debianutils/start_stop_daemon.c

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