src/dir/salvage.c

   1 /*
   2  * Copyright 2000, International Business Machines Corporation and others.
   3  * All Rights Reserved.
   4  *
   5  * This software has been released under the terms of the IBM Public
   6  * License.  For details, see the LICENSE file in the top-level source
   7  * directory or online at http://www.openafs.org/dl/license10.html
   8  */
   9
  10 /* This is the directory salvager.  It consists of two routines.  The first,
  11  * DirOK, checks to see if the directory looks good.  If the directory does
  12  * NOT look good, the approved procedure is to then call Salvage, which
  13  * copies all the good entries from the damaged dir into a new directory.
  14  */
  15
  16 #include <afsconfig.h>
  17 #include <afs/param.h>
  18
  19 #include <roken.h>
  20
  21 #include "dir.h"
  22 /* Defined in vol/vol-salvage.c */
  23 extern void Log(const char *format, ...)
  24     AFS_ATTRIBUTE_FORMAT(__printf__, 1, 2);
  25
  26 #define printf  Log             /* To make it work with volume salvager */
  27
  28 /* This routine is called with one parameter, the id (the same thing that is
  29  * passed to physio or the buffer package) of a directory to check.  It
  30  * returns 1 if the directory looks good, and 0 otherwise. */
  31
  32 #define MAXENAME 256
  33
  34 extern afs_int32 DErrno;
  35
  36 /* figure out how many pages in use in a directory, given ptr to its (locked)
  37  * header */
  38 static int
  39 ComputeUsedPages(struct DirHeader *dhp)
  40 {
  41     afs_int32 usedPages, i;
  42
  43     if (dhp->header.pgcount != 0) {
  44         /* new style */
  45         usedPages = ntohs(dhp->header.pgcount);
  46     } else {
  47         /* old style */
  48         usedPages = 0;
  49         for (i = 0; i < MAXPAGES; i++) {
  50             if (dhp->alloMap[i] == EPP) {
  51                 usedPages = i;
  52                 break;
  53             }
  54         }
  55         if (usedPages == 0)
  56             usedPages = MAXPAGES;
  57     }
  58     return usedPages;
  59 }
  60
  61 /**
  62  * check whether a directory object is ok.
  63  *
  64  * @param[in] file  opaque pointer to directory object fid
  65  *
  66  * @return operation status
  67  *    @retval 1 dir is fine, or something went wrong checking
  68  *    @retval 0 we *know* that the dir is bad
  69  */
  70 int
  71 DirOK(void *file)
  72 {
  73     struct DirHeader *dhp;
  74     struct PageHeader *pp;
  75     struct DirEntry *ep;
  76     struct DirBuffer headerbuf, pagebuf, entrybuf;
  77     int i, j, k, up;
  78     int havedot = 0, havedotdot = 0;
  79     int usedPages, count, entry;
  80     char eaMap[BIGMAXPAGES * EPP / 8];  /* Change eaSize initialization below, too. */
  81     int eaSize;
  82     afs_int32 entcount, maxents;
  83     unsigned short ne;
  84     int code;
  85
  86     eaSize = BIGMAXPAGES * EPP / 8;
  87
  88     /* Read the directory header */
  89     code = DRead(file,0, &headerbuf);
  90     if (code) {
  91         /* if DErrno is 0, then we know that the read worked, but was short,
  92          * and the damage is permanent.  Otherwise, we got an I/O or programming
  93          * error.  Claim the dir is OK, but log something.
  94          */
  95         if (DErrno != 0) {
  96             printf("Could not read first page in directory (%d)\n", DErrno);
  97             Die("dirok1");
  98             return 1;
  99         }
 100         printf("First page in directory does not exist.\n");
 101         return 0;
 102     }
 103     dhp = (struct DirHeader *)headerbuf.data;
 104
 105     /* Check magic number for first page */
 106     if (dhp->header.tag != htons(1234)) {
 107         printf("Bad first pageheader magic number.\n");
 108         DRelease(&headerbuf, 0);
 109         return 0;
 110     }
 111
 112     /* Verify that the number of free entries in each directory page
 113      * is within range (0-EPP). Also ensure directory is contiguous:
 114      * Once the first alloMap entry with EPP free entries is found,
 115      * the rest should match.
