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/param.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 <vfs/hammer/hammer_disk.h>
  53 #include <vfs/hammer/hammer_ioctl.h>
  54
  55 /*
  56  * Sorted list of transaction ids
  57  */
  58 struct undo_hist_entry;
  59 RB_HEAD(undo_hist_entry_rb_tree, undo_hist_entry);
  60 RB_PROTOTYPE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
  61         undo_hist_entry_compare, hammer_tid_t);
  62
  63 struct undo_hist_entry {
  64         RB_ENTRY(undo_hist_entry) rbnode;
  65         struct hammer_ioc_hist_entry tse;
  66         ino_t inum;
  67 };
  68
  69 enum undo_type { TYPE_FILE, TYPE_DIFF, TYPE_RDIFF, TYPE_HISTORY };
  70 enum undo_cmd { CMD_DUMP, CMD_ITERATEALL };
  71
  72 #define UNDO_FLAG_MULT          0x0001
  73 #define UNDO_FLAG_INOCHG        0x0002
  74 #define UNDO_FLAG_SETTID1       0x0004
  75 #define UNDO_FLAG_SETTID2       0x0008
  76
  77 static int undo_hist_entry_compare(struct undo_hist_entry *he1,
  78                     struct undo_hist_entry *he2);
  79 static void doiterate(const char *filename, const char *outFileName,
  80                    const char *outFilePostfix, 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 void dogenerate(const char *filename, const char *outFileName,
  85                    const char *outFilePostfix,
  86                    int flags, int idx, enum undo_type type,
  87                    struct hammer_ioc_hist_entry ts1,
  88                    struct hammer_ioc_hist_entry ts2);
  89 static void collect_history(int fd, int *error,
  90                    struct undo_hist_entry_rb_tree *tse_tree);
  91 static void collect_dir_history(const char *filename, int *error,
  92                    struct undo_hist_entry_rb_tree *dir_tree);
  93 static void clean_tree(struct undo_hist_entry_rb_tree *tree);
  94 static hammer_tid_t parse_delta_time(const char *timeStr, int *flags,
  95                    int ind_flag);
  96 static void runcmd(int fd, const char *cmd, ...);
  97 static char *timestamp(hammer_ioc_hist_entry_t hen);
  98 static void usage(void);
  99
 100 static int VerboseOpt;
 101
 102 RB_GENERATE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
 103         undo_hist_entry_compare, hammer_tid_t, tse.tid);
 104
 105
 106 int
 107 main(int ac, char **av)
 108 {
 109         const char *outFileName = NULL;
 110         const char *outFilePostfix = NULL;
 111         enum undo_cmd cmd;
 112         enum undo_type type;
 113         struct hammer_ioc_hist_entry ts1;
 114         struct hammer_ioc_hist_entry ts2;
 115         int c;
 116         int count_t;
 117         int flags;
 118
 119         bzero(&ts1, sizeof(ts1));
 120         bzero(&ts2, sizeof(ts2));
 121
 122         cmd = CMD_DUMP;
 123         type = TYPE_FILE;
 124         count_t = 0;
 125         flags = 0;
 126
 127         while ((c = getopt(ac, av, "adDiuvo:t:")) != -1) {
 128                 switch(c) {
 129                 case 'd':
 130                         type = TYPE_DIFF;
 131                         break;
 132                 case 'D':
 133                         type = TYPE_RDIFF;
 134                         break;
 135                 case 'i':
 136                         if (type != TYPE_FILE)
 137                                 usage();
 138                         type = TYPE_HISTORY;
 139                         cmd = CMD_ITERATEALL;
 140                         break;
 141                 case 'a':
 142                         cmd = CMD_ITERATEALL;
 143                         break;
 144                 case 'u':
 145                         outFilePostfix = ".undo";
 146                         break;
 147                 case 'v':
 148                         ++VerboseOpt;
 149                         break;
 150                 case 'o':
 151                         outFileName = optarg;
 152                         break;
 153                 case 't':
 154                         /*
 155                          * Parse one or two -t options.  If two are specified
 156                          * -d is implied (but may be overridden)
 157                          */
 158                         ++count_t;
 159                         if (count_t == 1) {
 160                                 ts1.tid = parse_delta_time(optarg, &flags,
 161                                                            UNDO_FLAG_SETTID1);
 162                         } else if (count_t == 2) {
 163                                 ts2.tid = parse_delta_time(optarg, &flags,
 164                                                            UNDO_FLAG_SETTID2);
 165                                 if (type == TYPE_FILE)
 166                                         type = TYPE_DIFF;
 167                         } else {
 168                                 usage();
 169                         }
 170                         break;
 171                 default:
 172                         usage();
 173                         /* NOT REACHED */
 174                         break;
 175                 }
 176         }
 177
 178         /*
 179          * Option validation
 180          */
 181         if (outFileName && outFilePostfix) {
 182                 fprintf(stderr, "The -o option may not be combined with -u\n");
 183                 usage();
 184         }
 185
 186         ac -= optind;
 187         av += optind;
 188         if (ac > 1)
 189                 flags |= UNDO_FLAG_MULT;
 190
 191         if (ac == 0)
 192                 usage();
 193
 194         /*
 195          * Validate the output template, if specified.
