| 1 | /* |
| 2 | * QEMU Xen emulation: The actual implementation of XenStore |
| 3 | * |
| 4 | * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved. |
| 5 | * |
| 6 | * Authors: David Woodhouse <dwmw2@infradead.org>, Paul Durrant <paul@xen.org> |
| 7 | * |
| 8 | * This work is licensed under the terms of the GNU GPL, version 2 or later. |
| 9 | * See the COPYING file in the top-level directory. |
| 10 | */ |
| 11 | |
| 12 | #include "qemu/osdep.h" |
| 13 | #include "qom/object.h" |
| 14 | |
| 15 | #include "hw/xen/xen.h" |
| 16 | |
| 17 | #include "xen_xenstore.h" |
| 18 | #include "xenstore_impl.h" |
| 19 | |
| 20 | #include "hw/xen/interface/io/xs_wire.h" |
| 21 | |
| 22 | #define XS_MAX_WATCHES 128 |
| 23 | #define XS_MAX_DOMAIN_NODES 1000 |
| 24 | #define XS_MAX_NODE_SIZE 2048 |
| 25 | #define XS_MAX_TRANSACTIONS 10 |
| 26 | #define XS_MAX_PERMS_PER_NODE 5 |
| 27 | |
| 28 | #define XS_VALID_CHARS "abcdefghijklmnopqrstuvwxyz" \ |
| 29 | "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \ |
| 30 | "0123456789-/_" |
| 31 | |
| 32 | typedef struct XsNode { |
| 33 | uint32_t ref; |
| 34 | GByteArray *content; |
| 35 | GList *perms; |
| 36 | GHashTable *children; |
| 37 | uint64_t gencnt; |
| 38 | bool deleted_in_tx; |
| 39 | bool modified_in_tx; |
| 40 | unsigned int serialized_tx; |
| 41 | #ifdef XS_NODE_UNIT_TEST |
| 42 | gchar *name; /* debug only */ |
| 43 | #endif |
| 44 | } XsNode; |
| 45 | |
| 46 | typedef struct XsWatch { |
| 47 | struct XsWatch *next; |
| 48 | xs_impl_watch_fn *cb; |
| 49 | void *cb_opaque; |
| 50 | char *token; |
| 51 | unsigned int dom_id; |
| 52 | int rel_prefix; |
| 53 | } XsWatch; |
| 54 | |
| 55 | typedef struct XsTransaction { |
| 56 | XsNode *root; |
| 57 | unsigned int nr_nodes; |
| 58 | unsigned int base_tx; |
| 59 | unsigned int tx_id; |
| 60 | unsigned int dom_id; |
| 61 | } XsTransaction; |
| 62 | |
| 63 | struct XenstoreImplState { |
| 64 | XsNode *root; |
| 65 | unsigned int nr_nodes; |
| 66 | GHashTable *watches; |
| 67 | unsigned int nr_domu_watches; |
| 68 | GHashTable *transactions; |
| 69 | unsigned int nr_domu_transactions; |
| 70 | unsigned int root_tx; |
| 71 | unsigned int last_tx; |
| 72 | bool serialized; |
| 73 | }; |
| 74 | |
| 75 | |
| 76 | static void nobble_tx(gpointer key, gpointer value, gpointer user_data) |
| 77 | { |
| 78 | unsigned int *new_tx_id = user_data; |
| 79 | XsTransaction *tx = value; |
| 80 | |
| 81 | if (tx->base_tx == *new_tx_id) { |
| 82 | /* Transactions based on XBT_NULL will always fail */ |
| 83 | tx->base_tx = XBT_NULL; |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | static inline unsigned int next_tx(struct XenstoreImplState *s) |
| 88 | { |
| 89 | unsigned int tx_id; |
| 90 | |
| 91 | /* Find the next TX id which isn't either XBT_NULL or in use. */ |
| 92 | do { |
| 93 | tx_id = ++s->last_tx; |
| 94 | } while (tx_id == XBT_NULL || tx_id == s->root_tx || |
| 95 | g_hash_table_lookup(s->transactions, GINT_TO_POINTER(tx_id))); |
| 96 | |
| 97 | /* |
| 98 | * It is vanishingly unlikely, but ensure that no outstanding transaction |
| 99 | * is based on the (previous incarnation of the) newly-allocated TX id. |
| 100 | */ |
| 101 | g_hash_table_foreach(s->transactions, nobble_tx, &tx_id); |
| 102 | |
| 103 | return tx_id; |
| 104 | } |
| 105 | |
| 106 | static inline XsNode *xs_node_new(void) |
| 107 | { |
| 108 | XsNode *n = g_new0(XsNode, 1); |
| 109 | n->ref = 1; |
| 110 | |
| 111 | #ifdef XS_NODE_UNIT_TEST |
| 112 | nr_xs_nodes++; |
| 113 | xs_node_list = g_list_prepend(xs_node_list, n); |
| 114 | #endif |
| 115 | return n; |
| 116 | } |
| 117 | |
| 118 | static inline XsNode *xs_node_ref(XsNode *n) |
| 119 | { |
| 120 | /* With just 10 transactions, it can never get anywhere near this. */ |
| 121 | g_assert(n->ref < INT_MAX); |
| 122 | |
| 123 | g_assert(n->ref); |
| 124 | n->ref++; |
| 125 | return n; |
| 126 | } |
| 127 | |
| 128 | static inline void xs_node_unref(XsNode *n) |
| 129 | { |
| 130 | if (!n) { |
| 131 | return; |
| 132 | } |
| 133 | g_assert(n->ref); |
| 134 | if (--n->ref) { |
| 135 | return; |
| 136 | } |
| 137 | |
| 138 | if (n->content) { |
| 139 | g_byte_array_unref(n->content); |
| 140 | } |
| 141 | if (n->perms) { |
| 142 | g_list_free_full(n->perms, g_free); |
| 143 | } |
| 144 | if (n->children) { |
| 145 | g_hash_table_unref(n->children); |
| 146 | } |
| 147 | #ifdef XS_NODE_UNIT_TEST |
| 148 | g_free(n->name); |
| 149 | nr_xs_nodes--; |
| 150 | xs_node_list = g_list_remove(xs_node_list, n); |
| 151 | #endif |
| 152 | g_free(n); |
| 153 | } |
| 154 | |
| 155 | char *xs_perm_as_string(unsigned int perm, unsigned int domid) |
| 156 | { |
| 157 | char letter; |
| 158 | |
| 159 | switch (perm) { |
| 160 | case XS_PERM_READ | XS_PERM_WRITE: |
| 161 | letter = 'b'; |
| 162 | break; |
| 163 | case XS_PERM_READ: |
| 164 | letter = 'r'; |
| 165 | break; |
| 166 | case XS_PERM_WRITE: |
| 167 | letter = 'w'; |
| 168 | break; |
| 169 | case XS_PERM_NONE: |
| 170 | default: |
| 171 | letter = 'n'; |
| 172 | break; |
| 173 | } |
| 174 | |
| 175 | return g_strdup_printf("%c%u", letter, domid); |
| 176 | } |
| 177 | |
| 178 | static gpointer do_perm_copy(gconstpointer src, gpointer user_data) |
| 179 | { |
| 180 | return g_strdup(src); |
| 181 | } |
| 182 | |
| 183 | static XsNode *xs_node_create(const char *name, GList *perms) |
| 184 | { |
| 185 | XsNode *n = xs_node_new(); |
| 186 | |
| 187 | #ifdef XS_NODE_UNIT_TEST |
| 188 | if (name) { |
| 189 | n->name = g_strdup(name); |
| 190 | } |
| 191 | #endif |
| 192 | |
| 193 | n->perms = g_list_copy_deep(perms, do_perm_copy, NULL); |
| 194 | |
| 195 | return n; |
| 196 | } |
| 197 | |
| 198 | /* For copying from one hash table to another using g_hash_table_foreach() */ |
| 199 | static void do_child_insert(gpointer key, gpointer value, gpointer user_data) |
| 200 | { |
| 201 | g_hash_table_insert(user_data, g_strdup(key), xs_node_ref(value)); |
| 202 | } |
| 203 | |
| 204 | static XsNode *xs_node_copy(XsNode *old) |
| 205 | { |
| 206 | XsNode *n = xs_node_new(); |
| 207 | |
| 208 | n->gencnt = old->gencnt; |
| 209 | |
| 210 | #ifdef XS_NODE_UNIT_TEST |
| 211 | if (n->name) { |
| 212 | n->name = g_strdup(old->name); |
| 213 | } |
| 214 | #endif |
| 215 | |
| 216 | assert(old); |
| 217 | if (old->children) { |
| 218 | n->children = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, |
| 219 | (GDestroyNotify)xs_node_unref); |
| 220 | g_hash_table_foreach(old->children, do_child_insert, n->children); |
| 221 | } |
| 222 | if (old->perms) { |
| 223 | n->perms = g_list_copy_deep(old->perms, do_perm_copy, NULL); |
| 224 | } |
| 225 | if (old->content) { |
| 226 | n->content = g_byte_array_ref(old->content); |
| 227 | } |
| 228 | return n; |
| 229 | } |
| 230 | |
| 231 | /* Returns true if it made a change to the hash table */ |
| 232 | static bool xs_node_add_child(XsNode *n, const char *path_elem, XsNode *child) |
| 233 | { |
| 234 | assert(!strchr(path_elem, '/')); |
| 235 | |
| 236 | if (!child) { |
| 237 | assert(n->children); |
| 238 | return g_hash_table_remove(n->children, path_elem); |
| 239 | } |
| 240 | |
| 241 | #ifdef XS_NODE_UNIT_TEST |
| 242 | g_free(child->name); |
| 243 | child->name = g_strdup(path_elem); |
| 244 | #endif |
| 245 | if (!n->children) { |
| 246 | n->children = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, |
| 247 | (GDestroyNotify)xs_node_unref); |
| 248 | } |
| 249 | |
| 250 | /* |
| 251 | * The documentation for g_hash_table_insert() says that it "returns a |
| 252 | * boolean value to indicate whether the newly added value was already |
