dss.c

   1 #include <string.h>
   2 #include <stdlib.h>
   3 #include <stdarg.h>
   4 #include <assert.h>
   5 #include <errno.h>
   6 #include <sys/types.h>
   7 #include <signal.h>
   8 #include <ctype.h>
   9 #include <sys/stat.h>
  10 #include <unistd.h>
  11 #include <inttypes.h>
  12 #include <sys/time.h>
  13 #include <time.h>
  14 #include <sys/wait.h>
  15 #include <fnmatch.h>
  16 #include <limits.h>
  17
  18
  19 #include "gcc-compat.h"
  20 #include "cmdline.h"
  21 #include "log.h"
  22 #include "string.h"
  23 #include "error.h"
  24 #include "fd.h"
  25 #include "exec.h"
  26 #include "daemon.h"
  27 #include "signal.h"
  28 #include "df.h"
  29 #include "time.h"
  30 #include "snap.h"
  31
  32 /** Command line and config file options. */
  33 static struct gengetopt_args_info conf;
  34 /** Non-NULL if we log to a file. */
  35 static FILE *logfile;
  36 /** The read end of the signal pipe */
  37 static int signal_pipe;
  38 /** Process id of current rsync process. */
  39 static pid_t rsync_pid;
  40 /** Whether the rsync process is currently stopped */
  41 static int rsync_stopped;
  42 /** Process id of current rm process. */
  43 static pid_t rm_pid;
  44 /** When the next snapshot is due. */
  45 static struct timeval next_snapshot_time;
  46 /** The pid of the pre-create hook. */
  47 static pid_t pre_create_hook_pid;
  48 /** The pid of the post-create hook. */
  49 static pid_t post_create_hook_pid;
  50 /** Creation time of the snapshot currently being created. */
  51 static int64_t current_snapshot_creation_time;
  52 /** Needed by the post-create hook. */
  53 static char *path_to_last_complete_snapshot;
  54 /** \sa \ref snap.h for details. */
  55 static unsigned snapshot_creation_status;
  56
  57
  58 DEFINE_DSS_ERRLIST;
  59
  60
  61 /* a litte cpp magic helps to DRY */
  62 #define COMMANDS \
  63         COMMAND(ls) \
  64         COMMAND(create) \
  65         COMMAND(prune) \
  66         COMMAND(run)
  67 #define COMMAND(x) static int com_ ##x(void);
  68 COMMANDS
  69 #undef COMMAND
  70 #define COMMAND(x) if (conf.x ##_given) return com_ ##x();
  71 static int call_command_handler(void)
  72 {
  73         COMMANDS
  74         DSS_EMERG_LOG("BUG: did not find command handler\n");
  75         exit(EXIT_FAILURE);
  76 }
  77 #undef COMMAND
  78 #undef COMMANDS
  79
  80 /**
  81  * The log function of dss.
  82  *
  83  * \param ll Loglevel.
  84  * \param fml Usual format string.
  85  *
  86  * All DSS_XXX_LOG() macros use this function.
  87  */
  88 __printf_2_3 void dss_log(int ll, const char* fmt,...)
  89 {
  90         va_list argp;
  91         FILE *outfd;
  92         struct tm *tm;
  93         time_t t1;
  94         char str[255] = "";
  95
  96         if (ll < conf.loglevel_arg)
  97                 return;
  98         outfd = logfile? logfile : stderr;
  99         time(&t1);
 100         tm = localtime(&t1);
 101         strftime(str, sizeof(str), "%b %d %H:%M:%S", tm);
 102         fprintf(outfd, "%s ", str);
 103         if (conf.loglevel_arg <= INFO)
 104                 fprintf(outfd, "%i: ", ll);
 105         va_start(argp, fmt);
 106         vfprintf(outfd, fmt, argp);
 107         va_end(argp);
 108 }
 109
 110 /**
 111  * Print a message either to stdout or to the log file.
 112  */
 113 static __printf_1_2 void dss_msg(const char* fmt,...)
