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 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 int64_t 97 lookup_gid(void *private_data, const char *gname, int64_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 # if HAVE_GETGRNAM_R 121 { 122 char _buffer[128]; 123 size_t bufsize = 128; 124 char *buffer = _buffer; 125 char *allocated = NULL; 126 struct group grent, *result; 127 int r; 128 129 for (;;) { 130 result = &grent; /* Old getgrnam_r ignores last arg. */ 131 r = getgrnam_r(gname, &grent, buffer, bufsize, &result); 132 if (r == 0) 133 break; 134 if (r != ERANGE) 135 break; 136 bufsize *= 2; 137 free(allocated); 138 allocated = malloc(bufsize); 139 if (allocated == NULL) 140 break; 141 buffer = allocated; 142 } 143 if (result != NULL) 144 gid = result->gr_gid; 145 free(allocated); 146 } 147 # else /* HAVE_GETGRNAM_R */ 148 { 149 struct group *result; 150 151 result = getgrnam(gname); 152 if (result != NULL) 153 gid = result->gr_gid; 154 } 155 # endif /* HAVE_GETGRNAM_R */ 156 #elif defined(_WIN32) && !defined(__CYGWIN__) 157 /* TODO: do a gname->gid lookup for Windows. */ 158 #else 159 #error No way to perform gid lookups on this platform 160 #endif 161 b->id = (gid_t)gid; 162 163 return (gid); 164 } 165 166 static int64_t 167 lookup_uid(void *private_data, const char *uname, int64_t uid) 168 { 169 int h; 170 struct bucket *b; 171 struct bucket *ucache = (struct bucket *)private_data; 172 173 /* If no uname, just use the uid provided. */ 174 if (uname == NULL || *uname == '\0') 175 return (uid); 176 177 /* Try to find uname in the cache. */ 178 h = hash(uname); 179 b = &ucache[h % cache_size ]; 180 if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0) 181 return ((uid_t)b->id); 182 183 /* Free the cache slot for a new entry. */ 184 if (b->name != NULL) 185 free(b->name); 186 b->name = strdup(uname); 187 /* Note: If strdup fails, that's okay; we just won't cache. */ 188 b->hash = h; 189 #if HAVE_PWD_H 190 # if HAVE_GETPWNAM_R 191 { 192 char _buffer[128]; 193 size_t bufsize = 128; 194 char *buffer = _buffer; 195 char *allocated = NULL; 196 struct passwd pwent, *result; 197 int r; 198 199 for (;;) { 200 result = &pwent; /* Old getpwnam_r ignores last arg. */ 201 r = getpwnam_r(uname, &pwent, buffer, bufsize, &result); 202 if (r == 0) 203 break; 204 if (r != ERANGE) 205 break; 206 bufsize *= 2; 207 free(allocated); 208 allocated = malloc(bufsize); 209 if (allocated == NULL) 210 break; 211 buffer = allocated; 212 } 213 if (result != NULL) 214 uid = result->pw_uid; 215 free(allocated); 216 } 217 # else /* HAVE_GETPWNAM_R */ 218 { 219 struct passwd *result; 220 221 result = getpwnam(uname); 222 if (result != NULL) 223 uid = result->pw_uid; 224 } 225 #endif /* HAVE_GETPWNAM_R */ 226 #elif defined(_WIN32) && !defined(__CYGWIN__) 227 /* TODO: do a uname->uid lookup for Windows. */ 228 #else 229 #error No way to look up uids on this platform 230 #endif 231 b->id = (uid_t)uid; 232 233 return (uid); 234 } 235 236 static void 237 cleanup(void *private) 238 { 239 size_t i; 240 struct bucket *cache = (struct bucket *)private; 241 242 for (i = 0; i < cache_size; i++) 243 free(cache[i].name); 244 free(cache); 245 } 246 247 248 static unsigned int 249 hash(const char *p) 250 { 251 /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm, 252 as used by ELF for hashing function names. */ 253 unsigned g, h = 0; 254 while (*p != '\0') { 255 h = (h << 4) + *p++; 256 if ((g = h & 0xF0000000) != 0) { 257 h ^= g >> 24; 258 h &= 0x0FFFFFFF; 259 } 260 } 261 return h; 262 } 263