busybox/debianutils/start_stop_daemon.c
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   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini start-stop-daemon implementation(s) for busybox
   4 *
   5 * Written by Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl>,
   6 * Adapted for busybox David Kimdon <dwhedon@gordian.com>
   7 *
   8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9 */
  10
  11/*
  12This is how it is supposed to work:
  13
  14start-stop-daemon [OPTIONS] [--start|--stop] [[--] arguments...]
  15
  16One (only) of these must be given:
  17        -S,--start              Start
  18        -K,--stop               Stop
  19
  20Search for matching processes.
  21If --stop is given, stop all matching processes (by sending a signal).
  22If --start is given, start a new process unless a matching process was found.
  23
  24Options controlling process matching
  25(if multiple conditions are specified, all must match):
  26        -u,--user USERNAME|UID  Only consider this user's processes
  27        -n,--name PROCESS_NAME  Look for processes by matching PROCESS_NAME
  28                                with comm field in /proc/$PID/stat.
  29                                Only basename is compared:
  30                                "ntpd" == "./ntpd" == "/path/to/ntpd".
  31[TODO: can PROCESS_NAME be a full pathname? Should we require full match then
  32with /proc/$PID/exe or argv[0] (comm can't be matched, it never contains path)]
  33        -x,--exec EXECUTABLE    Look for processes that were started with this
  34                                command in /proc/$PID/exe and /proc/$PID/cmdline
  35                                (/proc/$PID/cmdline is a bbox extension)
  36                                Unlike -n, we match against the full path:
  37                                "ntpd" != "./ntpd" != "/path/to/ntpd"
  38        -p,--pidfile PID_FILE   Look for processes with PID from this file
  39
  40Options which are valid for --start only:
  41        -x,--exec EXECUTABLE    Program to run (1st arg of execvp). Mandatory.
  42        -a,--startas NAME       argv[0] (defaults to EXECUTABLE)
  43        -b,--background         Put process into background
  44        -N,--nicelevel N        Add N to process' nice level
  45        -c,--chuid USER[:[GRP]] Change to specified user [and group]
  46        -m,--make-pidfile       Write PID to the pidfile
  47                                (both -m and -p must be given!)
  48
  49Options which are valid for --stop only:
  50        -s,--signal SIG         Signal to send (default:TERM)
  51        -t,--test               Exit with status 0 if process is found
  52                                (we don't actually start or stop daemons)
  53
  54Misc options:
  55        -o,--oknodo             Exit with status 0 if nothing is done
  56        -q,--quiet              Quiet
  57        -v,--verbose            Verbose
  58*/
  59//config:config START_STOP_DAEMON
  60//config:       bool "start-stop-daemon (12 kb)"
  61//config:       default y
  62//config:       help
  63//config:       start-stop-daemon is used to control the creation and
  64//config:       termination of system-level processes, usually the ones
  65//config:       started during the startup of the system.
  66//config:
  67//config:config FEATURE_START_STOP_DAEMON_LONG_OPTIONS
  68//config:       bool "Enable long options"
  69//config:       default y
  70//config:       depends on START_STOP_DAEMON && LONG_OPTS
  71//config:
  72//config:config FEATURE_START_STOP_DAEMON_FANCY
  73//config:       bool "Support additional arguments"
  74//config:       default y
  75//config:       depends on START_STOP_DAEMON
  76//config:       help
  77//config:       -o|--oknodo ignored since we exit with 0 anyway
  78//config:       -v|--verbose
  79//config:       -N|--nicelevel N
  80
  81//applet:IF_START_STOP_DAEMON(APPLET_ODDNAME(start-stop-daemon, start_stop_daemon, BB_DIR_SBIN, BB_SUID_DROP, start_stop_daemon))
  82/* not NOEXEC: uses bb_common_bufsiz1 */
  83
  84//kbuild:lib-$(CONFIG_START_STOP_DAEMON) += start_stop_daemon.o
  85
  86//usage:#define start_stop_daemon_trivial_usage
  87//usage:       "[OPTIONS] [-S|-K] ... [-- ARGS...]"