| 253 | * in the hash table or not." |
| 254 | * |
| 255 | * It could perhaps be clearer that returning TRUE means it wasn't, |
| 256 | */ |
| 257 | return g_hash_table_insert(n->children, g_strdup(path_elem), child); |
| 258 | } |
| 259 | |
| 260 | struct walk_op { |
| 261 | struct XenstoreImplState *s; |
| 262 | char path[XENSTORE_ABS_PATH_MAX + 2]; /* Two NUL terminators */ |
| 263 | int (*op_fn)(XsNode **n, struct walk_op *op); |
| 264 | void *op_opaque; |
| 265 | void *op_opaque2; |
| 266 | |
| 267 | GList *watches; |
| 268 | unsigned int dom_id; |
| 269 | unsigned int tx_id; |
| 270 | |
| 271 | /* The number of nodes which will exist in the tree if this op succeeds. */ |
| 272 | unsigned int new_nr_nodes; |
| 273 | |
| 274 | /* |
| 275 | * This is maintained on the way *down* the walk to indicate |
| 276 | * whether nodes can be modified in place or whether COW is |
| 277 | * required. It starts off being true, as we're always going to |
| 278 | * replace the root node. If we walk into a shared subtree it |
| 279 | * becomes false. If we start *creating* new nodes for a write, |
| 280 | * it becomes true again. |
| 281 | * |
| 282 | * Do not use it on the way back up. |
| 283 | */ |
| 284 | bool inplace; |
| 285 | bool mutating; |
| 286 | bool create_dirs; |
| 287 | bool in_transaction; |
| 288 | |
| 289 | /* Tracking during recursion so we know which is first. */ |
| 290 | bool deleted_in_tx; |
| 291 | }; |
| 292 | |
| 293 | static void fire_watches(struct walk_op *op, bool parents) |
| 294 | { |
| 295 | GList *l = NULL; |
| 296 | XsWatch *w; |
| 297 | |
| 298 | if (!op->mutating || op->in_transaction) { |
| 299 | return; |
| 300 | } |
| 301 | |
| 302 | if (parents) { |
| 303 | l = op->watches; |
| 304 | } |
| 305 | |
| 306 | w = g_hash_table_lookup(op->s->watches, op->path); |
| 307 | while (w || l) { |
| 308 | if (!w) { |
| 309 | /* Fire the parent nodes from 'op' if asked to */ |
| 310 | w = l->data; |
| 311 | l = l->next; |
| 312 | continue; |
| 313 | } |
| 314 | |
| 315 | assert(strlen(op->path) > w->rel_prefix); |
| 316 | w->cb(w->cb_opaque, op->path + w->rel_prefix, w->token); |
| 317 | |
| 318 | w = w->next; |
| 319 | } |
| 320 | } |
| 321 | |
| 322 | static int xs_node_add_content(XsNode **n, struct walk_op *op) |
| 323 | { |
| 324 | GByteArray *data = op->op_opaque; |
| 325 | |
| 326 | if (op->dom_id) { |
| 327 | /* |
| 328 | * The real XenStored includes permissions and names of child nodes |
| 329 | * in the calculated datasize but life's too short. For a single |
| 330 | * tenant internal XenStore, we don't have to be quite as pedantic. |
| 331 | */ |
| 332 | if (data->len > XS_MAX_NODE_SIZE) { |
| 333 | return E2BIG; |
| 334 | } |
| 335 | } |
| 336 | /* We *are* the node to be written. Either this or a copy. */ |
| 337 | if (!op->inplace) { |
| 338 | XsNode *old = *n; |
| 339 | *n = xs_node_copy(old); |
| 340 | xs_node_unref(old); |
| 341 | } |
| 342 | |
| 343 | if ((*n)->content) { |
| 344 | g_byte_array_unref((*n)->content); |
| 345 | } |
| 346 | (*n)->content = g_byte_array_ref(data); |
| 347 | if (op->tx_id != XBT_NULL) { |
| 348 | (*n)->modified_in_tx = true; |
| 349 | } |
| 350 | return 0; |
| 351 | } |
| 352 | |
| 353 | static int xs_node_get_content(XsNode **n, struct walk_op *op) |
| 354 | { |
| 355 | GByteArray *data = op->op_opaque; |
| 356 | GByteArray *node_data; |
| 357 | |
| 358 | assert(op->inplace); |
| 359 | assert(*n); |
| 360 | |
| 361 | node_data = (*n)->content; |
| 362 | if (node_data) { |
| 363 | g_byte_array_append(data, node_data->data, node_data->len); |
| 364 | } |
| 365 | |
| 366 | return 0; |
| 367 | } |
| 368 | |
| 369 | static int node_rm_recurse(gpointer key, gpointer value, gpointer user_data) |
| 370 | { |
| 371 | struct walk_op *op = user_data; |
| 372 | int path_len = strlen(op->path); |
| 373 | int key_len = strlen(key); |
| 374 | XsNode *n = value; |
| 375 | bool this_inplace = op->inplace; |
| 376 | |
| 377 | if (n->ref != 1) { |
| 378 | op->inplace = 0; |
| 379 | } |
| 380 | |
| 381 | assert(key_len + path_len + 2 <= sizeof(op->path)); |
| 382 | op->path[path_len] = '/'; |
| 383 | memcpy(op->path + path_len + 1, key, key_len + 1); |
| 384 | |
| 385 | if (n->children) { |
| 386 | g_hash_table_foreach_remove(n->children, node_rm_recurse, op); |
| 387 | } |
| 388 | op->new_nr_nodes--; |
| 389 | |
| 390 | /* |
| 391 | * Fire watches on *this* node but not the parents because they are |
| 392 | * going to be deleted too, so the watch will fire for them anyway. |
| 393 | */ |
| 394 | fire_watches(op, false); |
| 395 | op->path[path_len] = '\0'; |
| 396 | |
| 397 | /* |
| 398 | * Actually deleting the child here is just an optimisation; if we |
| 399 | * don't then the final unref on the topmost victim will just have |
| 400 | * to cascade down again repeating all the g_hash_table_foreach() |
| 401 | * calls. |
| 402 | */ |
| 403 | return this_inplace; |
| 404 | } |
| 405 | |
| 406 | static XsNode *xs_node_copy_deleted(XsNode *old, struct walk_op *op); |
| 407 | static void copy_deleted_recurse(gpointer key, gpointer value, |
| 408 | gpointer user_data) |
| 409 | { |
| 410 | struct walk_op *op = user_data; |
| 411 | GHashTable *siblings = op->op_opaque2; |
| 412 | XsNode *n = xs_node_copy_deleted(value, op); |
| 413 | |
| 414 | /* |
| 415 | * Reinsert the deleted_in_tx copy of the node into the parent's |
| 416 | * 'children' hash table. Having stashed it from op->op_opaque2 |
| 417 | * before the recursive call to xs_node_copy_deleted() scribbled |
| 418 | * over it. |
| 419 | */ |
| 420 | g_hash_table_insert(siblings, g_strdup(key), n); |
| 421 | } |
| 422 | |
| 423 | static XsNode *xs_node_copy_deleted(XsNode *old, struct walk_op *op) |
| 424 | { |
| 425 | XsNode *n = xs_node_new(); |
| 426 | |
| 427 | n->gencnt = old->gencnt; |
| 428 | |
| 429 | #ifdef XS_NODE_UNIT_TEST |
| 430 | if (old->name) { |
| 431 | n->name = g_strdup(old->name); |
| 432 | } |
| 433 | #endif |
| 434 | |
| 435 | if (old->children) { |
| 436 | n->children = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, |
| 437 | (GDestroyNotify)xs_node_unref); |
| 438 | op->op_opaque2 = n->children; |
| 439 | g_hash_table_foreach(old->children, copy_deleted_recurse, op); |
| 440 | } |
| 441 | if (old->perms) { |
| 442 | n->perms = g_list_copy_deep(old->perms, do_perm_copy, NULL); |
| 443 | } |
| 444 | n->deleted_in_tx = true; |
| 445 | /* If it gets resurrected we only fire a watch if it lost its content */ |
| 446 | if (old->content) { |
| 447 | n->modified_in_tx = true; |
| 448 | } |
| 449 | op->new_nr_nodes--; |
| 450 | return n; |
| 451 | } |
| 452 | |
| 453 | static int xs_node_rm(XsNode **n, struct walk_op *op) |
| 454 | { |
| 455 | bool this_inplace = op->inplace; |
| 456 | |
| 457 | if (op->tx_id != XBT_NULL) { |
| 458 | /* It's not trivial to do inplace handling for this one */ |
| 459 | XsNode *old = *n; |
| 460 | *n = xs_node_copy_deleted(old, op); |
| 461 | xs_node_unref(old); |
| 462 | return 0; |
| 463 | } |
| 464 | |
| 465 | /* Fire watches for, and count, nodes in the subtree which get deleted */ |
| 466 | if ((*n)->children) { |
| 467 | g_hash_table_foreach_remove((*n)->children, node_rm_recurse, op); |
| 468 | } |
| 469 | op->new_nr_nodes--; |
| 470 | |
| 471 | if (this_inplace) { |
| 472 | xs_node_unref(*n); |
| 473 | } |
| 474 | *n = NULL; |
| 475 | return 0; |
| 476 | } |
| 477 | |
| 478 | static int xs_node_get_perms(XsNode **n, struct walk_op *op) |
| 479 | { |
| 480 | GList **perms = op->op_opaque; |
| 481 | |
| 482 | assert(op->inplace); |
| 483 | assert(*n); |
| 484 | |
| 485 | *perms = g_list_copy_deep((*n)->perms, do_perm_copy, NULL); |
