usr.bin/undo/undo.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/usr.bin/undo/undo.c,v 1.6 2008/07/17 21:34:47 thomas Exp $
  35  */
  36 /*
  37  * UNDO - retrieve an older version of a file.
  38  */
  39
  40 #include <sys/types.h>
  41 #include <sys/stat.h>
  42 #include <sys/wait.h>
  43 #include <sys/tree.h>
  44 #include <sys/ioctl.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <stdarg.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50 #include <fcntl.h>
  51 #include <errno.h>
  52 #include <err.h>
  53 #include <vfs/hammer/hammer_disk.h>
  54 #include <vfs/hammer/hammer_ioctl.h>
  55
  56 /*
  57  * Sorted list of transaction ids
  58  */
  59 struct undo_hist_entry;
  60 RB_HEAD(undo_hist_entry_rb_tree, undo_hist_entry);
  61 RB_PROTOTYPE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
  62         undo_hist_entry_compare, hammer_tid_t);
  63
  64 struct undo_hist_entry {
  65         RB_ENTRY(undo_hist_entry) rbnode;
  66         struct hammer_ioc_hist_entry tse;
  67         ino_t inum;
  68 };
  69
  70 enum undo_type { TYPE_FILE, TYPE_DIFF, TYPE_RDIFF, TYPE_HISTORY };
  71 enum undo_cmd { CMD_DUMP, CMD_ITERATEALL };
  72
  73 #define UNDO_FLAG_MULT          0x0001
  74 #define UNDO_FLAG_INOCHG        0x0002
  75 #define UNDO_FLAG_TID_INDEX1    0x0004
  76 #define UNDO_FLAG_TID_INDEX2    0x0008
  77
  78 static int undo_hist_entry_compare(struct undo_hist_entry *he1,
  79                     struct undo_hist_entry *he2);
  80 static void doiterate(const char *filename, int flags,
  81                    struct hammer_ioc_hist_entry ts1,
  82                    struct hammer_ioc_hist_entry ts2,
  83                    enum undo_cmd cmd, enum undo_type type);
  84 static int doiterate_dump(const char *filename, int flags,
  85                    struct undo_hist_entry_rb_tree *ptse_tree,
  86                    struct hammer_ioc_hist_entry ts1,
  87                    struct hammer_ioc_hist_entry ts2,
  88                    enum undo_type type);
  89 static int doiterate_iterall(const char *filename, int flags,
  90                    struct undo_hist_entry_rb_tree *ptse_tree,
  91                    enum undo_type type);
  92 static void dogenerate(const char *filename, int flags,
  93                    struct hammer_ioc_hist_entry ts1,
  94                    struct hammer_ioc_hist_entry ts2,
  95                    int idx, enum undo_type type);
  96 static void __collect_history(int fd, int *error,
  97                    struct undo_hist_entry_rb_tree *tse_tree);
  98 static void collect_history(const char *filename, int *errorp,
  99                    struct undo_hist_entry_rb_tree *dir_tree);
 100 static void collect_dir_history(const char *filename, int *error,
 101                    struct undo_hist_entry_rb_tree *dir_tree);
 102 static void clean_tree(struct undo_hist_entry_rb_tree *tree);
 103 static hammer_tid_t parse_delta_time(const char *timeStr, int *flags,
 104                    int ind_flag);
 105 static FILE *_fopen(const char *filename, const char *mode);
 106 static void runcmd(int fd, const char *cmd, ...);
 107 static char *timestamp(struct hammer_ioc_hist_entry *hen);
 108 static void usage(void);
 109
 110 static int VerboseOpt;
 111 static const char *OutFileName = NULL;
 112 static const char *OutFilePostfix = NULL;
 113
 114 RB_GENERATE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
 115         undo_hist_entry_compare, hammer_tid_t, tse.tid);
 116
 117
 118 int
 119 main(int ac, char **av)
 120 {
 121         enum undo_cmd cmd;
 122         enum undo_type type;
 123         struct hammer_ioc_hist_entry ts1;
 124         struct hammer_ioc_hist_entry ts2;
 125         int c;
 126         int count_t;
 127         int flags;
 128
 129         bzero(&ts1, sizeof(ts1));
 130         bzero(&ts2, sizeof(ts2));
 131
 132         cmd = CMD_DUMP;
 133         type = TYPE_FILE;
 134         count_t = 0;
 135         flags = 0;
 136
 137         while ((c = getopt(ac, av, "adDiuvo:t:")) != -1) {
 138                 switch(c) {
 139                 case 'd':
 140                         type = TYPE_DIFF;
 141                         break;
 142                 case 'D':
 143                         type = TYPE_RDIFF;
 144                         break;
 145                 case 'i':
 146                         if (type != TYPE_FILE)
 147                                 usage();
 148                         type = TYPE_HISTORY;