 116      */
 117     up = 0;                     /* count of used pages if total pages < MAXPAGES */
 118     k = 0;                      /* found last page */
 119     for (i = 0; i < MAXPAGES; i++) {
 120         j = dhp->alloMap[i];
 121
 122         /* Check if in range */
 123         if (i == 0) {
 124             if ((j < 0) || (j > EPP - (13 + 2))) {
 125                 /* First page's dirheader uses 13 entries and at least
 126                  * two must exist for "." and ".."
 127                  */
 128                 printf("The dir header alloc map for page %d is bad.\n", i);
 129                 DRelease(&headerbuf, 0);
 130                 return 0;
 131             }
 132         } else {
 133             if ((j < 0) || (j > EPP)) {
 134                 printf("The dir header alloc map for page %d is bad.\n", i);
 135                 DRelease(&headerbuf, 0);
 136                 return 0;
 137             }
 138         }
 139
 140         /* Check if contiguous */
 141         if (k) {                /* last page found */
 142             if (j != EPP) {     /* remaining entries must be EPP */
 143                 printf
 144                     ("A partially-full page occurs in slot %d, after the dir end.\n",
 145                      i);
 146                 DRelease(&headerbuf, 0);
 147                 return 0;
 148             }
 149         } else if (j == EPP) {  /* is this the last page */
 150             k = 1;              /* yes */
 151         } else {                /* a used page */
 152             up++;               /* keep count */
 153         }
 154     }
 155
 156     /* Compute number of used directory pages and max entries in all
 157      ** those pages, the value of 'up' must be less than pgcount. The above
 158      ** loop only checks the first MAXPAGES in a directory. An alloMap does
 159      ** not exists for pages between MAXPAGES and BIGMAXPAGES */
 160     usedPages = ComputeUsedPages(dhp);
 161     if (usedPages < up) {
 162         printf
 163             ("Count of used directory pages does not match count in directory header\n");
 164         DRelease(&headerbuf, 0);
 165         return 0;
 166     }
 167
 168     /* For each directory page, check the magic number in each page
 169      * header, and check that number of free entries (from freebitmap)
 170      * matches the count in the alloMap from directory header.
 171      */
 172     for (i = 0; i < usedPages; i++) {
 173         /* Read the page header */
 174         code = DRead(file, i, &pagebuf);
 175         if (code) {
 176             DRelease(&headerbuf, 0);
 177             if (DErrno != 0) {
 178                 /* couldn't read page, but not because it wasn't there permanently */
 179                 printf("Failed to read dir page %d (errno %d)\n", i, DErrno);
 180                 Die("dirok2");
 181                 return 1;
 182             }
 183             printf("Directory shorter than alloMap indicates (page %d)\n", i);
 184             return 0;
 185         }
 186         pp = (struct PageHeader *)pagebuf.data;
 187
 188         /* check the tag field */
 189         if (pp->tag != htons(1234)) {
 190             printf("Directory page %d has a bad magic number.\n", i);
 191             DRelease(&pagebuf, 0);
 192             DRelease(&headerbuf, 0);
 193             return 0;
 194         }
 195
 196         /* Count the number of entries allocated in this single
 197          * directory page using the freebitmap in the page header.