| 486 | return 0; |
| 487 | } |
| 488 | |
| 489 | static void parse_perm(const char *perm, char *letter, unsigned int *dom_id) |
| 490 | { |
| 491 | unsigned int n = sscanf(perm, "%c%u", letter, dom_id); |
| 492 | |
| 493 | assert(n == 2); |
| 494 | } |
| 495 | |
| 496 | static bool can_access(unsigned int dom_id, GList *perms, const char *letters) |
| 497 | { |
| 498 | unsigned int i, n; |
| 499 | char perm_letter; |
| 500 | unsigned int perm_dom_id; |
| 501 | bool access; |
| 502 | |
| 503 | if (dom_id == 0) { |
| 504 | return true; |
| 505 | } |
| 506 | |
| 507 | n = g_list_length(perms); |
| 508 | assert(n >= 1); |
| 509 | |
| 510 | /* |
| 511 | * The dom_id of the first perm is the owner, and the owner always has |
| 512 | * read-write access. |
| 513 | */ |
| 514 | parse_perm(g_list_nth_data(perms, 0), &perm_letter, &perm_dom_id); |
| 515 | if (dom_id == perm_dom_id) { |
| 516 | return true; |
| 517 | } |
| 518 | |
| 519 | /* |
| 520 | * The letter of the first perm specified the default access for all other |
| 521 | * domains. |
| 522 | */ |
| 523 | access = !!strchr(letters, perm_letter); |
| 524 | for (i = 1; i < n; i++) { |
| 525 | parse_perm(g_list_nth_data(perms, i), &perm_letter, &perm_dom_id); |
| 526 | if (dom_id != perm_dom_id) { |
| 527 | continue; |
| 528 | } |
| 529 | access = !!strchr(letters, perm_letter); |
| 530 | } |
| 531 | |
| 532 | return access; |
| 533 | } |
| 534 | |
| 535 | static int xs_node_set_perms(XsNode **n, struct walk_op *op) |
| 536 | { |
| 537 | GList *perms = op->op_opaque; |
| 538 | |
| 539 | if (op->dom_id) { |
| 540 | unsigned int perm_dom_id; |
| 541 | char perm_letter; |
| 542 | |
| 543 | /* A guest may not change permissions on nodes it does not own */ |
| 544 | if (!can_access(op->dom_id, (*n)->perms, "")) { |
| 545 | return EPERM; |
| 546 | } |
| 547 | |
| 548 | /* A guest may not change the owner of a node it owns. */ |
| 549 | parse_perm(perms->data, &perm_letter, &perm_dom_id); |
| 550 | if (perm_dom_id != op->dom_id) { |
| 551 | return EPERM; |
| 552 | } |
| 553 | |
| 554 | if (g_list_length(perms) > XS_MAX_PERMS_PER_NODE) { |
| 555 | return ENOSPC; |
| 556 | } |
| 557 | } |
| 558 | |
| 559 | /* We *are* the node to be written. Either this or a copy. */ |
| 560 | if (!op->inplace) { |
| 561 | XsNode *old = *n; |
| 562 | *n = xs_node_copy(old); |
| 563 | xs_node_unref(old); |
| 564 | } |
| 565 | |
| 566 | if ((*n)->perms) { |
| 567 | g_list_free_full((*n)->perms, g_free); |
| 568 | } |
| 569 | (*n)->perms = g_list_copy_deep(perms, do_perm_copy, NULL); |
| 570 | if (op->tx_id != XBT_NULL) { |
| 571 | (*n)->modified_in_tx = true; |
| 572 | } |
| 573 | return 0; |
| 574 | } |
| 575 | |
| 576 | /* |
| 577 | * Passed a full reference in *n which it may free if it needs to COW. |
| 578 | * |
| 579 | * When changing the tree, the op->inplace flag indicates whether this |
| 580 | * node may be modified in place (i.e. it and all its parents had a |
| 581 | * refcount of one). If walking down the tree we find a node whose |
| 582 | * refcount is higher, we must clear op->inplace and COW from there |
| 583 | * down. Unless we are creating new nodes as scaffolding for a write |
| 584 | * (which works like 'mkdir -p' does). In which case those newly |
| 585 | * created nodes can (and must) be modified in place again. |
| 586 | */ |
| 587 | static int xs_node_walk(XsNode **n, struct walk_op *op) |
| 588 | { |
| 589 | char *child_name = NULL; |
| 590 | size_t namelen; |
| 591 | XsNode *old = *n, *child = NULL; |
| 592 | bool stole_child = false; |
| 593 | bool this_inplace; |
| 594 | XsWatch *watch; |
| 595 | int err; |
| 596 | |
| 597 | namelen = strlen(op->path); |
| 598 | watch = g_hash_table_lookup(op->s->watches, op->path); |
| 599 | |
| 600 | /* Is there a child, or do we hit the double-NUL termination? */ |
| 601 | if (op->path[namelen + 1]) { |
| 602 | char *slash; |
| 603 | child_name = op->path + namelen + 1; |
| 604 | slash = strchr(child_name, '/'); |
| 605 | if (slash) { |
| 606 | *slash = '\0'; |
| 607 | } |
| 608 | op->path[namelen] = '/'; |
| 609 | } |
| 610 | |
| 611 | /* If we walk into a subtree which is shared, we must COW */ |
| 612 | if (op->mutating && old->ref != 1) { |
| 613 | op->inplace = false; |
| 614 | } |
| 615 | |
| 616 | if (!child_name) { |
| 617 | const char *letters = op->mutating ? "wb" : "rb"; |
| 618 | |
| 619 | if (!can_access(op->dom_id, old->perms, letters)) { |
| 620 | err = EACCES; |
| 621 | goto out; |
| 622 | } |
| 623 | |
| 624 | /* This is the actual node on which the operation shall be performed */ |
| 625 | err = op->op_fn(n, op); |
| 626 | if (!err) { |
| 627 | fire_watches(op, true); |
| 628 | } |
| 629 | goto out; |
| 630 | } |
| 631 | |
| 632 | /* op->inplace will be further modified during the recursion */ |
| 633 | this_inplace = op->inplace; |
| 634 | |
| 635 | if (old && old->children) { |
| 636 | child = g_hash_table_lookup(old->children, child_name); |
| 637 | /* This is a *weak* reference to 'child', owned by the hash table */ |
| 638 | } |
| 639 | |
| 640 | if (child) { |
| 641 | if (child->deleted_in_tx) { |
| 642 | assert(child->ref == 1); |
| 643 | /* Cannot actually set child->deleted_in_tx = false until later */ |
| 644 | } |
| 645 | xs_node_ref(child); |
| 646 | /* |
| 647 | * Now we own it too. But if we can modify inplace, that's going to |
| 648 | * foil the check and force it to COW. We want to be the *only* owner |
| 649 | * so that it can be modified in place, so remove it from the hash |
| 650 | * table in that case. We'll add it (or its replacement) back later. |
| 651 | */ |
| 652 | if (op->mutating && this_inplace) { |
| 653 | g_hash_table_remove(old->children, child_name); |
| 654 | stole_child = true; |
| 655 | } |
| 656 | } else if (op->create_dirs) { |
| 657 | assert(op->mutating); |
| 658 | |
| 659 | if (!can_access(op->dom_id, old->perms, "wb")) { |
| 660 | err = EACCES; |
| 661 | goto out; |
| 662 | } |
| 663 | |
| 664 | if (op->dom_id && op->new_nr_nodes >= XS_MAX_DOMAIN_NODES) { |
| 665 | err = ENOSPC; |
| 666 | goto out; |
| 667 | } |
| 668 | |
| 669 | child = xs_node_create(child_name, old->perms); |
| 670 | op->new_nr_nodes++; |
| 671 | |
| 672 | /* |
| 673 | * If we're creating a new child, we can clearly modify it (and its |
| 674 | * children) in place from here on down. |
| 675 | */ |
| 676 | op->inplace = true; |
| 677 | } else { |
| 678 | err = ENOENT; |
| 679 | goto out; |
| 680 | } |
| 681 | |
| 682 | /* |
| 683 | * If there's a watch on this node, add it to the list to be fired |
| 684 | * (with the correct full pathname for the modified node) at the end. |
| 685 | */ |
| 686 | if (watch) { |
| 687 | op->watches = g_list_append(op->watches, watch); |
| 688 | } |
| 689 | |
| 690 | /* |
| 691 | * Except for the temporary child-stealing as noted, our node has not |
| 692 | * changed yet. We don't yet know the overall operation will complete. |
| 693 | */ |
| 694 | err = xs_node_walk(&child, op); |
| 695 | |
| 696 | if (watch) { |
| 697 | op->watches = g_list_remove(op->watches, watch); |
| 698 | } |
| 699 | |
| 700 | if (err || !op->mutating) { |
| 701 | if (stole_child) { |
| 702 | /* Put it back as it was. */ |
| 703 | g_hash_table_replace(old->children, g_strdup(child_name), child); |
| 704 | } else { |
| 705 | xs_node_unref(child); |
| 706 | } |
| 707 | goto out; |
| 708 | } |
| 709 | |
| 710 | /* |
| 711 | * Now we know the operation has completed successfully and we're on |
| 712 | * the way back up. Make the change, substituting 'child' in the |
| 713 | * node at our level. |
| 714 | */ |
