common/recover.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * %sccs.include.redist.c%
   6  */
   7
   8 #ifndef lint
   9 static char sccsid[] = "$Id: recover.c,v 8.40 1993/12/21 11:58:53 bostic Exp $ (Berkeley) $Date: 1993/12/21 11:58:53 $";
  10 #endif /* not lint */
  11
  12 #include <sys/param.h>
  13 #include <sys/stat.h>
  14 #include <sys/time.h>
  15
  16 /*
  17  * We include <sys/file.h>, because the flock(2) #defines were
  18  * found there on historical systems.  We also include <fcntl.h>
  19  * because the open(2) #defines are found there on newer systems.
  20  */
  21 #include <sys/file.h>
  22
  23 #include <netdb.h>                      /* MAXHOSTNAMELEN on some systems. */
  24
  25 #include <dirent.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <pwd.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32
  33 #include "vi.h"
  34 #include "pathnames.h"
  35
  36 /*
  37  * Recovery code.
  38  *
  39  * The basic scheme is there's a btree file, whose name we specify.  The first
  40  * time a file is modified, and then at RCV_PERIOD intervals after that, the
  41  * btree file is synced to disk.  Each time a keystroke is requested for a file
  42  * the terminal routines check to see if the file needs to be synced.  This, of
  43  * course means that the data structures had better be consistent each time the
  44  * key routines are called.
  45  *
  46  * We don't use timers other than to flag that the file should be synced.  This
  47  * would require that the SCR and EXF data structures be locked, the dbopen(3)
  48  * routines lock out the timers for each update, etc.  It's just not worth it.
  49  * The only way we can lose in the current scheme is if the file is saved, then
  50  * the user types furiously for RCV_PERIOD - 1 seconds, and types nothing more.
  51  * Not likely.
  52  *
  53  * When a file is first modified, a file which can be handed off to the mailer
  54  * is created.  The file contains normal headers, with two additions, which
  55  * occur in THIS order, as the FIRST TWO headers:
  56  *
  57  *      Vi-recover-file: file_name
  58  *      Vi-recover-path: recover_path
  59  *
  60  * Since newlines delimit the headers, this means that file names cannot
  61  * have newlines in them, but that's probably okay.
  62  *
  63  * Btree files are named "vi.XXXX" and recovery files are named "recover.XXXX".
  64  */
  65
  66 #define VI_FHEADER      "Vi-recover-file: "
  67 #define VI_PHEADER      "Vi-recover-path: "
  68
  69 static void     rcv_alrm __P((int));
  70 static int      rcv_mailfile __P((SCR *, EXF *));
  71 static void     rcv_syncit __P((SCR *, int));
  72
  73 /*
  74  * rcv_tmp --
  75  *      Build a file name that will be used as the recovery file.
  76  */
  77 int
  78 rcv_tmp(sp, ep, name)
  79         SCR *sp;
  80         EXF *ep;
  81         char *name;
  82 {
  83         struct stat sb;
  84         int fd;
  85         char *dp, *p, path[MAXPATHLEN];
  86
  87         /*
  88          * If the recovery directory doesn't exist, try and create it.  As
  89          * the recovery files are themselves protected from reading/writing
  90          * by other than the owner, the worst that can happen is that a user
  91          * would have permission to remove other users recovery files.  If
  92          * the sticky bit has the BSD semantics, that too will be impossible.
  93          */
  94         dp = O_STR(sp, O_RECDIR);
  95         if (stat(dp, &sb)) {
  96                 if (errno != ENOENT || mkdir(dp, 0)) {
  97                         msgq(sp, M_ERR, "Error: %s: %s", dp, strerror(errno));
  98                         return (1);
  99                 }
 100                 (void)chmod(dp, S_IRWXU | S_IRWXG | S_IRWXO | S_ISVTX);
 101         }
 102
 103         /* Newlines delimit the mail messages. */
 104         for (p = name; *p; ++p)
 105                 if (*p == '\n') {
 106                         msgq(sp, M_ERR,
 107                     "Files with newlines in the name are unrecoverable.");
 108                         return (1);
 109                 }
 110
 111         (void)snprintf(path, sizeof(path), "%s/vi.XXXXXX", dp);
 112
 113         /*
 114          * !!!
 115          * We depend on mkstemp(3) setting the permissions correctly.
 116          * GP's, we do it ourselves, to keep the window as small as
 117          * possible.
