external/bsd/am-utils/dist/amd/readdir.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (c) 1997-2009 Erez Zadok
   5  * Copyright (c) 1990 Jan-Simon Pendry
   6  * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
   7  * Copyright (c) 1990 The Regents of the University of California.
   8  * All rights reserved.
   9  *
  10  * This code is derived from software contributed to Berkeley by
  11  * Jan-Simon Pendry at Imperial College, London.
  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. All advertising materials mentioning features or use of this software
  22  *    must display the following acknowledgment:
  23  *      This product includes software developed by the University of
  24  *      California, Berkeley and its contributors.
  25  * 4. Neither the name of the University nor the names of its contributors
  26  *    may be used to endorse or promote products derived from this software
  27  *    without specific prior written permission.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  39  * SUCH DAMAGE.
  40  *
  41  *
  42  * File: am-utils/amd/readdir.c
  43  *
  44  */
  45
  46
  47 #ifdef HAVE_CONFIG_H
  48 # include <config.h>
  49 #endif /* HAVE_CONFIG_H */
  50 #include <am_defs.h>
  51 #include <amd.h>
  52
  53
  54 /****************************************************************************
  55  *** MACROS                                                               ***
  56  ****************************************************************************/
  57 #define DOT_DOT_COOKIE  (u_int) 1
  58 #define MAX_CHAIN       2048
  59
  60
  61 /****************************************************************************
  62  *** FORWARD DEFINITIONS                                                  ***
  63  ****************************************************************************/
  64 static int key_already_in_chain(char *keyname, const nfsentry *chain);
  65 static nfsentry *make_entry_chain(am_node *mp, const nfsentry *current_chain, int fully_browsable);
  66 static int amfs_readdir_browsable(am_node *mp, nfscookie cookie, nfsdirlist *dp, nfsentry *ep, u_int count, int fully_browsable);
  67
  68
  69 /****************************************************************************
  70  *** FUNCTIONS                                                             ***
  71  ****************************************************************************/
  72 /*
  73  * Was: NEW_TOPLVL_READDIR
  74  * Search a chain for an entry with some name.
  75  * -Erez Zadok <ezk@cs.columbia.edu>
  76  */
  77 static int
  78 key_already_in_chain(char *keyname, const nfsentry *chain)
  79 {
  80   const nfsentry *tmpchain = chain;
  81
  82   while (tmpchain) {
  83     if (keyname && tmpchain->ne_name && STREQ(keyname, tmpchain->ne_name))
  84         return 1;
  85     tmpchain = tmpchain->ne_nextentry;
  86   }
  87
  88   return 0;
  89 }
  90
  91
  92 /*
  93  * Create a chain of entries which are not linked.
  94  * -Erez Zadok <ezk@cs.columbia.edu>
  95  */
  96 static nfsentry *
  97 make_entry_chain(am_node *mp, const nfsentry *current_chain, int fully_browsable)
  98 {
  99   static u_int last_cookie = (u_int) 2; /* monotonically increasing */
 100   static nfsentry chain[MAX_CHAIN];
 101   static int max_entries = MAX_CHAIN;
 102   char *key;
 103   int num_entries = 0, i;
 104   u_int preflen = 0;
 105   nfsentry *retval = (nfsentry *) NULL;
 106   mntfs *mf;
 107   mnt_map *mmp;
 108
 109   if (!mp) {
 110     plog(XLOG_DEBUG, "make_entry_chain: mp is (NULL)");
 111     return retval;
 112   }
 113   mf = mp->am_mnt;
 114   if (!mf) {
 115     plog(XLOG_DEBUG, "make_entry_chain: mp->am_mnt is (NULL)");
 116     return retval;
 117   }
 118   mmp = (mnt_map *) mf->mf_private;
 119   if (!mmp) {
 120     plog(XLOG_DEBUG, "make_entry_chain: mp->am_mnt->mf_private is (NULL)");
 121     return retval;
 122   }
 123
 124   if (mp->am_pref)
 125     preflen = strlen(mp->am_pref);
 126
 127   /* iterate over keys */
 128   for (i = 0; i < NKVHASH; i++) {
 129     kv *k;
 130     for (k = mmp->kvhash[i]; k ; k = k->next) {
 131
 132       /*
 133        * Skip unwanted entries which are either not real entries or
 134        * very difficult to interpret (wildcards...)  This test needs
 135        * lots of improvement.  Any takers?
 136        */
 137       key = k->key;
 138       if (!key)
 139         continue;
 140
 141       /* Skip '/defaults' */
 142       if (STREQ(key, "/defaults"))
 143         continue;
 144
 145       /* Skip '*' */
 146       if (!fully_browsable && strchr(key, '*'))
 147         continue;
 148
 149       /*
 150        * If the map has a prefix-string then check if the key starts with
 151        * this string, and if it does, skip over this prefix.  If it has a
 152        * prefix and it doesn't match the start of the key, skip it.