 149                         cmd = CMD_ITERATEALL;
 150                         break;
 151                 case 'a':
 152                         cmd = CMD_ITERATEALL;
 153                         break;
 154                 case 'u':
 155                         OutFilePostfix = ".undo";
 156                         break;
 157                 case 'v':
 158                         ++VerboseOpt;
 159                         break;
 160                 case 'o':
 161                         OutFileName = optarg;
 162                         break;
 163                 case 't':
 164                         /*
 165                          * Parse one or two -t options.  If two are specified
 166                          * -d is implied (but may be overridden)
 167                          */
 168                         ++count_t;
 169                         if (count_t == 1) {
 170                                 ts1.tid = parse_delta_time(optarg, &flags,
 171                                                         UNDO_FLAG_TID_INDEX1);
 172                         } else if (count_t == 2) {
 173                                 ts2.tid = parse_delta_time(optarg, &flags,
 174                                                         UNDO_FLAG_TID_INDEX2);
 175                                 if (type == TYPE_FILE)
 176                                         type = TYPE_DIFF;
 177                         } else {
 178                                 usage();
 179                         }
 180                         break;
 181                 default:
 182                         usage();
 183                         /* NOT REACHED */
 184                         break;
 185                 }
 186         }
 187
 188         /*
 189          * Option validation
 190          */
 191         if (OutFileName && OutFilePostfix) {
 192                 fprintf(stderr, "The -o option may not be combined with -u\n");
 193                 usage();
 194         }
 195
 196         ac -= optind;
 197         av += optind;
 198         if (ac > 1)
 199                 flags |= UNDO_FLAG_MULT;
 200
 201         if (ac == 0)
 202                 usage();
 203
 204         /*
 205          * Validate the output template, if specified.
 206          */
 207         if (OutFileName && (flags & UNDO_FLAG_MULT)) {
 208                 const char *ptr = OutFileName;
 209                 int didStr = 0;
 210
 211                 while ((ptr = strchr(ptr, '%')) != NULL) {
 212                         if (ptr[1] == 's') {
 213                                 if (didStr) {
 214                                         fprintf(stderr, "Malformed output "
 215                                                         "template\n");
 216                                         usage();
 217                                 }
 218                                 didStr = 1;
 219                                 ++ptr;
 220                         } else if (ptr[1] != '%') {
 221                                 fprintf(stderr, "Malformed output template\n");
 222                                 usage();
 223                         } else {
 224                                 ptr += 2;
 225                         }
 226                 }
 227         }
 228
 229         while (ac) {
 230                 doiterate(*av, flags, ts1, ts2, cmd, type);
 231                 ++av;
 232                 --ac;
 233         }
 234         return(0);
 235 }
 236
 237 /*
 238  * Iterate through a file's history.  If cmd == CMD_DUMP we take the
 239  * next-to-last transaction id, unless another given.  Otherwise if
 240  * cmd == CMD_ITERATEALL we scan all transaction ids.
 241  *
 242  * Also iterate through the directory's history to locate other inodes that
 243  * used the particular file name.
 244  */
 245 static
 246 void
 247 doiterate(const char *filename, int flags,
 248           struct hammer_ioc_hist_entry ts1,
 249           struct hammer_ioc_hist_entry ts2,
 250           enum undo_cmd cmd, enum undo_type type)
 251 {
 252         struct undo_hist_entry_rb_tree dir_tree;
 253         struct undo_hist_entry_rb_tree tse_tree;
 254         struct undo_hist_entry *tse;
 255         struct stat sb;
 256         char *path = NULL;
 257         int error;
 258
 259         RB_INIT(&dir_tree);
 260         RB_INIT(&tse_tree);
 261
 262         /*
 263          * Use the directory history to locate all possible versions of
 264          * the file.