 196          */
 197         if (outFileName && (flags & UNDO_FLAG_MULT)) {
 198                 const char *ptr = outFileName;
 199                 int didStr = 0;
 200
 201                 while ((ptr = strchr(ptr, '%')) != NULL) {
 202                         if (ptr[1] == 's') {
 203                                 if (didStr) {
 204                                         fprintf(stderr, "Malformed output "
 205                                                         "template\n");
 206                                         usage();
 207                                 }
 208                                 didStr = 1;
 209                                 ++ptr;
 210                         } else if (ptr[1] != '%') {
 211                                 fprintf(stderr, "Malformed output template\n");
 212                                 usage();
 213                         } else {
 214                                 ptr += 2;
 215                         }
 216                 }
 217         }
 218
 219         while (ac) {
 220                 doiterate(*av, outFileName, outFilePostfix,
 221                           flags, ts1, ts2, cmd, type);
 222                 ++av;
 223                 --ac;
 224         }
 225         return(0);
 226 }
 227
 228 /*
 229  * Iterate through a file's history.  If cmd == CMD_DUMP we take the
 230  * next-to-last transaction id, unless another given.  Otherwise if
 231  * cmd == CMD_ITERATEALL we scan all transaction ids.
 232  *
 233  * Also iterate through the directory's history to locate other inodes that
 234  * used the particular file name.
 235  */
 236 static
 237 void
 238 doiterate(const char *filename, const char *outFileName,
 239           const char *outFilePostfix, int flags,
 240           struct hammer_ioc_hist_entry ts1,
 241           struct hammer_ioc_hist_entry ts2,
 242           enum undo_cmd cmd, enum undo_type type)
 243 {
 244         struct undo_hist_entry_rb_tree dir_tree;
 245         struct undo_hist_entry_rb_tree tse_tree;
 246         struct undo_hist_entry *tse1;
 247         struct undo_hist_entry *tse2;
 248         struct hammer_ioc_hist_entry tid_max;
 249         char *path = NULL;
 250         int i;
 251         int fd;
 252         int error;
 253
 254         RB_INIT(&dir_tree);
 255         RB_INIT(&tse_tree);
 256
 257         tid_max.tid = HAMMER_MAX_TID;
 258         tid_max.time32 = 0;
 259
 260         /*
 261          * Use the directory history to locate all possible versions of
 262          * the file.
