source: src/router/busybox/debianutils/start_stop_daemon.c @ 8864

/* vi: set sw=4 ts=4: */
/*
 * Mini start-stop-daemon implementation(s) for busybox
 *
 * Written by Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl>,
 * Adapted for busybox David Kimdon <dwhedon@gordian.com>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

/* NB: we have a problem here with /proc/NN/exe usage, similar to
 * one fixed in killall/pidof */

#include <getopt.h>
#include <sys/resource.h>

/* Override ENABLE_FEATURE_PIDFILE */
#define WANT_PIDFILE 1
#include "libbb.h"

static int signal_nr = 15;
static int user_id = -1;
static char *userspec;
static char *cmdname;
static char *execname;
static char *pidfile;
static smallint quiet;

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

static struct pid_list *found;

static int pid_is_exec(pid_t pid, const char *name)
{
        char buf[sizeof("/proc//exe") + sizeof(int)*3];
        char *execbuf;
        int n;

        sprintf(buf, "/proc/%u/exe", pid);
        n = strlen(name) + 1;
        execbuf = xzalloc(n + 1);
        readlink(buf, execbuf, n);

        /* if readlink fails, execbuf still contains "" */
        n = strcmp(execbuf, name);
        if (ENABLE_FEATURE_CLEAN_UP)
                free(execbuf);
        return !n; /* nonzero (true) if execbuf == name */
}

static int pid_is_user(int pid, int uid)
{
        struct stat sb;
        char buf[sizeof("/proc/") + sizeof(int)*3];

        sprintf(buf, "/proc/%u", 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 fname[sizeof("/proc//stat") + sizeof(int)*3];
        char *buf;
        int r = 0;

        sprintf(fname, "/proc/%u/stat", pid);
        buf = xmalloc_open_read_close(fname, NULL);
        if (buf) {
                char *p = strchr(buf, '(');
                if (p) {
                        char *pe = strrchr(++p, ')');
                        if (pe) {
                                *pe = '\0';
                                r = !strcmp(p, name);
                        }
                }
                free(buf);
        }
        return r;
}

static void check(int pid)
{
        struct pid_list *p;

        if (execname && !pid_is_exec(pid, execname)) {
                return;
        }
        if (userspec && !pid_is_user(pid, user_id)) {
                return;
        }
        if (cmdname && !pid_is_cmd(pid, cmdname)) {
                return;
        }
        p = xmalloc(sizeof(*p));
        p->next = found;
        p->pid = pid;
        found = p;
}

static void do_pidfile(void)
{
        FILE *f;
        unsigned pid;

        f = fopen(pidfile, "r");
        if (f) {
                if (fscanf(f, "%u", &pid) == 1)
                        check(pid);
                fclose(f);
        } else if (errno != ENOENT)
                bb_perror_msg_and_die("open pidfile %s", pidfile);
}

static void do_procinit(void)
{
        DIR *procdir;
        struct dirent *entry;
        int foundany, pid;

        if (pidfile) {
                do_pidfile();
                return;
        }

        procdir = xopendir("/proc");

        foundany = 0;
        while ((entry = readdir(procdir)) != NULL) {
                pid = bb_strtou(entry->d_name, NULL, 10);
                if (errno)
                        continue;
                foundany++;
                check(pid);
        }
        closedir(procdir);
        if (!foundany)
                bb_error_msg_and_die("nothing in /proc - not mounted?");
}

static int do_stop(void)
{
        char *what;
        struct pid_list *p;
        int killed = 0;

        do_procinit();

        if (cmdname) {
                if (ENABLE_FEATURE_CLEAN_UP) what = xstrdup(cmdname);
                if (!ENABLE_FEATURE_CLEAN_UP) what = cmdname;
        } else if (execname) {
                if (ENABLE_FEATURE_CLEAN_UP) what = xstrdup(execname);
                if (!ENABLE_FEATURE_CLEAN_UP) what = execname;
        } else if (pidfile)
                what = xasprintf("process in pidfile '%s'", pidfile);
        else if (userspec)
                what = xasprintf("process(es) owned by '%s'", userspec);
        else
                bb_error_msg_and_die("internal error, please report");

        if (!found) {
                if (!quiet)
                        printf("no %s found; none killed\n", what);
                killed = -1;
                goto ret;
        }
        for (p = found; p; p = p->next) {
                if (kill(p->pid, signal_nr) == 0) {
                        p->pid = - p->pid;
                        killed++;
                } else {
                        bb_perror_msg("warning: killing process %u", p->pid);
                }
        }
        if (!quiet && killed) {
                printf("stopped %s (pid", what);
                for (p = found; p; p = p->next)
                        if (p->pid < 0)
                                printf(" %u", - p->pid);
                puts(")");
        }
 ret:
        if (ENABLE_FEATURE_CLEAN_UP)
                free(what);
        return killed;
}

