bgpd: Refactor subgroup_announce_table() to reuse an existing helpers

[mirror_frr.git] / tools / start-stop-daemon.c

// SPDX-License-Identifier: NONE
/*
 * A rewrite of the original Debian's start-stop-daemon Perl script
 * in C (faster - it is executed many times during system startup).
 *
 * Written by Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl>,
 * public domain.  Based conceptually on start-stop-daemon.pl, by Ian
 * Jackson <ijackson@gnu.ai.mit.edu>.  May be used and distributed
 * freely for any purpose.  Changes by Christian Schwarz
 * <schwarz@monet.m.isar.de>, to make output conform to the Debian
 * Console Message Standard, also placed in public domain.  Minor
 * changes by Klee Dienes <klee@debian.org>, also placed in the Public
 * Domain.
 *
 * Changes by Ben Collins <bcollins@debian.org>, added --chuid, --background
 * and --make-pidfile options, placed in public domain aswell.
 *
 * Port to OpenBSD by Sontri Tomo Huynh <huynh.29@osu.edu>
 *                 and Andreas Schuldei <andreas@schuldei.org>
 *
 * Changes by Ian Jackson: added --retry (and associated rearrangements).
 *
 * Modified for Gentoo rc-scripts by Donny Davies <woodchip@gentoo.org>:
 *   I removed the BSD/Hurd/OtherOS stuff, added #include <stddef.h>
 *   and stuck in a #define VERSION "1.9.18".  Now it compiles without
 *   the whole automake/config.h dance.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_LXC
#define _GNU_SOURCE
#include <sched.h>
#endif /* HAVE_LXC */

#include <stddef.h>
#undef VERSION
#define VERSION "1.9.18"

#define MIN_POLL_INTERVAL 20000 /*us*/

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <signal.h>
#include <sys/stat.h>
#include <dirent.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <unistd.h>
#include <getopt.h>
#include <pwd.h>
#include <grp.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <termios.h>
#include <fcntl.h>
#include <limits.h>
#include <assert.h>
#include <ctype.h>
#ifdef linux
#include <linux/sched.h>
#endif

static int testmode = 0;
static int quietmode = 0;
static int exitnodo = 1;
static int start = 0;
static int stop = 0;
static int background = 0;
static int mpidfile = 0;
static int signal_nr = 15;
static const char *signal_str = NULL;
static int user_id = -1;
static int runas_uid = -1;
static int runas_gid = -1;
static const char *userspec = NULL;
static char *changeuser = NULL;
static const char *changegroup = NULL;
static char *changeroot = NULL;
static const char *cmdname = NULL;
static char *execname = NULL;
static char *startas = NULL;
static const char *pidfile = NULL;
static char what_stop[1024];
static const char *schedule_str = NULL;
static const char *progname = "";
static int nicelevel = 0;

static struct stat exec_stat;

struct pid_list {
	struct pid_list *next;
	pid_t pid;
};

static struct pid_list *found = NULL;
static struct pid_list *killed = NULL;

struct schedule_item {
	enum { sched_timeout, sched_signal, sched_goto, sched_forever } type;
	int value; /* seconds, signal no., or index into array */
	/* sched_forever is only seen within parse_schedule and callees */
};

static int schedule_length;
static struct schedule_item *schedule = NULL;

LIST_HEAD(namespace_head, namespace);

struct namespace
{
	LIST_ENTRY(namespace) list;
	const char *path;
	int nstype;
};

static struct namespace_head namespace_head;

static void *xmalloc(int size);
static void push(struct pid_list **list, pid_t pid);
static void do_help(void);
static void parse_options(int argc, char *const *argv);
static int pid_is_user(pid_t pid, uid_t uid);
static int pid_is_cmd(pid_t pid, const char *name);
static void check(pid_t pid);
static void do_pidfile(const char *name);
static void do_stop(int signal_nr, int quietmode, int *n_killed,
		    int *n_notkilled, int retry_nr);
static int pid_is_exec(pid_t pid, const struct stat *esb);

