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 1.4 2007/05/29 01:00:19 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 char _buffer[128]; 122 size_t bufsize = 128; 123 char *buffer = _buffer; 124 struct group grent, *result; 125 int r; 126 127 for (;;) { 128 r = getgrnam_r(gname, &grent, buffer, bufsize, &result); 129 if (r == 0) 130 break; 131 if (r != ERANGE) 132 break; 133 bufsize *= 2; 134 if (buffer != _buffer) 135 free(buffer); 136 buffer = malloc(bufsize); 137 if (buffer == NULL) 138 break; 139 } 140 if (result != NULL) 141 gid = result->gr_gid; 142 if (buffer != _buffer) 143 free(buffer); 144 } 145 #elif defined(_WIN32) && !defined(__CYGWIN__) 146 /* TODO: do a gname->gid lookup for Windows. */ 147 #else 148 #error No way to perform gid lookups on this platform 149 #endif 150 b->id = gid; 151 152 return (gid); 153 } 154 155 static uid_t 156 lookup_uid(void *private_data, const char *uname, uid_t uid) 157 { 158 int h; 159 struct bucket *b; 160 struct bucket *ucache = (struct bucket *)private_data; 161 162 /* If no uname, just use the uid provided. */ 163 if (uname == NULL || *uname == '\0') 164 return (uid); 165 166 /* Try to find uname in the cache. */ 167 h = hash(uname); 168 b = &ucache[h % cache_size ]; 169 if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0) 170 return ((uid_t)b->id); 171 172 /* Free the cache slot for a new entry. */ 173 if (b->name != NULL) 174 free(b->name); 175 b->name = strdup(uname); 176 /* Note: If strdup fails, that's okay; we just won't cache. */ 177 b->hash = h; 178 #if HAVE_PWD_H 179 { 180 char _buffer[128]; 181 size_t bufsize = 128; 182 char *buffer = _buffer; 183 struct passwd pwent, *result; 184 int r; 185 186 for (;;) { 187 r = getpwnam_r(uname, &pwent, buffer, bufsize, &result); 188 if (r == 0) 189 break; 190 if (r != ERANGE) 191 break; 192 bufsize *= 2; 193 if (buffer != _buffer) 194 free(buffer); 195 buffer = malloc(bufsize); 196 if (buffer == NULL) 197 break; 198 } 199 if (result != NULL) 200 uid = result->pw_uid; 201 if (buffer != _buffer) 202 free(buffer); 203 } 204 #elif defined(_WIN32) && !defined(__CYGWIN__) 205 /* TODO: do a uname->uid lookup for Windows. */ 206 #else 207 #error No way to look up uids on this platform 208 #endif 209 b->id = uid; 210 211 return (uid); 212 } 213 214 static void 215 cleanup(void *private) 216 { 217 size_t i; 218 struct bucket *cache = (struct bucket *)private; 219 220 for (i = 0; i < cache_size; i++) 221 free(cache[i].name); 222 free(cache); 223 } 224 225 226 static unsigned int 227 hash(const char *p) 228 { 229 /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm, 230 as used by ELF for hashing function names. */ 231 unsigned g, h = 0; 232 while (*p != '\0') { 233 h = ( h << 4 ) + *p++; 234 if (( g = h & 0xF0000000 )) { 235 h ^= g >> 24; 236 h &= 0x0FFFFFFF; 237 } 238 } 239 return h; 240 } 241