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 <assert.h>
  29 #include <errno.h>
  30 #include <stdlib.h>
  31
  32 #include "puffs.h"
  33 #include "puffs_priv.h"
  34 #include "hash.h"
  35
  36 /*
  37  * Generic routines for pathbuilding code
  38  */
  39
  40 int
  41 puffs_path_pcnbuild(struct puffs_usermount *pu, struct puffs_cn *pcn,
  42         puffs_cookie_t parent)
  43 {
  44         struct puffs_node *pn_parent = PU_CMAP(pu, parent);
  45         struct puffs_cn pcn_orig;
  46         struct puffs_pathobj po;
  47         int rv;
  48
  49         assert(pn_parent->pn_po.po_path != NULL);
  50         assert(pu->pu_flags & PUFFS_FLAG_BUILDPATH);
  51
  52         if (pu->pu_pathtransform) {
  53                 rv = pu->pu_pathtransform(pu, &pn_parent->pn_po, pcn, &po);
  54                 if (rv)
  55                         return rv;
  56         } else {
  57                 po.po_path = pcn->pcn_name;
  58                 po.po_len = pcn->pcn_namelen;
  59         }
  60
  61         if (pu->pu_namemod) {
  62                 /* XXX: gcc complains if I do assignment */
  63                 memcpy(&pcn_orig, pcn, sizeof(pcn_orig));
  64                 rv = pu->pu_namemod(pu, &pn_parent->pn_po, pcn);
  65                 if (rv)
  66                         return rv;
  67         }
  68
  69         rv = pu->pu_pathbuild(pu, &pn_parent->pn_po, &po, 0,
  70             &pcn->pcn_po_full);
  71         puffs_path_buildhash(pu, &pcn->pcn_po_full);
  72
  73         if (pu->pu_pathtransform)
  74                 pu->pu_pathfree(pu, &po);
  75
  76         if (pu->pu_namemod && rv)
  77                 *pcn = pcn_orig;
  78
  79         return rv;
  80 }
  81
  82 /*
  83  * substitute all (child) patch prefixes.  called from nodewalk, which
  84  * in turn is called from rename
  85  */
  86 void *
  87 puffs_path_prefixadj(struct puffs_usermount *pu, struct puffs_node *pn,
  88         void *arg)
  89 {
  90         struct puffs_pathinfo *pi = arg;
  91         struct puffs_pathobj localpo;
  92         struct puffs_pathobj oldpo;
  93         int rv;
  94
  95         /* can't be a path prefix */
  96         if (pn->pn_po.po_len < pi->pi_old->po_len)
  97                 return NULL;
  98
  99         if (pu->pu_pathcmp(pu, &pn->pn_po, pi->pi_old, pi->pi_old->po_len, 1))
 100                 return NULL;
 101
 102         /* otherwise we'd have two nodes with an equal path */
 103         assert(pn->pn_po.po_len > pi->pi_old->po_len);
 104
 105         /* found a matching prefix */
 106         rv = pu->pu_pathbuild(pu, pi->pi_new, &pn->pn_po,
 107             pi->pi_old->po_len, &localpo);
 108         /*
 109          * XXX: technically we shouldn't fail, but this is the only
 110          * sensible thing to do here.  If the buildpath routine fails,
 111          * we will have paths in an inconsistent state.  Should fix this,
 112          * either by having two separate passes or by doing other tricks
 113          * to make an invalid path with BUILDPATHS acceptable.
 114          */
 115         if (rv != 0)
 116                 abort();
 117
 118         /* adjust hash sum */
 119         puffs_path_buildhash(pu, &localpo);
 120
 121         /* out with the old and in with the new */
 122         oldpo = pn->pn_po;
 123         pn->pn_po = localpo;
 124         pu->pu_pathfree(pu, &oldpo);
 125
 126         /* continue the walk */
 127         return NULL;
 128 }
 129
 130 /*
 131  * called from nodewalk, checks for exact match
 132  */
 133 void *
 134 puffs_path_walkcmp(struct puffs_usermount *pu, struct puffs_node *pn, void *arg)
 135 {
 136         struct puffs_pathobj *po = arg;
 137         struct puffs_pathobj po2;
 138
 139         if (po->po_len != PNPLEN(pn))
 140                 return NULL;
 141
 142         /*
 143          * If hashing and the hash doesn't match, we know this is
 144          * definitely not a match.  Otherwise check for collisions.