 118          */
 119         if ((fd = mkstemp(path)) == -1) {
 120                 msgq(sp, M_ERR, "Error: %s: %s", dp, strerror(errno));
 121                 return (1);
 122         }
 123         (void)chmod(path, S_IRUSR | S_IWUSR);
 124         (void)close(fd);
 125
 126         if ((ep->rcv_path = strdup(path)) == NULL) {
 127                 msgq(sp, M_SYSERR, NULL);
 128                 (void)unlink(path);
 129                 return (1);
 130         }
 131
 132         /* We believe the file is recoverable. */
 133         F_SET(ep, F_RCV_ON);
 134         return (0);
 135 }
 136
 137 /*
 138  * rcv_init --
 139  *      Force the file to be snapshotted for recovery.
 140  */
 141 int
 142 rcv_init(sp, ep)
 143         SCR *sp;
 144         EXF *ep;
 145 {
 146         struct itimerval value;
 147         struct sigaction act;
 148         recno_t lno;
 149
 150         F_CLR(ep, F_FIRSTMODIFY | F_RCV_ON);
 151
 152         /* Build file to mail to the user. */
 153         if (rcv_mailfile(sp, ep))
 154                 goto err;
 155
 156         /* Force read of entire file. */
 157         if (file_lline(sp, ep, &lno))
 158                 goto err;
 159
 160         /* Turn on a busy message, and sync it to backing store. */
 161         busy_on(sp, 1, "Copying file for recovery...");
 162         if (ep->db->sync(ep->db, R_RECNOSYNC)) {
 163                 msgq(sp, M_ERR, "Preservation failed: %s: %s",
 164                     ep->rcv_path, strerror(errno));
 165                 busy_off(sp);
 166                 goto err;
 167         }
 168         busy_off(sp);
 169
 170         if (!F_ISSET(sp->gp, G_RECOVER_SET)) {
 171                 /* Install the recovery timer handler. */
 172                 act.sa_handler = rcv_alrm;
 173                 sigemptyset(&act.sa_mask);
 174                 act.sa_flags = 0;
 175                 (void)sigaction(SIGALRM, &act, NULL);
 176
 177                 /* Start the recovery timer. */
 178                 value.it_interval.tv_sec = value.it_value.tv_sec = RCV_PERIOD;
 179                 value.it_interval.tv_usec = value.it_value.tv_usec = 0;
 180                 if (setitimer(ITIMER_REAL, &value, NULL)) {
 181                         msgq(sp, M_ERR,
 182                             "Error: setitimer: %s", strerror(errno));
 183 err:                    msgq(sp, M_ERR,
 184                             "Recovery after system crash not possible.");
 185                         return (1);
 186                 }
 187         }
 188
 189         /* We believe the file is recoverable. */
 190         F_SET(ep, F_RCV_ON);
 191         return (0);
 192 }
 193
 194 /*
 195  * rcv_alrm --
 196  *      Recovery timer interrupt handler.
 197  */
 198 static void
 199 rcv_alrm(signo)
 200         int signo;
 201 {
 202         F_SET(__global_list, G_SIGALRM);
 203 }
 204
 205 /*
 206  * rcv_mailfile --
 207  *      Build the file to mail to the user.
 208  */
 209 static int
 210 rcv_mailfile(sp, ep)
 211         SCR *sp;
 212         EXF *ep;
 213 {
 214         struct passwd *pw;
 215         uid_t uid;
 216         FILE *fp;
 217         time_t now;
 218         int fd;
 219         char *p, *t, host[MAXHOSTNAMELEN], path[MAXPATHLEN];
 220
 221         if ((pw = getpwuid(uid = getuid())) == NULL) {
 222                 msgq(sp, M_ERR, "Information on user id %u not found.", uid);
 223                 return (1);
 224         }
 225
 226         (void)snprintf(path, sizeof(path),
 227             "%s/recover.XXXXXX", O_STR(sp, O_RECDIR));
 228         if ((fd = mkstemp(path)) == -1 || (fp = fdopen(fd, "w")) == NULL) {
 229                 msgq(sp, M_ERR,
 230                     "Error: %s: %s", O_STR(sp, O_RECDIR), strerror(errno));
 231                 if (fd != -1)
 232                         (void)close(fd);
 233                 return (1);
 234         }
 235
 236         /*
 237          * We keep an open lock on the file so that the recover option can
 238          * distinguish between files that are live and those that need to
 239          * be recovered.  There's an obvious window between the mkstemp call
 240          * and the lock, but it's pretty small.