 198          */
 199         count = 0;
 200         for (j = 0; j < EPP / 8; j++) {
 201             k = pp->freebitmap[j];
 202             if (k & 0x80)
 203                 count++;
 204             if (k & 0x40)
 205                 count++;
 206             if (k & 0x20)
 207                 count++;
 208             if (k & 0x10)
 209                 count++;
 210             if (k & 0x08)
 211                 count++;
 212             if (k & 0x04)
 213                 count++;
 214             if (k & 0x02)
 215                 count++;
 216             if (k & 0x01)
 217                 count++;
 218         }
 219         count = EPP - count;    /* Change to count of free entries */
 220
 221         /* Now check that the count of free entries matches the count in the alloMap */
 222         if ((i < MAXPAGES) && ((count & 0xff) != (dhp->alloMap[i] & 0xff))) {
 223             printf
 224                 ("Header alloMap count doesn't match count in freebitmap for page %d.\n",
 225                  i);
 226             DRelease(&pagebuf, 0);
 227             DRelease(&headerbuf, 0);
 228             return 0;
 229         }
 230
 231         DRelease(&pagebuf, 0);
 232     }
 233
 234     /* Initialize the in-memory freebit map for all pages. */
 235     for (i = 0; i < eaSize; i++) {
 236         eaMap[i] = 0;
 237         if (i < usedPages * (EPP / 8)) {
 238             if (i == 0) {
 239                 eaMap[i] = 0xff;        /* A dir header uses first 13 entries */
 240             } else if (i == 1) {
 241                 eaMap[i] = 0x1f;        /* A dir header uses first 13 entries */
 242             } else if ((i % 8) == 0) {
 243                 eaMap[i] = 0x01;        /* A page header uses only first entry */
 244             }
 245         }
 246     }
 247     maxents = usedPages * EPP;
 248
 249     /* Walk down all the hash lists, ensuring that each flag field has FFIRST
 250      * in it.  Mark the appropriate bits in the in-memory freebit map.
 251      * Check that the name is in the right hash bucket.
 252      * Also check for loops in the hash chain by counting the entries.
 253      */
 254     for (entcount = 0, i = 0; i < NHASHENT; i++) {
 255         for (entry = ntohs(dhp->hashTable[i]); entry; entry = ne) {
 256             /* Verify that the entry is within range */
 257             if (entry < 0 || entry >= maxents) {
 258                 printf("Out-of-range hash id %d in chain %d.\n", entry, i);
 259                 DRelease(&headerbuf, 0);
 260                 return 0;
 261             }
 262
 263             /* Read the directory entry */
 264             DErrno = 0;
 265             code = afs_dir_GetBlob(file, entry, &entrybuf);
 266             if (code) {
 267                 if (DErrno != 0) {
 268                     /* something went wrong reading the page, but it wasn't
 269                      * really something wrong with the dir that we can fix.
 270                      */
 271                     printf("Could not get dir blob %d (errno %d)\n", entry,
 272                            DErrno);
 273                     DRelease(&headerbuf, 0);
 274                     Die("dirok3");
 275                 }
 276                 printf("Invalid hash id %d in chain %d.\n", entry, i);
 277                 DRelease(&headerbuf, 0);
 278                 return 0;
 279             }
 280             ep = (struct DirEntry *)entrybuf.data;
 281
 282             ne = ntohs(ep->next);
 283
 284             /* There can't be more than maxents entries */
 285             if (++entcount >= maxents) {
 286                 printf("Directory's hash chain %d is circular.\n", i);
 287                 DRelease(&entrybuf, 0);
 288                 DRelease(&headerbuf, 0);
 289                 return 0;
 290             }
 291
 292             /* A null name is no good */
 293             if (ep->name[0] == '\000') {
 294                 printf("Dir entry %"AFS_PTR_FMT
 295                        " in chain %d has bogus (null) name.\n", ep, i);
 296                 DRelease(&entrybuf, 0);
 297                 DRelease(&headerbuf, 0);
 298                 return 0;
 299             }
 300
 301             /* The entry flag better be FFIRST */
 302             if (ep->flag != FFIRST) {
 303                 printf("Dir entry %"AFS_PTR_FMT
 304                        " in chain %d has bogus flag field.\n", ep, i);
 305                 DRelease(&entrybuf, 0);
 306                 DRelease(&headerbuf, 0);
 307                 return 0;
 308             }
 309
 310             /* Check the size of the name */
 311             j = strlen(ep->name);
 312             if (j >= MAXENAME) {        /* MAXENAME counts the null */
 313                 printf("Dir entry %"AFS_PTR_FMT
 314                        " in chain %d has too-long name.\n", ep, i);
 315                 DRelease(&entrybuf, 0);
 316                 DRelease(&headerbuf, 0);
 317                 return 0;
 318             }
 319
 320             /* The name used up k directory entries, set the bit in our in-memory
 321              * freebitmap for each entry used by the name.