 114 {
 115         FILE *outfd = conf.daemon_given? logfile : stdout;
 116         va_list argp;
 117         va_start(argp, fmt);
 118         vfprintf(outfd, fmt, argp);
 119         va_end(argp);
 120 }
 121
 122 /* TODO: Also consider number of inodes. */
 123 static int disk_space_low(void)
 124 {
 125         struct disk_space ds;
 126         int ret = get_disk_space(".", &ds);
 127
 128         if (ret < 0)
 129                 return ret;
 130         if (conf.min_free_mb_arg)
 131                 if (ds.free_mb < conf.min_free_mb_arg)
 132                         return 1;
 133         if (conf.min_free_percent_arg)
 134                 if (ds.percent_free < conf.min_free_percent_arg)
 135                         return 1;
 136         return 0;
 137 }
 138
 139 static void dss_get_snapshot_list(struct snapshot_list *sl)
 140 {
 141         get_snapshot_list(sl, conf.unit_interval_arg, conf.num_intervals_arg);
 142 }
 143
 144 static void compute_next_snapshot_time(void)
 145 {
 146         struct timeval now, unit_interval = {.tv_sec = 24 * 3600 * conf.unit_interval_arg},
 147                 tmp, diff;
 148         int64_t x = 0;
 149         unsigned wanted = desired_number_of_snapshots(0, conf.num_intervals_arg),
 150                 num_complete_snapshots = 0;
 151         int i, ret;
 152         struct snapshot *s = NULL;
 153         struct snapshot_list sl;
 154
 155         assert(snapshot_creation_status == SCS_READY);
 156         current_snapshot_creation_time = 0;
 157         dss_get_snapshot_list(&sl);
 158         FOR_EACH_SNAPSHOT(s, i, &sl) {
 159                 if (!(s->flags & SS_COMPLETE))
 160                         continue;
 161                 num_complete_snapshots++;
 162                 x += s->completion_time - s->creation_time;
 163         }
 164         assert(x >= 0);
 165         if (num_complete_snapshots)
 166                 x /= num_complete_snapshots; /* avg time to create one snapshot */
 167         x *= wanted; /* time to create all snapshots in interval 0 */
 168         tmp.tv_sec = x;
 169         tmp.tv_usec = 0;
 170         ret = tv_diff(&unit_interval, &tmp, &diff); /* total sleep time per unit interval */
 171         gettimeofday(&now, NULL);
 172         if (ret < 0 || !s)
 173                 goto min_sleep;
 174         tv_divide(wanted, &diff, &tmp); /* sleep time betweeen two snapshots */
 175         diff.tv_sec = s->completion_time;
 176         diff.tv_usec = 0;
 177         tv_add(&diff, &tmp, &next_snapshot_time);
 178         if (tv_diff(&now, &next_snapshot_time, NULL) < 0)
 179                 goto out;
 180 min_sleep:
 181         next_snapshot_time = now;
 182         next_snapshot_time.tv_sec += 60;
 183 out:
 184         free_snapshot_list(&sl);
 185 }
 186
 187
 188 static int remove_snapshot(struct snapshot *s)
 189 {
 190         int fds[3] = {0, 0, 0};
 191         assert(!rm_pid);
 192         char *new_name = being_deleted_name(s);
 193         int ret = dss_rename(s->name, new_name);
 194         char *argv[] = {"rm", "-rf", new_name, NULL};
 195
 196         if (ret < 0)
 197                 goto out;
 198         DSS_NOTICE_LOG("removing %s (interval = %i)\n", s->name, s->interval);
 199         ret = dss_exec(&rm_pid, argv[0], argv, fds);
 200 out:
 201         free(new_name);
 202         return ret;
 203 }
 204
 205 /*
 206  * return: 0: no redundant snapshots, 1: rm process started, negative: error
 207  */
 208 static int remove_redundant_snapshot(struct snapshot_list *sl)
 209 {
 210         int ret, i, interval;
 211         struct snapshot *s;
 212         unsigned missing = 0;
 213
 214         DSS_INFO_LOG("looking for intervals containing too many snapshots\n");
 215         for (interval = conf.num_intervals_arg - 1; interval >= 0; interval--) {
 216                 unsigned keep = desired_number_of_snapshots(interval, conf.num_intervals_arg);
 217                 unsigned num = sl->interval_count[interval];
 218                 struct snapshot *victim = NULL, *prev = NULL;
 219                 int64_t score = LONG_MAX;
 220
 221                 if (keep >= num)
 222                         missing += keep - num;
 223 //              DSS_DEBUG_LOG("interval %i: keep: %u, have: %u, missing: %u\n",
 224 //                      interval, keep, num, missing);
 225                 if (keep + missing >= num)
 226                         continue;
