Merge pull request #12798 from donaldsharp/rib_match_multicast

[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));
}