 241          */
 242         if ((ep->rcv_fd = dup(fd)) != -1)
 243                 (void)flock(ep->rcv_fd, LOCK_EX | LOCK_NB);
 244
 245         if ((ep->rcv_mpath = strdup(path)) == NULL) {
 246                 msgq(sp, M_SYSERR, NULL);
 247                 (void)fclose(fp);
 248                 return (1);
 249         }
 250
 251         t = FILENAME(sp->frp);
 252         if ((p = strrchr(t, '/')) == NULL)
 253                 p = t;
 254         else
 255                 ++p;
 256         (void)time(&now);
 257         (void)gethostname(host, sizeof(host));
 258         (void)fprintf(fp, "%s%s\n%s%s\n%s\n%s\n%s%s\n%s%s\n%s\n\n",
 259             VI_FHEADER, p,                      /* Non-standard. */
 260             VI_PHEADER, ep->rcv_path,           /* Non-standard. */
 261             "Reply-To: root",
 262             "From: root (Nvi recovery program)",
 263             "To: ", pw->pw_name,
 264             "Subject: Nvi saved the file ", p,
 265             "Precedence: bulk");                        /* For vacation(1). */
 266         (void)fprintf(fp, "%s%.24s%s%s\n%s%s",
 267             "On ", ctime(&now),
 268             ", the user ", pw->pw_name,
 269             "was editing a file named ", p);
 270         if (p != t)
 271                 (void)fprintf(fp, " (%s)", t);
 272         (void)fprintf(fp, "\n%s%s%s\n",
 273             "on the machine ", host, ", when it was saved for\nrecovery.");
 274         (void)fprintf(fp, "\n%s\n%s\n%s\n\n",
 275             "You can recover most, if not all, of the changes",
 276             "to this file using the -l and -r options to nvi(1)",
 277             "or nex(1).");
 278
 279         if (fflush(fp) || ferror(fp)) {
 280                 msgq(sp, M_SYSERR, NULL);
 281                 (void)fclose(fp);
 282                 return (1);
 283         }
 284         return (0);
 285 }
 286
 287 /*
 288  * rcv_sync --
 289  *      Sync the backing file.
 290  */
 291 int
 292 rcv_sync(sp, ep)
 293         SCR *sp;
 294         EXF *ep;
 295 {
 296         struct itimerval value;
 297
 298         if (ep->db->sync(ep->db, R_RECNOSYNC)) {
 299                 msgq(sp, M_ERR, "Automatic file backup failed: %s: %s",
 300                     ep->rcv_path, strerror(errno));
 301                 value.it_interval.tv_sec = value.it_interval.tv_usec = 0;
 302                 value.it_value.tv_sec = value.it_value.tv_usec = 0;
 303                 (void)setitimer(ITIMER_REAL, &value, NULL);
 304                 F_CLR(ep, F_RCV_ON);
 305                 return (1);
 306         }
 307         return (0);
 308 }
 309
 310 /*
 311  * rcv_hup --
 312  *      Recovery SIGHUP interrupt handler.  (Modem line dropped, or
 313  *      xterm window closed.)
 314  */
 315 void
 316 rcv_hup()
 317 {
 318         SCR *sp;
 319
 320         /*
 321          * Walk the lists of screens, sync'ing the files; only sync
 322          * each file once.  Send email to the user for each file saved.
 323          */
 324         for (sp = __global_list->dq.cqh_first;
 325             sp != (void *)&__global_list->dq; sp = sp->q.cqe_next)
 326                 rcv_syncit(sp, 1);
 327         for (sp = __global_list->hq.cqh_first;
 328             sp != (void *)&__global_list->hq; sp = sp->q.cqe_next)
 329                 rcv_syncit(sp, 1);
 330
 331         /*
 332          * Die with the proper exit status.  Don't bother using
 333          * sigaction(2) 'cause we want the default behavior.
 334          */
 335         (void)signal(SIGHUP, SIG_DFL);
 336         (void)kill(0, SIGHUP);
 337
 338         /* NOTREACHED */
 339         exit (1);
 340 }
 341
 342 /*
 343  * rcv_term --
 344  *      Recovery SIGTERM interrupt handler.  (Reboot or halt is running.)
 345  */
 346 void
 347 rcv_term()
 348 {
 349         SCR *sp;
 350
 351         /*
 352          * Walk the lists of screens, sync'ing the files; only sync
 353          * each file once.
