restore/symtab.c

   1 /*
   2  *      Ported to Linux's Second Extended File System as part of the
   3  *      dump and restore backup suit
   4  *      Remy Card <card@Linux.EU.Org>, 1994-1997
   5  *      Stelian Pop <stelian@popies.net>, 1999-2000
   6  *      Stelian Pop <stelian@popies.net> - Alcôve <www.alcove.com>, 2000-2002
   7  */
   8
   9 /*
  10  * Copyright (c) 1983, 1993
  11  *      The Regents of the University of California.  All rights reserved.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  */
  37
  38 #ifndef lint
  39 static const char rcsid[] =
  40         "$Id: symtab.c,v 1.26 2005/07/07 08:47:16 stelian Exp $";
  41 #endif /* not lint */
  42
  43 /*
  44  * These routines maintain the symbol table which tracks the state
  45  * of the file system being restored. They provide lookup by either
  46  * name or inode number. They also provide for creation, deletion,
  47  * and renaming of entries. Because of the dynamic nature of pathnames,
  48  * names should not be saved, but always constructed just before they
  49  * are needed, by calling "myname".
  50  */
  51
  52 #include <config.h>
  53 #include <compatlfs.h>
  54 #include <sys/param.h>
  55 #include <sys/stat.h>
  56
  57 #ifdef  __linux__
  58 #include <sys/time.h>
  59 #include <time.h>
  60 #ifdef HAVE_EXT2FS_EXT2_FS_H
  61 #include <ext2fs/ext2_fs.h>
  62 #else
  63 #include <linux/ext2_fs.h>
  64 #endif
  65 #include <bsdcompat.h>
  66 #else   /* __linux__ */
  67 #ifdef sunos
  68 #include <sys/fcntl.h>
  69 #include <bsdcompat.h>
  70 #else
  71 #include <ufs/ufs/dinode.h>
  72 #endif
  73 #endif  /* __linux__ */
  74
  75 #include <errno.h>
  76 #include <compaterr.h>
  77 #include <fcntl.h>
  78 #include <stdio.h>
  79 #include <stdlib.h>
  80 #include <string.h>
  81 #include <unistd.h>
  82
  83 #ifdef  __linux__
  84 #include <ext2fs/ext2fs.h>
  85 #endif
  86
  87 #include "restore.h"
  88 #include "extern.h"
  89
  90 /*
  91  * The following variables define the inode symbol table.
  92  * The primary hash table is dynamically allocated based on
  93  * the number of inodes in the file system (maxino), scaled by
  94  * HASHFACTOR. The variable "entry" points to the hash table;
  95  * the variable "entrytblsize" indicates its size (in entries).
  96  */
  97 #define HASHFACTOR 5
  98 static struct entry **entry;
  99 static long entrytblsize;
 100
 101 static void              addino __P((dump_ino_t, struct entry *));
 102 static struct entry     *lookupparent __P((char *));
 103 static void              removeentry __P((struct entry *));
 104 static int               dir_hash __P((char *));
 105
 106 /*
 107  * Returns a hash given a file name
 108  */
 109 static int
 110 dir_hash(char *name)
 111 {
 112         unsigned long hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
 113         int len = strlen(name);
 114
 115         while (len--) {
 116                 unsigned long hash = hash1 + (hash0 ^ (*name++ * 7152373));
 117                 if (hash & 0x80000000) hash -= 0x7fffffff;
 118                 hash1 = hash0;
 119                 hash0 = hash;
 120         }
 121         return hash0 % DIRHASH_SIZE;
 122 }
 123
 124 /*
 125  * Look up an entry by inode number
 126  */
 127 struct entry *
 128 lookupino(dump_ino_t inum)
 129 {
 130         struct entry *ep;
 131
 132         if (inum < WINO || inum >= maxino)
 133                 return (NULL);
 134         for (ep = entry[inum % entrytblsize]; ep != NULL; ep = ep->e_next)
 135                 if (ep->e_ino == inum)
 136                         return (ep);
 137         return (NULL);
 138 }
 139
 140 /*
 141  * Add an entry into the entry table
 142  */
 143 static void
 144 addino(dump_ino_t inum, struct entry *np)
 145 {
 146         struct entry **epp;
 147
 148         if (inum < WINO || inum >= maxino)
 149                 panic("addino: out of range %d\n", inum);
 150         epp = &entry[inum % entrytblsize];
 151         np->e_ino = inum;
 152         np->e_next = *epp;
 153         *epp = np;
 154         if (dflag)
 155                 for (np = np->e_next; np != NULL; np = np->e_next)
 156                         if (np->e_ino == inum)
 157                                 badentry(np, "duplicate inum");