 322              */
 323             k = afs_dir_NameBlobs(ep->name);
 324             for (j = 0; j < k; j++) {
 325                 eaMap[(entry + j) >> 3] |= (1 << ((entry + j) & 7));
 326             }
 327
 328             /* Hash the name and make sure it is in the correct name hash */
 329             if ((j = afs_dir_DirHash(ep->name)) != i) {
 330                 printf("Dir entry %"AFS_PTR_FMT
 331                        " should be in hash bucket %d but IS in %d.\n",
 332                        ep, j, i);
 333                 DRelease(&entrybuf, 0);
 334                 DRelease(&headerbuf, 0);
 335                 return 0;
 336             }
 337
 338             /* Check that if this is entry 13 (the 1st entry), then name must be "." */
 339             if (entry == 13) {
 340                 if (strcmp(ep->name, ".") == 0) {
 341                     havedot = 1;
 342                 } else {
 343                     printf
 344                         ("Dir entry %"AFS_PTR_FMT
 345                          ", index 13 has name '%s' should be '.'\n",
 346                          ep, ep->name);
 347                     DRelease(&entrybuf, 0);
 348                     DRelease(&headerbuf, 0);
 349                     return 0;
 350                 }
 351             }
 352
 353             /* Check that if this is entry 14 (the 2nd entry), then name must be ".." */
 354             if (entry == 14) {
 355                 if (strcmp(ep->name, "..") == 0) {
 356                     havedotdot = 1;
 357                 } else {
 358                     printf
 359                         ("Dir entry %"AFS_PTR_FMT
 360                          ", index 14 has name '%s' should be '..'\n",
 361                          ep, ep->name);
 362                     DRelease(&entrybuf, 0);
 363                     DRelease(&headerbuf, 0);
 364                     return 0;
 365                 }
 366             }
 367
 368             /* CHECK FOR DUPLICATE NAMES? */
 369
 370             DRelease(&entrybuf, 0);
 371         }
 372     }
 373
 374     /* Verify that we found '.' and '..' in the correct place */
 375     if (!havedot || !havedotdot) {
 376         printf
 377             ("Directory entry '.' or '..' does not exist or is in the wrong index.\n");
 378         DRelease(&headerbuf, 0);
 379         return 0;
 380     }
 381
 382     /* The in-memory freebit map has been computed.  Check that it
 383      * matches the one in the page header.
 384      * Note that if this matches, alloMap has already been checked against it.
 385      */
 386     for (i = 0; i < usedPages; i++) {
 387         code = DRead(file, i, &pagebuf);
 388         if (code) {
 389             printf
 390                 ("Failed on second attempt to read dir page %d (errno %d)\n",
 391                  i, DErrno);
 392             DRelease(&headerbuf, 0);
 393             /* if DErrno is 0, then the dir is really bad, and we return dir *not* OK.
 394              * otherwise, we want to return true (1), meaning the dir isn't known
 395              * to be bad (we can't tell, since I/Os are failing.
 396              */
 397             if (DErrno != 0)
 398                 Die("dirok4");
 399             else
 400                 return 0;       /* dir is really shorter */
 401         }
 402         pp = (struct PageHeader *)pagebuf.data;
 403
 404         count = i * (EPP / 8);
 405         for (j = 0; j < EPP / 8; j++) {
 406             if (eaMap[count + j] != pp->freebitmap[j]) {
 407                 printf
 408                     ("Entry freebitmap error, page %d, map offset %d, %x should be %x.\n",
 409                      i, j, pp->freebitmap[j], eaMap[count + j]);
 410                 DRelease(&pagebuf, 0);
 411                 DRelease(&headerbuf, 0);
 412                 return 0;
 413             }
 414         }
 415
 416         DRelease(&pagebuf, 0);
 417     }
 418
 419     /* Finally cleanup and return. */
 420     DRelease(&headerbuf, 0);
 421     return 1;
 422 }
 423
 424 /**
 425  * Salvage a directory object.
