| 1 | /* |
| 2 | * Copyright (C) 2018 - Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU General Public License, version 2 only, as |
| 6 | * published by the Free Software Foundation. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 11 | * more details. |
| 12 | * |
| 13 | * You should have received a copy of the GNU General Public License along with |
| 14 | * this program; if not, write to the Free Software Foundation, Inc., 51 |
| 15 | * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 16 | */ |
| 17 | |
| 18 | #include <sys/types.h> |
| 19 | #include <sys/stat.h> |
| 20 | #include <unistd.h> |
| 21 | #include <inttypes.h> |
| 22 | #include <urcu.h> |
| 23 | #include <urcu/ref.h> |
| 24 | #include <urcu/rculfhash.h> |
| 25 | #include <common/hashtable/utils.h> |
| 26 | #include <common/macros.h> |
| 27 | #include <common/defaults.h> |
| 28 | #include <common/error.h> |
| 29 | #include <lttng/constant.h> |
| 30 | |
| 31 | #include "inode.h" |
| 32 | |
| 33 | struct inode_id { |
| 34 | dev_t device; |
| 35 | ino_t inode; |
| 36 | }; |
| 37 | |
| 38 | struct lttng_inode_registry { |
| 39 | /* Hashtable of inode_id to lttng_inode. */ |
| 40 | struct cds_lfht *inodes; |
| 41 | }; |
| 42 | |
| 43 | struct lttng_inode { |
| 44 | struct inode_id id; |
| 45 | char *path; |
| 46 | bool unlink_pending; |
| 47 | /* Node in the lttng_inode_registry's ht. */ |
| 48 | struct cds_lfht_node registry_node; |
| 49 | /* Weak reference to ht containing the node. */ |
| 50 | struct cds_lfht *registry_ht; |
| 51 | struct urcu_ref ref; |
| 52 | struct rcu_head rcu_head; |
| 53 | }; |
| 54 | |
| 55 | static struct { |
| 56 | pthread_mutex_t lock; |
| 57 | bool initialized; |
| 58 | unsigned long value; |
| 59 | } seed = { |
| 60 | .lock = PTHREAD_MUTEX_INITIALIZER, |
| 61 | }; |
| 62 | |
| 63 | static |
| 64 | unsigned long lttng_inode_id_hash(struct inode_id *id) |
| 65 | { |
| 66 | uint64_t device = id->device, inode_no = id->inode; |
| 67 | |
| 68 | return hash_key_u64(&device, seed.value) ^ |
| 69 | hash_key_u64(&inode_no, seed.value); |
| 70 | } |
| 71 | |
| 72 | static |
| 73 | int lttng_inode_match(struct cds_lfht_node *node, const void *key) |
| 74 | { |
| 75 | const struct inode_id *id = key; |
| 76 | struct lttng_inode *inode = caa_container_of(node, struct lttng_inode, |
| 77 | registry_node); |
| 78 | |
| 79 | return inode->id.device == id->device && inode->id.inode == id->inode; |
| 80 | } |
| 81 | |
| 82 | static |
| 83 | void lttng_inode_delete(struct rcu_head *head) |
| 84 | { |
| 85 | struct lttng_inode *inode = caa_container_of(head, |
| 86 | struct lttng_inode, rcu_head); |
| 87 | |
| 88 | free(inode->path); |
| 89 | free(inode); |
| 90 | } |
| 91 | |
| 92 | static |
| 93 | void lttng_inode_destroy(struct lttng_inode *inode) |
| 94 | { |
| 95 | if (!inode) { |
| 96 | return; |
| 97 | } |
| 98 | if (inode->unlink_pending) { |
| 99 | int ret = unlink(inode->path); |
| 100 | |
| 101 | DBG("Unlinking %s during lttng_inode destruction", inode->path); |
| 102 | if (ret) { |
| 103 | PERROR("Failed to unlink %s", inode->path); |
| 104 | } |
| 105 | } |
| 106 | rcu_read_lock(); |
| 107 | cds_lfht_del(inode->registry_ht, &inode->registry_node); |
| 108 | rcu_read_unlock(); |
| 109 | call_rcu(&inode->rcu_head, lttng_inode_delete); |
| 110 | } |
| 111 | |
| 112 | static |
| 113 | void lttng_inode_release(struct urcu_ref *ref) |
| 114 | { |
| 115 | lttng_inode_destroy(caa_container_of(ref, struct lttng_inode, ref)); |