 153        */
 154       if (preflen) {
 155         if (preflen > strlen(key))
 156           continue;
 157         if (!NSTREQ(key, mp->am_pref, preflen))
 158           continue;
 159         key += preflen;
 160       }
 161
 162       /* no more '/' are allowed, unless browsable_dirs=full was used */
 163       if (!fully_browsable && strchr(key, '/'))
 164         continue;
 165
 166       /* no duplicates allowed */
 167       if (key_already_in_chain(key, current_chain))
 168         continue;
 169
 170       /* fill in a cell and link the entry */
 171       if (num_entries >= max_entries) {
 172         /* out of space */
 173         plog(XLOG_DEBUG, "make_entry_chain: no more space in chain");
 174         if (num_entries > 0) {
 175           chain[num_entries - 1].ne_nextentry = NULL;
 176           retval = &chain[0];
 177         }
 178         return retval;
 179       }
 180
 181       /* we have space.  put entry in next cell */
 182       ++last_cookie;
 183       chain[num_entries].ne_fileid = (u_int) last_cookie;
 184       *(u_int *) chain[num_entries].ne_cookie = (u_int) last_cookie;
 185       chain[num_entries].ne_name = key;
 186       if (num_entries < max_entries - 1) {      /* link to next one */
 187         chain[num_entries].ne_nextentry = &chain[num_entries + 1];
 188       }
 189       ++num_entries;
 190     } /* end of "while (k)" */
 191   } /* end of "for (i ... NKVHASH ..." */
 192
 193   /* terminate chain */
 194   if (num_entries > 0) {
 195     chain[num_entries - 1].ne_nextentry = NULL;
 196     retval = &chain[0];
 197   }
 198
 199   return retval;
 200 }
 201
 202
 203
 204 /* This one is called only if map is browsable */
 205 static int
 206 amfs_readdir_browsable(am_node *mp, nfscookie cookie, nfsdirlist *dp, nfsentry *ep, u_int count, int fully_browsable)
 207 {
 208   u_int gen = *(u_int *) cookie;
 209   int chain_length, i;
 210   static nfsentry *te, *te_next;
 211   static int j;
 212
 213   dp->dl_eof = FALSE;           /* assume readdir not done */
 214
 215   if (amuDebug(D_READDIR))
 216     plog(XLOG_DEBUG, "amfs_readdir_browsable gen=%u, count=%d",
 217          gen, count);
 218
 219   if (gen == 0) {
 220     /*
 221      * In the default instance (which is used to start a search) we return
 222      * "." and "..".
 223      *
 224      * This assumes that the count is big enough to allow both "." and ".."
 225      * to be returned in a single packet.  If it isn't (which would be
 226      * fairly unbelievable) then tough.
 227      */
 228     dlog("amfs_readdir_browsable: default search");
 229     /*
 230      * Check for enough room.  This is extremely approximate but is more
 231      * than enough space.  Really need 2 times:
 232      *      4byte fileid
 233      *      4byte cookie
 234      *      4byte name length
 235      *      4byte name
 236      * plus the dirlist structure */
 237     if (count < (2 * (2 * (sizeof(*ep) + sizeof("..") + 4) + sizeof(*dp))))
 238       return EINVAL;
 239
 240     /*
 241      * compute # of entries to send in this chain.
 242      * heuristics: 128 bytes per entry.
 243      * This is too much probably, but it seems to work better because
 244      * of the re-entrant nature of nfs_readdir, and esp. on systems
 245      * like OpenBSD 2.2.
 246      */
 247     chain_length = count / 128;
 248
 249     /* reset static state counters */
 250     te = te_next = NULL;
 251
 252     dp->dl_entries = ep;
 253
 254     /* construct "." */
 255     ep[0].ne_fileid = mp->am_gen;
 256     ep[0].ne_name = ".";
 257     ep[0].ne_nextentry = &ep[1];
 258     *(u_int *) ep[0].ne_cookie = 0;
 259
 260     /* construct ".." */
 261     if (mp->am_parent)
 262       ep[1].ne_fileid = mp->am_parent->am_gen;
 263     else
 264       ep[1].ne_fileid = mp->am_gen;
 265
 266     ep[1].ne_name = "..";
 267     ep[1].ne_nextentry = NULL;
 268     *(u_int *) ep[1].ne_cookie = DOT_DOT_COOKIE;
 269
 270     /*
 271      * If map is browsable, call a function make_entry_chain() to construct
 272      * a linked list of unmounted keys, and return it.  Then link the chain
 273      * to the regular list.  Get the chain only once, but return
 274      * chunks of it each time.