 426  *
 427  * @param[in] fromFile  fid of original, currently suspect directory object
 428  * @param[in] toFile    fid where salvager will place new, fixed directory
 429  * @param[in] vn        vnode of currently suspect directory
 430  * @param[in] vu        uniquifier of currently suspect directory
 431  * @param[in] pvn       vnode of parent directory
 432  * @param[in] pvu       uniquifier of parent directory
 433  *
 434  * @return operation status
 435  *    @retval 0 success
 436  */
 437 int
 438 DirSalvage(void *fromFile, void *toFile, afs_int32 vn, afs_int32 vu,
 439            afs_int32 pvn, afs_int32 pvu)
 440 {
 441     /* First do a MakeDir on the target. */
 442     afs_int32 dot[3], dotdot[3], lfid[3], code, usedPages;
 443     char tname[256];
 444     int i;
 445     char *tp;
 446     struct DirBuffer headerbuf, entrybuf;
 447     struct DirHeader *dhp;
 448     struct DirEntry *ep;
 449     int entry;
 450
 451     memset(dot, 0, sizeof(dot));
 452     memset(dotdot, 0, sizeof(dotdot));
 453     dot[1] = vn;
 454     dot[2] = vu;
 455     dotdot[1] = pvn;
 456     dotdot[2] = pvu;
 457
 458     afs_dir_MakeDir(toFile, dot, dotdot);       /* Returns no error code. */
 459
 460     /* Find out how many pages are valid, using stupid heuristic since DRead
 461      * never returns null.
 462      */
 463     code = DRead(fromFile, 0, &headerbuf);
 464     if (code) {
 465         printf("Failed to read first page of fromDir!\n");
 466         /* if DErrno != 0, then our call failed and we should let our
 467          * caller know that there's something wrong with the new dir.  If not,
 468          * then we return here anyway, with an empty, but at least good, directory.
 469          */
 470         return DErrno;
 471     }
 472     dhp = (struct DirHeader *)headerbuf.data;
 473
 474     usedPages = ComputeUsedPages(dhp);
 475
 476     /* Finally, enumerate all the entries, doing a create on them. */
 477     for (i = 0; i < NHASHENT; i++) {
 478         entry = ntohs(dhp->hashTable[i]);
 479         while (1) {
 480             if (!entry)
 481                 break;
 482             if (entry < 0 || entry >= usedPages * EPP) {
 483                 printf
 484                     ("Warning: bogus hash table entry encountered, ignoring.\n");
 485                 break;
 486             }
 487
 488             DErrno = 0;
 489             code = afs_dir_GetBlob(fromFile, entry, &entrybuf);
 490             if (code) {
 491                 if (DErrno) {
 492                     printf
 493                         ("can't continue down hash chain (entry %d, errno %d)\n",
 494                          entry, DErrno);
 495                     DRelease(&headerbuf, 0);
 496                     return DErrno;
 497                 }
 498                 printf
 499                     ("Warning: bogus hash chain encountered, switching to next.\n");
 500                 break;
 501             }
 502             ep = (struct DirEntry *)entrybuf.data;
 503
 504             strncpy(tname, ep->name, MAXENAME);
 505             tname[MAXENAME - 1] = '\000';       /* just in case */
 506             tp = tname;
 507
 508             entry = ntohs(ep->next);
 509
 510             if ((strcmp(tp, ".") != 0) && (strcmp(tp, "..") != 0)) {
 511                 lfid[1] = ntohl(ep->fid.vnode);
 512                 lfid[2] = ntohl(ep->fid.vunique);
 513                 code = afs_dir_Create(toFile, tname, lfid);
 514                 if (code) {
 515                     printf
 516                         ("Create of %s returned code %d, skipping to next hash chain.\n",
 517                          tname, code);
 518                     DRelease(&entrybuf, 0);
 519                     break;
 520                 }
 521             }
 522             DRelease(&entrybuf, 0);
 523         }
 524     }
 525
 526     /* Clean up things. */
 527     DRelease(&headerbuf, 0);
 528     return 0;
 529 }