| 116 | } |
| 117 | |
| 118 | static |
| 119 | void lttng_inode_get(struct lttng_inode *inode) |
| 120 | { |
| 121 | urcu_ref_get(&inode->ref); |
| 122 | } |
| 123 | |
| 124 | void lttng_inode_put(struct lttng_inode *inode) |
| 125 | { |
| 126 | urcu_ref_put(&inode->ref, lttng_inode_release); |
| 127 | } |
| 128 | |
| 129 | const char *lttng_inode_get_path(const struct lttng_inode *inode) |
| 130 | { |
| 131 | return inode->path; |
| 132 | } |
| 133 | |
| 134 | int lttng_inode_rename(struct lttng_inode *inode, const char *new_path, |
| 135 | bool overwrite) |
| 136 | { |
| 137 | int ret = 0; |
| 138 | char *new_path_copy = NULL; |
| 139 | |
| 140 | if (inode->unlink_pending) { |
| 141 | WARN("An attempt to rename an unlinked file, %s to %s, has been performed", |
| 142 | inode->path, new_path); |
| 143 | ret = -ENOENT; |
| 144 | goto end; |
| 145 | } |
| 146 | |
| 147 | if (!overwrite) { |
| 148 | struct stat statbuf; |
| 149 | |
| 150 | ret = stat(new_path, &statbuf); |
| 151 | if (ret == 0) { |
| 152 | ret = -EEXIST; |
| 153 | goto end; |
| 154 | } else if (ret < 0 && errno != ENOENT) { |
| 155 | PERROR("Failed to stat() %s", new_path); |
| 156 | ret = -errno; |
| 157 | goto end; |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | new_path_copy = strdup(new_path); |
| 162 | if (!new_path_copy) { |
| 163 | ERR("Failed to allocate storage for path %s", new_path); |
| 164 | ret = -ENOMEM; |
| 165 | goto end; |
| 166 | } |
| 167 | |
| 168 | ret = rename(inode->path, new_path); |
| 169 | if (ret) { |
| 170 | PERROR("Failed to rename %s to %s", inode->path, new_path); |
| 171 | ret = -errno; |
| 172 | goto end; |
| 173 | } |
| 174 | |
| 175 | free(inode->path); |
| 176 | inode->path = new_path_copy; |
| 177 | new_path_copy = NULL; |
| 178 | end: |
| 179 | free(new_path_copy); |
| 180 | return ret; |
| 181 | } |
| 182 | |
| 183 | int lttng_inode_defer_unlink(struct lttng_inode *inode) |
| 184 | { |
| 185 | int ret = 0; |
| 186 | uint16_t i = 0; |
| 187 | char suffix[sizeof("-deleted-65535")] = "-deleted"; |
| 188 | char new_path[LTTNG_PATH_MAX]; |
| 189 | size_t original_path_len = strlen(inode->path); |
| 190 | |
| 191 | if (inode->unlink_pending) { |
| 192 | WARN("An attempt to re-unlink %s has been performed, ignoring.", |
| 193 | inode->path); |
| 194 | ret = -ENOENT; |
| 195 | goto end; |
| 196 | } |
| 197 | |
| 198 | ret = lttng_strncpy(new_path, inode->path, sizeof(new_path)); |
| 199 | if (ret < 0) { |
| 200 | ret = -ENAMETOOLONG; |
| 201 | goto end; |
| 202 | } |
| 203 | |
| 204 | for (i = 0; i < UINT16_MAX; i++) { |
| 205 | int p_ret; |
| 206 | |
| 207 | if (i != 0) { |
| 208 | p_ret = snprintf(suffix, sizeof(suffix), "-deleted-%" PRIu16, i); |
| 209 | |
| 210 | if (p_ret < 0) { |
| 211 | PERROR("Failed to form suffix to rename file %s", |
| 212 | inode->path); |
| 213 | ret = -errno; |
| 214 | goto end; |
| 215 | } |
| 216 | assert(p_ret != sizeof(suffix)); |
| 217 | } else { |
| 218 | /* suffix is initialy set to '-deleted'. */ |
| 219 | p_ret = strlen(suffix); |
| 220 | } |
| 221 | |
| 222 | if (original_path_len + p_ret + 1 >= sizeof(new_path)) { |
| 223 | ret = -ENAMETOOLONG; |
| 224 | goto end; |
| 225 | } |
| 226 | |
| 227 | strcat(&new_path[original_path_len], suffix); |
| 228 | ret = lttng_inode_rename(inode, new_path, false); |
| 229 | if (ret != -EEXIST) { |
| 230 | break; |
| 231 | } |
| 232 | new_path[original_path_len] = '\0'; |
| 233 | } |
| 234 | if (!ret) { |
| 235 | inode->unlink_pending = true; |