 227                 /* redundant snapshot in this interval, pick snapshot with lowest score */
 228                 FOR_EACH_SNAPSHOT(s, i, sl) {
 229                         int64_t this_score;
 230
 231                         //DSS_DEBUG_LOG("checking %s\n", s->name);
 232                         if (s->interval > interval) {
 233                                 prev = s;
 234                                 continue;
 235                         }
 236                         if (s->interval < interval)
 237                                 break;
 238                         if (!victim) {
 239                                 victim = s;
 240                                 prev = s;
 241                                 continue;
 242                         }
 243                         assert(prev);
 244                         /* check if s is a better victim */
 245                         this_score = s->creation_time - prev->creation_time;
 246                         assert(this_score >= 0);
 247                         //DSS_DEBUG_LOG("%s: score %lli\n", s->name, (long long)score);
 248                         if (this_score < score) {
 249                                 score = this_score;
 250                                 victim = s;
 251                         }
 252                         prev = s;
 253                 }
 254                 assert(victim);
 255                 if (conf.dry_run_given) {
 256                         dss_msg("%s would be removed (interval = %i)\n",
 257                                 victim->name, victim->interval);
 258                         continue;
 259                 }
 260                 ret = remove_snapshot(victim);
 261                 return ret < 0? ret : 1;
 262         }
 263         return 0;
 264 }
 265
 266 static int remove_outdated_snapshot(struct snapshot_list *sl)
 267 {
 268         int i, ret;
 269         struct snapshot *s;
 270
 271         DSS_INFO_LOG("looking for snapshots belonging to intervals greater than %d\n",
 272                 conf.num_intervals_arg);
 273         FOR_EACH_SNAPSHOT(s, i, sl) {
 274                 if (s->interval <= conf.num_intervals_arg)
 275                         continue;
 276                 if (conf.dry_run_given) {
 277                         dss_msg("%s would be removed (interval = %i)\n",
 278                                 s->name, s->interval);
 279                         continue;
 280                 }
 281                 ret = remove_snapshot(s);
 282                 if (ret < 0)
 283                         return ret;
 284                 return 1;
 285         }
 286         return 0;
 287 }
 288
 289 static int remove_oldest_snapshot(struct snapshot_list *sl)
 290 {
 291         struct snapshot *s = get_oldest_snapshot(sl);
 292
 293         if (!s) /* no snapshot found */
 294                 return 0;
 295         DSS_INFO_LOG("oldest snapshot: %s\n", s->name);
 296         if (s->creation_time == current_snapshot_creation_time)
 297                 return 0; /* do not remove the snapshot currently being created */
 298         return remove_snapshot(s);
 299 }
 300
 301 static int rename_incomplete_snapshot(int64_t start)
 302 {
 303         char *old_name;
 304         int ret;
 305
 306         free(path_to_last_complete_snapshot);
 307         ret = complete_name(start, get_current_time(),
 308                 &path_to_last_complete_snapshot);
 309         if (ret < 0)
 310                 return ret;
 311         old_name = incomplete_name(start);
 312         ret = dss_rename(old_name, path_to_last_complete_snapshot);
 313         if (ret >= 0)
 314                 DSS_NOTICE_LOG("%s -> %s\n", old_name,
 315                         path_to_last_complete_snapshot);
 316         free(old_name);
 317         return ret;
 318 }
 319
 320 static int try_to_free_disk_space(int low_disk_space)
 321 {
 322         int ret;
 323         struct snapshot_list sl;
 324
 325         dss_get_snapshot_list(&sl);
 326         ret = remove_outdated_snapshot(&sl);
 327         if (ret) /* error, or we are removing something */
 328                 goto out;
 329         /* no outdated snapshot */
 330         ret = remove_redundant_snapshot(&sl);
 331         if (ret)
 332                 goto out;
 333         ret = 0;
 334         if (!low_disk_space)
 335                 goto out;