#ifdef __GNUC__
static void fatal(const char *format, ...)
	__attribute__((noreturn, format(printf, 1, 2)));
static void badusage(const char *msg) __attribute__((noreturn));
#else
static void fatal(const char *format, ...);
static void badusage(const char *msg);
#endif

/* This next part serves only to construct the TVCALC macro, which
 * is used for doing arithmetic on struct timeval's.  It works like this:
 *   TVCALC(result, expression);
 * where result is a struct timeval (and must be an lvalue) and
 * expression is the single expression for both components.  In this
 * expression you can use the special values TVELEM, which when fed a
 * const struct timeval* gives you the relevant component, and
 * TVADJUST.  TVADJUST is necessary when subtracting timevals, to make
 * it easier to renormalise.  Whenver you subtract timeval elements,
 * you must make sure that TVADJUST is added to the result of the
 * subtraction (before any resulting multiplication or what have you).
 * TVELEM must be linear in TVADJUST.
 */
typedef long tvselector(const struct timeval *);
static long tvselector_sec(const struct timeval *tv)
{
	return tv->tv_sec;
}
static long tvselector_usec(const struct timeval *tv)
{
	return tv->tv_usec;
}
#define TVCALC_ELEM(result, expr, sec, adj)                                    \
	{                                                                      \
		const long TVADJUST = adj;                                     \
		long (*const TVELEM)(const struct timeval *) =                 \
			tvselector_##sec;                                      \
		(result).tv_##sec = (expr);                                    \
	}
#define TVCALC(result, expr)                                                   \
	do {                                                                   \
		TVCALC_ELEM(result, expr, sec, (-1));                          \
		TVCALC_ELEM(result, expr, usec, (+1000000));                   \
		(result).tv_sec += (result).tv_usec / 1000000;                 \
		(result).tv_usec %= 1000000;                                   \
	} while (0)


static void fatal(const char *format, ...)
{
	va_list arglist;

	fprintf(stderr, "%s: ", progname);
	va_start(arglist, format);
	vfprintf(stderr, format, arglist);
	va_end(arglist);
	putc('\n', stderr);
	exit(2);
}


static void *xmalloc(int size)
{
	void *ptr;

	ptr = malloc(size);
	if (ptr)
		return ptr;
	fatal("malloc(%d) failed", size);
}

static void xgettimeofday(struct timeval *tv)
{
	if (gettimeofday(tv, 0) != 0)
		fatal("gettimeofday failed: %s", strerror(errno));
}

static void push(struct pid_list **list, pid_t pid)
{
	struct pid_list *p;

	p = xmalloc(sizeof(*p));
	p->next = *list;
	p->pid = pid;
	*list = p;
}

static void clear(struct pid_list **list)
{
	struct pid_list *here, *next;

	for (here = *list; here != NULL; here = next) {
		next = here->next;
		free(here);
	}

	*list = NULL;
}

#ifdef linux
static const char *next_dirname(const char *s)
{
	const char *cur;

	cur = s;

	if (*cur != '\0') {
		for (; *cur != '/'; ++cur)
			if (*cur == '\0')
				return cur;

		for (; *cur == '/'; ++cur)
			;
	}

	return cur;
}

static void add_namespace(const char *path)
{
	int nstype;
	const char *nsdirname, *nsname, *cur;
	struct namespace *namespace;

	cur = path;
	nsdirname = nsname = "";

	while ((cur = next_dirname(cur))[0] != '\0') {
		nsdirname = nsname;
		nsname = cur;
	}

	if (!strncmp(nsdirname, "ipcns/", strlen("ipcns/")))
		nstype = CLONE_NEWIPC;
	else if (!strncmp(nsdirname, "netns/", strlen("netns/")))
		nstype = CLONE_NEWNET;
	else if (!strncmp(nsdirname, "utcns/", strlen("utcns/")))
		nstype = CLONE_NEWUTS;
	else
		badusage("invalid namepspace path");

	namespace = xmalloc(sizeof(*namespace));
	namespace->path = path;
	namespace->nstype = nstype;
	LIST_INSERT_HEAD(&namespace_head, namespace, list);
}
#endif

