lib/libpuffs/path_puffs.c

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