 336         DSS_WARNING_LOG("disk space low and nothing obvious to remove\n");
 337         ret = remove_oldest_snapshot(&sl);
 338         if (ret)
 339                 goto out;
 340         DSS_CRIT_LOG("uhuhu: not enough disk space for a single snapshot\n");
 341         ret= -ENOSPC;
 342 out:
 343         free_snapshot_list(&sl);
 344         return ret;
 345 }
 346
 347 static int pre_create_hook(void)
 348 {
 349         int ret, fds[3] = {0, 0, 0};
 350
 351         if (!conf.pre_create_hook_given) {
 352                 snapshot_creation_status = SCS_PRE_HOOK_SUCCESS;
 353                 return 0;
 354         }
 355         DSS_NOTICE_LOG("executing %s\n", conf.pre_create_hook_arg);
 356         ret = dss_exec_cmdline_pid(&pre_create_hook_pid,
 357                 conf.pre_create_hook_arg, fds);
 358         if (ret < 0)
 359                 return ret;
 360         snapshot_creation_status = SCS_PRE_HOOK_RUNNING;
 361         return ret;
 362 }
 363
 364 static int post_create_hook(void)
 365 {
 366         int ret, fds[3] = {0, 0, 0};
 367         char *cmd;
 368
 369         if (!conf.post_create_hook_given) {
 370                 snapshot_creation_status = SCS_READY;
 371                 compute_next_snapshot_time();
 372                 return 0;
 373         }
 374         cmd = make_message("%s %s", conf.post_create_hook_arg,
 375                 path_to_last_complete_snapshot);
 376         DSS_NOTICE_LOG("executing %s\n", cmd);
 377         ret = dss_exec_cmdline_pid(&post_create_hook_pid, cmd, fds);
 378         free(cmd);
 379         if (ret < 0)
 380                 return ret;
 381         snapshot_creation_status = SCS_POST_HOOK_RUNNING;
 382         return ret;
 383 }
 384
 385 static void kill_process(pid_t pid)
 386 {
 387         if (!pid)
 388                 return;
 389         DSS_WARNING_LOG("sending SIGTERM to pid %d\n", (int)pid);
 390         kill(pid, SIGTERM);
 391 }
 392
 393 static void stop_rsync_process(void)
 394 {
 395         if (!rsync_pid || rsync_stopped)
 396                 return;
 397         kill(SIGSTOP, rsync_pid);
 398         rsync_stopped = 1;
 399 }
 400
 401 static void restart_rsync_process(void)
 402 {
 403         if (!rsync_pid || !rsync_stopped)
 404                 return;
 405         kill (SIGCONT, rsync_pid);
 406         rsync_stopped = 0;
 407 }
 408
 409
 410 /**
 411  * Print a log message about the exit status of a child.
 412  */
 413 static void log_termination_msg(pid_t pid, int status)
 414 {
 415         if (WIFEXITED(status))
 416                 DSS_INFO_LOG("child %i exited. Exit status: %i\n", (int)pid,
 417                         WEXITSTATUS(status));
 418         else if (WIFSIGNALED(status))
 419                 DSS_NOTICE_LOG("child %i was killed by signal %i\n", (int)pid,
 420                         WTERMSIG(status));
 421         else
 422                 DSS_WARNING_LOG("child %i terminated abormally\n", (int)pid);
 423 }
 424
 425 static int wait_for_process(pid_t pid, int *status)
 426 {
 427         int ret;
 428
 429         DSS_DEBUG_LOG("Waiting for process %d to terminate\n", (int)pid);
 430         for (;;) {
 431                 fd_set rfds;
 432
 433                 FD_ZERO(&rfds);
 434                 FD_SET(signal_pipe, &rfds);
 435                 ret = dss_select(signal_pipe + 1, &rfds, NULL, NULL);
 436                 if (ret < 0)
 437                         break;
 438                 ret = next_signal();
 439                 if (!ret)
 440                         continue;
 441                 if (ret == SIGCHLD) {
 442                         ret = waitpid(pid, status, 0);
 443                         if (ret >= 0)
 444                                 break;
 445                         if (errno != EINTR) { /* error */
 446                                 ret = -ERRNO_TO_DSS_ERROR(errno);
 447                                 break;
 448                         }
 449                 }
 450                 /* SIGINT or SIGTERM */
 451                 DSS_WARNING_LOG("sending SIGTERM to pid %d\n", (int)pid);
 452                 kill(pid, SIGTERM);
 453         }
 454         if (ret < 0)
 455                 DSS_ERROR_LOG("failed to wait for process %d\n", (int)pid);
 456         else
 457                 log_termination_msg(pid, *status);
 458         return ret;
 459 }
 460
 461 static int handle_rm_exit(int status)
 462 {
 463         rm_pid = 0;