#ifdef HAVE_LXC
static void set_namespaces(void)
{
	struct namespace *namespace;
	int fd;

	LIST_FOREACH (namespace, &namespace_head, list) {
		if ((fd = open(namespace->path, O_RDONLY)) == -1)
			fatal("open namespace %s: %s", namespace->path,
			      strerror(errno));
		if (setns(fd, namespace->nstype) == -1)
			fatal("setns %s: %s", namespace->path, strerror(errno));
	}
}
#else
static void set_namespaces(void)
{
	if (!LIST_EMPTY(&namespace_head))
		fatal("LCX namespaces not supported");
}
#endif

static void do_help(void)
{
	printf("start-stop-daemon " VERSION
	       " for Debian - small and fast C version written by\n"
	       "Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl>, public domain.\n"
	       "\n"
	       "Usage:\n"
	       "  start-stop-daemon -S|--start options ... -- arguments ...\n"
	       "  start-stop-daemon -K|--stop options ...\n"
	       "  start-stop-daemon -H|--help\n"
	       "  start-stop-daemon -V|--version\n"
	       "\n"
	       "Options (at least one of --exec|--pidfile|--user is required):\n"
	       "  -x|--exec <executable>        program to start/check if it is running\n"
	       "  -p|--pidfile <pid-file>       pid file to check\n"
	       "  -c|--chuid <name|uid[:group|gid]>\n"
	       "  		change to this user/group before starting process\n"
	       "  -u|--user <username>|<uid>    stop processes owned by this user\n"
	       "  -n|--name <process-name>      stop processes with this name\n"
	       "  -s|--signal <signal>          signal to send (default TERM)\n"
	       "  -a|--startas <pathname>       program to start (default is <executable>)\n"
	       "  -N|--nicelevel <incr>         add incr to the process's nice level\n"
	       "  -b|--background               force the process to detach\n"
	       "  -m|--make-pidfile             create the pidfile before starting\n"
	       "  -R|--retry <schedule>         check whether processes die, and retry\n"
	       "  -t|--test                     test mode, don't do anything\n"
	       "  -o|--oknodo                   exit status 0 (not 1) if nothing done\n"
	       "  -q|--quiet                    be more quiet\n"
	       "  -v|--verbose                  be more verbose\n"
	       "Retry <schedule> is <item>|/<item>/... where <item> is one of\n"
	       " -<signal-num>|[-]<signal-name>  send that signal\n"
	       " <timeout>                       wait that many seconds\n"
	       " forever                         repeat remainder forever\n"
	       "or <schedule> may be just <timeout>, meaning <signal>/<timeout>/KILL/<timeout>\n"
	       "\n"
	       "Exit status:  0 = done      1 = nothing done (=> 0 if --oknodo)\n"
	       "              3 = trouble   2 = with --retry, processes wouldn't die\n");
}


static void badusage(const char *msg)
{
	if (msg)
		fprintf(stderr, "%s: %s\n", progname, msg);
	fprintf(stderr, "Try `%s --help' for more information.\n", progname);
	exit(3);
}

struct sigpair {
	const char *name;
	int signal;
};

const struct sigpair siglist[] = {
	{"ABRT", SIGABRT}, {"ALRM", SIGALRM}, {"FPE", SIGFPE},
	{"HUP", SIGHUP},   {"ILL", SIGILL},   {"INT", SIGINT},
	{"KILL", SIGKILL}, {"PIPE", SIGPIPE}, {"QUIT", SIGQUIT},
	{"SEGV", SIGSEGV}, {"TERM", SIGTERM}, {"USR1", SIGUSR1},
	{"USR2", SIGUSR2}, {"CHLD", SIGCHLD}, {"CONT", SIGCONT},
	{"STOP", SIGSTOP}, {"TSTP", SIGTSTP}, {"TTIN", SIGTTIN},
	{"TTOU", SIGTTOU}};

static int parse_integer(const char *string, int *value_r)
{
	unsigned long ul;
	char *ep;

	if (!string[0])
		return -1;

	ul = strtoul(string, &ep, 10);
	if (ul > INT_MAX || *ep != '\0')
		return -1;