 263          */
 264         collect_dir_history(filename, &error, &dir_tree);
 265         RB_FOREACH(tse1, undo_hist_entry_rb_tree, &dir_tree) {
 266                 asprintf(&path, "%s@@0x%016jx", filename, (uintmax_t)tse1->tse.tid);
 267                 if ((fd = open(path, O_RDONLY)) > 0) {
 268                         collect_history(fd, &error, &tse_tree);
 269                         close(fd);
 270                 }
 271                 free(path);
 272         }
 273         if ((fd = open(filename, O_RDONLY)) > 0) {
 274                 collect_history(fd, &error, &tse_tree);
 275                 close(fd);
 276         }
 277         if (cmd == CMD_DUMP) {
 278                 if ((ts1.tid == 0 ||
 279                      flags & (UNDO_FLAG_SETTID1|UNDO_FLAG_SETTID2)) &&
 280                     RB_EMPTY(&tse_tree)) {
 281                         if ((fd = open(filename, O_RDONLY)) > 0) {
 282                                 collect_history(fd, &error, &tse_tree);
 283                                 close(fd);
 284                         }
 285                 }
 286                 /*
 287                  * Find entry if tid set to placeholder index
 288                  */
 289                 if (flags & UNDO_FLAG_SETTID1){
 290                         tse1 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
 291                         while (tse1 && ts1.tid--) {
 292                                 tse1 = RB_PREV(undo_hist_entry_rb_tree,
 293                                                &tse_tree, tse1);
 294                         }
 295                         if (tse1)
 296                                 ts1 = tse1->tse;
 297                         else
 298                                 ts1.tid = 0;
 299                 }
 300                 if (flags & UNDO_FLAG_SETTID2){
 301                         tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
 302                         while (tse2 && ts2.tid--) {
 303                                 tse2 = RB_PREV(undo_hist_entry_rb_tree,
 304                                                &tse_tree, tse2);
 305                         }
 306                         if (tse2)
 307                                 ts2 = tse2->tse;
 308                         else
 309                                 ts2.tid = 0;
 310                 }
 311
 312                 /*
 313                  * Single entry, most recent prior to current
 314                  */
 315                 if (ts1.tid == 0) {
 316                         tse2 = RB_MAX(undo_hist_entry_rb_tree, &tse_tree);
 317                         if (tse2) {
 318                                 ts2 = tse2->tse;
 319                                 tse1 = RB_PREV(undo_hist_entry_rb_tree,
 320                                                &tse_tree, tse2);
 321                                 if (tse1)
 322                                         ts1 = tse1->tse;
 323                         }
 324                 }
 325                 if (ts1.tid == 0) {
 326                         printf("%s: No UNDO history found\n", filename);
 327                 } else {
 328                         dogenerate(filename,
 329                                    outFileName, outFilePostfix,
 330                                    0, 0, type,
 331                                    ts1, ts2);
 332                 }
 333         } else if (RB_ROOT(&tse_tree)) {
 334                 /*
 335                  * Iterate entire history
 336                  */
 337                 printf("%s: ITERATE ENTIRE HISTORY\n", filename);
 338
 339                 tse1 = NULL;
 340                 i = 0;
 341                 RB_FOREACH(tse2, undo_hist_entry_rb_tree, &tse_tree) {
 342                         if (tse1) {
 343                                 dogenerate(filename,
 344                                            outFileName, outFilePostfix,
 345                                            flags, i, type,
 346                                            tse1->tse, tse2->tse);
 347                         }
 348                         if (tse1 && tse2->inum != tse1->inum)
 349                                 flags |= UNDO_FLAG_INOCHG;
 350                         else
 351                                 flags &= ~UNDO_FLAG_INOCHG;
 352                         tse1 = tse2;
 353                         ++i;
 354                 }
 355                 /*
 356                  * There is no delta to print for the last pair,
 357                  * because they are identical.
 358                  */
 359                 if (type != TYPE_DIFF && type != TYPE_RDIFF) {
 360                         dogenerate(filename,
 361                                    outFileName, outFilePostfix,
 362                                    flags, i, type,
 363                                    tse1->tse, tid_max);
 364                 }
 365         } else {
 366                 printf("%s: ITERATE ENTIRE HISTORY: %s\n",
 367                        filename, strerror(error));
 368         }
 369         clean_tree(&dir_tree);
 370         clean_tree(&tse_tree);
 371 }
 372
 373 /*
 374  * Generate output for a file as-of ts1 (ts1 may be 0!), if diffing then
 375  * through ts2.