  88//usage:#define start_stop_daemon_full_usage "\n\n"
  89//usage:       "Search for matching processes, and then\n"
  90//usage:       "-K: stop all matching processes\n"
  91//usage:       "-S: start a process unless a matching process is found\n"
  92//usage:     "\nProcess matching:"
  93//usage:     "\n        -u USERNAME|UID Match only this user's processes"
  94//usage:     "\n        -n NAME         Match processes with NAME"
  95//usage:     "\n                        in comm field in /proc/PID/stat"
  96//usage:     "\n        -x EXECUTABLE   Match processes with this command"
  97//usage:     "\n                        in /proc/PID/cmdline"
  98//usage:     "\n        -p FILE         Match a process with PID from FILE"
  99//usage:     "\n        All specified conditions must match"
 100//usage:     "\n-S only:"
 101//usage:     "\n        -x EXECUTABLE   Program to run"
 102//usage:     "\n        -a NAME         Zeroth argument"
 103//usage:     "\n        -b              Background"
 104//usage:        IF_FEATURE_START_STOP_DAEMON_FANCY(
 105//usage:     "\n        -N N            Change nice level"
 106//usage:        )
 107//usage:     "\n        -c USER[:[GRP]] Change user/group"
 108//usage:     "\n        -m              Write PID to pidfile specified by -p"
 109//usage:     "\n-K only:"
 110//usage:     "\n        -s SIG          Signal to send"
 111//usage:     "\n        -t              Match only, exit with 0 if found"
 112//usage:     "\nOther:"
 113//usage:        IF_FEATURE_START_STOP_DAEMON_FANCY(
 114//usage:     "\n        -o              Exit with status 0 if nothing is done"
 115//usage:     "\n        -v              Verbose"
 116//usage:        )
 117//usage:     "\n        -q              Quiet"
 118
 119/* Override ENABLE_FEATURE_PIDFILE */
 120#define WANT_PIDFILE 1
 121#include "libbb.h"
 122#include "common_bufsiz.h"
 123
 124struct pid_list {
 125        struct pid_list *next;
 126        pid_t pid;
 127};
 128
 129enum {
 130        CTX_STOP       = (1 <<  0),
 131        CTX_START      = (1 <<  1),
 132        OPT_BACKGROUND = (1 <<  2), // -b
 133        OPT_QUIET      = (1 <<  3), // -q
 134        OPT_TEST       = (1 <<  4), // -t
 135        OPT_MAKEPID    = (1 <<  5), // -m
 136        OPT_a          = (1 <<  6), // -a
 137        OPT_n          = (1 <<  7), // -n
 138        OPT_s          = (1 <<  8), // -s
 139        OPT_u          = (1 <<  9), // -u
 140        OPT_c          = (1 << 10), // -c
 141        OPT_x          = (1 << 11), // -x
 142        OPT_p          = (1 << 12), // -p
 143        OPT_OKNODO     = (1 << 13) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -o
 144        OPT_VERBOSE    = (1 << 14) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -v
 145        OPT_NICELEVEL  = (1 << 15) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -N
 146};
 147#define QUIET (option_mask32 & OPT_QUIET)
 148#define TEST  (option_mask32 & OPT_TEST)
 149
 150struct globals {
 151        struct pid_list *found_procs;
 152        char *userspec;
 153        char *cmdname;
 154        char *execname;
 155        char *pidfile;
 156        char *execname_cmpbuf;
 157        unsigned execname_sizeof;
 158        int user_id;
 159        smallint signal_nr;
 160#ifdef OLDER_VERSION_OF_X
 161        struct stat execstat;
 162#endif
 163} FIX_ALIASING;
 164#define G (*(struct globals*)bb_common_bufsiz1)
 165#define userspec          (G.userspec            )
 166#define cmdname           (G.cmdname             )
 167#define execname          (G.execname            )
 168#define pidfile           (G.pidfile             )
 169#define user_id           (G.user_id             )
 170#define signal_nr         (G.signal_nr           )
 171#define INIT_G() do { \
 172        setup_common_bufsiz(); \
 173        user_id = -1; \
 174        signal_nr = 15; \
 175} while (0)
 176
 177#ifdef OLDER_VERSION_OF_X
 178/* -x,--exec EXECUTABLE
 179 * Look for processes with matching /proc/$PID/exe.