	*value_r = ul;
	return 0;
}

static int parse_signal(const char *signal_str, int *signal_nr)
{
	unsigned int i;

	if (parse_integer(signal_str, signal_nr) == 0)
		return 0;

	for (i = 0; i < sizeof(siglist) / sizeof(siglist[0]); i++) {
		if (strcmp(signal_str, siglist[i].name) == 0) {
			*signal_nr = siglist[i].signal;
			return 0;
		}
	}
	return -1;
}

static void parse_schedule_item(const char *string, struct schedule_item *item)
{
	const char *after_hyph;

	if (!strcmp(string, "forever")) {
		item->type = sched_forever;
	} else if (isdigit((unsigned char)string[0])) {
		item->type = sched_timeout;
		if (parse_integer(string, &item->value) != 0)
			badusage("invalid timeout value in schedule");
	} else if ((after_hyph = string + (string[0] == '-'))
		   && parse_signal(after_hyph, &item->value) == 0) {
		item->type = sched_signal;
	} else {
		badusage(
			"invalid schedule item (must be [-]<signal-name>, -<signal-number>, <timeout> or `forever'");
	}
}

static void parse_schedule(const char *schedule_str)
{
	char item_buf[20];
	const char *slash;
	int count, repeatat;
	ptrdiff_t str_len;

	count = 0;
	for (slash = schedule_str; *slash; slash++)
		if (*slash == '/')
			count++;

	schedule_length = (count == 0) ? 4 : count + 1;
	schedule = xmalloc(sizeof(*schedule) * schedule_length);

	if (count == 0) {
		schedule[0].type = sched_signal;
		schedule[0].value = signal_nr;
		parse_schedule_item(schedule_str, &schedule[1]);
		if (schedule[1].type != sched_timeout) {
			badusage(
				"--retry takes timeout, or schedule list of at least two items");
		}
		schedule[2].type = sched_signal;
		schedule[2].value = SIGKILL;
		schedule[3] = schedule[1];
	} else {
		count = 0;
		repeatat = -1;
		while (schedule_str != NULL) {
			slash = strchr(schedule_str, '/');
			str_len = slash ? slash - schedule_str
					: (ptrdiff_t)strlen(schedule_str);
			if (str_len >= (ptrdiff_t)sizeof(item_buf))
				badusage(
					"invalid schedule item: far too long (you must delimit items with slashes)");
			memcpy(item_buf, schedule_str, str_len);
			item_buf[str_len] = 0;
			schedule_str = slash ? slash + 1 : NULL;

			parse_schedule_item(item_buf, &schedule[count]);
			if (schedule[count].type == sched_forever) {
				if (repeatat >= 0)
					badusage(
						"invalid schedule: `forever' appears more than once");
				repeatat = count;
				continue;
			}
			count++;
		}
		if (repeatat >= 0) {
			schedule[count].type = sched_goto;
			schedule[count].value = repeatat;
			count++;
		}
		assert(count == schedule_length);
	}
}

static void parse_options(int argc, char *const *argv)
{
	static struct option longopts[] = {
		{"help", 0, NULL, 'H'},       {"stop", 0, NULL, 'K'},
		{"start", 0, NULL, 'S'},      {"version", 0, NULL, 'V'},
		{"startas", 1, NULL, 'a'},    {"name", 1, NULL, 'n'},
		{"oknodo", 0, NULL, 'o'},     {"pidfile", 1, NULL, 'p'},
		{"quiet", 0, NULL, 'q'},      {"signal", 1, NULL, 's'},
		{"test", 0, NULL, 't'},       {"user", 1, NULL, 'u'},
		{"chroot", 1, NULL, 'r'},     {"namespace", 1, NULL, 'd'},
		{"verbose", 0, NULL, 'v'},    {"exec", 1, NULL, 'x'},
		{"chuid", 1, NULL, 'c'},      {"nicelevel", 1, NULL, 'N'},
		{"background", 0, NULL, 'b'}, {"make-pidfile", 0, NULL, 'm'},
		{"retry", 1, NULL, 'R'},      {NULL, 0, NULL, 0}};
	int c;