 265          */
 266         collect_dir_history(filename, &error, &dir_tree);
 267         RB_FOREACH(tse, undo_hist_entry_rb_tree, &dir_tree) {
 268                 asprintf(&path, "%s@@0x%016jx", filename, (uintmax_t)tse->tse.tid);
 269                 if (stat(path, &sb) == 0 && (sb.st_mode & S_IFIFO)) {
 270                         fprintf(stderr, "Warning: fake transaction id %s@@0x%016jx\n",
 271                                 filename,
 272                                 (uintmax_t)tse->tse.tid);
 273                         free(path);
 274                         continue;
 275                 }
 276                 collect_history(path, &error, &tse_tree);
 277                 free(path);
 278         }
 279         collect_history(filename, &error, &tse_tree);
 280
 281         switch (cmd) {
 282         case CMD_DUMP:
 283                 if (doiterate_dump(filename, flags, &tse_tree, ts1, ts2, type) == -1)
 284                         printf("%s: No UNDO history found\n", filename);
 285                 break;
 286         case CMD_ITERATEALL:
 287                 if (doiterate_iterall(filename, flags, &tse_tree, type) == -1)
 288                         printf("%s: No UNDO history found\n", filename);
 289                 break;
 290         default:
 291                 fprintf(stderr, "Invalid command %d\n", cmd);
 292                 break;
 293         }
 294
 295         clean_tree(&dir_tree);
 296         clean_tree(&tse_tree);
 297 }
 298
 299 static
 300 int
 301 doiterate_dump(const char *filename, int flags,
 302                 struct undo_hist_entry_rb_tree *ptse_tree,
 303                 struct hammer_ioc_hist_entry ts1,
 304                 struct hammer_ioc_hist_entry ts2,
 305                 enum undo_type type)
 306 {
 307         struct undo_hist_entry *tse1;
 308         struct undo_hist_entry *tse2;
 309
 310         /*
 311          * Find entry if tid set to placeholder index
 312          */
 313         if (flags & UNDO_FLAG_TID_INDEX1) {
 314                 tse1 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
 315                 while (tse1 && ts1.tid--) {
 316                         tse1 = RB_PREV(undo_hist_entry_rb_tree,
 317                                        ptse_tree, tse1);
 318                 }
 319                 if (tse1)
 320                         ts1 = tse1->tse;
 321                 else
 322                         ts1.tid = 0;
 323         }
 324         if (flags & UNDO_FLAG_TID_INDEX2) {
 325                 tse2 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
 326                 while (tse2 && ts2.tid--) {
 327                         tse2 = RB_PREV(undo_hist_entry_rb_tree,
 328                                        ptse_tree, tse2);
 329                 }
 330                 if (tse2)
 331                         ts2 = tse2->tse;
 332                 else
 333                         ts2.tid = 0;
 334         }
 335
 336         /*
 337          * Single entry, most recent prior to current
 338          */
 339         if (ts1.tid == 0) {
 340                 tse2 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
 341                 if (tse2) {
 342                         ts2 = tse2->tse;
 343                         tse1 = RB_PREV(undo_hist_entry_rb_tree,
 344                                        ptse_tree, tse2);
 345                         if (tse1)
 346                                 ts1 = tse1->tse;
 347                 }
 348         }
 349
 350         if (ts1.tid) {
 351                 dogenerate(filename, 0, ts1, ts2, 0, type);
 352                 return(0);
 353         }
 354         return(-1);
 355 }
 356
 357 static
 358 int
 359 doiterate_iterall(const char *filename, int flags,
 360                 struct undo_hist_entry_rb_tree *ptse_tree,
 361                 enum undo_type type)
 362 {
 363         struct undo_hist_entry *tse1;
 364         struct undo_hist_entry *tse2;
 365         struct hammer_ioc_hist_entry tid_max;
 366         int i;
 367
 368         if (RB_ROOT(ptse_tree) == NULL)
 369                 return(-1);
 370
 371         /*
 372          * Iterate entire history
 373          */
 374         printf("%s: ITERATE ENTIRE HISTORY\n", filename);
 375
 376         tse1 = NULL;
 377         i = 0;
 378         RB_FOREACH(tse2, undo_hist_entry_rb_tree, ptse_tree) {
 379                 if (tse1) {
 380                         dogenerate(filename, flags, tse1->tse, tse2->tse, i, type);
 381                 }
 382                 if (tse1 && tse2->inum != tse1->inum)
 383                         flags |= UNDO_FLAG_INOCHG;
 384                 else
 385                         flags &= ~UNDO_FLAG_INOCHG;
 386                 tse1 = tse2;
 387                 ++i;
 388         }
 389
 390         /*
 391          * There is no delta to print for the last pair,
 392          * because they are identical.