 275      */
 276     te = make_entry_chain(mp, dp->dl_entries, fully_browsable);
 277     if (!te)
 278       return 0;
 279     if (amuDebug(D_READDIR)) {
 280       nfsentry *ne;
 281       for (j = 0, ne = te; ne; ne = ne->ne_nextentry)
 282         plog(XLOG_DEBUG, "gen1 key %4d \"%s\"", j++, ne->ne_name);
 283     }
 284
 285     /* return only "chain_length" entries */
 286     te_next = te;
 287     for (i=1; i<chain_length; ++i) {
 288       te_next = te_next->ne_nextentry;
 289       if (!te_next)
 290         break;
 291     }
 292     if (te_next) {
 293       nfsentry *te_saved = te_next->ne_nextentry;
 294       te_next->ne_nextentry = NULL; /* terminate "te" chain */
 295       te_next = te_saved;       /* save rest of "te" for next iteration */
 296       dp->dl_eof = FALSE;       /* tell readdir there's more */
 297     } else {
 298       dp->dl_eof = TRUE;        /* tell readdir that's it */
 299     }
 300     ep[1].ne_nextentry = te;    /* append this chunk of "te" chain */
 301     if (amuDebug(D_READDIR)) {
 302       nfsentry *ne;
 303       for (j = 0, ne = te; ne; ne = ne->ne_nextentry)
 304         plog(XLOG_DEBUG, "gen2 key %4d \"%s\"", j++, ne->ne_name);
 305       for (j = 0, ne = ep; ne; ne = ne->ne_nextentry)
 306         plog(XLOG_DEBUG, "gen2+ key %4d \"%s\" fi=%d ck=%d",
 307              j++, ne->ne_name, ne->ne_fileid, *(u_int *)ne->ne_cookie);
 308       plog(XLOG_DEBUG, "EOF is %d", dp->dl_eof);
 309     }
 310     return 0;
 311   } /* end of "if (gen == 0)" statement */
 312
 313   dlog("amfs_readdir_browsable: real child");
 314
 315   if (gen == DOT_DOT_COOKIE) {
 316     dlog("amfs_readdir_browsable: End of readdir in %s", mp->am_path);
 317     dp->dl_eof = TRUE;
 318     dp->dl_entries = NULL;
 319     return 0;
 320   }
 321
 322   /*
 323    * If browsable directories, then continue serving readdir() with another
 324    * chunk of entries, starting from where we left off (when gen was equal
 325    * to 0).  Once again, assume last chunk served to readdir.
 326    */
 327   dp->dl_eof = TRUE;
 328   dp->dl_entries = ep;
 329
 330   te = te_next;                 /* reset 'te' from last saved te_next */
 331   if (!te) {                    /* another indicator of end of readdir */
 332     dp->dl_entries = NULL;
 333     return 0;
 334   }
 335   /*
 336    * compute # of entries to send in this chain.
 337    * heuristics: 128 bytes per entry.
 338    */
 339   chain_length = count / 128;
 340
 341   /* return only "chain_length" entries */
 342   for (i = 1; i < chain_length; ++i) {
 343     te_next = te_next->ne_nextentry;
 344     if (!te_next)
 345       break;
 346   }
 347   if (te_next) {
 348     nfsentry *te_saved = te_next->ne_nextentry;
 349     te_next->ne_nextentry = NULL; /* terminate "te" chain */
 350     te_next = te_saved;         /* save rest of "te" for next iteration */
 351     dp->dl_eof = FALSE;         /* tell readdir there's more */
 352   }
 353   ep = te;                      /* send next chunk of "te" chain */
 354   dp->dl_entries = ep;
 355   if (amuDebug(D_READDIR)) {
 356     nfsentry *ne;
 357     plog(XLOG_DEBUG, "dl_entries=%p, te_next=%p, dl_eof=%d",
 358          dp->dl_entries, te_next, dp->dl_eof);
 359     for (ne = te; ne; ne = ne->ne_nextentry)
 360       plog(XLOG_DEBUG, "gen3 key %4d \"%s\"", j++, ne->ne_name);
 361   }
 362   return 0;
 363 }
 364
 365
 366 /*
 367  * This readdir function which call a special version of it that allows
 368  * browsing if browsable_dirs=yes was set on the map.
 369  */
 370 int
 371 amfs_generic_readdir(am_node *mp, nfscookie cookie, nfsdirlist *dp, nfsentry *ep, u_int count)
 372 {
 373   u_int gen = *(u_int *) cookie;
 374   am_node *xp;
 375   mntent_t mnt;
 376
 377   dp->dl_eof = FALSE;           /* assume readdir not done */
 378
 379   /* check if map is browsable */
 380   if (mp->am_mnt && mp->am_mnt->mf_mopts) {
 381     mnt.mnt_opts = mp->am_mnt->mf_mopts;
 382     if (amu_hasmntopt(&mnt, "fullybrowsable"))
 383       return amfs_readdir_browsable(mp, cookie, dp, ep, count, TRUE);
 384     if (amu_hasmntopt(&mnt, "browsable"))
 385       return amfs_readdir_browsable(mp, cookie, dp, ep, count, FALSE);
 386   }
 387
 388   /* when gen is 0, we start reading from the beginning of the directory */
 389   if (gen == 0) {
 390     /*
 391      * In the default instance (which is used to start a search) we return
 392      * "." and "..".