	for (;;) {
		c = getopt_long(argc, argv,
				"HKSVa:n:op:qr:d:s:tu:vx:c:N:bmR:", longopts,
				(int *)0);
		if (c == -1)
			break;
		switch (c) {
		case 'H': /* --help */
			do_help();
			exit(0);
		case 'K': /* --stop */
			stop = 1;
			break;
		case 'S': /* --start */
			start = 1;
			break;
		case 'V': /* --version */
			printf("start-stop-daemon " VERSION "\n");
			exit(0);
		case 'a': /* --startas <pathname> */
			startas = optarg;
			break;
		case 'n': /* --name <process-name> */
			cmdname = optarg;
			break;
		case 'o': /* --oknodo */
			exitnodo = 0;
			break;
		case 'p': /* --pidfile <pid-file> */
			pidfile = optarg;
			break;
		case 'q': /* --quiet */
			quietmode = 1;
			break;
		case 's': /* --signal <signal> */
			signal_str = optarg;
			break;
		case 't': /* --test */
			testmode = 1;
			break;
		case 'u': /* --user <username>|<uid> */
			userspec = optarg;
			break;
		case 'v': /* --verbose */
			quietmode = -1;
			break;
		case 'x': /* --exec <executable> */
			execname = optarg;
			break;
		case 'c': /* --chuid <username>|<uid> */
			changeuser = strtok(optarg, ":");
			changegroup = strtok(NULL, ":");
			break;
		case 'r': /* --chroot /new/root */
			changeroot = optarg;
			break;
		case 'd': /* --namespace /.../<ipcns>|<netns>|<utsns>/name */
#ifdef linux
			add_namespace(optarg);
#endif
			break;
		case 'N': /* --nice */
			nicelevel = atoi(optarg);
			break;
		case 'b': /* --background */
			background = 1;
			break;
		case 'm': /* --make-pidfile */
			mpidfile = 1;
			break;
		case 'R': /* --retry <schedule>|<timeout> */
			schedule_str = optarg;
			break;
		default:
			badusage(NULL); /* message printed by getopt */
		}
	}

	if (signal_str != NULL) {
		if (parse_signal(signal_str, &signal_nr) != 0)
			badusage(
				"signal value must be numeric or name of signal (KILL, INTR, ...)");
	}

	if (schedule_str != NULL) {
		parse_schedule(schedule_str);
	}

	if (start == stop)
		badusage("need one of --start or --stop");

	if (!execname && !pidfile && !userspec && !cmdname)
		badusage(
			"need at least one of --exec, --pidfile, --user or --name");

	if (!startas)
		startas = execname;

	if (start && !startas)
		badusage("--start needs --exec or --startas");

	if (mpidfile && pidfile == NULL)
		badusage("--make-pidfile is only relevant with --pidfile");

	if (background && !start)
		badusage("--background is only relevant with --start");
}

static int pid_is_exec(pid_t pid, const struct stat *esb)
{
	struct stat sb;
	char buf[PATH_MAX];

	snprintf(buf, sizeof(buf), "/proc/%ld/exe", (long)pid);
	if (stat(buf, &sb) != 0)
		return 0;
	return (sb.st_dev == esb->st_dev && sb.st_ino == esb->st_ino);
}


static int pid_is_user(pid_t pid, uid_t uid)
{
	struct stat sb;
	char buf[PATH_MAX];

	snprintf(buf, sizeof(buf), "/proc/%ld", (long)pid);
	if (stat(buf, &sb) != 0)
		return 0;
	return (sb.st_uid == uid);
}


static int pid_is_cmd(pid_t pid, const char *name)
{
	char buf[PATH_MAX];
	FILE *f;
	int c;