 145          */
 146         if (pu->pu_flags & PUFFS_FLAG_HASHPATH)
 147                 if (pn->pn_po.po_hash != po->po_hash)
 148                         return NULL;
 149
 150         po2.po_path = PNPATH(pn);
 151         po2.po_len = PNPLEN(pn);
 152
 153         if (pu->pu_pathcmp(pu, po, &po2, PNPLEN(pn), 0) == 0)
 154                 return pn;
 155         return NULL;
 156 }
 157
 158 /*
 159  * Hash sum building routine.  Use string hash if the buildpath routine
 160  * is the standard one, otherwise use binary hashes.  A bit whimsical
 161  * way to choose the routine, but the binary works for strings also,
 162  * so don't sweat it.
 163  */
 164 void
 165 puffs_path_buildhash(struct puffs_usermount *pu, struct puffs_pathobj *po)
 166 {
 167
 168         if ((pu->pu_flags & PUFFS_FLAG_HASHPATH) == 0)
 169                 return;
 170
 171         if (pu->pu_pathbuild == puffs_stdpath_buildpath)
 172                 po->po_hash = hash32_strn(po->po_path, po->po_len,
 173                     HASH32_STR_INIT);
 174         else
 175                 po->po_hash = hash32_buf(po->po_path, po->po_len,
 176                     HASH32_BUF_INIT);
 177 }
 178
 179 /*
 180  * Routines provided to file systems which consider a path a tuple of
 181  * strings and / the component separator.
 182  */
 183
 184 /*ARGSUSED*/
 185 int
 186 puffs_stdpath_cmppath(struct puffs_usermount *pu, struct puffs_pathobj *c1,
 187         struct puffs_pathobj *c2, size_t clen, int checkprefix)
 188 {
 189         char *p;
 190         int rv;
 191
 192         rv = strncmp(c1->po_path, c2->po_path, clen);
 193         if (rv)
 194                 return 1;
 195
 196         if (checkprefix == 0)
 197                 return 0;
 198
 199         /* sanity for next step */
 200         if (!(c1->po_len > c2->po_len))
 201                 return 1;
 202
 203         /* check if it's really a complete path prefix */
 204         p = c1->po_path;
 205         if ((*(p + clen)) != '/')
 206                 return 1;
 207
 208         return 0;
 209 }
 210
 211 /*ARGSUSED*/
 212 int
 213 puffs_stdpath_buildpath(struct puffs_usermount *pu,
 214         const struct puffs_pathobj *po_pre, const struct puffs_pathobj *po_comp,
 215         size_t offset, struct puffs_pathobj *newpath)
 216 {
 217         char *path, *pcomp;
 218         size_t plen, complen;
 219         size_t prelen;
 220         int isdotdot;
 221
 222         complen = po_comp->po_len - offset;
 223
 224         /* seek to correct place & remove all leading '/' from component */
 225         pcomp = po_comp->po_path;
 226         pcomp += offset;
 227         while (*pcomp == '/') {
 228                 pcomp++;
 229                 complen--;
 230         }
 231
 232         /* todotdot or nottodotdot */
 233         if (complen == 2 && strcmp(pcomp, "..") == 0)
 234                 isdotdot = 1;
 235         else
 236                 isdotdot = 0;
 237
 238         /*
 239          * Strip trailing components from the preceending component.
 240          * This is an issue only for the root node, which we might want
 241          * to be at path "/" for some file systems.
 242          */
 243         prelen = po_pre->po_len;
 244         while (prelen > 0 && *((char *)po_pre->po_path + (prelen-1)) == '/') {
 245                 assert(isdotdot == 0);
 246                 prelen--;
 247         }
 248
 249         if (isdotdot) {
 250                 char *slash; /* sweet char of mine */
 251
 252                 slash = strrchr(po_pre->po_path, '/');
 253                 assert(slash != NULL);
 254
 255                 plen = slash - (char *)po_pre->po_path;
 256
 257                 /*
 258                  * As the converse to not stripping the initial "/" above,
 259                  * don't nuke it here either.
 260                  */
 261                 if (plen == 0)
 262                         plen++;
 263
 264                 path = malloc(plen + 1);
 265                 if (path == NULL)
 266                         return errno;
 267
 268                 strlcpy(path, po_pre->po_path, plen+1);
 269         } else {
 270                 /* + '/' + '\0' */
 271                 plen = prelen + 1 + complen;
 272                 path = malloc(plen + 1);
 273                 if (path == NULL)
 274                         return errno;
 275
 276                 strlcpy(path, po_pre->po_path, prelen+1);
 277                 strcat(path, "/");
 278                 strncat(path, pcomp, complen);
 279         }
 280
 281         newpath->po_path = path;
 282         newpath->po_len = plen;
 283
 284         return 0;
 285 }
 286
 287 /*ARGSUSED*/
 288 void
 289 puffs_stdpath_freepath(struct puffs_usermount *pu, struct puffs_pathobj *po)
 290 {
 291
 292         free(po->po_path);
 293 }