 180 * Match is performed using device+inode.
 181 */
 182static int pid_is_exec(pid_t pid)
 183{
 184        struct stat st;
 185        char buf[sizeof("/proc/%u/exe") + sizeof(int)*3];
 186
 187        sprintf(buf, "/proc/%u/exe", (unsigned)pid);
 188        if (stat(buf, &st) < 0)
 189                return 0;
 190        if (st.st_dev == G.execstat.st_dev
 191         && st.st_ino == G.execstat.st_ino)
 192                return 1;
 193        return 0;
 194}
 195#else
 196static int pid_is_exec(pid_t pid)
 197{
 198        ssize_t bytes;
 199        char buf[sizeof("/proc/%u/cmdline") + sizeof(int)*3];
 200        char *procname, *exelink;
 201        int match;
 202
 203        procname = buf + sprintf(buf, "/proc/%u/exe", (unsigned)pid) - 3;
 204
 205        exelink = xmalloc_readlink(buf);
 206        match = (exelink && strcmp(execname, exelink) == 0);
 207        free(exelink);
 208        if (match)
 209                return match;
 210
 211        strcpy(procname, "cmdline");
 212        bytes = open_read_close(buf, G.execname_cmpbuf, G.execname_sizeof);
 213        if (bytes > 0) {
 214                G.execname_cmpbuf[bytes] = '\0';
 215                return strcmp(execname, G.execname_cmpbuf) == 0;
 216        }
 217        return 0;
 218}
 219#endif
 220
 221static int pid_is_name(pid_t pid)
 222{
 223        /* /proc/PID/stat is "PID (comm_15_bytes_max) ..." */
 224        char buf[32]; /* should be enough */
 225        char *p, *pe;
 226
 227        sprintf(buf, "/proc/%u/stat", (unsigned)pid);
 228        if (open_read_close(buf, buf, sizeof(buf) - 1) < 0)
 229                return 0;
 230        buf[sizeof(buf) - 1] = '\0'; /* paranoia */
 231        p = strchr(buf, '(');
 232        if (!p)
 233                return 0;
 234        pe = strrchr(++p, ')');
 235        if (!pe)
 236                return 0;
 237        *pe = '\0';
 238        /* we require comm to match and to not be truncated */
 239        /* in Linux, if comm is 15 chars, it may be a truncated
 240         * name, so we don't allow that to match */
 241        if (strlen(p) >= COMM_LEN - 1) /* COMM_LEN is 16 */
 242                return 0;
 243        return strcmp(p, cmdname) == 0;
 244}
 245
 246static int pid_is_user(int pid)
 247{
 248        struct stat sb;
 249        char buf[sizeof("/proc/") + sizeof(int)*3];
 250
 251        sprintf(buf, "/proc/%u", (unsigned)pid);
 252        if (stat(buf, &sb) != 0)
 253                return 0;
 254        return (sb.st_uid == (uid_t)user_id);
 255}
 256
 257static void check(int pid)
 258{
 259        struct pid_list *p;
 260
 261        if (execname && !pid_is_exec(pid)) {
 262                return;
 263        }
 264        if (cmdname && !pid_is_name(pid)) {
 265                return;
 266        }
 267        if (userspec && !pid_is_user(pid)) {
 268                return;
 269        }
 270        p = xmalloc(sizeof(*p));
 271        p->next = G.found_procs;
 272        p->pid = pid;
 273        G.found_procs = p;
 274}
 275
 276static void do_pidfile(void)
 277{
 278        FILE *f;
 279        unsigned pid;
 280
 281        f = fopen_for_read(pidfile);
 282        if (f) {
 283                if (fscanf(f, "%u", &pid) == 1)
 284                        check(pid);
 285                fclose(f);
 286        } else if (errno != ENOENT)
 287                bb_perror_msg_and_die("open pidfile %s", pidfile);
 288}
 289
 290static void do_procinit(void)
 291{
 292        DIR *procdir;
 293        struct dirent *entry;
 294        int pid;
 295
 296        if (pidfile) {
 297                do_pidfile();
 298                return;
 299        }
 300
 301        procdir = xopendir("/proc");
 302
 303        pid = 0;
 304        while (1) {
 305                errno = 0; /* clear any previous error */
 306                entry = readdir(procdir);
 307// TODO: this check is too generic, it's better
 308// to check for exact errno(s) which mean that we got stale entry
 309                if (errno) /* Stale entry, process has died after opendir */
