contrib/libarchive/libarchive/archive_write_disk_set_standard_lookup.c

   1 /*-
   2  * Copyright (c) 2003-2007 Tim Kientzle
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "archive_platform.h"
  27 __FBSDID("$FreeBSD: head/lib/libarchive/archive_write_disk_set_standard_lookup.c 201083 2009-12-28 02:09:57Z kientzle $");
  28
  29 #ifdef HAVE_SYS_TYPES_H
  30 #include <sys/types.h>
  31 #endif
  32 #ifdef HAVE_ERRNO_H
  33 #include <errno.h>
  34 #endif
  35 #ifdef HAVE_GRP_H
  36 #include <grp.h>
  37 #endif
  38 #ifdef HAVE_PWD_H
  39 #include <pwd.h>
  40 #endif
  41 #ifdef HAVE_STDLIB_H
  42 #include <stdlib.h>
  43 #endif
  44 #ifdef HAVE_STRING_H
  45 #include <string.h>
  46 #endif
  47
  48 #include "archive.h"
  49 #include "archive_private.h"
  50 #include "archive_read_private.h"
  51 #include "archive_write_disk_private.h"
  52
  53 struct bucket {
  54         char    *name;
  55         int      hash;
  56         id_t     id;
  57 };
  58
  59 static const size_t cache_size = 127;
  60 static unsigned int     hash(const char *);
  61 static int64_t  lookup_gid(void *, const char *uname, int64_t);
  62 static int64_t  lookup_uid(void *, const char *uname, int64_t);
  63 static void     cleanup(void *);
  64
  65 /*
  66  * Installs functions that use getpwnam()/getgrnam()---along with
  67  * a simple cache to accelerate such lookups---into the archive_write_disk
  68  * object.  This is in a separate file because getpwnam()/getgrnam()
  69  * can pull in a LOT of library code (including NIS/LDAP functions, which
  70  * pull in DNS resolvers, etc).  This can easily top 500kB, which makes
  71  * it inappropriate for some space-constrained applications.
  72  *
  73  * Applications that are size-sensitive may want to just use the
  74  * real default functions (defined in archive_write_disk.c) that just
  75  * use the uid/gid without the lookup.  Or define your own custom functions
  76  * if you prefer.
  77  *
  78  * TODO: Replace these hash tables with simpler move-to-front LRU
  79  * lists with a bounded size (128 items?).  The hash is a bit faster,
  80  * but has a bad pathology in which it thrashes a single bucket.  Even
  81  * walking a list of 128 items is a lot faster than calling
  82  * getpwnam()!
  83  */
  84 int
  85 archive_write_disk_set_standard_lookup(struct archive *a)
  86 {
  87         struct bucket *ucache = malloc(cache_size * sizeof(struct bucket));
  88         struct bucket *gcache = malloc(cache_size * sizeof(struct bucket));
  89         if (ucache == NULL || gcache == NULL) {
  90                 free(ucache);
  91                 free(gcache);
  92                 return (ARCHIVE_FATAL);
  93         }
  94         memset(ucache, 0, cache_size * sizeof(struct bucket));
  95         memset(gcache, 0, cache_size * sizeof(struct bucket));
  96         archive_write_disk_set_group_lookup(a, gcache, lookup_gid, cleanup);
  97         archive_write_disk_set_user_lookup(a, ucache, lookup_uid, cleanup);
  98         return (ARCHIVE_OK);
  99 }
 100
 101 static int64_t
 102 lookup_gid(void *private_data, const char *gname, int64_t gid)
 103 {
 104         int h;
 105         struct bucket *b;
 106         struct bucket *gcache = (struct bucket *)private_data;
 107
 108         /* If no gname, just use the gid provided. */
 109         if (gname == NULL || *gname == '\0')
 110                 return (gid);
 111
 112         /* Try to find gname in the cache. */
 113         h = hash(gname);
 114         b = &gcache[h % cache_size ];
 115         if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
 116                 return ((gid_t)b->id);
 117
 118         /* Free the cache slot for a new entry. */
 119         if (b->name != NULL)
 120                 free(b->name);
 121         b->name = strdup(gname);
 122         /* Note: If strdup fails, that's okay; we just won't cache. */
 123         b->hash = h;
 124 #if HAVE_GRP_H
 125 #  if HAVE_GETGRNAM_R
 126         {
 127                 char _buffer[128];
 128                 size_t bufsize = 128;
 129                 char *buffer = _buffer;
 130                 char *allocated = NULL;
 131                 struct group    grent, *result;
 132                 int r;
 133
 134                 for (;;) {
 135                         result = &grent; /* Old getgrnam_r ignores last arg. */
 136                         r = getgrnam_r(gname, &grent, buffer, bufsize, &result);
 137                         if (r == 0)
