lib/libpuffs/paths.c

   1 /*      $NetBSD: paths.c,v 1.8 2008/08/12 19:44:39 pooka Exp $  */
   2
   3 /*
   4  * Copyright (c) 2007  Antti Kantee.  All Rights Reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
  16  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  18  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 #include <sys/cdefs.h>
  29 #if !defined(lint)
  30 __RCSID("$NetBSD: paths.c,v 1.8 2008/08/12 19:44:39 pooka Exp $");
  31 #endif /* !lint */
  32
  33 #include <sys/hash.h>
  34
  35 #include <assert.h>
  36 #include <errno.h>
  37 #include <puffs.h>
  38 #include <stdlib.h>
  39
  40 #include "puffs_priv.h"
  41
  42 /*
  43  * Generic routines for pathbuilding code
  44  */
  45
  46 int
  47 puffs_path_pcnbuild(struct puffs_usermount *pu, struct puffs_cn *pcn,
  48         puffs_cookie_t parent)
  49 {
  50         struct puffs_node *pn_parent = PU_CMAP(pu, parent);
  51         struct puffs_cn pcn_orig;
  52         struct puffs_pathobj po;
  53         int rv;
  54
  55         assert(pn_parent->pn_po.po_path != NULL);
  56         assert(pu->pu_flags & PUFFS_FLAG_BUILDPATH);
  57
  58         if (pu->pu_pathtransform) {
  59                 rv = pu->pu_pathtransform(pu, &pn_parent->pn_po, pcn, &po);
  60                 if (rv)
  61                         return rv;
  62         } else {
  63                 po.po_path = pcn->pcn_name;
  64                 po.po_len = pcn->pcn_namelen;
  65         }
  66
  67         if (pu->pu_namemod) {
  68                 /* XXX: gcc complains if I do assignment */
  69                 memcpy(&pcn_orig, pcn, sizeof(pcn_orig));
  70                 rv = pu->pu_namemod(pu, &pn_parent->pn_po, pcn);
  71                 if (rv)
  72                         return rv;
  73         }
  74
  75         rv = pu->pu_pathbuild(pu, &pn_parent->pn_po, &po, 0,
  76             &pcn->pcn_po_full);
  77         puffs_path_buildhash(pu, &pcn->pcn_po_full);
  78
  79         if (pu->pu_pathtransform)
  80                 pu->pu_pathfree(pu, &po);
  81
  82         if (pu->pu_namemod && rv)
  83                 *pcn = pcn_orig;
  84
  85         return rv;
  86 }
  87
  88 /*
  89  * substitute all (child) patch prefixes.  called from nodewalk, which
  90  * in turn is called from rename
  91  */
  92 void *
  93 puffs_path_prefixadj(struct puffs_usermount *pu, struct puffs_node *pn,
  94         void *arg)
  95 {
  96         struct puffs_pathinfo *pi = arg;
  97         struct puffs_pathobj localpo;
  98         struct puffs_pathobj oldpo;
  99         int rv;
 100
 101         /* can't be a path prefix */
 102         if (pn->pn_po.po_len < pi->pi_old->po_len)
 103                 return NULL;
 104
 105         if (pu->pu_pathcmp(pu, &pn->pn_po, pi->pi_old, pi->pi_old->po_len, 1))
 106                 return NULL;
 107
 108         /* otherwise we'd have two nodes with an equal path */
 109         assert(pn->pn_po.po_len > pi->pi_old->po_len);
 110
 111         /* found a matching prefix */
 112         rv = pu->pu_pathbuild(pu, pi->pi_new, &pn->pn_po,
 113             pi->pi_old->po_len, &localpo);
 114         /*
 115          * XXX: technically we shouldn't fail, but this is the only
 116          * sensible thing to do here.  If the buildpath routine fails,
 117          * we will have paths in an inconsistent state.  Should fix this,
 118          * either by having two separate passes or by doing other tricks
 119          * to make an invalid path with BUILDPATHS acceptable.
 120          */
 121         if (rv != 0)
 122                 abort();
 123
 124         /* adjust hash sum */
 125         puffs_path_buildhash(pu, &localpo);
 126
 127         /* out with the old and in with the new */
 128         oldpo = pn->pn_po;
 129         pn->pn_po = localpo;
 130         pu->pu_pathfree(pu, &oldpo);
 131
 132         /* continue the walk */
 133         return NULL;
 134 }
 135
 136 /*
 137  * called from nodewalk, checks for exact match
 138  */
 139 void *
 140 puffs_path_walkcmp(struct puffs_usermount *pu, struct puffs_node *pn, void *arg)
 141 {
 142         struct puffs_pathobj *po = arg;
 143         struct puffs_pathobj po2;
 144
 145         if (po->po_len != PNPLEN(pn))
 146                 return NULL;
 147
 148         /*
 149          * If hashing and the hash doesn't match, we know this is
 150          * definitely not a match.  Otherwise check for collisions.