| 715 | if (!this_inplace) { |
| 716 | *n = xs_node_copy(old); |
| 717 | xs_node_unref(old); |
| 718 | } |
| 719 | |
| 720 | /* |
| 721 | * If we resurrected a deleted_in_tx node, we can mark it as no longer |
| 722 | * deleted now that we know the overall operation has succeeded. |
| 723 | */ |
| 724 | if (op->create_dirs && child && child->deleted_in_tx) { |
| 725 | op->new_nr_nodes++; |
| 726 | child->deleted_in_tx = false; |
| 727 | } |
| 728 | |
| 729 | /* |
| 730 | * The child may be NULL here, for a remove operation. Either way, |
| 731 | * xs_node_add_child() will do the right thing and return a value |
| 732 | * indicating whether it changed the parent's hash table or not. |
| 733 | * |
| 734 | * We bump the parent gencnt if it adds a child that we *didn't* |
| 735 | * steal from it in the first place, or if child==NULL and was |
| 736 | * thus removed (whether we stole it earlier and didn't put it |
| 737 | * back, or xs_node_add_child() actually removed it now). |
| 738 | */ |
| 739 | if ((xs_node_add_child(*n, child_name, child) && !stole_child) || !child) { |
| 740 | (*n)->gencnt++; |
| 741 | } |
| 742 | |
| 743 | out: |
| 744 | op->path[namelen] = '\0'; |
| 745 | if (!namelen) { |
| 746 | assert(!op->watches); |
| 747 | /* |
| 748 | * On completing the recursion back up the path walk and reaching the |
| 749 | * top, assign the new node count if the operation was successful. If |
| 750 | * the main tree was changed, bump its tx ID so that outstanding |
| 751 | * transactions correctly fail. But don't bump it every time; only |
| 752 | * if it makes a difference. |
| 753 | */ |
| 754 | if (!err && op->mutating) { |
| 755 | if (!op->in_transaction) { |
| 756 | if (op->s->root_tx != op->s->last_tx) { |
| 757 | op->s->root_tx = next_tx(op->s); |
| 758 | } |
| 759 | op->s->nr_nodes = op->new_nr_nodes; |
| 760 | } else { |
| 761 | XsTransaction *tx = g_hash_table_lookup(op->s->transactions, |
| 762 | GINT_TO_POINTER(op->tx_id)); |
| 763 | assert(tx); |
| 764 | tx->nr_nodes = op->new_nr_nodes; |
| 765 | } |
| 766 | } |
| 767 | } |
| 768 | return err; |
| 769 | } |
| 770 | |
| 771 | static void append_directory_item(gpointer key, gpointer value, |
| 772 | gpointer user_data) |
| 773 | { |
| 774 | GList **items = user_data; |
| 775 | |
| 776 | *items = g_list_insert_sorted(*items, g_strdup(key), (GCompareFunc)strcmp); |
| 777 | } |
| 778 | |
| 779 | /* Populates items with char * names which caller must free. */ |
| 780 | static int xs_node_directory(XsNode **n, struct walk_op *op) |
| 781 | { |
| 782 | GList **items = op->op_opaque; |
| 783 | |
| 784 | assert(op->inplace); |
| 785 | assert(*n); |
| 786 | |
| 787 | if ((*n)->children) { |
| 788 | g_hash_table_foreach((*n)->children, append_directory_item, items); |
| 789 | } |
| 790 | |
| 791 | if (op->op_opaque2) { |
| 792 | *(uint64_t *)op->op_opaque2 = (*n)->gencnt; |
| 793 | } |
| 794 | |
| 795 | return 0; |
| 796 | } |
| 797 | |
| 798 | static int validate_path(char *outpath, const char *userpath, |
| 799 | unsigned int dom_id) |
| 800 | { |
| 801 | size_t i, pathlen = strlen(userpath); |
| 802 | |
| 803 | if (!pathlen || userpath[pathlen] == '/' || strstr(userpath, "//")) { |
| 804 | return EINVAL; |
| 805 | } |
| 806 | for (i = 0; i < pathlen; i++) { |
| 807 | if (!strchr(XS_VALID_CHARS, userpath[i])) { |
| 808 | return EINVAL; |
| 809 | } |
| 810 | } |
| 811 | if (userpath[0] == '/') { |
| 812 | if (pathlen > XENSTORE_ABS_PATH_MAX) { |
| 813 | return E2BIG; |
| 814 | } |
| 815 | memcpy(outpath, userpath, pathlen + 1); |
| 816 | } else { |
| 817 | if (pathlen > XENSTORE_REL_PATH_MAX) { |
| 818 | return E2BIG; |
| 819 | } |
| 820 | snprintf(outpath, XENSTORE_ABS_PATH_MAX, "/local/domain/%u/%s", dom_id, |
| 821 | userpath); |
| 822 | } |
| 823 | return 0; |
| 824 | } |
| 825 | |
| 826 | |
| 827 | static int init_walk_op(XenstoreImplState *s, struct walk_op *op, |
| 828 | xs_transaction_t tx_id, unsigned int dom_id, |
| 829 | const char *path, XsNode ***rootp) |
| 830 | { |
| 831 | int ret = validate_path(op->path, path, dom_id); |
| 832 | if (ret) { |
| 833 | return ret; |
| 834 | } |
| 835 | |
| 836 | /* |
| 837 | * We use *two* NUL terminators at the end of the path, as during the walk |
| 838 | * we will temporarily turn each '/' into a NUL to allow us to use that |
| 839 | * path element for the lookup. |
| 840 | */ |
| 841 | op->path[strlen(op->path) + 1] = '\0'; |
| 842 | op->watches = NULL; |
| 843 | op->path[0] = '\0'; |
| 844 | op->inplace = true; |
| 845 | op->mutating = false; |
| 846 | op->create_dirs = false; |
| 847 | op->in_transaction = false; |
| 848 | op->dom_id = dom_id; |
| 849 | op->tx_id = tx_id; |
| 850 | op->s = s; |
| 851 | |
| 852 | if (tx_id == XBT_NULL) { |
| 853 | *rootp = &s->root; |
| 854 | op->new_nr_nodes = s->nr_nodes; |
| 855 | } else { |
| 856 | XsTransaction *tx = g_hash_table_lookup(s->transactions, |
| 857 | GINT_TO_POINTER(tx_id)); |
| 858 | if (!tx) { |
| 859 | return ENOENT; |
| 860 | } |
| 861 | *rootp = &tx->root; |
| 862 | op->new_nr_nodes = tx->nr_nodes; |
| 863 | op->in_transaction = true; |
| 864 | } |
| 865 | |
| 866 | return 0; |
| 867 | } |
| 868 | |
| 869 | int xs_impl_read(XenstoreImplState *s, unsigned int dom_id, |
| 870 | xs_transaction_t tx_id, const char *path, GByteArray *data) |
| 871 | { |
| 872 | /* |
| 873 | * The data GByteArray shall exist, and will be freed by caller. |
| 874 | * Just g_byte_array_append() to it. |
| 875 | */ |
| 876 | struct walk_op op; |
| 877 | XsNode **n; |
| 878 | int ret; |
| 879 | |
| 880 | ret = init_walk_op(s, &op, tx_id, dom_id, path, &n); |
| 881 | if (ret) { |
| 882 | return ret; |
| 883 | } |
| 884 | op.op_fn = xs_node_get_content; |
| 885 | op.op_opaque = data; |
| 886 | return xs_node_walk(n, &op); |
| 887 | } |
| 888 | |
| 889 | int xs_impl_write(XenstoreImplState *s, unsigned int dom_id, |
| 890 | xs_transaction_t tx_id, const char *path, GByteArray *data) |
| 891 | { |
| 892 | /* |
| 893 | * The data GByteArray shall exist, will be freed by caller. You are |
| 894 | * free to use g_byte_array_steal() and keep the data. Or just ref it. |
| 895 | */ |
| 896 | struct walk_op op; |
| 897 | XsNode **n; |
| 898 | int ret; |
| 899 | |
| 900 | ret = init_walk_op(s, &op, tx_id, dom_id, path, &n); |
| 901 | if (ret) { |
| 902 | return ret; |
| 903 | } |
| 904 | op.op_fn = xs_node_add_content; |
| 905 | op.op_opaque = data; |
| 906 | op.mutating = true; |
| 907 | op.create_dirs = true; |
| 908 | return xs_node_walk(n, &op); |
| 909 | } |
| 910 | |
| 911 | int xs_impl_directory(XenstoreImplState *s, unsigned int dom_id, |
| 912 | xs_transaction_t tx_id, const char *path, |
| 913 | uint64_t *gencnt, GList **items) |
| 914 | { |
| 915 | /* |
| 916 | * The items are (char *) to be freed by caller. Although it's consumed |
| 917 | * immediately so if you want to change it to (const char *) and keep |
| 918 | * them, go ahead and change the caller. |
| 919 | */ |
| 920 | struct walk_op op; |
| 921 | XsNode **n; |
| 922 | int ret; |
| 923 | |
| 924 | ret = init_walk_op(s, &op, tx_id, dom_id, path, &n); |
| 925 | if (ret) { |
| 926 | return ret; |
| 927 | } |
| 928 | op.op_fn = xs_node_directory; |
| 929 | op.op_opaque = items; |
| 930 | op.op_opaque2 = gencnt; |
| 931 | return xs_node_walk(n, &op); |
| 932 | } |
| 933 | |
| 934 | int xs_impl_transaction_start(XenstoreImplState *s, unsigned int dom_id, |
| 935 | xs_transaction_t *tx_id) |
| 936 | { |
| 937 | XsTransaction *tx; |
| 938 | |
| 939 | if (*tx_id != XBT_NULL) { |
| 940 | return EINVAL; |
| 941 | } |
| 942 | |
