now do authenticated work... */

    exit(EXIT_SUCCESS);
}

int
main(int argc, char *argv[])
{
    int semid, key, perms;
    struct sembuf sops[2];

    if (argc != 2 || strcmp(argv[1], "--help") == 0)
        usageErr("%s sem-op\n", argv[0]);

    key = 12345;
    perms = S_IRUSR | S_IWUSR;

    semid = semget(key, 1, IPC_CREAT | IPC_EXCL | perms);

    if (semid != -1) {                  /* Successfully created the semaphore */
        union semun arg;
        struct sembuf sop;

        sleep(5);
        printf("%ld: created semaphore\n", (long) getpid());

        arg.val = 0;                    /* So initialize it to 0 */
        if (semctl(semid, 0, SETVAL, arg) == -1)
            errExit("semctl 1");
        printf("%ld: initialized semaphore\n", (long) getpid());

        /* Perform a "no-op" semaphore operation - changes sem_otime
           so other processes can see we've initialized the set. */

        sop.sem_num = 0;                /* Operate on semaphore 0 */
        sop.sem_op = 0;                 /* Wait for value to equal 0 */
        sop.sem_flg = 0;
        if (semop(semid, &sop, 1) == -1)
            errExit("semop");
        printf("%ld: completed dummy semop()\n", (long) getpid());

    } else {                            /* We didn't create the semaphore set */

        if (errno != EEXIST) {          /* Unexpected error from semget() */
            errExit("semget 1");

        } else {                        /* Someone else already created it */
            const int MAX_TRIES = 10;
            int j;
            union semun arg;
            struct semid_ds ds;

            semid = semget(key, 1, perms);      /* So just get ID */
            if (semid == -1)
                errExit("semget 2");

            printf("%ld: got semaphore key\n", (long) getpid());
            /* Wait until another process has called semop() */

            arg.buf = &ds;
            for (j = 0; j < MAX_TRIES; j++) {
                printf("Try %d\n", j);
                if (semctl(semid, 0, IPC_STAT, arg) == -1)
                    errExit("semctl 2");

                if (ds.sem_otime != 0)          /* Semop() performed? */
                    break;                      /* Yes, quit loop */
                sleep(1);                       /* If not, wait and retry */
            }

            if (ds.sem_otime == 0)              /* Loop ran to completion! */
                fatal("Existing semaphore not initialized");
        }
    }

    /* Now perform some operation on the semaphore */

    sops[0].sem_num = 0;                        /* Operate on semaphore 0... */
    sops[0].sem_op = getInt(argv[1], 0, "sem-op");
    sops[0].sem_flg = 0;
    if (semop(semid, sops, 1) == -1)
        errExit("semop");

    exit(EXIT_SUCCESS);
}

int
main(int argc, char *argv[])
{
    int epfd, ready, fd, s, j, numOpenFds;
    struct epoll_event ev;
    struct epoll_event evlist[MAX_EVENTS];
    char buf[MAX_BUF];

    if (argc < 2 || strcmp(argv[1], "--help") == 0)
        usageErr("%s file...\n", argv[0]);

    epfd = epoll_create(argc - 1);
    if (epfd == -1)
        errExit("epoll_create");

    /* Open each file on command line, and add it to the "interest
       list" for the epoll instance */

    for (j = 1; j < argc; j++) {
        fd = open(argv[j], O_RDONLY);
        if (fd == -1)
            errExit("open");
        printf("Opened \"%s\" on fd %d\n", argv[j], fd);

        ev.events = EPOLLIN;            /* Only interested in input events */
        ev.data.fd = fd;
        if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev) == -1)
            errExit("epoll_ctl");
    }

    numOpenFds = argc - 1;

    while (numOpenFds > 0) {

        /* Fetch up to MAX_EVENTS items from the ready list of the
           epoll instance */

        printf("About to epoll_wait()\n");
        ready = epoll_wait(epfd, evlist, MAX_EVENTS, -1);
        if (ready == -1) {
            if (errno == EINTR)
                continue;               /* Restart if interrupted by signal */
            else
                errExit("epoll_wait");
        }

        printf("Ready: %d\n", ready);

        /* Deal with returned list of events */

        for (j = 0; j < ready; j++) {
            printf("  fd=%d; events: %s%s%s\n", evlist[j].data.fd,
                    (evlist[j].events & EPOLLIN)  ? "EPOLLIN "  : "",
                    (evlist[j].events & EPOLLHUP) ? "EPOLLHUP " : "",
                    (evlist[j].events & EPOLLERR) ? "EPOLLERR " : "");

            if (evlist[j].events & EPOLLIN) {
                s = read(evlist[j].data.fd, buf, MAX_BUF);
                if (s == -1)
                    errExit("read");
                printf("    read %d bytes: %.*s\n", s, s, buf);

            } else if (evlist[j].events & (EPOLLHUP | EPOLLERR)) {

                /* After the epoll_wait(), EPOLLIN and EPOLLHUP may both have
                   been set. But we'll only get here, and thus close the file
                   descriptor, if EPOLLIN was not set. This ensures that all
                   outstanding input (possibly more than MAX_BUF bytes) is
                   consumed (by further loop iterations) before the file
                   descriptor is closed. */

                printf("    closing fd %d\n", evlist[j].data.fd);
                if (close(evlist[j].data.fd) == -1)
                    errExit("close");
                numOpenFds--;
            }
        }
    }

    printf("All file descriptors closed; bye\n");
    exit(EXIT_SUCCESS);
}