 464         if (!WIFEXITED(status))
 465                 return -E_INVOLUNTARY_EXIT;
 466         if (WEXITSTATUS(status))
 467                 return -E_BAD_EXIT_CODE;
 468         return 1;
 469 }
 470
 471 static int wait_for_rm_process(void)
 472 {
 473         int status, ret = wait_for_process(rm_pid, &status);
 474
 475         if (ret < 0)
 476                 return ret;
 477         return handle_rm_exit(status);
 478 }
 479
 480 static int handle_rsync_exit(int status)
 481 {
 482         int es, ret;
 483
 484         if (!WIFEXITED(status)) {
 485                 DSS_ERROR_LOG("rsync process %d died involuntary\n", (int)rsync_pid);
 486                 ret = -E_INVOLUNTARY_EXIT;
 487                 snapshot_creation_status = SCS_READY;
 488                 compute_next_snapshot_time();
 489                 goto out;
 490         }
 491         es = WEXITSTATUS(status);
 492         if (es != 0 && es != 23 && es != 24) {
 493                 DSS_ERROR_LOG("rsync process %d returned %d\n", (int)rsync_pid, es);
 494                 ret = -E_BAD_EXIT_CODE;
 495                 snapshot_creation_status = SCS_READY;
 496                 compute_next_snapshot_time();
 497                 goto out;
 498         }
 499         ret = rename_incomplete_snapshot(current_snapshot_creation_time);
 500         if (ret < 0)
 501                 goto out;
 502         snapshot_creation_status = SCS_RSYNC_SUCCESS;
 503 out:
 504         rsync_pid = 0;
 505         rsync_stopped = 0;
 506         return ret;
 507 }
 508
 509 static int handle_pre_create_hook_exit(int status)
 510 {
 511         int es, ret;
 512
 513         if (!WIFEXITED(status)) {
 514                 snapshot_creation_status = SCS_READY;
 515                 compute_next_snapshot_time();
 516                 ret = -E_INVOLUNTARY_EXIT;
 517                 goto out;
 518         }
 519         es = WEXITSTATUS(status);
 520         if (es) {
 521                 snapshot_creation_status = SCS_READY;
 522                 compute_next_snapshot_time();
 523                 ret = -E_BAD_EXIT_CODE;
 524                 goto out;
 525         }
 526         snapshot_creation_status = SCS_PRE_HOOK_SUCCESS;
 527         ret = 1;
 528 out:
 529         pre_create_hook_pid = 0;
 530         return ret;
 531 }
 532
 533 static int handle_sigchld(void)
 534 {
 535         pid_t pid;
 536         int status, ret = reap_child(&pid, &status);
 537
 538         if (ret <= 0)
 539                 return ret;
 540         if (pid == rsync_pid)
 541                 return handle_rsync_exit(status);
 542         if (pid == rm_pid)
 543                 return handle_rm_exit(status);
 544         if (pid == pre_create_hook_pid)
 545                 return handle_pre_create_hook_exit(status);
 546         if (pid == post_create_hook_pid) {
 547                 snapshot_creation_status = SCS_READY;
 548                 compute_next_snapshot_time();
 549                 return 1;
 550         }
 551         DSS_EMERG_LOG("BUG: unknown process %d died\n", (int)pid);
 552         exit(EXIT_FAILURE);
 553 }
 554
 555 static int check_config(void)
 556 {
 557         if (conf.unit_interval_arg <= 0) {
 558                 DSS_ERROR_LOG("bad unit interval: %i\n", conf.unit_interval_arg);
 559                 return -E_INVALID_NUMBER;
 560         }
 561         DSS_DEBUG_LOG("unit interval: %i day(s)\n", conf.unit_interval_arg);
 562         if (conf.num_intervals_arg <= 0) {
 563                 DSS_ERROR_LOG("bad number of intervals  %i\n", conf.num_intervals_arg);
 564                 return -E_INVALID_NUMBER;
 565         }
 566         DSS_DEBUG_LOG("number of intervals: %i\n", conf.num_intervals_arg);
 567         return 1;
 568 }
 569
 570 /* exits on errors */
 571 static void parse_config_file(int override)
 572 {
 573         int ret;
 574         char *config_file;
 575         struct stat statbuf;
 576         char *old_logfile_arg = NULL;
 577         int old_daemon_given = 0;
 578
 579         if (conf.config_file_given)
 580                 config_file = dss_strdup(conf.config_file_arg);
 581         else {
 582                 char *home = get_homedir();
 583                 config_file = make_message("%s/.dssrc", home);
 584                 free(home);
 585         }
 586         if (override) { /* SIGHUP */
 587                 if (conf.logfile_given)