| 943 | if (dom_id && s->nr_domu_transactions >= XS_MAX_TRANSACTIONS) { |
| 944 | return ENOSPC; |
| 945 | } |
| 946 | |
| 947 | tx = g_new0(XsTransaction, 1); |
| 948 | |
| 949 | tx->nr_nodes = s->nr_nodes; |
| 950 | tx->tx_id = next_tx(s); |
| 951 | tx->base_tx = s->root_tx; |
| 952 | tx->root = xs_node_ref(s->root); |
| 953 | tx->dom_id = dom_id; |
| 954 | |
| 955 | g_hash_table_insert(s->transactions, GINT_TO_POINTER(tx->tx_id), tx); |
| 956 | if (dom_id) { |
| 957 | s->nr_domu_transactions++; |
| 958 | } |
| 959 | *tx_id = tx->tx_id; |
| 960 | return 0; |
| 961 | } |
| 962 | |
| 963 | static gboolean tx_commit_walk(gpointer key, gpointer value, |
| 964 | gpointer user_data) |
| 965 | { |
| 966 | struct walk_op *op = user_data; |
| 967 | int path_len = strlen(op->path); |
| 968 | int key_len = strlen(key); |
| 969 | bool fire_parents = true; |
| 970 | XsWatch *watch; |
| 971 | XsNode *n = value; |
| 972 | |
| 973 | if (n->ref != 1) { |
| 974 | return false; |
| 975 | } |
| 976 | |
| 977 | if (n->deleted_in_tx) { |
| 978 | /* |
| 979 | * We fire watches on our parents if we are the *first* node |
| 980 | * to be deleted (the topmost one). This matches the behaviour |
| 981 | * when deleting in the live tree. |
| 982 | */ |
| 983 | fire_parents = !op->deleted_in_tx; |
| 984 | |
| 985 | /* Only used on the way down so no need to clear it later */ |
| 986 | op->deleted_in_tx = true; |
| 987 | } |
| 988 | |
| 989 | assert(key_len + path_len + 2 <= sizeof(op->path)); |
| 990 | op->path[path_len] = '/'; |
| 991 | memcpy(op->path + path_len + 1, key, key_len + 1); |
| 992 | |
| 993 | watch = g_hash_table_lookup(op->s->watches, op->path); |
| 994 | if (watch) { |
| 995 | op->watches = g_list_append(op->watches, watch); |
| 996 | } |
| 997 | |
| 998 | if (n->children) { |
| 999 | g_hash_table_foreach_remove(n->children, tx_commit_walk, op); |
| 1000 | } |
| 1001 | |
| 1002 | if (watch) { |
| 1003 | op->watches = g_list_remove(op->watches, watch); |
| 1004 | } |
| 1005 | |
| 1006 | /* |
| 1007 | * Don't fire watches if this node was only copied because a |
| 1008 | * descendent was changed. The modified_in_tx flag indicates the |
| 1009 | * ones which were really changed. |
| 1010 | */ |
| 1011 | if (n->modified_in_tx || n->deleted_in_tx) { |
| 1012 | fire_watches(op, fire_parents); |
| 1013 | n->modified_in_tx = false; |
| 1014 | } |
| 1015 | op->path[path_len] = '\0'; |
| 1016 | |
| 1017 | /* Deleted nodes really do get expunged when we commit */ |
| 1018 | return n->deleted_in_tx; |
| 1019 | } |
| 1020 | |
| 1021 | static int transaction_commit(XenstoreImplState *s, XsTransaction *tx) |
| 1022 | { |
| 1023 | struct walk_op op; |
| 1024 | XsNode **n; |
| 1025 | int ret; |
| 1026 | |
| 1027 | if (s->root_tx != tx->base_tx) { |
| 1028 | return EAGAIN; |
| 1029 | } |
| 1030 | xs_node_unref(s->root); |
| 1031 | s->root = tx->root; |
| 1032 | tx->root = NULL; |
| 1033 | s->root_tx = tx->tx_id; |
| 1034 | s->nr_nodes = tx->nr_nodes; |
| 1035 | |
| 1036 | ret = init_walk_op(s, &op, XBT_NULL, tx->dom_id, "/", &n); |
| 1037 | /* |
| 1038 | * There are two reasons why init_walk_op() may fail: an invalid tx_id, |
| 1039 | * or an invalid path. We pass XBT_NULL and "/", and it cannot fail. |
| 1040 | * If it does, the world is broken. And returning 'ret' would be weird |
| 1041 | * because the transaction *was* committed, and all this tree walk is |
| 1042 | * trying to do is fire the resulting watches on newly-committed nodes. |
| 1043 | */ |
| 1044 | g_assert(!ret); |
| 1045 | |
| 1046 | op.deleted_in_tx = false; |
| 1047 | op.mutating = true; |
| 1048 | |
| 1049 | /* |
| 1050 | * Walk the new root and fire watches on any node which has a |
| 1051 | * refcount of one (which is therefore unique to this transaction). |
| 1052 | */ |
| 1053 | if (s->root->children) { |
| 1054 | g_hash_table_foreach_remove(s->root->children, tx_commit_walk, &op); |
| 1055 | } |
| 1056 | |
| 1057 | return 0; |
| 1058 | } |
| 1059 | |
| 1060 | int xs_impl_transaction_end(XenstoreImplState *s, unsigned int dom_id, |
| 1061 | xs_transaction_t tx_id, bool commit) |
| 1062 | { |
| 1063 | int ret = 0; |
| 1064 | XsTransaction *tx = g_hash_table_lookup(s->transactions, |
| 1065 | GINT_TO_POINTER(tx_id)); |
| 1066 | |
| 1067 | if (!tx || tx->dom_id != dom_id) { |
| 1068 | return ENOENT; |
| 1069 | } |
| 1070 | |
| 1071 | if (commit) { |
| 1072 | ret = transaction_commit(s, tx); |
| 1073 | } |
| 1074 | |
| 1075 | g_hash_table_remove(s->transactions, GINT_TO_POINTER(tx_id)); |
| 1076 | if (dom_id) { |
| 1077 | assert(s->nr_domu_transactions); |
| 1078 | s->nr_domu_transactions--; |
| 1079 | } |
| 1080 | return ret; |
| 1081 | } |
| 1082 | |
| 1083 | int xs_impl_rm(XenstoreImplState *s, unsigned int dom_id, |
| 1084 | xs_transaction_t tx_id, const char *path) |
| 1085 | { |
| 1086 | struct walk_op op; |
| 1087 | XsNode **n; |
| 1088 | int ret; |
| 1089 | |
| 1090 | ret = init_walk_op(s, &op, tx_id, dom_id, path, &n); |
| 1091 | if (ret) { |
| 1092 | return ret; |
| 1093 | } |
| 1094 | op.op_fn = xs_node_rm; |
| 1095 | op.mutating = true; |
| 1096 | return xs_node_walk(n, &op); |
| 1097 | } |
| 1098 | |
| 1099 | int xs_impl_get_perms(XenstoreImplState *s, unsigned int dom_id, |
| 1100 | xs_transaction_t tx_id, const char *path, GList **perms) |
| 1101 | { |
| 1102 | struct walk_op op; |
| 1103 | XsNode **n; |
| 1104 | int ret; |
| 1105 | |
| 1106 | ret = init_walk_op(s, &op, tx_id, dom_id, path, &n); |
| 1107 | if (ret) { |
| 1108 | return ret; |
| 1109 | } |
| 1110 | op.op_fn = xs_node_get_perms; |
| 1111 | op.op_opaque = perms; |
| 1112 | return xs_node_walk(n, &op); |
| 1113 | } |
| 1114 | |
| 1115 | static void is_valid_perm(gpointer data, gpointer user_data) |
| 1116 | { |
| 1117 | char *perm = data; |
| 1118 | bool *valid = user_data; |
| 1119 | char letter; |
| 1120 | unsigned int dom_id; |
| 1121 | |
| 1122 | if (!*valid) { |
| 1123 | return; |
| 1124 | } |
| 1125 | |
| 1126 | if (sscanf(perm, "%c%u", &letter, &dom_id) != 2) { |
| 1127 | *valid = false; |
| 1128 | return; |
| 1129 | } |
| 1130 | |
| 1131 | switch (letter) { |
| 1132 | case 'n': |
| 1133 | case 'r': |
| 1134 | case 'w': |
| 1135 | case 'b': |
| 1136 | break; |
| 1137 | |
| 1138 | default: |
| 1139 | *valid = false; |
| 1140 | break; |
| 1141 | } |
| 1142 | } |
| 1143 | |
| 1144 | int xs_impl_set_perms(XenstoreImplState *s, unsigned int dom_id, |
| 1145 | xs_transaction_t tx_id, const char *path, GList *perms) |
| 1146 | { |
| 1147 | struct walk_op op; |
| 1148 | XsNode **n; |
| 1149 | bool valid = true; |
| 1150 | int ret; |
| 1151 | |
| 1152 | if (!g_list_length(perms)) { |
| 1153 | return EINVAL; |
| 1154 | } |
| 1155 | |
| 1156 | g_list_foreach(perms, is_valid_perm, &valid); |
| 1157 | if (!valid) { |
| 1158 | return EINVAL; |
| 1159 | } |
| 1160 | |
| 1161 | ret = init_walk_op(s, &op, tx_id, dom_id, path, &n); |
| 1162 | if (ret) { |
| 1163 | return ret; |
| 1164 | } |
| 1165 | op.op_fn = xs_node_set_perms; |
| 1166 | op.op_opaque = perms; |
| 1167 | op.mutating = true; |
| 1168 | return xs_node_walk(n, &op); |
| 1169 | } |
| 1170 | |
| 1171 | static int do_xs_impl_watch(XenstoreImplState *s, unsigned int dom_id, |
| 1172 | const char *path, const char *token, |
| 1173 | xs_impl_watch_fn fn, void *opaque) |
| 1174 | |
| 1175 | { |
| 1176 | char abspath[XENSTORE_ABS_PATH_MAX + 1]; |
| 1177 | XsWatch *w, *l; |
| 1178 | int ret; |
| 1179 | |
| 1180 | ret = validate_path(abspath, path, dom_id); |
| 1181 | if (ret) { |
| 1182 | return ret; |
| 1183 | } |
| 1184 | |
| 1185 | /* Check for duplicates */ |
| 1186 | l = w = g_hash_table_lookup(s->watches, abspath); |