	snprintf(buf, sizeof(buf), "/proc/%ld/stat", (long)pid);
	f = fopen(buf, "r");
	if (!f)
		return 0;
	while ((c = getc(f)) != EOF && c != '(')
		;
	if (c != '(') {
		fclose(f);
		return 0;
	}
	/* this hopefully handles command names containing ')' */
	while ((c = getc(f)) != EOF && c == *name)
		name++;
	fclose(f);
	return (c == ')' && *name == '\0');
}


static void check(pid_t pid)
{
	if (execname && !pid_is_exec(pid, &exec_stat))
		return;
	if (userspec && !pid_is_user(pid, user_id))
		return;
	if (cmdname && !pid_is_cmd(pid, cmdname))
		return;
	push(&found, pid);
}

static void do_pidfile(const char *name)
{
	FILE *f;
	long pid;

	f = fopen(name, "r");
	if (f) {
		if (fscanf(f, "%ld", &pid) == 1)
			check((pid_t)pid);
		fclose(f);
	} else if (errno != ENOENT)
		fatal("open pidfile %s: %s", name, strerror(errno));
}

/* WTA: this  needs to be an autoconf check for /proc/pid existance.
 */
static void do_procinit(void)
{
	DIR *procdir;
	struct dirent *entry;
	int foundany;
	long pid;

	procdir = opendir("/proc");
	if (!procdir)
		fatal("opendir /proc: %s", strerror(errno));

	foundany = 0;
	while ((entry = readdir(procdir)) != NULL) {
		if (sscanf(entry->d_name, "%ld", &pid) != 1)
			continue;
		foundany++;
		check((pid_t)pid);
	}
	closedir(procdir);
	if (!foundany)
		fatal("nothing in /proc - not mounted?");
}

static void do_findprocs(void)
{
	clear(&found);

	if (pidfile)
		do_pidfile(pidfile);
	else
		do_procinit();
}

/* return 1 on failure */
static void do_stop(int signal_nr, int quietmode, int *n_killed,
		    int *n_notkilled, int retry_nr)
{
	struct pid_list *p;

	do_findprocs();

	*n_killed = 0;
	*n_notkilled = 0;

	if (!found)
		return;

	clear(&killed);

	for (p = found; p; p = p->next) {
		if (testmode)
			printf("Would send signal %d to %ld.\n", signal_nr,
			       (long)p->pid);
		else if (kill(p->pid, signal_nr) == 0) {
			push(&killed, p->pid);
			(*n_killed)++;
		} else {
			printf("%s: warning: failed to kill %ld: %s\n",
			       progname, (long)p->pid, strerror(errno));
			(*n_notkilled)++;
		}
	}
	if (quietmode < 0 && killed) {
		printf("Stopped %s (pid", what_stop);
		for (p = killed; p; p = p->next)
			printf(" %ld", (long)p->pid);
		putchar(')');
		if (retry_nr > 0)
			printf(", retry #%d", retry_nr);
		printf(".\n");
	}
}


static void set_what_stop(const char *str)
{
	strncpy(what_stop, str, sizeof(what_stop));
	what_stop[sizeof(what_stop) - 1] = '\0';
}

static int run_stop_schedule(void)
{
	int r, position, n_killed, n_notkilled, value, ratio, anykilled,
		retry_nr;
	struct timeval stopat, before, after, interval, maxinterval;

	if (testmode) {
		if (schedule != NULL) {
			printf("Ignoring --retry in test mode\n");
			schedule = NULL;
		}
	}

	if (cmdname)
		set_what_stop(cmdname);
	else if (execname)
		set_what_stop(execname);
	else if (pidfile)
		sprintf(what_stop, "process in pidfile `%.200s'", pidfile);
	else if (userspec)
		sprintf(what_stop, "process(es) owned by `%.200s'", userspec);
	else
		fatal("internal error, please report");

	anykilled = 0;
	retry_nr = 0;
	n_killed = 0;

	if (schedule == NULL) {
		do_stop(signal_nr, quietmode, &n_killed, &n_notkilled, 0);
		if (n_notkilled > 0 && quietmode <= 0)
			printf("%d pids were not killed\n", n_notkilled);
		if (n_killed)
			anykilled = 1;
		goto x_finished;
	}