 393          */
 394         if (type != TYPE_DIFF && type != TYPE_RDIFF) {
 395                 tid_max.tid = HAMMER_MAX_TID;
 396                 tid_max.time32 = 0;
 397                 dogenerate(filename, flags, tse1->tse, tid_max, i, type);
 398         }
 399         return(0);
 400 }
 401
 402 /*
 403  * Generate output for a file as-of ts1 (ts1 may be 0!), if diffing then
 404  * through ts2.
 405  */
 406 static
 407 void
 408 dogenerate(const char *filename, int flags,
 409            struct hammer_ioc_hist_entry ts1,
 410            struct hammer_ioc_hist_entry ts2,
 411            int idx, enum undo_type type)
 412 {
 413         struct stat st;
 414         const char *elm;
 415         char *ipath1 = NULL;
 416         char *ipath2 = NULL;
 417         FILE *fi;
 418         FILE *fp;
 419         char *buf;
 420         char *path;
 421         time_t t;
 422         struct tm *tp;
 423         char datestr[64];
 424         int n;
 425
 426         /*
 427          * Open the input file.  If ts1 is 0 try to locate the most recent
 428          * version of the file prior to the current version.
 429          */
 430         if (ts1.tid == 0)
 431                 asprintf(&ipath1, "%s", filename);
 432         else
 433                 asprintf(&ipath1, "%s@@0x%016jx", filename, (uintmax_t)ts1.tid);
 434
 435         if (ts2.tid == 0)
 436                 asprintf(&ipath2, "%s", filename);
 437         else
 438                 asprintf(&ipath2, "%s@@0x%016jx", filename, (uintmax_t)ts2.tid);
 439
 440         if (lstat(ipath1, &st) < 0 && lstat(ipath2, &st) < 0) {
 441                 if (idx == 0 || VerboseOpt) {
 442                         fprintf(stderr, "Unable to access either %s or %s\n",
 443                                 ipath1, ipath2);
 444                 }
 445                 free(ipath1);
 446                 free(ipath2);
 447                 return;
 448         }
 449
 450         /*
 451          * elm is the last component of the input file name
 452          */
 453         if ((elm = strrchr(filename, '/')) != NULL)
 454                 ++elm;
 455         else
 456                 elm = filename;
 457
 458         /*
 459          * Where do we stuff our output?
 460          */
 461         if (OutFileName) {
 462                 if (flags & UNDO_FLAG_MULT) {
 463                         asprintf(&path, OutFileName, elm);
 464                         fp = _fopen(path, "w");
 465                         free(path);
 466                 } else {
 467                         fp = _fopen(OutFileName, "w");
 468                 }
 469         } else if (OutFilePostfix) {
 470                 if (idx >= 0) {
 471                         asprintf(&path, "%s%s.%04d", filename,
 472                                  OutFilePostfix, idx);
 473                 } else {
 474                         asprintf(&path, "%s%s", filename, OutFilePostfix);
 475                 }
 476                 fp = _fopen(path, "w");
 477                 free(path);
 478         } else {
 479                 if ((flags & UNDO_FLAG_MULT) && type == TYPE_FILE) {
 480                         if (idx >= 0) {
 481                                 printf("\n>>> %s %04d 0x%016jx %s\n\n",
 482                                        filename, idx, (uintmax_t)ts1.tid,
 483                                        timestamp(&ts1));
 484                         } else {
 485                                 printf("\n>>> %s ---- 0x%016jx %s\n\n",
 486                                        filename, (uintmax_t)ts1.tid,
 487                                        timestamp(&ts1));
 488                         }
 489                 } else if (idx >= 0 && type == TYPE_FILE) {
 490                         printf("\n>>> %s %04d 0x%016jx %s\n\n",
 491                                filename, idx, (uintmax_t)ts1.tid,
 492                                timestamp(&ts1));
 493                 }
 494                 fp = stdout;
 495         }
 496
 497         switch(type) {
 498         case TYPE_FILE:
 499                 buf = malloc(8192);
 500                 if (buf == NULL)
 501                         err(1, "malloc");
 502                 if ((fi = fopen(ipath1, "r")) != NULL) {