#if ENABLE_FEATURE_START_STOP_DAEMON_LONG_OPTIONS
static const char start_stop_daemon_longopts[] ALIGN1 =
        "stop\0"         No_argument       "K"
        "start\0"        No_argument       "S"
        "background\0"   No_argument       "b"
        "quiet\0"        No_argument       "q"
        "make-pidfile\0" No_argument       "m"
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
        "oknodo\0"       No_argument       "o"
        "verbose\0"      No_argument       "v"
        "nicelevel\0"    Required_argument "N"
#endif
        "startas\0"      Required_argument "a"
        "name\0"         Required_argument "n"
        "signal\0"       Required_argument "s"
        "user\0"         Required_argument "u"
        "chuid\0"        Required_argument "c"
        "exec\0"         Required_argument "x"
        "pidfile\0"      Required_argument "p"
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
        "retry\0"        Required_argument "R"
#endif
        ;
#endif

enum {
        CTX_STOP       = 0x1,
        CTX_START      = 0x2,
        OPT_BACKGROUND = 0x4, // -b
        OPT_QUIET      = 0x8, // -q
        OPT_MAKEPID    = 0x10, // -m
        OPT_a          = 0x20, // -a
        OPT_n          = 0x40, // -n
        OPT_s          = 0x80, // -s
        OPT_u          = 0x100, // -u
        OPT_c          = 0x200, // -c
        OPT_x          = 0x400, // -x
        OPT_p          = 0x800, // -p
        OPT_OKNODO     = 0x1000 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -o
        OPT_VERBOSE    = 0x2000 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -v
        OPT_NICELEVEL  = 0x4000 * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -N
};

int start_stop_daemon_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int start_stop_daemon_main(int argc, char **argv)
{
        unsigned opt;
        char *signame;
        char *startas;
        char *chuid;
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
//      char *retry_arg = NULL;
//      int retries = -1;
        char *opt_N;
#endif
#if ENABLE_FEATURE_START_STOP_DAEMON_LONG_OPTIONS
        applet_long_options = start_stop_daemon_longopts;
#endif

        /* Check required one context option was given */
        opt_complementary = "K:S:K--S:S--K:m?p:K?xpun:S?xa";
        opt = getopt32(argv, "KSbqma:n:s:u:c:x:p:"
                USE_FEATURE_START_STOP_DAEMON_FANCY("ovN:"),
//              USE_FEATURE_START_STOP_DAEMON_FANCY("ovN:R:"),
                &startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile
                USE_FEATURE_START_STOP_DAEMON_FANCY(,&opt_N)
//              USE_FEATURE_START_STOP_DAEMON_FANCY(,&retry_arg)
        );

        quiet = (opt & OPT_QUIET) && !(opt & OPT_VERBOSE);

        if (opt & OPT_s) {
                signal_nr = get_signum(signame);
                if (signal_nr < 0) bb_show_usage();
        }

        if (!(opt & OPT_a))
                startas = execname;

//      USE_FEATURE_START_STOP_DAEMON_FANCY(
//              if (retry_arg)
//                      retries = xatoi_u(retry_arg);
//      )
        argc -= optind;
        argv += optind;

        if (userspec) {
                user_id = bb_strtou(userspec, NULL, 10);
                if (errno)
                        user_id = xuname2uid(userspec);
        }

        if (opt & CTX_STOP) {
                int i = do_stop();
                return (opt & OPT_OKNODO) ? 0 : (i <= 0);
        }

        do_procinit();

        if (found) {
                if (!quiet)
                        printf("%s already running\n%d\n", execname, found->pid);
                return !(opt & OPT_OKNODO);
        }
        *--argv = startas;
        if (opt & OPT_BACKGROUND) {
#if BB_MMU
                bb_daemonize(0);
#else
                pid_t pid = vfork();
                if (pid < 0) /* error */
                        bb_perror_msg_and_die("vfork");
                if (pid != 0) {
                        /* parent */
                        /* why _exit? the child may have changed the stack,
                         * so "return 0" may do bad things */
                        _exit(0);
                }
                /* child */
                setsid(); /* detach from controlling tty */
                /* Redirect stdio to /dev/null, close extra FDs.
                 * We do not actually daemonize because of DAEMON_ONLY_SANITIZE */
                bb_daemonize_or_rexec(
                        DAEMON_DEVNULL_STDIO
                        + DAEMON_CLOSE_EXTRA_FDS
                        + DAEMON_ONLY_SANITIZE,
                        NULL /* argv, unused */ );
#endif
        }
        if (opt & OPT_MAKEPID) {
                /* user wants _us_ to make the pidfile */
                write_pidfile(pidfile);
        }
        if (opt & OPT_c) {
                struct bb_uidgid_t ugid;
                parse_chown_usergroup_or_die(&ugid, chuid);
                if (ugid.gid != (gid_t) -1) xsetgid(ugid.gid);
                if (ugid.uid != (uid_t) -1) xsetuid(ugid.uid);
        }
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
        if (opt & OPT_NICELEVEL) {
                /* Set process priority */
                int prio = getpriority(PRIO_PROCESS, 0) + xatoi_range(opt_N, INT_MIN/2, INT_MAX/2);
                if (setpriority(PRIO_PROCESS, 0, prio) < 0) {
                        bb_perror_msg_and_die("setpriority(%d)", prio);
                }
        }
#endif
        execv(startas, argv);
        bb_perror_msg_and_die("cannot start %s", startas);
}