 354          */
 355         for (sp = __global_list->dq.cqh_first;
 356             sp != (void *)&__global_list->dq; sp = sp->q.cqe_next)
 357                 rcv_syncit(sp, 0);
 358         for (sp = __global_list->hq.cqh_first;
 359             sp != (void *)&__global_list->hq; sp = sp->q.cqe_next)
 360                 rcv_syncit(sp, 0);
 361
 362         /*
 363          * Die with the proper exit status.  Don't bother using
 364          * sigaction(2) 'cause we want the default behavior.
 365          */
 366         (void)signal(SIGTERM, SIG_DFL);
 367         (void)kill(0, SIGTERM);
 368
 369         /* NOTREACHED */
 370         exit (1);
 371 }
 372
 373 /*
 374  * rcv_syncit --
 375  *      Sync the file, optionally send mail.
 376  */
 377 static void
 378 rcv_syncit(sp, email)
 379         SCR *sp;
 380         int email;
 381 {
 382         EXF *ep;
 383         char comm[1024];
 384
 385         if ((ep = sp->ep) == NULL ||
 386             !F_ISSET(ep, F_MODIFIED) || !F_ISSET(ep, F_RCV_ON))
 387                 return;
 388
 389         (void)ep->db->sync(ep->db, R_RECNOSYNC);
 390         F_SET(ep, F_RCV_NORM);
 391
 392         /*
 393          * !!!
 394          * If you need to port this to a system that doesn't have sendmail,
 395          * the -t flag being used causes sendmail to read the message for
 396          * the recipients instead of us specifying them some other way.
 397          */
 398         if (email) {
 399                 (void)snprintf(comm, sizeof(comm),
 400                     "%s -t < %s", _PATH_SENDMAIL, ep->rcv_mpath);
 401                 (void)system(comm);
 402         }
 403         (void)file_end(sp, ep, 1);
 404 }
 405
 406 /*
 407  *      people making love
 408  *      never exactly the same
 409  *      just like a snowflake
 410  *
 411  * rcv_list --
 412  *      List the files that can be recovered by this user.
 413  */
 414 int
 415 rcv_list(sp)
 416         SCR *sp;
 417 {
 418         struct dirent *dp;
 419         struct stat sb;
 420         DIR *dirp;
 421         FILE *fp;
 422         int found;
 423         char *p, file[1024];
 424
 425         if (chdir(O_STR(sp, O_RECDIR)) || (dirp = opendir(".")) == NULL) {
 426                 (void)fprintf(stderr,
 427                     "vi: %s: %s\n", O_STR(sp, O_RECDIR), strerror(errno));
 428                 return (1);
 429         }
 430
 431         for (found = 0; (dp = readdir(dirp)) != NULL;) {
 432                 if (strncmp(dp->d_name, "recover.", 8))
 433                         continue;
 434
 435                 /* If it's readable, it's recoverable. */
 436                 if ((fp = fopen(dp->d_name, "r")) == NULL)
 437                         continue;
 438
 439                 /* If it's locked, it's live. */
 440                 if (flock(fileno(fp), LOCK_EX | LOCK_NB)) {
 441                         (void)fclose(fp);
 442                         continue;
 443                 }
 444
 445                 /* Check the header, get the file name. */
 446                 if (fgets(file, sizeof(file), fp) == NULL ||
 447                     strncmp(file, VI_FHEADER, sizeof(VI_FHEADER) - 1) ||
 448                     (p = strchr(file, '\n')) == NULL) {
 449                         (void)fprintf(stderr,
 450                             "vi: %s: malformed recovery file.\n", dp->d_name);
 451                         goto next;
 452                 }
 453                 *p = '\0';
 454
 455                 /* Get the last modification time. */
 456                 if (fstat(fileno(fp), &sb)) {
 457                         (void)fprintf(stderr,
 458                             "vi: %s: %s\n", dp->d_name, strerror(errno));
 459                         goto next;
 460                 }
 461
 462                 /* Display. */
 463                 (void)printf("%s: %s",
 464                     file + sizeof(VI_FHEADER) - 1, ctime(&sb.st_mtime));
 465                 found = 1;
 466
 467 next:           (void)fclose(fp);
 468         }
 469         if (found == 0)
 470                 (void)printf("vi: no files to recover.\n");
 471         (void)closedir(dirp);
 472         return (0);
 473 }
 474
 475 /*
 476  * rcv_read --
 477  *      Start a recovered file as the file to edit.