 158 }
 159
 160 /*
 161  * Delete an entry from the entry table
 162  */
 163 void
 164 deleteino(dump_ino_t inum)
 165 {
 166         struct entry *next;
 167         struct entry **prev;
 168
 169         if (inum < WINO || inum >= maxino)
 170                 panic("deleteino: out of range %d\n", inum);
 171         prev = &entry[inum % entrytblsize];
 172         for (next = *prev; next != NULL; next = next->e_next) {
 173                 if (next->e_ino == inum) {
 174                         next->e_ino = 0;
 175                         *prev = next->e_next;
 176                         return;
 177                 }
 178                 prev = &next->e_next;
 179         }
 180         panic("deleteino: %d not found\n", inum);
 181 }
 182
 183 /*
 184  * Look up an entry by name
 185  */
 186 struct entry *
 187 lookupname(char *name)
 188 {
 189         struct entry *ep, *oldep;
 190         char *np, *cp;
 191         char buf[MAXPATHLEN];
 192
 193         ep = lookupino(ROOTINO);
 194
 195         cp = name;
 196         if (*cp == '.')
 197                 ++cp;
 198         if (*cp == '/')
 199                 ++cp;
 200         if (*cp == '\0')
 201                 return ep;
 202
 203         while (ep != NULL) {
 204                 for (np = buf; *cp != '/' && *cp != '\0' &&
 205                                 np < &buf[sizeof(buf)]; )
 206                         *np++ = *cp++;
 207                 if (np == &buf[sizeof(buf)])
 208                         break;
 209                 *np = '\0';
 210
 211                 oldep = ep;
 212
 213                 if (ep->e_entries != NULL) {
 214
 215                         ep = ep->e_entries[dir_hash(buf)];
 216                         for ( ; ep != NULL; ep = ep->e_sibling)
 217                                 if (strcmp(ep->e_name, buf) == 0)
 218                                         break;
 219
 220                         /* search all hash lists for renamed inodes */
 221                         if (ep == NULL) {
 222                                 int j;
 223                                 for (j = 0; j < DIRHASH_SIZE; j++) {
 224                                         ep = oldep->e_entries[j];
 225                                         for ( ; ep != NULL; ep = ep->e_sibling)
 226                                                 if (strcmp(ep->e_name, buf) == 0)
 227                                                         break;
 228                                         if (ep != NULL)
 229                                                 break;
 230                                 }
 231                         }
 232                 }
 233
 234                 if (ep == NULL)
 235                         break;
 236                 if (*cp++ == '\0')
 237                         return (ep);
 238         }
 239         return (NULL);
 240 }
 241
 242 /*
 243  * Look up the parent of a pathname
 244  */
 245 static struct entry *
 246 lookupparent(char *name)
 247 {
 248         struct entry *ep;
 249         char *tailindex;
 250
 251         tailindex = strrchr(name, '/');
 252         if (tailindex == NULL)
 253                 return (NULL);
 254         *tailindex = '\0';
 255         ep = lookupname(name);
 256         *tailindex = '/';
 257         if (ep == NULL)
 258                 return (NULL);
 259         if (ep->e_type != NODE)
 260                 panic("%s is not a directory\n", name);
 261         return (ep);
 262 }
 263
 264 /*
 265  * Determine the current pathname of a node or leaf
 266  */
 267 char *
 268 myname(struct entry *ep)
 269 {
 270         char *cp;
 271         static char namebuf[MAXPATHLEN];
 272
 273         for (cp = &namebuf[MAXPATHLEN - 2]; cp > &namebuf[ep->e_namlen]; ) {
 274                 cp -= ep->e_namlen;
 275                 memmove(cp, ep->e_name, (size_t)ep->e_namlen);
 276                 if (ep == lookupino(ROOTINO))
 277                         return (cp);
 278                 *(--cp) = '/';
 279                 ep = ep->e_parent;
 280         }
 281         panic("%s: pathname too long\n", cp);
 282         return(cp);
 283 }
 284
 285 /*
 286  * Unused symbol table entries are linked together on a free list
 287  * headed by the following pointer.