 310                        continue;
 311                if (!entry) /* EOF, no more entries */
 312                        break;
 313                pid = bb_strtou(entry->d_name, NULL, 10);
 314                if (errno) /* NaN */
 315                        continue;
 316                check(pid);
 317        }
 318        closedir(procdir);
 319        if (!pid)
 320                bb_error_msg_and_die("nothing in /proc - not mounted?");
 321}
 322
 323static int do_stop(void)
 324{
 325        char *what;
 326        struct pid_list *p;
 327        int killed = 0;
 328
 329        if (cmdname) {
 330                if (ENABLE_FEATURE_CLEAN_UP) what = xstrdup(cmdname);
 331                if (!ENABLE_FEATURE_CLEAN_UP) what = cmdname;
 332        } else if (execname) {
 333                if (ENABLE_FEATURE_CLEAN_UP) what = xstrdup(execname);
 334                if (!ENABLE_FEATURE_CLEAN_UP) what = execname;
 335        } else if (pidfile) {
 336                what = xasprintf("process in pidfile '%s'", pidfile);
 337        } else if (userspec) {
 338                what = xasprintf("process(es) owned by '%s'", userspec);
 339        } else {
 340                bb_error_msg_and_die("internal error, please report");
 341        }
 342
 343        if (!G.found_procs) {
 344                if (!QUIET)
 345                        printf("no %s found; none killed\n", what);
 346                killed = -1;
 347                goto ret;
 348        }
 349        for (p = G.found_procs; p; p = p->next) {
 350                if (kill(p->pid, TEST ? 0 : signal_nr) == 0) {
 351                        killed++;
 352                } else {
 353                        bb_perror_msg("warning: killing process %u", (unsigned)p->pid);
 354                        p->pid = 0;
 355                        if (TEST) {
 356                                /* Example: -K --test --pidfile PIDFILE detected
 357                                 * that PIDFILE's pid doesn't exist */
 358                                killed = -1;
 359                                goto ret;
 360                        }
 361                }
 362        }
 363        if (!QUIET && killed) {
 364                printf("stopped %s (pid", what);
 365                for (p = G.found_procs; p; p = p->next)
 366                        if (p->pid)
 367                                printf(" %u", (unsigned)p->pid);
 368                puts(")");
 369        }
 370 ret:
 371        if (ENABLE_FEATURE_CLEAN_UP)
 372                free(what);
 373        return killed;
 374}
 375
 376#if ENABLE_FEATURE_START_STOP_DAEMON_LONG_OPTIONS
 377static const char start_stop_daemon_longopts[] ALIGN1 =
 378        "stop\0"         No_argument       "K"
 379        "start\0"        No_argument       "S"
 380        "background\0"   No_argument       "b"
 381        "quiet\0"        No_argument       "q"
 382        "test\0"         No_argument       "t"
 383        "make-pidfile\0" No_argument       "m"
 384# if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
 385        "oknodo\0"       No_argument       "o"
 386        "verbose\0"      No_argument       "v"
 387        "nicelevel\0"    Required_argument "N"
 388# endif
 389        "startas\0"      Required_argument "a"
 390        "name\0"         Required_argument "n"
 391        "signal\0"       Required_argument "s"
 392        "user\0"         Required_argument "u"
 393        "chuid\0"        Required_argument "c"
 394        "exec\0"         Required_argument "x"
 395        "pidfile\0"      Required_argument "p"
 396# if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
 397        "retry\0"        Required_argument "R"
 398# endif
 399        ;
 400# define GETOPT32 getopt32long
 401# define LONGOPTS start_stop_daemon_longopts,
 402#else
 403# define GETOPT32 getopt32
 404# define LONGOPTS
 405#endif
 406
 407int start_stop_daemon_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 408int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
 409{
 410        unsigned opt;