 478  */
 479 int
 480 rcv_read(sp, name)
 481         SCR *sp;
 482         char *name;
 483 {
 484         struct dirent *dp;
 485         struct stat sb;
 486         DIR *dirp;
 487         FREF *frp;
 488         FILE *fp;
 489         time_t rec_mtime;
 490         int found, requested;
 491         char *p, *t, *recp, *pathp;
 492         char recpath[MAXPATHLEN], file[MAXPATHLEN], path[MAXPATHLEN];
 493
 494         if ((dirp = opendir(O_STR(sp, O_RECDIR))) == NULL) {
 495                 msgq(sp, M_ERR,
 496                     "%s: %s", O_STR(sp, O_RECDIR), strerror(errno));
 497                 return (1);
 498         }
 499
 500         recp = pathp = NULL;
 501         for (found = requested = 0; (dp = readdir(dirp)) != NULL;) {
 502                 if (strncmp(dp->d_name, "recover.", 8))
 503                         continue;
 504
 505                 /* If it's readable, it's recoverable. */
 506                 (void)snprintf(recpath, sizeof(recpath),
 507                     "%s/%s", O_STR(sp, O_RECDIR), dp->d_name);
 508                 if ((fp = fopen(recpath, "r")) == NULL)
 509                         continue;
 510
 511                 /* If it's locked, it's live. */
 512                 if (flock(fileno(fp), LOCK_EX | LOCK_NB)) {
 513                         (void)fclose(fp);
 514                         continue;
 515                 }
 516
 517                 /* Check the headers. */
 518                 if (fgets(file, sizeof(file), fp) == NULL ||
 519                     strncmp(file, VI_FHEADER, sizeof(VI_FHEADER) - 1) ||
 520                     (p = strchr(file, '\n')) == NULL ||
 521                     fgets(path, sizeof(path), fp) == NULL ||
 522                     strncmp(path, VI_PHEADER, sizeof(VI_PHEADER) - 1) ||
 523                     (t = strchr(path, '\n')) == NULL) {
 524                         msgq(sp, M_ERR,
 525                             "%s: malformed recovery file.", recpath);
 526                         goto next;
 527                 }
 528                 ++found;
 529                 *t = *p = '\0';
 530
 531                 /* Get the last modification time. */
 532                 if (fstat(fileno(fp), &sb)) {
 533                         msgq(sp, M_ERR,
 534                             "vi: %s: %s", dp->d_name, strerror(errno));
 535                         goto next;
 536                 }
 537
 538                 /* Check the file name. */
 539                 if (strcmp(file + sizeof(VI_FHEADER) - 1, name))
 540                         goto next;
 541
 542                 ++requested;
 543
 544                 /* If we've found more than one, take the most recent. */
 545                 if (recp == NULL || rec_mtime < sb.st_mtime) {
 546                         p = recp;
 547                         t = pathp;
 548                         if ((recp = strdup(recpath)) == NULL) {
 549                                 msgq(sp, M_ERR,
 550                                     "vi: Error: %s.\n", strerror(errno));
 551                                 recp = p;
 552                                 goto next;
 553                         }
 554                         if ((pathp = strdup(path)) == NULL) {
 555                                 msgq(sp, M_ERR,
 556                                     "vi: Error: %s.\n", strerror(errno));
 557                                 FREE(recp, strlen(recp) + 1);
 558                                 recp = p;
 559                                 pathp = t;
 560                                 goto next;
 561                         }
 562                         if (p != NULL) {
 563                                 FREE(p, strlen(p) + 1);
 564                                 FREE(t, strlen(t) + 1);
 565                         }
 566                         rec_mtime = sb.st_mtime;
 567                 }
 568
 569 next:           (void)fclose(fp);
 570         }
 571         (void)closedir(dirp);
 572
 573         if (recp == NULL) {
 574                 msgq(sp, M_INFO,
 575                     "No files named %s, owned by you, to edit.", name);
 576                 return (1);
 577         }
 578         if (found) {
 579                 if (requested > 1)
 580                         msgq(sp, M_INFO,
 581                    "There are older versions of this file for you to recover.");
 582                 if (found > requested)
 583                         msgq(sp, M_INFO,
 584                             "There are other files that you can recover.");
 585         }
 586
 587         /* Create the FREF structure, start the btree file. */
 588         if ((frp = file_add(sp, NULL, name, 0)) == NULL ||
 589             file_init(sp, frp, pathp + sizeof(VI_PHEADER) - 1, 0)) {
 590                 FREE(recp, strlen(recp) + 1);
 591                 FREE(pathp, strlen(pathp) + 1);
 592                 return (1);
 593         }
 594         sp->ep->rcv_mpath = recp;
 595         return (0);
 596 }