 288  */
 289 static struct entry *freelist = NULL;
 290
 291 /*
 292  * add an entry to the symbol table
 293  */
 294 struct entry *
 295 addentry(char *name, dump_ino_t inum, int type)
 296 {
 297         struct entry *np, *ep;
 298
 299         if (freelist != NULL) {
 300                 np = freelist;
 301                 freelist = np->e_next;
 302                 memset(np, 0, sizeof(struct entry));
 303         } else {
 304                 np = (struct entry *)calloc(1, sizeof(struct entry));
 305                 if (np == NULL)
 306                         errx(1, "no memory to extend symbol table");
 307         }
 308         np->e_type = type & ~LINK;
 309         if (type & NODE) {
 310                 np->e_entries = calloc(1, DIRHASH_SIZE * sizeof(struct entry *));
 311                 if (np->e_entries == NULL)
 312                         panic("unable to allocate directory entries\n");
 313         }
 314         ep = lookupparent(name);
 315         if (ep == NULL) {
 316                 if (inum != ROOTINO || lookupino(ROOTINO) != NULL)
 317                         panic("bad name to addentry %s\n", name);
 318                 np->e_name = savename(name);
 319                 np->e_namlen = strlen(name);
 320                 np->e_parent = np;
 321                 addino(ROOTINO, np);
 322                 return (np);
 323         }
 324         np->e_name = savename(strrchr(name, '/') + 1);
 325         np->e_namlen = strlen(np->e_name);
 326         np->e_parent = ep;
 327         np->e_sibling = ep->e_entries[dir_hash(np->e_name)];
 328         ep->e_entries[dir_hash(np->e_name)] = np;
 329         if (type & LINK) {
 330                 ep = lookupino(inum);
 331                 if (ep == NULL)
 332                         panic("link to non-existent name\n");
 333                 np->e_ino = inum;
 334                 np->e_links = ep->e_links;
 335                 ep->e_links = np;
 336         } else if (inum != 0) {
 337                 if (lookupino(inum) != NULL)
 338                         panic("duplicate entry\n");
 339                 addino(inum, np);
 340         }
 341         return (np);
 342 }
 343
 344 /*
 345  * delete an entry from the symbol table
 346  */
 347 void
 348 freeentry(struct entry *ep)
 349 {
 350         struct entry *np;
 351         dump_ino_t inum;
 352
 353         if (ep->e_flags != REMOVED)
 354                 badentry(ep, "not marked REMOVED");
 355         if (ep->e_type == NODE) {
 356                 if (ep->e_links != NULL)
 357                         badentry(ep, "freeing referenced directory");
 358                 if (ep->e_entries != NULL) {
 359                         int i;
 360                         for (i = 0; i < DIRHASH_SIZE; i++) {
 361                                 if (ep->e_entries[i] != NULL)
 362                                         badentry(ep, "freeing non-empty directory");
 363                         }
 364                 }
 365         }
 366         if (ep->e_ino != 0) {
 367                 np = lookupino(ep->e_ino);
 368                 if (np == NULL)
 369                         badentry(ep, "lookupino failed");
 370                 if (np == ep) {
 371                         inum = ep->e_ino;
 372                         deleteino(inum);
 373                         if (ep->e_links != NULL)
 374                                 addino(inum, ep->e_links);
 375                 } else {
 376                         for (; np != NULL; np = np->e_links) {
 377                                 if (np->e_links == ep) {
 378                                         np->e_links = ep->e_links;
 379                                         break;
 380                                 }
 381                         }
 382                         if (np == NULL)
 383                                 badentry(ep, "link not found");
 384                 }
 385         }
 386         removeentry(ep);
 387         freename(ep->e_name);
 388         ep->e_next = freelist;
 389         freelist = ep;
 390 }
 391
 392 /*
 393  * Relocate an entry in the tree structure
 394  */
 395 void
 396 moveentry(struct entry *ep, char *newname)
 397 {
 398         struct entry *np;
 399         char *cp;
 400
 401         np = lookupparent(newname);
 402         if (np == NULL)
 403                 badentry(ep, "cannot move ROOT");
 404         if (np != ep->e_parent) {
 405                 removeentry(ep);
 406                 ep->e_parent = np;