 411        char *signame;
 412        char *startas = NULL;
 413        char *chuid;
 414#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
 415//      char *retry_arg = NULL;
 416//      int retries = -1;
 417        char *opt_N;
 418#endif
 419
 420        INIT_G();
 421
 422        opt = GETOPT32(argv, "^"
 423                "KSbqtma:n:s:u:c:x:p:"
 424                IF_FEATURE_START_STOP_DAEMON_FANCY("ovN:R:")
 425                        /* -K or -S is required; they are mutually exclusive */
 426                        /* -p is required if -m is given */
 427                        /* -xpun (at least one) is required if -K is given */
 428//                      /* -xa (at least one) is required if -S is given */
 429//WRONG: "start-stop-daemon -S -- sleep 5" is a valid invocation
 430                        /* -q turns off -v */
 431                        "\0"
 432                        "K:S:K--S:S--K:m?p:K?xpun"
 433                        IF_FEATURE_START_STOP_DAEMON_FANCY("q-v"),
 434                LONGOPTS
 435                &startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile
 436                IF_FEATURE_START_STOP_DAEMON_FANCY(,&opt_N)
 437                /* We accept and ignore -R <param> / --retry <param> */
 438                IF_FEATURE_START_STOP_DAEMON_FANCY(,NULL)
 439        );
 440
 441        if (opt & OPT_s) {
 442                signal_nr = get_signum(signame);
 443                if (signal_nr < 0) bb_show_usage();
 444        }
 445
 446        //argc -= optind;
 447        argv += optind;
 448// ARGS contains zeroth arg if -x/-a is not given, else it starts with 1st arg.
 449// These will try to execute "[/bin/]sleep 5":
 450// "start-stop-daemon -S               -- sleep 5"
 451// "start-stop-daemon -S -x /bin/sleep -- 5"
 452// "start-stop-daemon -S -a sleep      -- 5"
 453// NB: -n option does _not_ behave in this way: this will try to execute "5":
 454// "start-stop-daemon -S -n sleep      -- 5"
 455        if (opt & CTX_START) {
 456                if (!execname) { /* -x is not given */
 457                        execname = startas;
 458                        if (!execname) { /* neither -x nor -a is given */
 459                                execname = argv[0];
 460                                if (!execname)
 461                                        bb_show_usage();
 462                                argv++;
 463                        }
 464                }
 465                if (!startas) /* -a is not given: use -x EXECUTABLE or argv[0] */
 466                        startas = execname;
 467                *--argv = startas;
 468        }
 469        if (execname) {
 470                G.execname_sizeof = strlen(execname) + 1;
 471                G.execname_cmpbuf = xmalloc(G.execname_sizeof + 1);
 472        }
 473//      IF_FEATURE_START_STOP_DAEMON_FANCY(
 474//              if (retry_arg)
 475//                      retries = xatoi_positive(retry_arg);
 476//      )
 477        if (userspec) {
 478                user_id = bb_strtou(userspec, NULL, 10);
 479                if (errno)
 480                        user_id = xuname2uid(userspec);
 481        }
 482
 483        /* Both start and stop need to know current processes */
 484        do_procinit();
 485
 486        if (opt & CTX_STOP) {
 487                int i = do_stop();
 488                return (opt & OPT_OKNODO) ? 0 : (i <= 0);
 489        }
 490
 491        /* else: CTX_START (-S). execname can't be NULL. */
 492
 493        if (G.found_procs) {
 494                if (!QUIET)
 495                        printf("%s is already running\n", execname);
 496                return !(opt & OPT_OKNODO);
 497        }
 498
 499#ifdef OLDER_VERSION_OF_X
 500        if (execname)
 501                xstat(execname, &G.execstat);
 502#endif
 503
 504        if (opt & OPT_BACKGROUND) {
 505                /* Daemons usually call bb_daemonize_or_rexec(), but SSD can do
 506                 * without: SSD is not itself a daemon, it _execs_ a daemon.