 503                         while ((n = fread(buf, 1, 8192, fi)) > 0)
 504                                 fwrite(buf, 1, n, fp);
 505                         fclose(fi);
 506                 }
 507                 free(buf);
 508                 break;
 509         case TYPE_DIFF:
 510                 printf("diff -N -r -u %s %s (to %s)\n",
 511                        ipath1, ipath2, timestamp(&ts2));
 512                 fflush(stdout);
 513                 runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u",
 514                         ipath1, ipath2, NULL);
 515                 break;
 516         case TYPE_RDIFF:
 517                 printf("diff -N -r -u %s %s\n", ipath2, ipath1);
 518                 fflush(stdout);
 519                 runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u",
 520                         ipath2, ipath1, NULL);
 521                 break;
 522         case TYPE_HISTORY:
 523                 t = (time_t)ts1.time32;
 524                 tp = localtime(&t);
 525                 strftime(datestr, sizeof(datestr), "%d-%b-%Y %H:%M:%S", tp);
 526                 printf("\t0x%016jx %s", (uintmax_t)ts1.tid, datestr);
 527                 if (flags & UNDO_FLAG_INOCHG)
 528                         printf(" inode-change");
 529                 if (lstat(ipath1, &st) < 0)
 530                         printf(" file-deleted");
 531                 printf("\n");
 532                 break;
 533         }
 534
 535         if (fp != stdout)
 536                 fclose(fp);
 537 }
 538
 539 static
 540 void
 541 clean_tree(struct undo_hist_entry_rb_tree *tree)
 542 {
 543         struct undo_hist_entry *tse;
 544
 545         while ((tse = RB_ROOT(tree)) != NULL) {
 546                 RB_REMOVE(undo_hist_entry_rb_tree, tree, tse);
 547                 free(tse);
 548         }
 549 }
 550
 551 static
 552 void
 553 __collect_history(int fd, int *errorp, struct undo_hist_entry_rb_tree *tse_tree)
 554 {
 555         struct hammer_ioc_history hist;
 556         struct undo_hist_entry *tse;
 557         struct stat st;
 558         int i;
 559
 560         /*
 561          * Setup
 562          */
 563         bzero(&hist, sizeof(hist));
 564         hist.beg_tid = HAMMER_MIN_TID;
 565         hist.end_tid = HAMMER_MAX_TID;
 566         hist.head.flags |= HAMMER_IOC_HISTORY_ATKEY;
 567         hist.key = 0;
 568         hist.nxt_key = HAMMER_MAX_KEY;
 569
 570         *errorp = 0;
 571
 572         /*
 573          * Save the inode so inode changes can be reported.
 574          */
 575         st.st_ino = 0;
 576         fstat(fd, &st);
 577
 578         /*
 579          * Collect a unique set of transaction ids
 580          */
 581         if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
 582                 *errorp = errno;
 583                 return;
 584         }
 585         for (;;) {
 586                 for (i = 0; i < hist.count; ++i) {
 587                         tse = malloc(sizeof(*tse));
 588                         tse->tse = hist.hist_ary[i];
 589                         tse->inum = st.st_ino;
 590                         if (RB_INSERT(undo_hist_entry_rb_tree, tse_tree, tse)) {
 591                                 free(tse);
 592                         }
 593                 }
 594                 if (hist.head.flags & HAMMER_IOC_HISTORY_EOF)
 595                         break;
 596                 if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_KEY) {
 597                         hist.key = hist.nxt_key;
 598                         hist.nxt_key = HAMMER_MAX_KEY;
 599                 }
 600                 if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_TID)
 601                         hist.beg_tid = hist.nxt_tid;
 602                 if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
 603                         *errorp = errno;
 604                         break;
 605                 }
 606         }
 607 }
 608
 609 static
 610 void
 611 collect_history(const char *filename, int *errorp,
 612                 struct undo_hist_entry_rb_tree *dir_tree)
 613 {
 614         int fd;
 615
 616         fd = open(filename, O_RDONLY);
 617         if (fd == -1) {