 407                 ep->e_sibling = np->e_entries[dir_hash(ep->e_name)];
 408                 np->e_entries[dir_hash(ep->e_name)] = ep;
 409         }
 410         cp = strrchr(newname, '/') + 1;
 411         freename(ep->e_name);
 412         ep->e_name = savename(cp);
 413         ep->e_namlen = strlen(cp);
 414         if (strcmp(gentempname(ep), ep->e_name) == 0)
 415                 ep->e_flags |= TMPNAME;
 416         else
 417                 ep->e_flags &= ~TMPNAME;
 418 }
 419
 420 /*
 421  * Remove an entry in the tree structure
 422  */
 423 static void
 424 removeentry(struct entry *ep)
 425 {
 426         struct entry *np = ep->e_parent;
 427         struct entry *entry = np->e_entries[dir_hash(ep->e_name)];
 428
 429         if (entry == ep) {
 430                 np->e_entries[dir_hash(ep->e_name)] = ep->e_sibling;
 431         } else {
 432                 for (np = entry; np != NULL; np = np->e_sibling) {
 433                         if (np->e_sibling == ep) {
 434                                 np->e_sibling = ep->e_sibling;
 435                                 break;
 436                         }
 437                 }
 438                 if (np == NULL) {
 439
 440                         /* search all hash lists for renamed inodes */
 441                         int j;
 442                         for (j = 0; j < DIRHASH_SIZE; j++) {
 443                                 np = ep->e_parent;
 444                                 entry = np->e_entries[j];
 445                                 if (entry == ep) {
 446                                         np->e_entries[j] = ep->e_sibling;
 447                                         return;
 448                                 }
 449                                 else {
 450                                         for (np = entry; np != NULL; np = np->e_sibling) {
 451                                                 if (np->e_sibling == ep) {
 452                                                         np->e_sibling = ep->e_sibling;
 453                                                         return;
 454                                                 }
 455                                         }
 456                                 }
 457                         }
 458                         badentry(ep, "cannot find entry in parent list");
 459                 }
 460         }
 461 }
 462
 463 /*
 464  * Table of unused string entries, sorted by length.
 465  *
 466  * Entries are allocated in STRTBLINCR sized pieces so that names
 467  * of similar lengths can use the same entry. The value of STRTBLINCR
 468  * is chosen so that every entry has at least enough space to hold
 469  * a "struct strtbl" header. Thus every entry can be linked onto an
 470  * appropriate free list.
 471  *
 472  * NB. The macro "allocsize" below assumes that "struct strhdr"
 473  *     has a size that is a power of two.
 474  */
 475 struct strhdr {
 476         struct strhdr *next;
 477 };
 478
 479 #define STRTBLINCR      (sizeof(struct strhdr))
 480 #define allocsize(size) (((size) + 1 + STRTBLINCR - 1) & ~(STRTBLINCR - 1))
 481
 482 static struct strhdr strtblhdr[allocsize(MAXNAMLEN) / STRTBLINCR];
 483
 484 /*
 485  * Allocate space for a name. It first looks to see if it already
 486  * has an appropriate sized entry, and if not allocates a new one.
 487  */
 488 char *
 489 savename(char *name)
 490 {
 491         struct strhdr *np;
 492         long len;
 493         char *cp;
 494
 495         if (name == NULL)
 496                 panic("bad name\n");
 497         len = strlen(name);
 498         np = strtblhdr[len / STRTBLINCR].next;
 499         if (np != NULL) {
 500                 strtblhdr[len / STRTBLINCR].next = np->next;
 501                 cp = (char *)np;
 502         } else {
 503                 cp = malloc((unsigned)allocsize(len));
 504                 if (cp == NULL)
 505                         errx(1, "no space for string table");
 506         }
 507         (void) strcpy(cp, name);
 508         return (cp);
 509 }
 510
 511 /*
 512  * Free space for a name. The resulting entry is linked onto the
 513  * appropriate free list.
 514  */
 515 void
 516 freename(char *name)
 517 {
 518         struct strhdr *tp, *np;
 519
 520         tp = &strtblhdr[strlen(name) / STRTBLINCR];
 521         np = (struct strhdr *)name;
 522         np->next = tp->next;
 523         tp->next = np;
 524 }
 525
 526 /*
 527  * Useful quantities placed at the end of a dumped symbol table.