	for (position = 0; position < schedule_length;) {
		value = schedule[position].value;
		n_notkilled = 0;

		switch (schedule[position].type) {

		case sched_goto:
			position = value;
			continue;

		case sched_signal:
			do_stop(value, quietmode, &n_killed, &n_notkilled,
				retry_nr++);
			if (!n_killed)
				goto x_finished;
			else
				anykilled = 1;
			goto next_item;

		case sched_timeout:
			/* We want to keep polling for the processes, to see if
			 * they've exited,
			 * or until the timeout expires.
			 *
			 * This is a somewhat complicated algorithm to try to
			 * ensure that we
			 * notice reasonably quickly when all the processes have
			 * exited, but
			 * don't spend too much CPU time polling.  In
			 * particular, on a fast
			 * machine with quick-exiting daemons we don't want to
			 * delay system
			 * shutdown too much, whereas on a slow one, or where
			 * processes are
			 * taking some time to exit, we want to increase the
			 * polling
			 * interval.
			 *
			 * The algorithm is as follows: we measure the elapsed
			 * time it takes
			 * to do one poll(), and wait a multiple of this time
			 * for the next
			 * poll.  However, if that would put us past the end of
			 * the timeout
			 * period we wait only as long as the timeout period,
			 * but in any case
			 * we always wait at least MIN_POLL_INTERVAL (20ms).
			 * The multiple
			 * (`ratio') starts out as 2, and increases by 1 for
			 * each poll to a
			 * maximum of 10; so we use up to between 30% and 10% of
			 * the
			 * machine's resources (assuming a few reasonable things
			 * about system
			 * performance).
			 */
			xgettimeofday(&stopat);
			stopat.tv_sec += value;
			ratio = 1;
			for (;;) {
				xgettimeofday(&before);
				if (timercmp(&before, &stopat, >))
					goto next_item;

				do_stop(0, 1, &n_killed, &n_notkilled, 0);
				if (!n_killed)
					goto x_finished;

				xgettimeofday(&after);

				if (!timercmp(&after, &stopat, <))
					goto next_item;

				if (ratio < 10)
					ratio++;

				TVCALC(interval,
				       ratio * (TVELEM(&after) - TVELEM(&before)
						+ TVADJUST));
				TVCALC(maxinterval,
				       TVELEM(&stopat) - TVELEM(&after)
					       + TVADJUST);

				if (timercmp(&interval, &maxinterval, >))
					interval = maxinterval;

				if (interval.tv_sec == 0
				    && interval.tv_usec <= MIN_POLL_INTERVAL)
					interval.tv_usec = MIN_POLL_INTERVAL;

				r = select(0, 0, 0, 0, &interval);
				if (r < 0 && errno != EINTR)
					fatal("select() failed for pause: %s",
					      strerror(errno));
			}

		case sched_forever:
			assert(!"schedule[].type value must be valid");
		}

	next_item:
		position++;
	}

	if (quietmode <= 0)
		printf("Program %s, %d process(es), refused to die.\n",
		       what_stop, n_killed);

	return 2;

x_finished:
	if (!anykilled) {
		if (quietmode <= 0)
			printf("No %s found running; none killed.\n",
			       what_stop);
		return exitnodo;
	} else {
		return 0;
	}
}

/*
int main(int argc, char **argv) NONRETURNING;
*/

int main(int argc, char **argv)
{
	progname = argv[0];

