source: MondoRescue/branches/3.2/mindi-busybox/debianutils/start_stop_daemon.c@ 3232

/* 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 source tree.
 */

/*
This is how it is supposed to work:

start-stop-daemon [OPTIONS] [--start|--stop] [[--] arguments...]

One (only) of these must be given:
        -S,--start              Start
        -K,--stop               Stop

Search for matching processes.
If --stop is given, stop all matching processes (by sending a signal).
If --start is given, start a new process unless a matching process was found.

Options controlling process matching
(if multiple conditions are specified, all must match):
        -u,--user USERNAME|UID  Only consider this user's processes
        -n,--name PROCESS_NAME  Look for processes by matching PROCESS_NAME
                                with comm field in /proc/$PID/stat.
                                Only basename is compared:
                                "ntpd" == "./ntpd" == "/path/to/ntpd".
[TODO: can PROCESS_NAME be a full pathname? Should we require full match then
with /proc/$PID/exe or argv[0] (comm can't be matched, it never contains path)]
        -x,--exec EXECUTABLE    Look for processes that were started with this
                                command in /proc/$PID/exe and /proc/$PID/cmdline
                                (/proc/$PID/cmdline is a bbox extension)
                                Unlike -n, we match against the full path:
                                "ntpd" != "./ntpd" != "/path/to/ntpd"
        -p,--pidfile PID_FILE   Look for processes with PID from this file

Options which are valid for --start only:
        -x,--exec EXECUTABLE    Program to run (1st arg of execvp). Mandatory.
        -a,--startas NAME       argv[0] (defaults to EXECUTABLE)
        -b,--background         Put process into background
        -N,--nicelevel N        Add N to process' nice level
        -c,--chuid USER[:[GRP]] Change to specified user [and group]
        -m,--make-pidfile       Write PID to the pidfile
                                (both -m and -p must be given!)

Options which are valid for --stop only:
        -s,--signal SIG         Signal to send (default:TERM)
        -t,--test               Exit with status 0 if process is found
                                (we don't actually start or stop daemons)

Misc options:
        -o,--oknodo             Exit with status 0 if nothing is done
        -q,--quiet              Quiet
        -v,--verbose            Verbose
*/

//usage:#define start_stop_daemon_trivial_usage
//usage:       "[OPTIONS] [-S|-K] ... [-- ARGS...]"
//usage:#define start_stop_daemon_full_usage "\n\n"
//usage:       "Search for matching processes, and then\n"
//usage:       "-K: stop all matching processes.\n"
//usage:       "-S: start a process unless a matching process is found.\n"
//usage:    IF_FEATURE_START_STOP_DAEMON_LONG_OPTIONS(
//usage:     "\nProcess matching:"
//usage:     "\n    -u,--user USERNAME|UID  Match only this user's processes"
//usage:     "\n    -n,--name NAME      Match processes with NAME"
//usage:     "\n                in comm field in /proc/PID/stat"
//usage:     "\n    -x,--exec EXECUTABLE    Match processes with this command"
//usage:     "\n                in /proc/PID/{exe,cmdline}"
//usage:     "\n    -p,--pidfile FILE   Match a process with PID from the file"
//usage:     "\n    All specified conditions must match"
//usage:     "\n-S only:"
//usage:     "\n    -x,--exec EXECUTABLE    Program to run"
//usage:     "\n    -a,--startas NAME   Zeroth argument"
//usage:     "\n    -b,--background     Background"
//usage:    IF_FEATURE_START_STOP_DAEMON_FANCY(
//usage:     "\n    -N,--nicelevel N    Change nice level"
//usage:    )
//usage:     "\n    -c,--chuid USER[:[GRP]] Change to user/group"
//usage:     "\n    -m,--make-pidfile   Write PID to the pidfile specified by -p"
//usage:     "\n-K only:"
//usage:     "\n    -s,--signal SIG     Signal to send"
//usage:     "\n    -t,--test       Match only, exit with 0 if a process is found"
//usage:     "\nOther:"
//usage:    IF_FEATURE_START_STOP_DAEMON_FANCY(
//usage:     "\n    -o,--oknodo     Exit with status 0 if nothing is done"
//usage:     "\n    -v,--verbose        Verbose"
//usage:    )
//usage:     "\n    -q,--quiet      Quiet"
//usage:    )
//usage:    IF_NOT_FEATURE_START_STOP_DAEMON_LONG_OPTIONS(
//usage:     "\nProcess matching:"
//usage:     "\n    -u USERNAME|UID Match only this user's processes"
//usage:     "\n    -n NAME     Match processes with NAME"
//usage:     "\n            in comm field in /proc/PID/stat"
//usage:     "\n    -x EXECUTABLE   Match processes with this command"
//usage:     "\n            command in /proc/PID/cmdline"
//usage:     "\n    -p FILE     Match a process with PID from the file"
//usage:     "\n    All specified conditions must match"
//usage:     "\n-S only:"
//usage:     "\n    -x EXECUTABLE   Program to run"
//usage:     "\n    -a NAME     Zeroth argument"
//usage:     "\n    -b      Background"
//usage:    IF_FEATURE_START_STOP_DAEMON_FANCY(
//usage:     "\n    -N N        Change nice level"
//usage:    )
//usage:     "\n    -c USER[:[GRP]] Change to user/group"
//usage:     "\n    -m      Write PID to the pidfile specified by -p"
//usage:     "\n-K only:"
//usage:     "\n    -s SIG      Signal to send"
//usage:     "\n    -t      Match only, exit with 0 if a process is found"
//usage:     "\nOther:"
//usage:    IF_FEATURE_START_STOP_DAEMON_FANCY(
//usage:     "\n    -o      Exit with status 0 if nothing is done"
//usage:     "\n    -v      Verbose"
//usage:    )
//usage:     "\n    -q      Quiet"
//usage:    )