 376  */
 377 static
 378 void
 379 dogenerate(const char *filename, const char *outFileName,
 380            const char *outFilePostfix,
 381            int flags, int idx, enum undo_type type,
 382            struct hammer_ioc_hist_entry ts1,
 383            struct hammer_ioc_hist_entry ts2)
 384 {
 385         struct stat st;
 386         const char *elm;
 387         char *ipath1 = NULL;
 388         char *ipath2 = NULL;
 389         FILE *fi;
 390         FILE *fp;
 391         char *buf;
 392         char *path;
 393         time_t t;
 394         struct tm *tp;
 395         char datestr[64];
 396         int n;
 397
 398         buf = malloc(8192);
 399
 400         /*
 401          * Open the input file.  If ts1 is 0 try to locate the most recent
 402          * version of the file prior to the current version.
 403          */
 404         if (ts1.tid == 0)
 405                 asprintf(&ipath1, "%s", filename);
 406         else
 407                 asprintf(&ipath1, "%s@@0x%016jx", filename, (uintmax_t)ts1.tid);
 408
 409         if (ts2.tid == 0)
 410                 asprintf(&ipath2, "%s", filename);
 411         else
 412                 asprintf(&ipath2, "%s@@0x%016jx", filename, (uintmax_t)ts2.tid);
 413
 414         if (lstat(ipath1, &st) < 0 && lstat(ipath2, &st) < 0) {
 415                 if (idx == 0 || VerboseOpt) {
 416                         fprintf(stderr, "Unable to access either %s or %s\n",
 417                                 ipath1, ipath2);
 418                 }
 419                 free(ipath1);
 420                 free(ipath2);
 421                 goto done;
 422         }
 423
 424         /*
 425          * elm is the last component of the input file name
 426          */
 427         if ((elm = strrchr(filename, '/')) != NULL)
 428                 ++elm;
 429         else
 430                 elm = filename;
 431
 432         /*
 433          * Where do we stuff our output?
 434          */
 435         if (outFileName) {
 436                 if (flags & UNDO_FLAG_MULT) {
 437                         asprintf(&path, outFileName, elm);
 438                         fp = fopen(path, "w");
 439                         if (fp == NULL) {
 440                                 perror(path);
 441                                 exit(1);
 442                         }
 443                         free(path);
 444                 } else {
 445                         fp = fopen(outFileName, "w");
 446                         if (fp == NULL) {
 447                                 perror(outFileName);
 448                                 exit(1);
 449                         }
 450                 }
 451         } else if (outFilePostfix) {
 452                 if (idx >= 0) {
 453                         asprintf(&path, "%s%s.%04d", filename,
 454                                  outFilePostfix, idx);
 455                 } else {
 456                         asprintf(&path, "%s%s", filename, outFilePostfix);
 457                 }
 458                 fp = fopen(path, "w");
 459                 if (fp == NULL) {
 460                         perror(path);
 461                         exit(1);
 462                 }
 463                 free(path);
 464         } else {
 465                 if ((flags & UNDO_FLAG_MULT) && type == TYPE_FILE) {
 466                         if (idx >= 0) {
 467                                 printf("\n>>> %s %04d 0x%016jx %s\n\n",
 468                                        filename, idx, (uintmax_t)ts1.tid,
 469                                        timestamp(&ts1));
 470                         } else {
 471                                 printf("\n>>> %s ---- 0x%016jx %s\n\n",
 472                                        filename, (uintmax_t)ts1.tid,
 473                                        timestamp(&ts1));
 474                         }
 475                 } else if (idx >= 0 && type == TYPE_FILE) {
 476                         printf("\n>>> %s %04d 0x%016jx %s\n\n",
 477                                filename, idx, (uintmax_t)ts1.tid,
 478                                timestamp(&ts1));
 479                 }
 480                 fp = stdout;
 481         }
 482