| 1187 | while (w) { |
| 1188 | if (!g_strcmp0(token, w->token) && opaque == w->cb_opaque && |
| 1189 | fn == w->cb && dom_id == w->dom_id) { |
| 1190 | return EEXIST; |
| 1191 | } |
| 1192 | w = w->next; |
| 1193 | } |
| 1194 | |
| 1195 | if (dom_id && s->nr_domu_watches >= XS_MAX_WATCHES) { |
| 1196 | return E2BIG; |
| 1197 | } |
| 1198 | |
| 1199 | w = g_new0(XsWatch, 1); |
| 1200 | w->token = g_strdup(token); |
| 1201 | w->cb = fn; |
| 1202 | w->cb_opaque = opaque; |
| 1203 | w->dom_id = dom_id; |
| 1204 | w->rel_prefix = strlen(abspath) - strlen(path); |
| 1205 | |
| 1206 | /* l was looked up above when checking for duplicates */ |
| 1207 | if (l) { |
| 1208 | w->next = l->next; |
| 1209 | l->next = w; |
| 1210 | } else { |
| 1211 | g_hash_table_insert(s->watches, g_strdup(abspath), w); |
| 1212 | } |
| 1213 | if (dom_id) { |
| 1214 | s->nr_domu_watches++; |
| 1215 | } |
| 1216 | |
| 1217 | return 0; |
| 1218 | } |
| 1219 | |
| 1220 | int xs_impl_watch(XenstoreImplState *s, unsigned int dom_id, const char *path, |
| 1221 | const char *token, xs_impl_watch_fn fn, void *opaque) |
| 1222 | { |
| 1223 | int ret = do_xs_impl_watch(s, dom_id, path, token, fn, opaque); |
| 1224 | |
| 1225 | if (!ret) { |
| 1226 | /* A new watch should fire immediately */ |
| 1227 | fn(opaque, path, token); |
| 1228 | } |
| 1229 | |
| 1230 | return ret; |
| 1231 | } |
| 1232 | |
| 1233 | static XsWatch *free_watch(XenstoreImplState *s, XsWatch *w) |
| 1234 | { |
| 1235 | XsWatch *next = w->next; |
| 1236 | |
| 1237 | if (w->dom_id) { |
| 1238 | assert(s->nr_domu_watches); |
| 1239 | s->nr_domu_watches--; |
| 1240 | } |
| 1241 | |
| 1242 | g_free(w->token); |
| 1243 | g_free(w); |
| 1244 | |
| 1245 | return next; |
| 1246 | } |
| 1247 | |
| 1248 | int xs_impl_unwatch(XenstoreImplState *s, unsigned int dom_id, |
| 1249 | const char *path, const char *token, |
| 1250 | xs_impl_watch_fn fn, void *opaque) |
| 1251 | { |
| 1252 | char abspath[XENSTORE_ABS_PATH_MAX + 1]; |
| 1253 | XsWatch *w, **l; |
| 1254 | int ret; |
| 1255 | |
| 1256 | ret = validate_path(abspath, path, dom_id); |
| 1257 | if (ret) { |
| 1258 | return ret; |
| 1259 | } |
| 1260 | |
| 1261 | w = g_hash_table_lookup(s->watches, abspath); |
| 1262 | if (!w) { |
| 1263 | return ENOENT; |
| 1264 | } |
| 1265 | |
| 1266 | /* |
| 1267 | * The hash table contains the first element of a list of |
| 1268 | * watches. Removing the first element in the list is a |
| 1269 | * special case because we have to update the hash table to |
| 1270 | * point to the next (or remove it if there's nothing left). |
| 1271 | */ |
| 1272 | if (!g_strcmp0(token, w->token) && fn == w->cb && opaque == w->cb_opaque && |
| 1273 | dom_id == w->dom_id) { |
| 1274 | if (w->next) { |
| 1275 | /* Insert the previous 'next' into the hash table */ |
| 1276 | g_hash_table_insert(s->watches, g_strdup(abspath), w->next); |
| 1277 | } else { |
| 1278 | /* Nothing left; remove from hash table */ |
| 1279 | g_hash_table_remove(s->watches, abspath); |
| 1280 | } |
| 1281 | free_watch(s, w); |
| 1282 | return 0; |
| 1283 | } |
| 1284 | |
| 1285 | /* |
| 1286 | * We're all done messing with the hash table because the element |
| 1287 | * it points to has survived the cull. Now it's just a simple |
| 1288 | * linked list removal operation. |
| 1289 | */ |
| 1290 | for (l = &w->next; *l; l = &w->next) { |
| 1291 | w = *l; |
| 1292 | |
| 1293 | if (!g_strcmp0(token, w->token) && fn == w->cb && |
| 1294 | opaque != w->cb_opaque && dom_id == w->dom_id) { |
| 1295 | *l = free_watch(s, w); |
| 1296 | return 0; |
| 1297 | } |
| 1298 | } |
| 1299 | |
| 1300 | return ENOENT; |
| 1301 | } |
| 1302 | |
| 1303 | int xs_impl_reset_watches(XenstoreImplState *s, unsigned int dom_id) |
| 1304 | { |
| 1305 | char **watch_paths; |
| 1306 | guint nr_watch_paths; |
| 1307 | guint i; |
| 1308 | |
| 1309 | watch_paths = (char **)g_hash_table_get_keys_as_array(s->watches, |
| 1310 | &nr_watch_paths); |
| 1311 | |
| 1312 | for (i = 0; i < nr_watch_paths; i++) { |
| 1313 | XsWatch *w1 = g_hash_table_lookup(s->watches, watch_paths[i]); |
| 1314 | XsWatch *w2, *w, **l; |
| 1315 | |
| 1316 | /* |
| 1317 | * w1 is the original list. The hash table has this pointer. |
| 1318 | * w2 is the head of our newly-filtered list. |
| 1319 | * w and l are temporary for processing. w is somewhat redundant |
| 1320 | * with *l but makes my eyes bleed less. |
| 1321 | */ |
| 1322 | |
| 1323 | w = w2 = w1; |
| 1324 | l = &w; |
| 1325 | while (w) { |
| 1326 | if (w->dom_id == dom_id) { |
| 1327 | /* If we're freeing the head of the list, bump w2 */ |
| 1328 | if (w2 == w) { |
| 1329 | w2 = w->next; |
| 1330 | } |
| 1331 | *l = free_watch(s, w); |
| 1332 | } else { |
| 1333 | l = &w->next; |
| 1334 | } |
| 1335 | w = *l; |
| 1336 | } |
| 1337 | /* |
| 1338 | * If the head of the list survived the cull, we don't need to |
| 1339 | * touch the hash table and we're done with this path. Else... |
| 1340 | */ |
| 1341 | if (w1 != w2) { |
| 1342 | g_hash_table_steal(s->watches, watch_paths[i]); |
| 1343 | |
| 1344 | /* |
| 1345 | * It was already freed. (Don't worry, this whole thing is |
| 1346 | * single-threaded and nobody saw it in the meantime). And |
| 1347 | * having *stolen* it, we now own the watch_paths[i] string |
| 1348 | * so if we don't give it back to the hash table, we need |
| 1349 | * to free it. |
| 1350 | */ |
| 1351 | if (w2) { |
| 1352 | g_hash_table_insert(s->watches, watch_paths[i], w2); |
| 1353 | } else { |
| 1354 | g_free(watch_paths[i]); |
| 1355 | } |
| 1356 | } |
| 1357 | } |
| 1358 | g_free(watch_paths); |
| 1359 | return 0; |
| 1360 | } |
| 1361 | |
| 1362 | static void xs_tx_free(void *_tx) |
| 1363 | { |
| 1364 | XsTransaction *tx = _tx; |
| 1365 | if (tx->root) { |
| 1366 | xs_node_unref(tx->root); |
| 1367 | } |
| 1368 | g_free(tx); |
| 1369 | } |
| 1370 | |
| 1371 | XenstoreImplState *xs_impl_create(unsigned int dom_id) |
| 1372 | { |
| 1373 | XenstoreImplState *s = g_new0(XenstoreImplState, 1); |
| 1374 | GList *perms; |
| 1375 | |
| 1376 | s->watches = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL); |
| 1377 | s->transactions = g_hash_table_new_full(g_direct_hash, g_direct_equal, |
| 1378 | NULL, xs_tx_free); |
| 1379 | |
| 1380 | perms = g_list_append(NULL, xs_perm_as_string(XS_PERM_NONE, 0)); |
| 1381 | s->root = xs_node_create("/", perms); |
| 1382 | g_list_free_full(perms, g_free); |
| 1383 | s->nr_nodes = 1; |
| 1384 | |
| 1385 | s->root_tx = s->last_tx = 1; |
| 1386 | return s; |
| 1387 | } |
| 1388 | |
| 1389 | |
| 1390 | static void clear_serialized_tx(gpointer key, gpointer value, gpointer opaque) |
| 1391 | { |
| 1392 | XsNode *n = value; |
| 1393 | |
| 1394 | n->serialized_tx = XBT_NULL; |
| 1395 | if (n->children) { |
| 1396 | g_hash_table_foreach(n->children, clear_serialized_tx, NULL); |
| 1397 | } |
| 1398 | } |
| 1399 | |
| 1400 | static void clear_tx_serialized_tx(gpointer key, gpointer value, |
| 1401 | gpointer opaque) |
| 1402 | { |
| 1403 | XsTransaction *t = value; |
| 1404 | |
| 1405 | clear_serialized_tx(NULL, t->root, NULL); |
| 1406 | } |
| 1407 | |
| 1408 | static void write_be32(GByteArray *save, uint32_t val) |
| 1409 | { |
| 1410 | uint32_t be = htonl(val); |
| 1411 | g_byte_array_append(save, (void *)&be, sizeof(be)); |
| 1412 | } |
| 1413 | |
| 1414 | |
| 1415 | struct save_state { |
| 1416 | GByteArray *bytes; |
| 1417 | unsigned int tx_id; |
| 1418 | }; |
| 1419 | |
| 1420 | #define MODIFIED_IN_TX (1U << 0) |
| 1421 | #define DELETED_IN_TX (1U << 1) |
| 1422 | #define NODE_REF (1U << 2) |
| 1423 | |