 138                                 break;
 139                         if (r != ERANGE)
 140                                 break;
 141                         bufsize *= 2;
 142                         free(allocated);
 143                         allocated = malloc(bufsize);
 144                         if (allocated == NULL)
 145                                 break;
 146                         buffer = allocated;
 147                 }
 148                 if (result != NULL)
 149                         gid = result->gr_gid;
 150                 free(allocated);
 151         }
 152 #  else /* HAVE_GETGRNAM_R */
 153         {
 154                 struct group *result;
 155
 156                 result = getgrnam(gname);
 157                 if (result != NULL)
 158                         gid = result->gr_gid;
 159         }
 160 #  endif /* HAVE_GETGRNAM_R */
 161 #elif defined(_WIN32) && !defined(__CYGWIN__)
 162         /* TODO: do a gname->gid lookup for Windows. */
 163 #else
 164         #error No way to perform gid lookups on this platform
 165 #endif
 166         b->id = (gid_t)gid;
 167
 168         return (gid);
 169 }
 170
 171 static int64_t
 172 lookup_uid(void *private_data, const char *uname, int64_t uid)
 173 {
 174         int h;
 175         struct bucket *b;
 176         struct bucket *ucache = (struct bucket *)private_data;
 177
 178         /* If no uname, just use the uid provided. */
 179         if (uname == NULL || *uname == '\0')
 180                 return (uid);
 181
 182         /* Try to find uname in the cache. */
 183         h = hash(uname);
 184         b = &ucache[h % cache_size ];
 185         if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
 186                 return ((uid_t)b->id);
 187
 188         /* Free the cache slot for a new entry. */
 189         if (b->name != NULL)
 190                 free(b->name);
 191         b->name = strdup(uname);
 192         /* Note: If strdup fails, that's okay; we just won't cache. */
 193         b->hash = h;
 194 #if HAVE_PWD_H
 195 #  if HAVE_GETPWNAM_R
 196         {
 197                 char _buffer[128];
 198                 size_t bufsize = 128;
 199                 char *buffer = _buffer;
 200                 char *allocated = NULL;
 201                 struct passwd   pwent, *result;
 202                 int r;
 203
 204                 for (;;) {
 205                         result = &pwent; /* Old getpwnam_r ignores last arg. */
 206                         r = getpwnam_r(uname, &pwent, buffer, bufsize, &result);
 207                         if (r == 0)
 208                                 break;
 209                         if (r != ERANGE)
 210                                 break;
 211                         bufsize *= 2;
 212                         free(allocated);
 213                         allocated = malloc(bufsize);
 214                         if (allocated == NULL)
 215                                 break;
 216                         buffer = allocated;
 217                 }
 218                 if (result != NULL)
 219                         uid = result->pw_uid;
 220                 free(allocated);
 221         }
 222 #  else /* HAVE_GETPWNAM_R */
 223         {
 224                 struct passwd *result;
 225
 226                 result = getpwnam(uname);
 227                 if (result != NULL)
 228                         uid = result->pw_uid;
 229         }
 230 #endif  /* HAVE_GETPWNAM_R */
 231 #elif defined(_WIN32) && !defined(__CYGWIN__)
 232         /* TODO: do a uname->uid lookup for Windows. */
 233 #else
 234         #error No way to look up uids on this platform
 235 #endif
 236         b->id = (uid_t)uid;
 237
 238         return (uid);
 239 }
 240
 241 static void
 242 cleanup(void *private)
 243 {
 244         size_t i;
 245         struct bucket *cache = (struct bucket *)private;
 246
 247         for (i = 0; i < cache_size; i++)
 248                 free(cache[i].name);
 249         free(cache);
 250 }
 251
 252
 253 static unsigned int
 254 hash(const char *p)
 255 {
 256         /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
 257            as used by ELF for hashing function names. */
 258         unsigned g, h = 0;
 259         while (*p != '\0') {
 260                 h = (h << 4) + *p++;
 261                 if ((g = h & 0xF0000000) != 0) {
 262                         h ^= g >> 24;
 263                         h &= 0x0FFFFFFF;
 264                 }
 265         }
 266         return h;
 267 }