contrib/libarchive-2/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: src/lib/libarchive/archive_write_disk_set_standard_lookup.c,v 1.2 2007/04/20 15:32:13 kientzle Exp $");
  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 gid_t    lookup_gid(void *, const char *uname, gid_t);
  62 static uid_t    lookup_uid(void *, const char *uname, uid_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 resolveers, 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         memset(ucache, 0, cache_size * sizeof(struct bucket));
  90         memset(gcache, 0, cache_size * sizeof(struct bucket));
  91         archive_write_disk_set_group_lookup(a, gcache, lookup_gid, cleanup);
  92         archive_write_disk_set_user_lookup(a, ucache, lookup_uid, cleanup);
  93         return (ARCHIVE_OK);
  94 }
  95
  96 static gid_t
  97 lookup_gid(void *private_data, const char *gname, gid_t gid)
  98 {
  99         int h;
 100         struct bucket *b;
 101         struct bucket *gcache = (struct bucket *)private_data;
 102
 103         /* If no gname, just use the gid provided. */
 104         if (gname == NULL || *gname == '\0')
 105                 return (gid);
 106
 107         /* Try to find gname in the cache. */
 108         h = hash(gname);
 109         b = &gcache[h % cache_size ];
 110         if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0)
 111                 return ((gid_t)b->id);
 112
 113         /* Free the cache slot for a new entry. */
 114         if (b->name != NULL)
 115                 free(b->name);
 116         b->name = strdup(gname);
 117         /* Note: If strdup fails, that's okay; we just won't cache. */
 118         b->hash = h;
 119 #if HAVE_GRP_H
 120         {
 121                 struct group    *grent = getgrnam(gname);
 122                 if (grent != NULL)
 123                         gid = grent->gr_gid;
 124         }
 125 #elif _WIN32
 126         /* TODO: do a gname->gid lookup for Windows. */
 127 #endif
 128         b->id = gid;
 129
 130         return (gid);
 131 }
 132
 133 static uid_t
 134 lookup_uid(void *private_data, const char *uname, uid_t uid)
 135 {
 136         int h;
 137         struct bucket *b;
 138         struct bucket *ucache = (struct bucket *)private_data;
 139
 140         /* If no uname, just use the uid provided. */
 141         if (uname == NULL || *uname == '\0')
 142                 return (uid);
 143
 144         /* Try to find uname in the cache. */
 145         h = hash(uname);
 146         b = &ucache[h % cache_size ];
 147         if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0)
 148                 return ((uid_t)b->id);
 149
 150         /* Free the cache slot for a new entry. */
 151         if (b->name != NULL)
 152                 free(b->name);
 153         b->name = strdup(uname);
 154         /* Note: If strdup fails, that's okay; we just won't cache. */
 155         b->hash = h;
 156 #if HAVE_PWD_H
 157         {
 158                 struct passwd   *pwent = getpwnam(uname);
 159                 if (pwent != NULL)
 160                         uid = pwent->pw_uid;
 161         }
 162 #elif _WIN32
 163         /* TODO: do a uname->uid lookup for Windows. */
 164 #endif
 165         b->id = uid;
 166
 167         return (uid);
 168 }
 169
 170 static void
 171 cleanup(void *private)
 172 {
 173         size_t i;
 174         struct bucket *cache = (struct bucket *)private;
 175
 176         for (i = 0; i < cache_size; i++)
 177                 free(cache[i].name);
 178         free(cache);
 179 }
 180
 181
 182 static unsigned int
 183 hash(const char *p)
 184 {
 185         /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm,
 186            as used by ELF for hashing function names. */
 187         unsigned g, h = 0;
 188         while (*p != '\0') {
 189                 h = ( h << 4 ) + *p++;
 190                 if (( g = h & 0xF0000000 )) {
 191                         h ^= g >> 24;
 192                         h &= 0x0FFFFFFF;
 193                 }
 194         }
 195         return h;
 196 }