| 236 | } |
| 237 | end: |
| 238 | return ret; |
| 239 | } |
| 240 | |
| 241 | static |
| 242 | struct lttng_inode *lttng_inode_create(const struct inode_id *id, |
| 243 | const char *path, struct cds_lfht *ht) |
| 244 | { |
| 245 | struct lttng_inode *inode = zmalloc(sizeof(*inode)); |
| 246 | |
| 247 | if (!inode) { |
| 248 | goto end; |
| 249 | } |
| 250 | |
| 251 | urcu_ref_init(&inode->ref); |
| 252 | cds_lfht_node_init(&inode->registry_node); |
| 253 | inode->id = *id; |
| 254 | inode->path = strdup(path); |
| 255 | inode->registry_ht = ht; |
| 256 | if (!inode->path) { |
| 257 | goto error; |
| 258 | } |
| 259 | end: |
| 260 | return inode; |
| 261 | error: |
| 262 | lttng_inode_destroy(inode); |
| 263 | return NULL; |
| 264 | } |
| 265 | |
| 266 | struct lttng_inode_registry *lttng_inode_registry_create(void) |
| 267 | { |
| 268 | struct lttng_inode_registry *registry = zmalloc(sizeof(*registry)); |
| 269 | |
| 270 | if (!registry) { |
| 271 | goto end; |
| 272 | } |
| 273 | |
| 274 | pthread_mutex_lock(&seed.lock); |
| 275 | if (!seed.initialized) { |
| 276 | seed.value = (unsigned long) time(NULL); |
| 277 | seed.initialized = true; |
| 278 | } |
| 279 | pthread_mutex_unlock(&seed.lock); |
| 280 | |
| 281 | registry->inodes = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0, |
| 282 | CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL); |
| 283 | if (!registry->inodes) { |
| 284 | goto error; |
| 285 | } |
| 286 | end: |
| 287 | return registry; |
| 288 | error: |
| 289 | lttng_inode_registry_destroy(registry); |
| 290 | return NULL; |
| 291 | } |
| 292 | |
| 293 | void lttng_inode_registry_destroy(struct lttng_inode_registry *registry) |
| 294 | { |
| 295 | if (!registry) { |
| 296 | return; |
| 297 | } |
| 298 | if (registry->inodes) { |
| 299 | int ret = cds_lfht_destroy(registry->inodes, NULL); |
| 300 | |
| 301 | assert(!ret); |
| 302 | } |
| 303 | free(registry); |
| 304 | } |
| 305 | |
| 306 | struct lttng_inode *lttng_inode_registry_get_inode( |
| 307 | struct lttng_inode_registry *registry, |
| 308 | int fd, const char *path) |
| 309 | { |
| 310 | int ret; |
| 311 | struct stat statbuf; |
| 312 | struct inode_id id; |
| 313 | struct cds_lfht_iter iter; |
| 314 | struct cds_lfht_node *node; |
| 315 | struct lttng_inode *inode = NULL; |
| 316 | |
| 317 | ret = fstat(fd, &statbuf); |
| 318 | if (ret < 0) { |
| 319 | PERROR("stat() failed on file %s, fd = %i", path, fd); |
| 320 | goto end; |
| 321 | } |
| 322 | |
| 323 | id.device = statbuf.st_dev; |
| 324 | id.inode = statbuf.st_ino; |
| 325 | |
| 326 | rcu_read_lock(); |
| 327 | cds_lfht_lookup(registry->inodes, |
| 328 | lttng_inode_id_hash(&id), |
| 329 | lttng_inode_match, |
| 330 | &id, |
| 331 | &iter); |
| 332 | node = cds_lfht_iter_get_node(&iter); |
| 333 | if (node) { |
| 334 | inode = caa_container_of(node, struct lttng_inode, registry_node); |
| 335 | /* Renames should happen through the fs-handle interface. */ |
| 336 | assert(!strcmp(path, inode->path)); |
| 337 | lttng_inode_get(inode); |
| 338 | goto end_unlock; |
| 339 | } |
| 340 | |
| 341 | inode = lttng_inode_create(&id, path, registry->inodes); |
| 342 | node = cds_lfht_add_unique(registry->inodes, |
| 343 | lttng_inode_id_hash(&inode->id), |
| 344 | lttng_inode_match, |
| 345 | &inode->id, |
| 346 | &inode->registry_node); |
| 347 | assert(node == &inode->registry_node); |
| 348 | end_unlock: |
| 349 | rcu_read_unlock(); |
| 350 | end: |
| 351 | return inode; |
| 352 | } |