 393      *
 394      * This assumes that the count is big enough to allow both "." and ".."
 395      * to be returned in a single packet.  If it isn't (which would be
 396      * fairly unbelievable) then tough.
 397      */
 398     dlog("amfs_generic_readdir: default search");
 399     /*
 400      * Check for enough room.  This is extremely approximate but is more
 401      * than enough space.  Really need 2 times:
 402      *      4byte fileid
 403      *      4byte cookie
 404      *      4byte name length
 405      *      4byte name
 406      * plus the dirlist structure */
 407     if (count < (2 * (2 * (sizeof(*ep) + sizeof("..") + 4) + sizeof(*dp))))
 408       return EINVAL;
 409
 410     xp = next_nonerror_node(mp->am_child);
 411     dp->dl_entries = ep;
 412
 413     /* construct "." */
 414     ep[0].ne_fileid = mp->am_gen;
 415     ep[0].ne_name = ".";
 416     ep[0].ne_nextentry = &ep[1];
 417     *(u_int *) ep[0].ne_cookie = 0;
 418
 419     /* construct ".." */
 420     if (mp->am_parent)
 421       ep[1].ne_fileid = mp->am_parent->am_gen;
 422     else
 423       ep[1].ne_fileid = mp->am_gen;
 424     ep[1].ne_name = "..";
 425     ep[1].ne_nextentry = NULL;
 426     *(u_int *) ep[1].ne_cookie = (xp ? xp->am_gen : DOT_DOT_COOKIE);
 427
 428     if (!xp)
 429       dp->dl_eof = TRUE;        /* by default assume readdir done */
 430
 431     if (amuDebug(D_READDIR)) {
 432       nfsentry *ne;
 433       int j;
 434       for (j = 0, ne = ep; ne; ne = ne->ne_nextentry)
 435         plog(XLOG_DEBUG, "gen1 key %4d \"%s\" fi=%d ck=%d",
 436              j++, ne->ne_name, ne->ne_fileid, *(u_int *)ne->ne_cookie);
 437     }
 438     return 0;
 439   }
 440   dlog("amfs_generic_readdir: real child");
 441
 442   if (gen == DOT_DOT_COOKIE) {
 443     dlog("amfs_generic_readdir: End of readdir in %s", mp->am_path);
 444     dp->dl_eof = TRUE;
 445     dp->dl_entries = NULL;
 446     if (amuDebug(D_READDIR))
 447       plog(XLOG_DEBUG, "end of readdir eof=TRUE, dl_entries=0\n");
 448     return 0;
 449   }
 450
 451   /* non-browsable directories code */
 452   xp = mp->am_child;
 453   while (xp && xp->am_gen != gen)
 454     xp = xp->am_osib;
 455
 456   if (xp) {
 457     int nbytes = count / 2;     /* conservative */
 458     int todo = MAX_READDIR_ENTRIES;
 459
 460     dp->dl_entries = ep;
 461     do {
 462       am_node *xp_next = next_nonerror_node(xp->am_osib);
 463
 464       if (xp_next) {
 465         *(u_int *) ep->ne_cookie = xp_next->am_gen;
 466       } else {
 467         *(u_int *) ep->ne_cookie = DOT_DOT_COOKIE;
 468         dp->dl_eof = TRUE;
 469       }
 470
 471       ep->ne_fileid = xp->am_gen;
 472       ep->ne_name = xp->am_name;
 473       nbytes -= sizeof(*ep) + 1;
 474       if (xp->am_name)
 475         nbytes -= strlen(xp->am_name);
 476
 477       xp = xp_next;
 478
 479       if (nbytes > 0 && !dp->dl_eof && todo > 1) {
 480         ep->ne_nextentry = ep + 1;
 481         ep++;
 482         --todo;
 483       } else {
 484         todo = 0;
 485       }
 486     } while (todo > 0);
 487
 488     ep->ne_nextentry = NULL;
 489
 490     if (amuDebug(D_READDIR)) {
 491       nfsentry *ne;
 492       int j;
 493       for (j=0,ne=ep; ne; ne=ne->ne_nextentry)
 494         plog(XLOG_DEBUG, "gen2 key %4d \"%s\" fi=%d ck=%d",
 495              j++, ne->ne_name, ne->ne_fileid, *(u_int *)ne->ne_cookie);
 496     }
 497     return 0;
 498   }
 499   return ESTALE;
 500 }