	LIST_INIT(&namespace_head);

	parse_options(argc, argv);
	argc -= optind;
	argv += optind;

	if (execname && stat(execname, &exec_stat))
		fatal("stat %s: %s", execname, strerror(errno));

	if (userspec && sscanf(userspec, "%d", &user_id) != 1) {
		struct passwd *pw;

		pw = getpwnam(userspec);
		if (!pw)
			fatal("user `%s' not found\n", userspec);

		user_id = pw->pw_uid;
	}

	if (changegroup && sscanf(changegroup, "%d", &runas_gid) != 1) {
		struct group *gr = getgrnam(changegroup);
		if (!gr)
			fatal("group `%s' not found\n", changegroup);
		runas_gid = gr->gr_gid;
	}
	if (changeuser && sscanf(changeuser, "%d", &runas_uid) != 1) {
		struct passwd *pw = getpwnam(changeuser);
		if (!pw)
			fatal("user `%s' not found\n", changeuser);
		runas_uid = pw->pw_uid;
		if (changegroup
		    == NULL) { /* pass the default group of this user */
			changegroup = ""; /* just empty */
			runas_gid = pw->pw_gid;
		}
	}

	if (stop) {
		int i = run_stop_schedule();
		exit(i);
	}

	do_findprocs();

	if (found) {
		if (quietmode <= 0)
			printf("%s already running.\n", execname);
		exit(exitnodo);
	}
	if (testmode) {
		printf("Would start %s ", startas);
		while (argc-- > 0)
			printf("%s ", *argv++);
		if (changeuser != NULL) {
			printf(" (as user %s[%d]", changeuser, runas_uid);
			if (changegroup != NULL)
				printf(", and group %s[%d])", changegroup,
				       runas_gid);
			else
				printf(")");
		}
		if (changeroot != NULL)
			printf(" in directory %s", changeroot);
		if (nicelevel)
			printf(", and add %i to the priority", nicelevel);
		printf(".\n");
		exit(0);
	}
	if (quietmode < 0)
		printf("Starting %s...\n", startas);
	*--argv = startas;
	if (changeroot != NULL) {
		if (chdir(changeroot) < 0)
			fatal("Unable to chdir() to %s", changeroot);
		if (chroot(changeroot) < 0)
			fatal("Unable to chroot() to %s", changeroot);
	}
	if (changeuser != NULL) {
		if (setgid(runas_gid))
			fatal("Unable to set gid to %d", runas_gid);
		if (initgroups(changeuser, runas_gid))
			fatal("Unable to set initgroups() with gid %d",
			      runas_gid);
		if (setuid(runas_uid))
			fatal("Unable to set uid to %s", changeuser);
	}

	if (background) { /* ok, we need to detach this process */
		int i, fd;
		if (quietmode < 0)
			printf("Detaching to start %s...", startas);
		i = fork();
		if (i < 0) {
			fatal("Unable to fork.\n");
		}
		if (i) { /* parent */
			if (quietmode < 0)
				printf("done.\n");
			exit(0);
		}
		/* child continues here */
		/* now close all extra fds */
		for (i = getdtablesize() - 1; i >= 0; --i)
			close(i);
		/* change tty */
		fd = open("/dev/tty", O_RDWR);
		if (fd >= 0) {
			if (ioctl(fd, TIOCNOTTY, 0) < 0)
				printf("ioctl TIOCNOTTY failed: %s\n",
				       strerror(errno));
			close(fd);
		}
		chdir("/");
		umask(022);    /* set a default for dumb programs */
		setpgid(0, 0); /* set the process group */
		fd = open("/dev/null", O_RDWR); /* stdin */
		if (fd >= 0) {
			dup(fd);		/* stdout */
			dup(fd);		/* stderr */
		}
	}
	if (nicelevel) {
		errno = 0;
		if (nice(nicelevel) < 0 && errno)
			fatal("Unable to alter nice level by %i: %s", nicelevel,
			      strerror(errno));
	}
	if (mpidfile
	    && pidfile != NULL) { /* user wants _us_ to make the pidfile :) */
		FILE *pidf = fopen(pidfile, "w");
		pid_t pidt = getpid();
		if (pidf == NULL)
			fatal("Unable to open pidfile `%s' for writing: %s",
			      pidfile, strerror(errno));
		fprintf(pidf, "%ld\n", (long)pidt);
		fclose(pidf);
	}
	set_namespaces();
	execv(startas, argv);
	fatal("Unable to start %s: %s", startas, strerror(errno));
}