#include <sys/resource.h>

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

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

enum {
    CTX_STOP       = (1 <<  0),
    CTX_START      = (1 <<  1),
    OPT_BACKGROUND = (1 <<  2), // -b
    OPT_QUIET      = (1 <<  3), // -q
    OPT_TEST       = (1 <<  4), // -t
    OPT_MAKEPID    = (1 <<  5), // -m
    OPT_a          = (1 <<  6), // -a
    OPT_n          = (1 <<  7), // -n
    OPT_s          = (1 <<  8), // -s
    OPT_u          = (1 <<  9), // -u
    OPT_c          = (1 << 10), // -c
    OPT_x          = (1 << 11), // -x
    OPT_p          = (1 << 12), // -p
    OPT_OKNODO     = (1 << 13) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -o
    OPT_VERBOSE    = (1 << 14) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -v
    OPT_NICELEVEL  = (1 << 15) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -N
};
#define QUIET (option_mask32 & OPT_QUIET)
#define TEST  (option_mask32 & OPT_TEST)

struct globals {
    struct pid_list *found_procs;
    char *userspec;
    char *cmdname;
    char *execname;
    char *pidfile;
    char *execname_cmpbuf;
    unsigned execname_sizeof;
    int user_id;
    smallint signal_nr;
} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
#define userspec          (G.userspec            )
#define cmdname           (G.cmdname             )
#define execname          (G.execname            )
#define pidfile           (G.pidfile             )
#define user_id           (G.user_id             )
#define signal_nr         (G.signal_nr           )
#define INIT_G() do { \
    user_id = -1; \
    signal_nr = 15; \
} while (0)

#ifdef OLDER_VERSION_OF_X
/* -x,--exec EXECUTABLE
 * Look for processes with matching /proc/$PID/exe.
 * Match is performed using device+inode.
 */
static int pid_is_exec(pid_t pid)
{
    struct stat st;
    char buf[sizeof("/proc/%u/exe") + sizeof(int)*3];

    sprintf(buf, "/proc/%u/exe", (unsigned)pid);
    if (stat(buf, &st) < 0)
        return 0;
    if (st.st_dev == execstat.st_dev
     && st.st_ino == execstat.st_ino)
        return 1;
    return 0;
}
#endif

static int pid_is_exec(pid_t pid)
{
    ssize_t bytes;
    char buf[sizeof("/proc/%u/cmdline") + sizeof(int)*3];
    char *procname, *exelink;
    int match;

    procname = buf + sprintf(buf, "/proc/%u/exe", (unsigned)pid) - 3;

    exelink = xmalloc_readlink(buf);
    match = (exelink && strcmp(execname, exelink) == 0);
    free(exelink);
    if (match)
        return match;

    strcpy(procname, "cmdline");
    bytes = open_read_close(buf, G.execname_cmpbuf, G.execname_sizeof);
    if (bytes > 0) {
        G.execname_cmpbuf[bytes] = '\0';
        return strcmp(execname, G.execname_cmpbuf) == 0;
    }
    return 0;
}

static int pid_is_name(pid_t pid)
{
    /* /proc/PID/stat is "PID (comm_15_bytes_max) ..." */
    char buf[32]; /* should be enough */
    char *p, *pe;

    sprintf(buf, "/proc/%u/stat", (unsigned)pid);
    if (open_read_close(buf, buf, sizeof(buf) - 1) < 0)
        return 0;
    buf[sizeof(buf) - 1] = '\0'; /* paranoia */
    p = strchr(buf, '(');
    if (!p)
        return 0;
    pe = strrchr(++p, ')');
    if (!pe)
        return 0;
    *pe = '\0';
    /* we require comm to match and to not be truncated */
    /* in Linux, if comm is 15 chars, it may be a truncated
     * name, so we don't allow that to match */
    if (strlen(p) >= COMM_LEN - 1) /* COMM_LEN is 16 */
        return 0;
    return strcmp(p, cmdname) == 0;
}

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

    sprintf(buf, "/proc/%u", (unsigned)pid);
    if (stat(buf, &sb) != 0)
        return 0;
    return (sb.st_uid == (uid_t)user_id);
}

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

    if (execname && !pid_is_exec(pid)) {
        return;
    }
    if (cmdname && !pid_is_name(pid)) {
        return;
    }
    if (userspec && !pid_is_user(pid)) {
        return;
    }
    p = xmalloc(sizeof(*p));
    p->next = G.found_procs;
    p->pid = pid;
    G.found_procs = p;
}