 483         switch(type) {
 484         case TYPE_FILE:
 485                 if ((fi = fopen(ipath1, "r")) != NULL) {
 486                         while ((n = fread(buf, 1, 8192, fi)) > 0)
 487                                 fwrite(buf, 1, n, fp);
 488                         fclose(fi);
 489                 }
 490                 break;
 491         case TYPE_DIFF:
 492                 printf("diff -N -r -u %s %s (to %s)\n",
 493                        ipath1, ipath2, timestamp(&ts2));
 494                 fflush(stdout);
 495                 runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath1, ipath2, NULL);
 496                 break;
 497         case TYPE_RDIFF:
 498                 printf("diff -N -r -u %s %s\n", ipath2, ipath1);
 499                 fflush(stdout);
 500                 runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u", ipath2, ipath1, NULL);
 501                 break;
 502         case TYPE_HISTORY:
 503                 t = (time_t)ts1.time32;
 504                 tp = localtime(&t);
 505                 strftime(datestr, sizeof(datestr), "%d-%b-%Y %H:%M:%S", tp);
 506                 printf("\t0x%016jx %s", (uintmax_t)ts1.tid, datestr);
 507                 if (flags & UNDO_FLAG_INOCHG)
 508                         printf(" inode-change");
 509                 if (lstat(ipath1, &st) < 0)
 510                         printf(" file-deleted");
 511                 printf("\n");
 512                 break;
 513         }
 514
 515         if (fp != stdout)
 516                 fclose(fp);
 517 done:
 518         free(buf);
 519 }
 520
 521 static
 522 void
 523 clean_tree(struct undo_hist_entry_rb_tree *tree)
 524 {
 525         struct undo_hist_entry *tse;
 526
 527         while ((tse = RB_ROOT(tree)) != NULL) {
 528                 RB_REMOVE(undo_hist_entry_rb_tree, tree, tse);
 529                 free(tse);
 530         }
 531 }
 532
 533 static
 534 void
 535 collect_history(int fd, int *errorp, struct undo_hist_entry_rb_tree *tse_tree)
 536 {
 537         struct hammer_ioc_history hist;
 538         struct undo_hist_entry *tse;
 539         struct stat st;
 540         int istmp;
 541         int i;
 542
 543         /*
 544          * Setup
 545          */
 546         bzero(&hist, sizeof(hist));
 547         hist.beg_tid = HAMMER_MIN_TID;
 548         hist.end_tid = HAMMER_MAX_TID;
 549         hist.head.flags |= HAMMER_IOC_HISTORY_ATKEY;
 550         hist.key = 0;
 551         hist.nxt_key = HAMMER_MAX_KEY;
 552
 553         *errorp = 0;
 554
 555         if (tse_tree == NULL) {
 556                 tse_tree = malloc(sizeof(*tse_tree));
 557                 RB_INIT(tse_tree);
 558                 istmp = 1;
 559         } else {
 560                 istmp = 0;
 561         }
 562
 563         /*
 564          * Save the inode so inode changes can be reported.
 565          */
 566         st.st_ino = 0;
 567         fstat(fd, &st);
 568
 569         /*
 570          * Collect a unique set of transaction ids
 571          */
 572         if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
 573                 *errorp = errno;
 574                 goto done;
 575         }
 576         for (;;) {
 577                 for (i = 0; i < hist.count; ++i) {
 578                         tse = malloc(sizeof(*tse));
 579                         tse->tse = hist.hist_ary[i];
 580                         tse->inum = st.st_ino;
 581                         if (RB_INSERT(undo_hist_entry_rb_tree, tse_tree, tse)) {
 582                                 free(tse);
 583                         }
 584                 }
 585                 if (hist.head.flags & HAMMER_IOC_HISTORY_EOF)
 586                         break;
 587                 if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_KEY) {
 588                         hist.key = hist.nxt_key;
 589                         hist.nxt_key = HAMMER_MAX_KEY;
 590                 }
 591                 if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_TID)
 592                         hist.beg_tid = hist.nxt_tid;
 593                 if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
 594                         *errorp = errno;
 595                         break;
