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 53struct bucket { 54 char *name; 55 int hash; 56 id_t id; 57}; 58 59static const size_t cache_size = 127; 60static unsigned int hash(const char *); 61static gid_t lookup_gid(void *, const char *uname, gid_t); 62static uid_t lookup_uid(void *, const char *uname, uid_t); 63static 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 */ 84int 85archive_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 96static gid_t 97lookup_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 result = &grent; /* Old getgrnam_r ignores last arg. */ 129 r = getgrnam_r(gname, &grent, buffer, bufsize, &result); 130 if (r == 0) 131 break; 132 if (r != ERANGE) 133 break; 134 bufsize *= 2; 135 if (buffer != _buffer) 136 free(buffer); 137 buffer = malloc(bufsize); 138 if (buffer == NULL) 139 break; 140 } 141 if (result != NULL) 142 gid = result->gr_gid; 143 if (buffer != _buffer) 144 free(buffer); 145 } 146#elif defined(_WIN32) && !defined(__CYGWIN__) 147 /* TODO: do a gname->gid lookup for Windows. */ 148#else 149 #error No way to perform gid lookups on this platform 150#endif 151 b->id = gid; 152 153 return (gid); 154} 155 156static uid_t 157lookup_uid(void *private_data, const char *uname, uid_t uid) 158{ 159 int h; 160 struct bucket *b; 161 struct bucket *ucache = (struct bucket *)private_data; 162 163 /* If no uname, just use the uid provided. */ 164 if (uname == NULL || *uname == '\0') 165 return (uid); 166 167 /* Try to find uname in the cache. */ 168 h = hash(uname); 169 b = &ucache[h % cache_size ]; 170 if (b->name != NULL && b->hash == h && strcmp(uname, b->name) == 0) 171 return ((uid_t)b->id); 172 173 /* Free the cache slot for a new entry. */ 174 if (b->name != NULL) 175 free(b->name); 176 b->name = strdup(uname); 177 /* Note: If strdup fails, that's okay; we just won't cache. */ 178 b->hash = h; 179#if HAVE_PWD_H 180 { 181 char _buffer[128]; 182 size_t bufsize = 128; 183 char *buffer = _buffer; 184 struct passwd pwent, *result; 185 int r; 186 187 for (;;) { 188 result = &pwent; /* Old getpwnam_r ignores last arg. */ 189 r = getpwnam_r(uname, &pwent, buffer, bufsize, &result); 190 if (r == 0) 191 break; 192 if (r != ERANGE) 193 break; 194 bufsize *= 2; 195 if (buffer != _buffer) 196 free(buffer); 197 buffer = malloc(bufsize); 198 if (buffer == NULL) 199 break; 200 } 201 if (result != NULL) 202 uid = result->pw_uid; 203 if (buffer != _buffer) 204 free(buffer); 205 } 206#elif defined(_WIN32) && !defined(__CYGWIN__) 207 /* TODO: do a uname->uid lookup for Windows. */ 208#else 209 #error No way to look up uids on this platform 210#endif 211 b->id = uid; 212 213 return (uid); 214} 215 216static void 217cleanup(void *private) 218{ 219 size_t i; 220 struct bucket *cache = (struct bucket *)private; 221 222 for (i = 0; i < cache_size; i++) 223 free(cache[i].name); 224 free(cache); 225} 226 227 228static unsigned int 229hash(const char *p) 230{ 231 /* A 32-bit version of Peter Weinberger's (PJW) hash algorithm, 232 as used by ELF for hashing function names. */ 233 unsigned g, h = 0; 234 while (*p != '\0') { 235 h = (h << 4) + *p++; 236 if ((g = h & 0xF0000000) != 0) { 237 h ^= g >> 24; 238 h &= 0x0FFFFFFF; 239 } 240 } 241 return h; 242} 243