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

    f = fopen_for_read(pidfile);
    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 pid;

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

    procdir = xopendir("/proc");

    pid = 0;
    while (1) {
        errno = 0; /* clear any previous error */
        entry = readdir(procdir);
// TODO: this check is too generic, it's better
// to check for exact errno(s) which mean that we got stale entry
        if (errno) /* Stale entry, process has died after opendir */
            continue;
        if (!entry) /* EOF, no more entries */
            break;
        pid = bb_strtou(entry->d_name, NULL, 10);
        if (errno) /* NaN */
            continue;
        check(pid);
    }
    closedir(procdir);
    if (!pid)
        bb_error_msg_and_die("nothing in /proc - not mounted?");
}

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

    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 (!G.found_procs) {
        if (!QUIET)
            printf("no %s found; none killed\n", what);
        killed = -1;
        goto ret;
    }
    for (p = G.found_procs; p; p = p->next) {
        if (kill(p->pid, TEST ? 0 : signal_nr) == 0) {
            killed++;
        } else {
            bb_perror_msg("warning: killing process %u", (unsigned)p->pid);
            p->pid = 0;
            if (TEST) {
                /* Example: -K --test --pidfile PIDFILE detected
                 * that PIDFILE's pid doesn't exist */
                killed = -1;
                goto ret;
            }
        }
    }
    if (!QUIET && killed) {
        printf("stopped %s (pid", what);
        for (p = G.found_procs; p; p = p->next)
            if (p->pid)
                printf(" %u", (unsigned)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"
    "test\0"         No_argument       "t"
    "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

int start_stop_daemon_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
{
    unsigned opt;
    char *signame;
    char *startas;
    char *chuid;
#ifdef OLDER_VERSION_OF_X
    struct stat execstat;
#endif
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
//  char *retry_arg = NULL;
//  int retries = -1;
    char *opt_N;
#endif

    INIT_G();

#if ENABLE_FEATURE_START_STOP_DAEMON_LONG_OPTIONS
    applet_long_options = start_stop_daemon_longopts;
#endif

    /* -K or -S is required; they are mutually exclusive */
    /* -p is required if -m is given */
    /* -xpun (at least one) is required if -K is given */
    /* -xa (at least one) is required if -S is given */
    /* -q turns off -v */
    opt_complementary = "K:S:K--S:S--K:m?p:K?xpun:S?xa"
        IF_FEATURE_START_STOP_DAEMON_FANCY("q-v");
    opt = getopt32(argv, "KSbqtma:n:s:u:c:x:p:"
        IF_FEATURE_START_STOP_DAEMON_FANCY("ovN:R:"),
        &startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile
        IF_FEATURE_START_STOP_DAEMON_FANCY(,&opt_N)
        /* We accept and ignore -R <param> / --retry <param> */
        IF_FEATURE_START_STOP_DAEMON_FANCY(,NULL)
    );

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

    if (!(opt & OPT_a))
        startas = execname;
    if (!execname) /* in case -a is given and -x is not */
        execname = startas;
    if (execname) {
        G.execname_sizeof = strlen(execname) + 1;
        G.execname_cmpbuf = xmalloc(G.execname_sizeof + 1);
    }

//  IF_FEATURE_START_STOP_DAEMON_FANCY(
//      if (retry_arg)
//          retries = xatoi_positive(retry_arg);
//  )
    //argc -= optind;
    argv += optind;

    if (userspec) {
        user_id = bb_strtou(userspec, NULL, 10);
        if (errno)
            user_id = xuname2uid(userspec);
    }
    /* Both start and stop need to know current processes */
    do_procinit();

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

    if (G.found_procs) {
        if (!QUIET)
            printf("%s is already running\n%u\n", execname, (unsigned)G.found_procs->pid);
        return !(opt & OPT_OKNODO);
    }

#ifdef OLDER_VERSION_OF_X
    if (execname)
        xstat(execname, &execstat);
#endif

    *--argv = startas;
    if (opt & OPT_BACKGROUND) {
#if BB_MMU
        bb_daemonize(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS + DAEMON_DOUBLE_FORK);
        /* DAEMON_DEVNULL_STDIO is superfluous -
         * it's always done by bb_daemonize() */
#else
        pid_t pid = xvfork();
        if (pid != 0) {
            /* parent */
            /* why _exit? the child may have changed the stack,
             * so "return 0" may do bad things */
            _exit(EXIT_SUCCESS);
        }
        /* 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 = { -1, -1 };
        parse_chown_usergroup_or_die(&ugid, chuid);
        if (ugid.uid != (uid_t) -1) {
            struct passwd *pw = xgetpwuid(ugid.uid);
            if (ugid.gid != (gid_t) -1)
                pw->pw_gid = ugid.gid;
            /* initgroups, setgid, setuid: */
            change_identity(pw);
        } else if (ugid.gid != (gid_t) -1) {
            xsetgid(ugid.gid);
            setgroups(1, &ugid.gid);
        }
    }
#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
    execvp(startas, argv);
    bb_perror_msg_and_die("can't execute '%s'", startas);
}