 618                 *errorp = errno;
 619                 return;
 620         }
 621         __collect_history(fd, errorp, dir_tree);
 622         close(fd);
 623 }
 624
 625 static
 626 void
 627 collect_dir_history(const char *filename, int *errorp,
 628                     struct undo_hist_entry_rb_tree *dir_tree)
 629 {
 630         char *dirname;
 631
 632         if (strrchr(filename, '/')) {
 633                 dirname = strdup(filename);
 634                 *strrchr(dirname, '/') = 0;
 635         } else {
 636                 dirname = strdup(".");
 637         }
 638
 639         collect_history(dirname, errorp, dir_tree);
 640         free(dirname);
 641 }
 642
 643 static
 644 hammer_tid_t
 645 parse_delta_time(const char *timeStr, int *flags, int ind_flag)
 646 {
 647         hammer_tid_t tid;
 648
 649         tid = strtoull(timeStr, NULL, 0);
 650         if (timeStr[0] == '+')
 651                 ++timeStr;
 652         if (timeStr[0] >= '0' && timeStr[0] <= '9' && timeStr[1] != 'x')
 653                 *flags |= ind_flag;
 654         return(tid);
 655 }
 656
 657 static
 658 FILE*
 659 _fopen(const char *filename, const char *mode)
 660 {
 661         FILE *fp;
 662
 663         fp = fopen(filename, mode);
 664         if (fp == NULL)
 665                 err(1, "%s", filename);
 666         return(fp);
 667 }
 668
 669 static void
 670 runcmd(int fd, const char *cmd, ...)
 671 {
 672         va_list va;
 673         pid_t pid;
 674         char **av;
 675         int ac;
 676         int i;
 677
 678         va_start(va, cmd);
 679         for (ac = 0; va_arg(va, void *) != NULL; ++ac)
 680                 ;
 681         va_end(va);
 682
 683         av = malloc((ac + 1) * sizeof(char *));
 684         va_start(va, cmd);
 685         for (i = 0; i < ac; ++i)
 686                 av[i] = va_arg(va, char *);
 687         va_end(va);
 688         av[i] = NULL;
 689
 690         if ((pid = fork()) < 0) {
 691                 err(1, "fork");
 692         } else if (pid == 0) {
 693                 if (fd != 1) {
 694                         dup2(fd, 1);
 695                         close(fd);
 696                 }
 697                 execv(cmd, av);
 698                 _exit(1);
 699         } else {
 700                 while (waitpid(pid, NULL, 0) != pid)
 701                         ;
 702         }
 703         free(av);
 704 }
 705
 706 /*
 707  * Convert tid to timestamp.
 708  */
 709 static char *
 710 timestamp(struct hammer_ioc_hist_entry *hen)
 711 {
 712         static char timebuf[64];
 713         time_t t = (time_t)hen->time32;
 714         struct tm *tp;
 715
 716         tp = localtime(&t);
 717         strftime(timebuf, sizeof(timebuf), "%d-%b-%Y %H:%M:%S", tp);
 718         return(timebuf);
 719 }
 720
 721 static
 722 int
 723 undo_hist_entry_compare(struct undo_hist_entry *he1,
 724                         struct undo_hist_entry *he2)
 725 {
 726         if (he1->tse.tid < he2->tse.tid)
 727                 return(-1);
 728         if (he1->tse.tid > he2->tse.tid)
 729                 return(1);
 730         return(0);
 731 }
 732
 733 static void
 734 usage(void)
 735 {
 736         fprintf(stderr, "undo [-adDiuv] [-o outfile] "
 737                         "[-t transaction-id] [-t transaction-id] path...\n"
 738                         "    -a       Iterate all historical segments\n"
 739                         "    -d       Forward diff\n"
 740                         "    -D       Reverse diff\n"
 741                         "    -i       Dump history transaction ids\n"
 742                         "    -u       Generate .undo files\n"
 743                         "    -v       Verbose\n"
 744                         "    -o file  Output to the specified file\n"
 745                         "    -t TID   Retrieve as of transaction-id, TID\n"
 746                         "             (a second `-t TID' to diff two)\n"
 747                         "    transaction ids must be prefixed with 0x, and\n"
 748                         "    otherwise may specify an index starting at 0\n"
 749                         "    and iterating backwards through the history.\n"
 750         );
 751         exit(1);
 752 }
 753