 588                         old_logfile_arg = dss_strdup(conf.logfile_arg);
 589                 old_daemon_given = conf.daemon_given;
 590         }
 591
 592         ret = stat(config_file, &statbuf);
 593         if (ret && conf.config_file_given) {
 594                 ret = -ERRNO_TO_DSS_ERROR(errno);
 595                 DSS_ERROR_LOG("failed to stat config file %s\n", config_file);
 596                 goto out;
 597         }
 598         if (!ret) {
 599                 struct cmdline_parser_params params = {
 600                         .override = override,
 601                         .initialize = 0,
 602                         .check_required = 1,
 603                         .check_ambiguity = 0
 604                 };
 605                 cmdline_parser_config_file(config_file, &conf, &params);
 606         }
 607         ret = check_config();
 608         if (ret < 0)
 609                 goto out;
 610         if (override) {
 611                 /* don't change daemon mode on SIGHUP */
 612                 conf.daemon_given = old_daemon_given;
 613                 close_log(logfile);
 614                 logfile = NULL;
 615                 if (conf.logfile_given)
 616                         free(old_logfile_arg);
 617                 else if (conf.daemon_given) { /* re-use old logfile */
 618                         conf.logfile_arg = old_logfile_arg;
 619                         conf.logfile_given = 1;
 620                 }
 621         }
 622         if (conf.logfile_given) {
 623                 logfile = open_log(conf.logfile_arg);
 624                 log_welcome(conf.loglevel_arg);
 625         }
 626         DSS_EMERG_LOG("loglevel: %d\n", conf.loglevel_arg);
 627 //      cmdline_parser_dump(logfile? logfile : stdout, &conf);
 628         ret = dss_chdir(conf.dest_dir_arg);
 629 out:
 630         free(config_file);
 631         if (ret >= 0)
 632                 return;
 633         DSS_EMERG_LOG("%s\n", dss_strerror(-ret));
 634         exit(EXIT_FAILURE);
 635 }
 636
 637 static void handle_sighup(void)
 638 {
 639         DSS_NOTICE_LOG("SIGHUP\n");
 640         parse_config_file(1);
 641 }
 642
 643 static void handle_signal(void)
 644 {
 645         int sig, ret = next_signal();
 646
 647         if (ret <= 0)
 648                 goto out;
 649         sig = ret;
 650         switch (sig) {
 651         case SIGINT:
 652         case SIGTERM:
 653                 restart_rsync_process();
 654                 kill_process(rsync_pid);
 655                 kill_process(rm_pid);
 656                 exit(EXIT_FAILURE);
 657         case SIGHUP:
 658                 handle_sighup();
 659                 ret = 1;
 660                 break;
 661         case SIGCHLD:
 662                 ret = handle_sigchld();
 663                 break;
 664         }
 665 out:
 666         if (ret < 0)
 667                 DSS_ERROR_LOG("%s\n", dss_strerror(-ret));
 668 }
 669
 670 static void create_rsync_argv(char ***argv, int64_t *num)
 671 {
 672         char *logname, *newest;
 673         int i = 0, j;
 674         struct snapshot_list sl;
 675
 676         dss_get_snapshot_list(&sl);
 677         newest = name_of_newest_complete_snapshot(&sl);
 678         free_snapshot_list(&sl);
 679
 680         *argv = dss_malloc((15 + conf.rsync_option_given) * sizeof(char *));
 681         (*argv)[i++] = dss_strdup("rsync");
 682         (*argv)[i++] = dss_strdup("-aq");
 683         (*argv)[i++] = dss_strdup("--delete");
 684         for (j = 0; j < conf.rsync_option_given; j++)
 685                 (*argv)[i++] = dss_strdup(conf.rsync_option_arg[j]);
 686         if (newest) {
 687                 DSS_INFO_LOG("using %s as reference snapshot\n", newest);
 688                 (*argv)[i++] = make_message("--link-dest=../%s", newest);
 689                 free(newest);
 690         } else
 691                 DSS_INFO_LOG("no previous snapshot found\n");
 692         if (conf.exclude_patterns_given) {
 693                 (*argv)[i++] = dss_strdup("--exclude-from");
 694                 (*argv)[i++] = dss_strdup(conf.exclude_patterns_arg);
 695
 696         }
 697         logname = dss_logname();
 698         if (conf.remote_user_given && !strcmp(conf.remote_user_arg, logname))
 699                 (*argv)[i++] = dss_strdup(conf.source_dir_arg);
 700         else
 701                 (*argv)[i++] = make_message("%s@%s:%s/", conf.remote_user_given?