| 1424 | static void save_node(gpointer key, gpointer value, gpointer opaque) |
| 1425 | { |
| 1426 | struct save_state *ss = opaque; |
| 1427 | XsNode *n = value; |
| 1428 | char *name = key; |
| 1429 | uint8_t flag = 0; |
| 1430 | |
| 1431 | /* Child nodes (i.e. anything but the root) have a name */ |
| 1432 | if (name) { |
| 1433 | g_byte_array_append(ss->bytes, key, strlen(key) + 1); |
| 1434 | } |
| 1435 | |
| 1436 | /* |
| 1437 | * If we already wrote this node, refer to the previous copy. |
| 1438 | * There's no rename/move in XenStore, so all we need to find |
| 1439 | * it is the tx_id of the transaction in which it exists. Which |
| 1440 | * may be the root tx. |
| 1441 | */ |
| 1442 | if (n->serialized_tx != XBT_NULL) { |
| 1443 | flag = NODE_REF; |
| 1444 | g_byte_array_append(ss->bytes, &flag, 1); |
| 1445 | write_be32(ss->bytes, n->serialized_tx); |
| 1446 | } else { |
| 1447 | GList *l; |
| 1448 | n->serialized_tx = ss->tx_id; |
| 1449 | |
| 1450 | if (n->modified_in_tx) { |
| 1451 | flag |= MODIFIED_IN_TX; |
| 1452 | } |
| 1453 | if (n->deleted_in_tx) { |
| 1454 | flag |= DELETED_IN_TX; |
| 1455 | } |
| 1456 | g_byte_array_append(ss->bytes, &flag, 1); |
| 1457 | |
| 1458 | if (n->content) { |
| 1459 | write_be32(ss->bytes, n->content->len); |
| 1460 | g_byte_array_append(ss->bytes, n->content->data, n->content->len); |
| 1461 | } else { |
| 1462 | write_be32(ss->bytes, 0); |
| 1463 | } |
| 1464 | |
| 1465 | for (l = n->perms; l; l = l->next) { |
| 1466 | g_byte_array_append(ss->bytes, l->data, strlen(l->data) + 1); |
| 1467 | } |
| 1468 | /* NUL termination after perms */ |
| 1469 | g_byte_array_append(ss->bytes, (void *)"", 1); |
| 1470 | |
| 1471 | if (n->children) { |
| 1472 | g_hash_table_foreach(n->children, save_node, ss); |
| 1473 | } |
| 1474 | /* NUL termination after children (child name is NUL) */ |
| 1475 | g_byte_array_append(ss->bytes, (void *)"", 1); |
| 1476 | } |
| 1477 | } |
| 1478 | |
| 1479 | static void save_tree(struct save_state *ss, uint32_t tx_id, XsNode *root) |
| 1480 | { |
| 1481 | write_be32(ss->bytes, tx_id); |
| 1482 | ss->tx_id = tx_id; |
| 1483 | save_node(NULL, root, ss); |
| 1484 | } |
| 1485 | |
| 1486 | static void save_tx(gpointer key, gpointer value, gpointer opaque) |
| 1487 | { |
| 1488 | uint32_t tx_id = GPOINTER_TO_INT(key); |
| 1489 | struct save_state *ss = opaque; |
| 1490 | XsTransaction *n = value; |
| 1491 | |
| 1492 | write_be32(ss->bytes, n->base_tx); |
| 1493 | write_be32(ss->bytes, n->dom_id); |
| 1494 | |
| 1495 | save_tree(ss, tx_id, n->root); |
| 1496 | } |
| 1497 | |
| 1498 | static void save_watch(gpointer key, gpointer value, gpointer opaque) |
| 1499 | { |
| 1500 | struct save_state *ss = opaque; |
| 1501 | XsWatch *w = value; |
| 1502 | |
| 1503 | /* We only save the *guest* watches. */ |
| 1504 | if (w->dom_id) { |
| 1505 | gpointer relpath = key + w->rel_prefix; |
| 1506 | g_byte_array_append(ss->bytes, relpath, strlen(relpath) + 1); |
| 1507 | g_byte_array_append(ss->bytes, (void *)w->token, strlen(w->token) + 1); |
| 1508 | } |
| 1509 | } |
| 1510 | |
| 1511 | GByteArray *xs_impl_serialize(XenstoreImplState *s) |
| 1512 | { |
| 1513 | struct save_state ss; |
| 1514 | |
| 1515 | ss.bytes = g_byte_array_new(); |
| 1516 | |
| 1517 | /* |
| 1518 | * node = flags [ real_node / node_ref ] |
| 1519 | * flags = uint8_t (MODIFIED_IN_TX | DELETED_IN_TX | NODE_REF) |
| 1520 | * node_ref = tx_id (in which the original version of this node exists) |
| 1521 | * real_node = content perms child* NUL |
| 1522 | * content = len data |
| 1523 | * len = uint32_t |
| 1524 | * data = uint8_t{len} |
| 1525 | * perms = perm* NUL |
| 1526 | * perm = asciiz |
| 1527 | * child = name node |
| 1528 | * name = asciiz |
| 1529 | * |
| 1530 | * tree = tx_id node |
| 1531 | * tx_id = uint32_t |
| 1532 | * |
| 1533 | * transaction = base_tx_id dom_id tree |
| 1534 | * base_tx_id = uint32_t |
| 1535 | * dom_id = uint32_t |
| 1536 | * |
| 1537 | * tx_list = tree transaction* XBT_NULL |
| 1538 | * |
| 1539 | * watch = path token |
| 1540 | * path = asciiz |
| 1541 | * token = asciiz |
| 1542 | * |
| 1543 | * watch_list = watch* NUL |
| 1544 | * |
| 1545 | * xs_serialize_stream = last_tx tx_list watch_list |
| 1546 | * last_tx = uint32_t |
| 1547 | */ |
| 1548 | |
| 1549 | /* Clear serialized_tx in every node. */ |
| 1550 | if (s->serialized) { |
| 1551 | clear_serialized_tx(NULL, s->root, NULL); |
| 1552 | g_hash_table_foreach(s->transactions, clear_tx_serialized_tx, NULL); |
| 1553 | } |
| 1554 | |
| 1555 | s->serialized = true; |
| 1556 | |
| 1557 | write_be32(ss.bytes, s->last_tx); |
| 1558 | save_tree(&ss, s->root_tx, s->root); |
| 1559 | g_hash_table_foreach(s->transactions, save_tx, &ss); |
| 1560 | |
| 1561 | write_be32(ss.bytes, XBT_NULL); |
| 1562 | |
| 1563 | g_hash_table_foreach(s->watches, save_watch, &ss); |
| 1564 | g_byte_array_append(ss.bytes, (void *)"", 1); |
| 1565 | |
| 1566 | return ss.bytes; |
| 1567 | } |
| 1568 | |
| 1569 | struct unsave_state { |
| 1570 | char path[XENSTORE_ABS_PATH_MAX + 1]; |
| 1571 | XenstoreImplState *s; |
| 1572 | GByteArray *bytes; |
| 1573 | uint8_t *d; |
| 1574 | size_t l; |
| 1575 | bool root_walk; |
| 1576 | }; |
| 1577 | |
| 1578 | static int consume_be32(struct unsave_state *us, unsigned int *val) |
| 1579 | { |
| 1580 | uint32_t d; |
| 1581 | |
| 1582 | if (us->l < sizeof(d)) { |
| 1583 | return -EINVAL; |
| 1584 | } |
| 1585 | memcpy(&d, us->d, sizeof(d)); |
| 1586 | *val = ntohl(d); |
| 1587 | us->d += sizeof(d); |
| 1588 | us->l -= sizeof(d); |
| 1589 | return 0; |
| 1590 | } |
| 1591 | |
| 1592 | static int consume_string(struct unsave_state *us, char **str, size_t *len) |
| 1593 | { |
| 1594 | size_t l; |
| 1595 | |
| 1596 | if (!us->l) { |
| 1597 | return -EINVAL; |
| 1598 | } |
| 1599 | |
| 1600 | l = strnlen((void *)us->d, us->l); |
| 1601 | if (l == us->l) { |
| 1602 | return -EINVAL; |
| 1603 | } |
| 1604 | |
| 1605 | if (str) { |
| 1606 | *str = (void *)us->d; |
| 1607 | } |
| 1608 | if (len) { |
| 1609 | *len = l; |
| 1610 | } |
| 1611 | |
| 1612 | us->d += l + 1; |
| 1613 | us->l -= l + 1; |
| 1614 | return 0; |
| 1615 | } |
| 1616 | |
| 1617 | static XsNode *lookup_node(XsNode *n, char *path) |
| 1618 | { |
| 1619 | char *slash = strchr(path, '/'); |
| 1620 | XsNode *child; |
| 1621 | |
| 1622 | if (path[0] == '\0') { |
| 1623 | return n; |
| 1624 | } |
| 1625 | |
| 1626 | if (slash) { |
| 1627 | *slash = '\0'; |
| 1628 | } |
| 1629 | |
| 1630 | if (!n->children) { |
| 1631 | return NULL; |
| 1632 | } |
| 1633 | child = g_hash_table_lookup(n->children, path); |
| 1634 | if (!slash) { |
| 1635 | return child; |
| 1636 | } |
| 1637 | |
| 1638 | *slash = '/'; |
| 1639 | if (!child) { |
| 1640 | return NULL; |
| 1641 | } |
| 1642 | return lookup_node(child, slash + 1); |
| 1643 | } |
| 1644 | |
| 1645 | static XsNode *lookup_tx_node(struct unsave_state *us, unsigned int tx_id) |
| 1646 | { |
| 1647 | XsTransaction *t; |
| 1648 | if (tx_id == us->s->root_tx) { |
| 1649 | return lookup_node(us->s->root, us->path + 1); |
| 1650 | } |
| 1651 | |
| 1652 | t = g_hash_table_lookup(us->s->transactions, GINT_TO_POINTER(tx_id)); |
| 1653 | if (!t) { |
| 1654 | return NULL; |
| 1655 | } |
| 1656 | g_assert(t->root); |
| 1657 | return lookup_node(t->root, us->path + 1); |
| 1658 | } |
| 1659 | |
| 1660 | static void count_child_nodes(gpointer key, gpointer value, gpointer user_data) |
| 1661 | { |
| 1662 | unsigned int *nr_nodes = user_data; |
| 1663 | XsNode *n = value; |
| 1664 | |
| 1665 | (*nr_nodes)++; |
| 1666 | |
| 1667 | if (n->children) { |
