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 = calloc(cache_size, sizeof(struct bucket)); 88 struct bucket *gcache = calloc(cache_size, sizeof(struct bucket)); 89 if (ucache == NULL || gcache == NULL) { 90 free(ucache); 91 free(gcache); 92 return (ARCHIVE_FATAL); 93 } 94 archive_write_disk_set_group_lookup(a, gcache, lookup_gid, cleanup); 95 archive_write_disk_set_user_lookup(a, ucache, lookup_uid, cleanup); 96 return (ARCHIVE_OK); 97 } 98 99 static int64_t 100 lookup_gid(void *private_data, const char *gname, int64_t gid) 101 { 102 int h; 103 struct bucket *b; 104 struct bucket *gcache = (struct bucket *)private_data; 105 106 /* If no gname, just use the gid provided. */ 107 if (gname == NULL || *gname == '\0') 108 return (gid); 109 110 /* Try to find gname in the cache. */ 111 h = hash(gname); 112 b = &gcache[h % cache_size ]; 113 if (b->name != NULL && b->hash == h && strcmp(gname, b->name) == 0) 114 return ((gid_t)b->id); 115 116 /* Free the cache slot for a new entry. */ 117 free(b->name); 118 b->name = strdup(gname); 119 /* Note: If strdup fails, that's okay; we just won't cache. */ 120 b->hash = h; 121 #if HAVE_GRP_H 122 # if HAVE_GETGRNAM_R 123 { 124 char _buffer[128]; 125 size_t bufsize = 128; 126 char *buffer = _buffer; 127 char *allocated = NULL; 128 struct group grent, *result; 129 int r; 130 131 for (;;) { 132 result = &grent; /* Old getgrnam_r ignores last arg. */ 133 r = getgrnam_r(gname, &grent, buffer, bufsize, &result); 134 if (r == 0) 135 break; 136 if (r != ERANGE) 137 break; 138 bufsize *= 2; 139 free(allocated); 140 allocated = malloc(bufsize); 141 if (allocated == NULL) 142 break; 143 buffer = allocated; 144 } 145 if (result != NULL) 146 gid = result->gr_gid; 147 free(allocated); 148 } 149 # else /* HAVE_GETGRNAM_R */ 150 { 151 struct group *result; 152 153 result = getgrnam(gname); 154 if (result != NULL) 155 gid = result->gr_gid; 156 } 157 # endif /* HAVE_GETGRNAM_R */ 158 #elif defined(_WIN32) && !defined(__CYGWIN__) 159 /* TODO: do a gname->gid lookup for Windows. */ 160 #else 161 #error No way to perform gid lookups on this platform 162 #endif 163 b->id = (gid_t)gid; 164 165 return (gid); 166 } 167 168 static int64_t 169 lookup_uid(void *private_data, const char *uname, int64_t uid) 170 { 171 int h; 172 struct bucket *b; 173 struct bucket *ucache = (struct bucket *)private_data; 174 175 /* If no uname, just use the uid provided. */ 176 if (uname == NULL || *uname == '\0') 177 return (uid); 178 179 /* Try to find uname in the cache. */ 180 h = hash(uname); 181 b = &ucache[h % cache_size ]; 182 if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0) 183 return ((uid_t)b->id); 184 185 /* Free the cache slot for a new entry. */ 186 free(b->name); 187 b->name = strdup(uname); 188 /* Note: If strdup fails, that's okay; we just won't cache. */ 189 b->hash = h; 190 #if HAVE_PWD_H 191 # if HAVE_GETPWNAM_R 192 { 193 char _buffer[128]; 194 size_t bufsize = 128; 195 char *buffer = _buffer; 196 char *allocated = NULL; 197 struct passwd pwent, *result; 198 int r; 199 200 for (;;) { 201 result = &pwent; /* Old getpwnam_r ignores last arg. */ 202 r = getpwnam_r(uname, &pwent, buffer, bufsize, &result); 203 if (r == 0) 204 break; 205 if (r != ERANGE) 206 break; 207 bufsize *= 2; 208 free(allocated); 209 allocated = malloc(bufsize); 210 if (allocated == NULL) 211 break; 212 buffer = allocated; 213 } 214 if (result != NULL) 215 uid = result->pw_uid; 216 free(allocated); 217 } 218 # else /* HAVE_GETPWNAM_R */ 219 { 220 struct passwd *result; 221 222 result = getpwnam(uname); 223 if (result != NULL) 224 uid = result->pw_uid; 225 } 226 #endif /* HAVE_GETPWNAM_R */ 227 #elif defined(_WIN32) && !defined(__CYGWIN__) 228 /* TODO: do a uname->uid lookup for Windows. */ 229 #else 230 #error No way to look up uids on this platform 231 #endif 232 b->id = (uid_t)uid; 233 234 return (uid); 235 } 236 237 static void 238 cleanup(void *private) 239 { 240 size_t i; 241 struct bucket *cache = (struct bucket *)private; 242 243 for (i = 0; i < cache_size; i++) 244 free(cache[i].name); 245 free(cache); 246 } 247 248 249 static unsigned int 250 hash(const char *p) 251 { 252 /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm, 253 as used by ELF for hashing function names. */ 254 unsigned g, h = 0; 255 while (*p != '\0') { 256 h = (h << 4) + *p++; 257 if ((g = h & 0xF0000000) != 0) { 258 h ^= g >> 24; 259 h &= 0x0FFFFFFF; 260 } 261 } 262 return h; 263 } 264