 702                         conf.remote_user_arg : logname,
 703                         conf.remote_host_arg, conf.source_dir_arg);
 704         free(logname);
 705         *num = get_current_time();
 706         (*argv)[i++] = incomplete_name(*num);
 707         (*argv)[i++] = NULL;
 708         for (j = 0; j < i; j++)
 709                 DSS_DEBUG_LOG("argv[%d] = %s\n", j, (*argv)[j]);
 710 }
 711
 712 static void free_rsync_argv(char **argv)
 713 {
 714         int i;
 715         for (i = 0; argv[i]; i++)
 716                 free(argv[i]);
 717         free(argv);
 718 }
 719
 720 static int create_snapshot(char **argv)
 721 {
 722         int ret, fds[3] = {0, 0, 0};
 723         char *name;
 724
 725         name = incomplete_name(current_snapshot_creation_time);
 726         DSS_NOTICE_LOG("creating new snapshot %s\n", name);
 727         free(name);
 728         ret = dss_exec(&rsync_pid, argv[0], argv, fds);
 729         if (ret < 0)
 730                 return ret;
 731         snapshot_creation_status = SCS_RSYNC_RUNNING;
 732         return ret;
 733 }
 734
 735 static int select_loop(void)
 736 {
 737         int ret;
 738         struct timeval tv = {.tv_sec = 0, .tv_usec = 0};
 739
 740         for (;;) {
 741                 fd_set rfds;
 742                 int low_disk_space;
 743                 char **rsync_argv;
 744                 struct timeval now, *tvp = &tv;
 745
 746                 if (rsync_pid)
 747                         tv.tv_sec = 60; /* check every 60 seconds for free disk space */
 748                 else if (rm_pid)
 749                         tvp = NULL; /* sleep until rm process dies */
 750                 FD_ZERO(&rfds);
 751                 FD_SET(signal_pipe, &rfds);
 752                 DSS_DEBUG_LOG("tvp: %p, tv_sec: %lu\n", tvp, (long unsigned) tv.tv_sec);
 753                 ret = dss_select(signal_pipe + 1, &rfds, NULL, tvp);
 754                 if (ret < 0)
 755                         return ret;
 756                 if (FD_ISSET(signal_pipe, &rfds))
 757                         handle_signal();
 758                 if (rm_pid)
 759                         continue;
 760                 ret = disk_space_low();
 761                 if (ret < 0)
 762                         break;
 763                 low_disk_space = ret;
 764                 ret = try_to_free_disk_space(low_disk_space);
 765                 if (ret < 0)
 766                         break;
 767                 if (rm_pid) {
 768                         stop_rsync_process();
 769                         continue;
 770                 }
 771                 restart_rsync_process();
 772                 gettimeofday(&now, NULL);
 773                 if (tv_diff(&next_snapshot_time, &now, &tv) > 0)
 774                         continue;
 775                 switch (snapshot_creation_status) {
 776                 case SCS_READY:
 777                         ret = pre_create_hook();
 778                         if (ret < 0)
 779                                 goto out;
 780                         continue;
 781                 case SCS_PRE_HOOK_RUNNING:
 782                         continue;
 783                 case SCS_PRE_HOOK_SUCCESS:
 784                         create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
 785                         ret = create_snapshot(rsync_argv);
 786                         free_rsync_argv(rsync_argv);
 787                         if (ret < 0)
 788                                 goto out;
 789                         continue;
 790                 case SCS_RSYNC_RUNNING:
 791                         continue;
 792                 case SCS_RSYNC_SUCCESS:
 793                         ret = post_create_hook();
 794                         if (ret < 0)
 795                                 goto out;
 796                         continue;
 797                 case SCS_POST_HOOK_RUNNING:
 798                         continue;
 799                 }
 800         }
 801 out:
 802         return ret;
 803 }
 804
 805 static int com_run(void)
 806 {
 807         int ret;
 808
 809         if (conf.dry_run_given) {
 810                 DSS_ERROR_LOG("dry_run not supported by this command\n");
 811                 return -E_SYNTAX;
 812         }
 813         ret = install_sighandler(SIGHUP);
 814         if (ret < 0)
 815                 return ret;
 816         compute_next_snapshot_time();
 817         return select_loop();
 818 }
 819
 820 static int com_prune(void)
 821 {
 822         int ret;
 823         struct snapshot_list sl;
 824         struct disk_space ds;
 825
 826         ret = get_disk_space(".", &ds);
 827         if (ret < 0)
 828                 return ret;
 829         log_disk_space(&ds);