 528  */
 529 struct symtableheader {
 530         int32_t volno;
 531         int32_t stringsize;
 532         int32_t hashsize;
 533         int32_t entrytblsize;
 534         time_t  dumptime;
 535         time_t  dumpdate;
 536         dump_ino_t maxino;
 537         int32_t ntrec;
 538         int32_t zflag;
 539 };
 540
 541 /*
 542  * dump a snapshot of the symbol table
 543  */
 544 void
 545 dumpsymtable(char *filename, long checkpt)
 546 {
 547         struct entry *ep, *tep;
 548         dump_ino_t i;
 549         struct entry temp, *tentry;
 550         long mynum = 1, stroff = 0, hashoff = 0;
 551         FILE *fd;
 552         struct symtableheader hdr;
 553         struct entry *temphash[DIRHASH_SIZE];
 554
 555         Vprintf(stdout, "Check pointing the restore\n");
 556         if (Nflag)
 557                 return;
 558         if ((fd = FOPEN(filename, "w")) == NULL) {
 559                 warn("fopen");
 560                 panic("cannot create save file %s for symbol table\n",
 561                         filename);
 562         }
 563         clearerr(fd);
 564         /*
 565          * Assign indices to each entry
 566          * Write out the string entries
 567          */
 568         for (i = WINO; i <= maxino; i++) {
 569                 for (ep = lookupino(i); ep != NULL; ep = ep->e_links) {
 570                         ep->e_index = mynum++;
 571                         (void) fwrite(ep->e_name, sizeof(char),
 572                                (int)allocsize(ep->e_namlen), fd);
 573                 }
 574         }
 575         /*
 576          * Write out e_entries tables
 577          */
 578         for (i = WINO; i <= maxino; i++) {
 579                 for (ep = lookupino(i); ep != NULL; ep = ep->e_links) {
 580                         if (ep->e_entries != NULL) {
 581                                 int j;
 582                                 memcpy(temphash, ep->e_entries, DIRHASH_SIZE * sizeof(struct entry *));
 583                                 for (j = 0; j < DIRHASH_SIZE; j++) {
 584                                         if (temphash[j])
 585                                                 temphash[j] = (struct entry *)ep->e_entries[j]->e_index;
 586                                 }
 587                                 fwrite(temphash, DIRHASH_SIZE, sizeof(struct entry *), fd);
 588                         }
 589                 }
 590         }
 591         /*
 592          * Convert pointers to indexes, and output
 593          */
 594         tep = &temp;
 595         stroff = 0;
 596         hashoff = 0;
 597         for (i = WINO; i <= maxino; i++) {
 598                 for (ep = lookupino(i); ep != NULL; ep = ep->e_links) {
 599                         memmove(tep, ep, sizeof(struct entry));
 600                         tep->e_name = (char *)stroff;
 601                         stroff += allocsize(ep->e_namlen);
 602                         tep->e_parent = (struct entry *)ep->e_parent->e_index;
 603                         if (ep->e_links != NULL)
 604                                 tep->e_links =
 605                                         (struct entry *)ep->e_links->e_index;
 606                         if (ep->e_sibling != NULL)
 607                                 tep->e_sibling =
 608                                         (struct entry *)ep->e_sibling->e_index;
 609                         if (ep->e_entries != NULL) {
 610                                 tep->e_entries = (struct entry **)hashoff;
 611                                 hashoff += DIRHASH_SIZE * sizeof(struct entry *);
 612                         }
 613                         if (ep->e_next != NULL)
 614                                 tep->e_next =
 615                                         (struct entry *)ep->e_next->e_index;
 616                         (void) fwrite((char *)tep, sizeof(struct entry), 1, fd);
 617                 }
 618         }
 619         /*
 620          * Convert entry pointers to indexes, and output
 621          */
 622         for (i = 0; (long)i < entrytblsize; i++) {
 623                 if (entry[i] == NULL)
 624                         tentry = NULL;
 625                 else
 626                         tentry = (struct entry *)entry[i]->e_index;
 627                 (void) fwrite((char *)&tentry, sizeof(struct entry *), 1, fd);
 628         }
 629         hdr.volno = checkpt;
 630         hdr.maxino = maxino;
 631         hdr.entrytblsize = entrytblsize;
 632         hdr.stringsize = stroff;
 633         hdr.hashsize = hashoff;
 634         hdr.dumptime = dumptime;
 635         hdr.dumpdate = dumpdate;
 636         hdr.ntrec = ntrec;
 637         hdr.zflag = zflag;
 638         (void) fwrite((char *)&hdr, sizeof(struct symtableheader), 1, fd);