 151          */
 152         if (pu->pu_flags & PUFFS_FLAG_HASHPATH)
 153                 if (pn->pn_po.po_hash != po->po_hash)
 154                         return NULL;
 155
 156         po2.po_path = PNPATH(pn);
 157         po2.po_len = PNPLEN(pn);
 158
 159         if (pu->pu_pathcmp(pu, po, &po2, PNPLEN(pn), 0) == 0)
 160                 return pn;
 161         return NULL;
 162 }
 163
 164 /*
 165  * Hash sum building routine.  Use string hash if the buildpath routine
 166  * is the standard one, otherwise use binary hashes.  A bit whimsical
 167  * way to choose the routine, but the binary works for strings also,
 168  * so don't sweat it.
 169  */
 170 void
 171 puffs_path_buildhash(struct puffs_usermount *pu, struct puffs_pathobj *po)
 172 {
 173
 174         if ((pu->pu_flags & PUFFS_FLAG_HASHPATH) == 0)
 175                 return;
 176
 177         if (pu->pu_pathbuild == puffs_stdpath_buildpath)
 178                 po->po_hash = hash32_strn(po->po_path, po->po_len,
 179                     HASH32_STR_INIT);
 180         else
 181                 po->po_hash = hash32_buf(po->po_path, po->po_len,
 182                     HASH32_BUF_INIT);
 183 }
 184
 185 /*
 186  * Routines provided to file systems which consider a path a tuple of
 187  * strings and / the component separator.
 188  */
 189
 190 /*ARGSUSED*/
 191 int
 192 puffs_stdpath_cmppath(struct puffs_usermount *pu, struct puffs_pathobj *c1,
 193         struct puffs_pathobj *c2, size_t clen, int checkprefix)
 194 {
 195         char *p;
 196         int rv;
 197
 198         rv = strncmp(c1->po_path, c2->po_path, clen);
 199         if (rv)
 200                 return 1;
 201
 202         if (checkprefix == 0)
 203                 return 0;
 204
 205         /* sanity for next step */
 206         if (!(c1->po_len > c2->po_len))
 207                 return 1;
 208
 209         /* check if it's really a complete path prefix */
 210         p = c1->po_path;
 211         if ((*(p + clen)) != '/')
 212                 return 1;
 213
 214         return 0;
 215 }
 216
 217 /*ARGSUSED*/
 218 int
 219 puffs_stdpath_buildpath(struct puffs_usermount *pu,
 220         const struct puffs_pathobj *po_pre, const struct puffs_pathobj *po_comp,
 221         size_t offset, struct puffs_pathobj *newpath)
 222 {
 223         char *path, *pcomp;
 224         size_t plen, complen;
 225         size_t prelen;
 226         int isdotdot;
 227
 228         complen = po_comp->po_len - offset;
 229
 230         /* seek to correct place & remove all leading '/' from component */
 231         pcomp = po_comp->po_path;
 232         pcomp += offset;
 233         while (*pcomp == '/') {
 234                 pcomp++;
 235                 complen--;
 236         }
 237
 238         /* todotdot or nottodotdot */
 239         if (complen == 2 && strcmp(pcomp, "..") == 0)
 240                 isdotdot = 1;
 241         else
 242                 isdotdot = 0;
 243
 244         /*
 245          * Strip trailing components from the preceending component.
 246          * This is an issue only for the root node, which we might want
 247          * to be at path "/" for some file systems.
 248          */
 249         prelen = po_pre->po_len;
 250         while (prelen > 0 && *((char *)po_pre->po_path + (prelen-1)) == '/') {
 251                 assert(isdotdot == 0);
 252                 prelen--;
 253         }
 254
 255         if (isdotdot) {
 256                 char *slash; /* sweet char of mine */
 257
 258                 slash = strrchr(po_pre->po_path, '/');
 259                 assert(slash != NULL);
 260
 261                 plen = slash - (char *)po_pre->po_path;
 262
 263                 /*
 264                  * As the converse to not stripping the initial "/" above,
 265                  * don't nuke it here either.
 266                  */
 267                 if (plen == 0)
 268                         plen++;
 269
 270                 path = malloc(plen + 1);
 271                 if (path == NULL)
 272                         return errno;
 273
 274                 strlcpy(path, po_pre->po_path, plen+1);
 275         } else {
 276                 /* + '/' + '\0' */
 277                 plen = prelen + 1 + complen;
 278                 path = malloc(plen + 1);
 279                 if (path == NULL)
 280                         return errno;
 281
 282                 strlcpy(path, po_pre->po_path, prelen+1);
 283                 strcat(path, "/");
 284                 strncat(path, pcomp, complen);
 285         }
 286
 287         newpath->po_path = path;
 288         newpath->po_len = plen;
 289
 290         return 0;
 291 }
 292
 293 /*ARGSUSED*/
 294 void
 295 puffs_stdpath_freepath(struct puffs_usermount *pu, struct puffs_pathobj *po)
 296 {
 297
 298         free(po->po_path);
 299 }