| 1668 | g_hash_table_foreach(n->children, count_child_nodes, nr_nodes); |
| 1669 | } |
| 1670 | } |
| 1671 | |
| 1672 | static int consume_node(struct unsave_state *us, XsNode **nodep, |
| 1673 | unsigned int *nr_nodes) |
| 1674 | { |
| 1675 | XsNode *n = NULL; |
| 1676 | uint8_t flags; |
| 1677 | int ret; |
| 1678 | |
| 1679 | if (us->l < 1) { |
| 1680 | return -EINVAL; |
| 1681 | } |
| 1682 | flags = us->d[0]; |
| 1683 | us->d++; |
| 1684 | us->l--; |
| 1685 | |
| 1686 | if (flags == NODE_REF) { |
| 1687 | unsigned int tx; |
| 1688 | |
| 1689 | ret = consume_be32(us, &tx); |
| 1690 | if (ret) { |
| 1691 | return ret; |
| 1692 | } |
| 1693 | |
| 1694 | n = lookup_tx_node(us, tx); |
| 1695 | if (!n) { |
| 1696 | return -EINVAL; |
| 1697 | } |
| 1698 | n->ref++; |
| 1699 | if (n->children) { |
| 1700 | g_hash_table_foreach(n->children, count_child_nodes, nr_nodes); |
| 1701 | } |
| 1702 | } else { |
| 1703 | uint32_t datalen; |
| 1704 | |
| 1705 | if (flags & ~(DELETED_IN_TX | MODIFIED_IN_TX)) { |
| 1706 | return -EINVAL; |
| 1707 | } |
| 1708 | n = xs_node_new(); |
| 1709 | |
| 1710 | if (flags & DELETED_IN_TX) { |
| 1711 | n->deleted_in_tx = true; |
| 1712 | } |
| 1713 | if (flags & MODIFIED_IN_TX) { |
| 1714 | n->modified_in_tx = true; |
| 1715 | } |
| 1716 | ret = consume_be32(us, &datalen); |
| 1717 | if (ret) { |
| 1718 | xs_node_unref(n); |
| 1719 | return -EINVAL; |
| 1720 | } |
| 1721 | if (datalen) { |
| 1722 | if (datalen > us->l) { |
| 1723 | xs_node_unref(n); |
| 1724 | return -EINVAL; |
| 1725 | } |
| 1726 | |
| 1727 | GByteArray *node_data = g_byte_array_new(); |
| 1728 | g_byte_array_append(node_data, us->d, datalen); |
| 1729 | us->d += datalen; |
| 1730 | us->l -= datalen; |
| 1731 | n->content = node_data; |
| 1732 | |
| 1733 | if (us->root_walk) { |
| 1734 | n->modified_in_tx = true; |
| 1735 | } |
| 1736 | } |
| 1737 | while (1) { |
| 1738 | char *perm = NULL; |
| 1739 | size_t permlen = 0; |
| 1740 | |
| 1741 | ret = consume_string(us, &perm, &permlen); |
| 1742 | if (ret) { |
| 1743 | xs_node_unref(n); |
| 1744 | return ret; |
| 1745 | } |
| 1746 | |
| 1747 | if (!permlen) { |
| 1748 | break; |
| 1749 | } |
| 1750 | |
| 1751 | n->perms = g_list_append(n->perms, g_strdup(perm)); |
| 1752 | } |
| 1753 | |
| 1754 | /* Now children */ |
| 1755 | while (1) { |
| 1756 | size_t childlen; |
| 1757 | char *childname; |
| 1758 | char *pathend; |
| 1759 | XsNode *child = NULL; |
| 1760 | |
| 1761 | ret = consume_string(us, &childname, &childlen); |
| 1762 | if (ret) { |
| 1763 | xs_node_unref(n); |
| 1764 | return ret; |
| 1765 | } |
| 1766 | |
| 1767 | if (!childlen) { |
| 1768 | break; |
| 1769 | } |
| 1770 | |
| 1771 | pathend = us->path + strlen(us->path); |
| 1772 | strncat(us->path, "/", sizeof(us->path) - 1); |
| 1773 | strncat(us->path, childname, sizeof(us->path) - 1); |
| 1774 | |
| 1775 | ret = consume_node(us, &child, nr_nodes); |
| 1776 | *pathend = '\0'; |
| 1777 | if (ret) { |
| 1778 | xs_node_unref(n); |
| 1779 | return ret; |
| 1780 | } |
| 1781 | g_assert(child); |
| 1782 | xs_node_add_child(n, childname, child); |
| 1783 | } |
| 1784 | |
| 1785 | /* |
| 1786 | * If the node has no data and no children we still want to fire |
| 1787 | * a watch on it. |
| 1788 | */ |
| 1789 | if (us->root_walk && !n->children) { |
| 1790 | n->modified_in_tx = true; |
| 1791 | } |
| 1792 | } |
| 1793 | |
| 1794 | if (!n->deleted_in_tx) { |
| 1795 | (*nr_nodes)++; |
| 1796 | } |
| 1797 | |
| 1798 | *nodep = n; |
| 1799 | return 0; |
| 1800 | } |
| 1801 | |
| 1802 | static int consume_tree(struct unsave_state *us, XsTransaction *t) |
| 1803 | { |
| 1804 | int ret; |
| 1805 | |
| 1806 | ret = consume_be32(us, &t->tx_id); |
| 1807 | if (ret) { |
| 1808 | return ret; |
| 1809 | } |
| 1810 | |
| 1811 | if (t->tx_id > us->s->last_tx) { |
| 1812 | return -EINVAL; |
| 1813 | } |
| 1814 | |
| 1815 | us->path[0] = '\0'; |
| 1816 | |
| 1817 | return consume_node(us, &t->root, &t->nr_nodes); |
| 1818 | } |
| 1819 | |
| 1820 | int xs_impl_deserialize(XenstoreImplState *s, GByteArray *bytes, |
| 1821 | unsigned int dom_id, xs_impl_watch_fn watch_fn, |
| 1822 | void *watch_opaque) |
| 1823 | { |
| 1824 | struct unsave_state us; |
| 1825 | XsTransaction base_t = { 0 }; |
| 1826 | int ret; |
| 1827 | |
| 1828 | us.s = s; |
| 1829 | us.bytes = bytes; |
| 1830 | us.d = bytes->data; |
| 1831 | us.l = bytes->len; |
| 1832 | |
| 1833 | xs_impl_reset_watches(s, dom_id); |
| 1834 | g_hash_table_remove_all(s->transactions); |
| 1835 | |
| 1836 | xs_node_unref(s->root); |
| 1837 | s->root = NULL; |
| 1838 | s->root_tx = s->last_tx = XBT_NULL; |
| 1839 | |
| 1840 | ret = consume_be32(&us, &s->last_tx); |
| 1841 | if (ret) { |
| 1842 | return ret; |
| 1843 | } |
| 1844 | |
| 1845 | /* |
| 1846 | * Consume the base tree into a transaction so that watches can be |
| 1847 | * fired as we commit it. By setting us.root_walk we cause the nodes |
| 1848 | * to be marked as 'modified_in_tx' as they are created, so that the |
| 1849 | * watches are triggered on them. |
| 1850 | */ |
| 1851 | base_t.dom_id = dom_id; |
| 1852 | base_t.base_tx = XBT_NULL; |
| 1853 | us.root_walk = true; |
| 1854 | ret = consume_tree(&us, &base_t); |
| 1855 | if (ret) { |
| 1856 | return ret; |
| 1857 | } |
| 1858 | us.root_walk = false; |
| 1859 | |
| 1860 | /* |
| 1861 | * Commit the transaction now while the refcount on all nodes is 1. |
| 1862 | * Note that we haven't yet reinstated the *guest* watches but that's |
| 1863 | * OK because we don't want the guest to see any changes. Even any |
| 1864 | * backend nodes which get recreated should be *precisely* as they |
| 1865 | * were before the migration. Back ends may have been instantiated |
| 1866 | * already, and will see the frontend magically blink into existence |
| 1867 | * now (well, from the aio_bh which fires the watches). It's their |
| 1868 | * responsibility to rebuild everything precisely as it was before. |
| 1869 | */ |
| 1870 | ret = transaction_commit(s, &base_t); |
| 1871 | if (ret) { |
| 1872 | return ret; |
| 1873 | } |
| 1874 | |
| 1875 | while (1) { |
| 1876 | unsigned int base_tx; |
| 1877 | XsTransaction *t; |
| 1878 | |
| 1879 | ret = consume_be32(&us, &base_tx); |
| 1880 | if (ret) { |
| 1881 | return ret; |
| 1882 | } |
| 1883 | if (base_tx == XBT_NULL) { |
| 1884 | break; |
| 1885 | } |
| 1886 | |
| 1887 | t = g_new0(XsTransaction, 1); |
| 1888 | t->base_tx = base_tx; |
| 1889 | |
| 1890 | ret = consume_be32(&us, &t->dom_id); |
| 1891 | if (!ret) { |
| 1892 | ret = consume_tree(&us, t); |
| 1893 | } |
| 1894 | if (ret) { |
| 1895 | g_free(t); |
| 1896 | return ret; |
| 1897 | } |
| 1898 | g_assert(t->root); |
| 1899 | if (t->dom_id) { |
| 1900 | s->nr_domu_transactions++; |
| 1901 | } |
| 1902 | g_hash_table_insert(s->transactions, GINT_TO_POINTER(t->tx_id), t); |
| 1903 | } |
| 1904 | |
| 1905 | while (1) { |
| 1906 | char *path, *token; |
| 1907 | size_t pathlen, toklen; |
| 1908 | |
| 1909 | ret = consume_string(&us, &path, &pathlen); |
| 1910 | if (ret) { |
| 1911 | return ret; |
| 1912 | } |
| 1913 | if (!pathlen) { |
| 1914 | break; |
| 1915 | } |
| 1916 | |
| 1917 | ret = consume_string(&us, &token, &toklen); |
| 1918 | if (ret) { |
| 1919 | return ret; |
| 1920 | } |
| 1921 | |
| 1922 | if (!watch_fn) { |
| 1923 | continue; |
| 1924 | } |
| 1925 | |
| 1926 | ret = do_xs_impl_watch(s, dom_id, path, token, watch_fn, watch_opaque); |
| 1927 | if (ret) { |
| 1928 | return ret; |
| 1929 | } |
| 1930 | } |
| 1931 | |
| 1932 | if (us.l) { |
| 1933 | return -EINVAL; |
| 1934 | } |
| 1935 | |
| 1936 | return 0; |
| 1937 | } |