 830         for (;;) {
 831                 dss_get_snapshot_list(&sl);
 832                 ret = remove_outdated_snapshot(&sl);
 833                 free_snapshot_list(&sl);
 834                 if (ret < 0)
 835                         return ret;
 836                 if (!ret)
 837                         break;
 838                 ret = wait_for_rm_process();
 839                 if (ret < 0)
 840                         goto out;
 841         }
 842         for (;;) {
 843                 dss_get_snapshot_list(&sl);
 844                 ret = remove_redundant_snapshot(&sl);
 845                 free_snapshot_list(&sl);
 846                 if (ret < 0)
 847                         return ret;
 848                 if (!ret)
 849                         break;
 850                 ret = wait_for_rm_process();
 851                 if (ret < 0)
 852                         goto out;
 853         }
 854         return 1;
 855 out:
 856         return ret;
 857 }
 858
 859 static int com_create(void)
 860 {
 861         int ret, status;
 862         char **rsync_argv;
 863
 864         if (conf.dry_run_given) {
 865                 int i;
 866                 char *msg = NULL;
 867                 create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
 868                 for (i = 0; rsync_argv[i]; i++) {
 869                         char *tmp = msg;
 870                         msg = make_message("%s%s%s", tmp? tmp : "",
 871                                 tmp? " " : "", rsync_argv[i]);
 872                         free(tmp);
 873                 }
 874                 free_rsync_argv(rsync_argv);
 875                 dss_msg("%s\n", msg);
 876                 free(msg);
 877                 return 1;
 878         }
 879         ret = pre_create_hook();
 880         if (ret < 0)
 881                 return ret;
 882         if (pre_create_hook_pid) {
 883                 ret = wait_for_process(pre_create_hook_pid, &status);
 884                 if (ret < 0)
 885                         return ret;
 886                 ret = handle_pre_create_hook_exit(status);
 887                 if (ret < 0)
 888                         return ret;
 889         }
 890         create_rsync_argv(&rsync_argv, &current_snapshot_creation_time);
 891         ret = create_snapshot(rsync_argv);
 892         if (ret < 0)
 893                 goto out;
 894         ret = wait_for_process(rsync_pid, &status);
 895         if (ret < 0)
 896                 goto out;
 897         ret = handle_rsync_exit(status);
 898         if (ret < 0)
 899                 goto out;
 900         post_create_hook();
 901         if (post_create_hook_pid)
 902                 ret = wait_for_process(post_create_hook_pid, &status);
 903 out:
 904         free_rsync_argv(rsync_argv);
 905         return ret;
 906 }
 907
 908 static int com_ls(void)
 909 {
 910         int i;
 911         struct snapshot_list sl;
 912         struct snapshot *s;
 913
 914         dss_get_snapshot_list(&sl);
 915         FOR_EACH_SNAPSHOT(s, i, &sl)
 916                 dss_msg("%u\t%s\n", s->interval, s->name);
 917         free_snapshot_list(&sl);
 918         return 1;
 919 }
 920
 921 static void setup_signal_handling(void)
 922 {
 923         int ret;
 924
 925         DSS_INFO_LOG("setting up signal handlers\n");
 926         signal_pipe = signal_init(); /* always successful */
 927         ret = install_sighandler(SIGINT);
 928         if (ret < 0)
 929                 goto err;
 930         ret = install_sighandler(SIGTERM);
 931         if (ret < 0)
 932                 goto err;
 933         ret = install_sighandler(SIGCHLD);
 934         if (ret < 0)
 935                 goto err;
 936         return;
 937 err:
 938         DSS_EMERG_LOG("could not install signal handlers\n");
 939         exit(EXIT_FAILURE);
 940 }
 941
 942 /**
 943  * The main function of dss.
 944  *
 945  * \param argc Usual argument count.
 946  * \param argv Usual argument vector.
 947  */
 948 int main(int argc, char **argv)
 949 {
 950         int ret;
 951         struct cmdline_parser_params params = {
 952                 .override = 0,
 953                 .initialize = 1,
 954                 .check_required = 0,
 955                 .check_ambiguity = 0
 956         };
 957
 958         cmdline_parser_ext(argc, argv, &conf, &params); /* aborts on errors */
 959         parse_config_file(0);
 960
 961         if (conf.daemon_given)
 962                 daemon_init();
 963         setup_signal_handling();
 964         ret = call_command_handler();
 965         if (ret < 0)
 966                 DSS_EMERG_LOG("%s\n", dss_strerror(-ret));
 967         exit(ret >= 0? EXIT_SUCCESS : EXIT_FAILURE);
 968 }