 507                 * The usual NOMMU problem of "child can't run indefinitely,
 508                 * it must exec" does not bite us: we exec anyway.
 509                 *
 510                 * bb_daemonize(DAEMON_DEVNULL_STDIO | DAEMON_CLOSE_EXTRA_FDS | DAEMON_DOUBLE_FORK)
 511                 * can be used on MMU systems, but use of vfork()
 512                 * is preferable since we want to create pidfile
 513                 * _before_ parent returns, and vfork() on Linux
 514                 * ensures that (by blocking parent until exec in the child).
 515                 */
 516                pid_t pid = xvfork();
 517                if (pid != 0) {
 518                        /* Parent */
 519                        /* why _exit? the child may have changed the stack,
 520                         * so "return 0" may do bad things
 521                         */
 522                        _exit(EXIT_SUCCESS);
 523                }
 524                /* Child */
 525                setsid(); /* detach from controlling tty */
 526                /* Redirect stdio to /dev/null, close extra FDs */
 527                bb_daemon_helper(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS);
 528                /* On Linux, session leader can acquire ctty
 529                 * unknowingly, by opening a tty.
 530                 * Prevent this: stop being a session leader.
 531                 */
 532                pid = xvfork();
 533                if (pid != 0)
 534                        _exit(EXIT_SUCCESS); /* Parent */
 535        }
 536        if (opt & OPT_MAKEPID) {
 537                /* User wants _us_ to make the pidfile */
 538                write_pidfile(pidfile);
 539        }
 540#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
 541        if (opt & OPT_NICELEVEL) {
 542                /* Set process priority (must be before OPT_c) */
 543                int prio = getpriority(PRIO_PROCESS, 0) + xatoi_range(opt_N, INT_MIN/2, INT_MAX/2);
 544                if (setpriority(PRIO_PROCESS, 0, prio) < 0) {
 545                        bb_perror_msg_and_die("setpriority(%d)", prio);
 546                }
 547        }
 548#endif
 549        if (opt & OPT_c) {
 550                struct bb_uidgid_t ugid;
 551                parse_chown_usergroup_or_die(&ugid, chuid);
 552                if (ugid.uid != (uid_t) -1L) {
 553                        struct passwd *pw = xgetpwuid(ugid.uid);
 554                        if (ugid.gid != (gid_t) -1L)
 555                                pw->pw_gid = ugid.gid;
 556                        /* initgroups, setgid, setuid: */
 557                        change_identity(pw);
 558                } else if (ugid.gid != (gid_t) -1L) {
 559                        xsetgid(ugid.gid);
 560                        setgroups(1, &ugid.gid);
 561                }
 562        }
 563        /* Try:
 564         * strace -oLOG start-stop-daemon -S -x /bin/usleep -a qwerty 500000
 565         * should exec "/bin/usleep", but argv[0] should be "qwerty":
 566         */
 567        execvp(execname, argv);
 568        bb_perror_msg_and_die("can't execute '%s'", startas);
 569}
 570