 639         if (ferror(fd)) {
 640                 warn("fwrite");
 641                 panic("output error to file %s writing symbol table\n",
 642                         filename);
 643         }
 644         (void) fclose(fd);
 645 }
 646
 647 /*
 648  * Initialize a symbol table from a file
 649  */
 650 void
 651 initsymtable(char *filename)
 652 {
 653         char *base;
 654         long tblsize;
 655         struct entry *ep;
 656         struct entry *baseep, *lep;
 657         struct symtableheader hdr;
 658         struct STAT stbuf;
 659         long i;
 660         int fd;
 661
 662         Vprintf(stdout, "Initialize symbol table.\n");
 663         if (filename == NULL) {
 664                 entrytblsize = maxino / HASHFACTOR;
 665                 entry = (struct entry **)
 666                         calloc((unsigned)entrytblsize, sizeof(struct entry *));
 667                 if (entry == (struct entry **)NULL)
 668                         errx(1, "no memory for entry table");
 669                 ep = addentry(".", ROOTINO, NODE);
 670                 ep->e_flags |= NEW;
 671                 return;
 672         }
 673         if ((fd = OPEN(filename, O_RDONLY, 0)) < 0) {
 674                 warn("open");
 675                 errx(1, "cannot open symbol table file %s", filename);
 676         }
 677         if (FSTAT(fd, &stbuf) < 0) {
 678                 warn("stat");
 679                 errx(1, "cannot stat symbol table file %s", filename);
 680         }
 681         tblsize = stbuf.st_size - sizeof(struct symtableheader);
 682         base = calloc(sizeof(char), (unsigned)tblsize);
 683         if (base == NULL)
 684                 errx(1, "cannot allocate space for symbol table");
 685         if (read(fd, base, (int)tblsize) < 0 ||
 686             read(fd, (char *)&hdr, sizeof(struct symtableheader)) < 0) {
 687                 warn("read");
 688                 errx(1, "cannot read symbol table file %s", filename);
 689         }
 690         switch (command) {
 691         case 'r':
 692                 /*
 693                  * For normal continuation, insure that we are using
 694                  * the next incremental tape
 695                  */
 696                 if (hdr.dumpdate != dumptime)
 697                         errx(1, "Incremental tape too %s",
 698                                 (hdr.dumpdate < dumptime) ? "low" : "high");
 699                 break;
 700         case 'R':
 701                 /*
 702                  * For restart, insure that we are using the same tape
 703                  */
 704                 curfile.action = SKIP;
 705                 dumptime = hdr.dumptime;
 706                 dumpdate = hdr.dumpdate;
 707                 zflag = hdr.zflag;
 708                 if (!bflag)
 709                         newtapebuf(hdr.ntrec);
 710                 getvol(hdr.volno);
 711                 break;
 712         default:
 713                 panic("initsymtable called from command %c\n", command);
 714                 break;
 715         }
 716         if (hdr.maxino > maxino) {
 717                 resizemaps(maxino, hdr.maxino);
 718                 maxino = hdr.maxino;
 719         }
 720         entrytblsize = hdr.entrytblsize;
 721         entry = (struct entry **)
 722                 (base + tblsize - (entrytblsize * sizeof(struct entry *)));
 723         baseep = (struct entry *)(base + hdr.stringsize + hdr.hashsize - sizeof(struct entry));
 724         lep = (struct entry *)entry;
 725         for (i = 0; i < entrytblsize; i++) {
 726                 if (entry[i] == NULL)
 727                         continue;
 728                 entry[i] = &baseep[(long)entry[i]];
 729         }
 730         for (ep = &baseep[1]; ep < lep; ep++) {
 731                 ep->e_name = base + (long)ep->e_name;
 732                 ep->e_parent = &baseep[(long)ep->e_parent];
 733                 if (ep->e_sibling != NULL)
 734                         ep->e_sibling = &baseep[(long)ep->e_sibling];
 735                 if (ep->e_links != NULL)
 736                         ep->e_links = &baseep[(long)ep->e_links];
 737                 if (ep->e_type == NODE) {
 738                         int i;
 739                         ep->e_entries = (struct entry **)(base + hdr.stringsize + (long)ep->e_entries);
 740                         for (i = 0; i < DIRHASH_SIZE; i++) {
 741                                 if (ep->e_entries[i])
 742                                         ep->e_entries[i] = &baseep[(long)ep->e_entries[i]];
 743                         }
 744                 }
 745                 else
 746                         ep->e_entries = NULL;
 747                 if (ep->e_next != NULL)
 748                         ep->e_next = &baseep[(long)ep->e_next];
 749         }
 750 }