 596                 }
 597         }
 598
 599         /*
 600          * Cleanup
 601          */
 602 done:
 603         if (istmp) {
 604                 clean_tree(tse_tree);
 605                 free(tse_tree);
 606         }
 607 }
 608
 609 static
 610 void
 611 collect_dir_history(const char *filename, int *errorp,
 612                     struct undo_hist_entry_rb_tree *dir_tree)
 613 {
 614         char *dirname;
 615         int fd;
 616         int error;
 617
 618         *errorp = 0;
 619         if (strrchr(filename, '/')) {
 620                 dirname = strdup(filename);
 621                 *strrchr(dirname, '/') = 0;
 622         } else {
 623                 dirname = strdup(".");
 624         }
 625         if ((fd = open(dirname, O_RDONLY)) > 0) {
 626                 collect_history(fd, &error, dir_tree);
 627                 close(fd);
 628         }
 629 }
 630
 631 static
 632 hammer_tid_t
 633 parse_delta_time(const char *timeStr, int *flags, int ind_flag)
 634 {
 635         hammer_tid_t tid;
 636
 637         tid = strtoull(timeStr, NULL, 0);
 638         if (timeStr[0] == '+')
 639                 ++timeStr;
 640         if (timeStr[0] >= '0' && timeStr[0] <= '9' && timeStr[1] != 'x')
 641                 *flags |= ind_flag;
 642         return(tid);
 643 }
 644
 645 static void
 646 runcmd(int fd, const char *cmd, ...)
 647 {
 648         va_list va;
 649         pid_t pid;
 650         char **av;
 651         int ac;
 652         int i;
 653
 654         va_start(va, cmd);
 655         for (ac = 0; va_arg(va, void *) != NULL; ++ac)
 656                 ;
 657         va_end(va);
 658
 659         av = malloc((ac + 1) * sizeof(char *));
 660         va_start(va, cmd);
 661         for (i = 0; i < ac; ++i)
 662                 av[i] = va_arg(va, char *);
 663         va_end(va);
 664         av[i] = NULL;
 665
 666         if ((pid = fork()) < 0) {
 667                 perror("fork");
 668                 exit(1);
 669         } else if (pid == 0) {
 670                 if (fd != 1) {
 671                         dup2(fd, 1);
 672                         close(fd);
 673                 }
 674                 execv(cmd, av);
 675                 _exit(1);
 676         } else {
 677                 while (waitpid(pid, NULL, 0) != pid)
 678                         ;
 679         }
 680         free(av);
 681 }
 682
 683 /*
 684  * Convert tid to timestamp.
 685  */
 686 static char *
 687 timestamp(hammer_ioc_hist_entry_t hen)
 688 {
 689         static char timebuf[64];
 690         time_t t = (time_t)hen->time32;
 691         struct tm *tp;
 692
 693         tp = localtime(&t);
 694         strftime(timebuf, sizeof(timebuf), "%d-%b-%Y %H:%M:%S", tp);
 695         return(timebuf);
 696 }
 697
 698 static
 699 int
 700 undo_hist_entry_compare(struct undo_hist_entry *he1,
 701                         struct undo_hist_entry *he2)
 702 {
 703         if (he1->tse.tid < he2->tse.tid)
 704                 return(-1);
 705         if (he1->tse.tid > he2->tse.tid)
 706                 return(1);
 707         return(0);
 708 }
 709
 710 static void
 711 usage(void)
 712 {
 713         fprintf(stderr, "undo [-adDiuv] [-o outfile] "
 714                         "[-t transaction-id] [-t transaction-id] path...\n"
 715                         "    -a       Iterate all historical segments\n"
 716                         "    -d       Forward diff\n"
 717                         "    -D       Reverse diff\n"
 718                         "    -i       Dump history transaction ids\n"
 719                         "    -u       Generate .undo files\n"
 720                         "    -v       Verbose\n"
 721                         "    -o file  Output to the specified file\n"
 722                         "    -t TID   Retrieve as of transaction-id, TID\n"
 723                         "             (a second `-t TID' to diff two)\n"
 724                         "    transaction ids must be prefixed with 0x, and\n"
 725                         "    otherwise may specify an index starting at 0\n"
 726                         "    and iterating backwards through the history.\n"
 727         );
 728         exit(1);
 729 }
 730