zcp.c revision 325536
1/* 2 * CDDL HEADER START 3 * 4 * This file and its contents are supplied under the terms of the 5 * Common Development and Distribution License ("CDDL"), version 1.0. 6 * You may only use this file in accordance with the terms of version 7 * 1.0 of the CDDL. 8 * 9 * A full copy of the text of the CDDL should have accompanied this 10 * source. A copy of the CDDL is also available via the Internet at 11 * http://www.illumos.org/license/CDDL. 12 * 13 * CDDL HEADER END 14 */ 15 16/* 17 * Copyright (c) 2016 by Delphix. All rights reserved. 18 */ 19 20/* 21 * ZFS Channel Programs (ZCP) 22 * 23 * The ZCP interface allows various ZFS commands and operations ZFS 24 * administrative operations (e.g. creating and destroying snapshots, typically 25 * performed via an ioctl to /dev/zfs by the zfs(1M) command and 26 * libzfs/libzfs_core) to be run * programmatically as a Lua script. A ZCP 27 * script is run as a dsl_sync_task and fully executed during one transaction 28 * group sync. This ensures that no other changes can be written concurrently 29 * with a running Lua script. Combining multiple calls to the exposed ZFS 30 * functions into one script gives a number of benefits: 31 * 32 * 1. Atomicity. For some compound or iterative operations, it's useful to be 33 * able to guarantee that the state of a pool has not changed between calls to 34 * ZFS. 35 * 36 * 2. Performance. If a large number of changes need to be made (e.g. deleting 37 * many filesystems), there can be a significant performance penalty as a 38 * result of the need to wait for a transaction group sync to pass for every 39 * single operation. When expressed as a single ZCP script, all these changes 40 * can be performed at once in one txg sync. 41 * 42 * A modified version of the Lua 5.2 interpreter is used to run channel program 43 * scripts. The Lua 5.2 manual can be found at: 44 * 45 * http://www.lua.org/manual/5.2/ 46 * 47 * If being run by a user (via an ioctl syscall), executing a ZCP script 48 * requires root privileges in the global zone. 49 * 50 * Scripts are passed to zcp_eval() as a string, then run in a synctask by 51 * zcp_eval_sync(). Arguments can be passed into the Lua script as an nvlist, 52 * which will be converted to a Lua table. Similarly, values returned from 53 * a ZCP script will be converted to an nvlist. See zcp_lua_to_nvlist_impl() 54 * for details on exact allowed types and conversion. 55 * 56 * ZFS functionality is exposed to a ZCP script as a library of function calls. 57 * These calls are sorted into submodules, such as zfs.list and zfs.sync, for 58 * iterators and synctasks, respectively. Each of these submodules resides in 59 * its own source file, with a zcp_*_info structure describing each library 60 * call in the submodule. 61 * 62 * Error handling in ZCP scripts is handled by a number of different methods 63 * based on severity: 64 * 65 * 1. Memory and time limits are in place to prevent a channel program from 66 * consuming excessive system or running forever. If one of these limits is 67 * hit, the channel program will be stopped immediately and return from 68 * zcp_eval() with an error code. No attempt will be made to roll back or undo 69 * any changes made by the channel program before the error occured. 70 * Consumers invoking zcp_eval() from elsewhere in the kernel may pass a time 71 * limit of 0, disabling the time limit. 72 * 73 * 2. Internal Lua errors can occur as a result of a syntax error, calling a 74 * library function with incorrect arguments, invoking the error() function, 75 * failing an assert(), or other runtime errors. In these cases the channel 76 * program will stop executing and return from zcp_eval() with an error code. 77 * In place of a return value, an error message will also be returned in the 78 * 'result' nvlist containing information about the error. No attempt will be 79 * made to roll back or undo any changes made by the channel program before the 80 * error occured. 81 * 82 * 3. If an error occurs inside a ZFS library call which returns an error code, 83 * the error is returned to the Lua script to be handled as desired. 84 * 85 * In the first two cases, Lua's error-throwing mechanism is used, which 86 * longjumps out of the script execution with luaL_error() and returns with the 87 * error. 88 * 89 * See zfs-program(1M) for more information on high level usage. 90 */ 91 92#include "lua.h" 93#include "lualib.h" 94#include "lauxlib.h" 95 96#include <sys/dsl_prop.h> 97#include <sys/dsl_synctask.h> 98#include <sys/dsl_dataset.h> 99#include <sys/zcp.h> 100#include <sys/zcp_iter.h> 101#include <sys/zcp_prop.h> 102#include <sys/zcp_global.h> 103#ifdef illumos 104#include <util/sscanf.h> 105#endif 106 107#ifdef __FreeBSD__ 108#define ECHRNG EDOM 109#define ETIME ETIMEDOUT 110#endif 111 112uint64_t zfs_lua_check_instrlimit_interval = 100; 113uint64_t zfs_lua_max_instrlimit = ZCP_MAX_INSTRLIMIT; 114uint64_t zfs_lua_max_memlimit = ZCP_MAX_MEMLIMIT; 115 116static int zcp_nvpair_value_to_lua(lua_State *, nvpair_t *, char *, int); 117static int zcp_lua_to_nvlist_impl(lua_State *, int, nvlist_t *, const char *, 118 int); 119 120typedef struct zcp_alloc_arg { 121 boolean_t aa_must_succeed; 122 int64_t aa_alloc_remaining; 123 int64_t aa_alloc_limit; 124} zcp_alloc_arg_t; 125 126typedef struct zcp_eval_arg { 127 lua_State *ea_state; 128 zcp_alloc_arg_t *ea_allocargs; 129 cred_t *ea_cred; 130 nvlist_t *ea_outnvl; 131 int ea_result; 132 uint64_t ea_instrlimit; 133} zcp_eval_arg_t; 134 135/*ARGSUSED*/ 136static int 137zcp_eval_check(void *arg, dmu_tx_t *tx) 138{ 139 return (0); 140} 141 142/* 143 * The outer-most error callback handler for use with lua_pcall(). On 144 * error Lua will call this callback with a single argument that 145 * represents the error value. In most cases this will be a string 146 * containing an error message, but channel programs can use Lua's 147 * error() function to return arbitrary objects as errors. This callback 148 * returns (on the Lua stack) the original error object along with a traceback. 149 * 150 * Fatal Lua errors can occur while resources are held, so we also call any 151 * registered cleanup function here. 152 */ 153static int 154zcp_error_handler(lua_State *state) 155{ 156 const char *msg; 157 158 zcp_cleanup(state); 159 160 VERIFY3U(1, ==, lua_gettop(state)); 161 msg = lua_tostring(state, 1); 162 luaL_traceback(state, state, msg, 1); 163 return (1); 164} 165 166int 167zcp_argerror(lua_State *state, int narg, const char *msg, ...) 168{ 169 va_list alist; 170 171 va_start(alist, msg); 172 const char *buf = lua_pushvfstring(state, msg, alist); 173 va_end(alist); 174 175 return (luaL_argerror(state, narg, buf)); 176} 177 178/* 179 * Install a new cleanup function, which will be invoked with the given 180 * opaque argument if a fatal error causes the Lua interpreter to longjump out 181 * of a function call. 182 * 183 * If an error occurs, the cleanup function will be invoked exactly once and 184 * then unreigstered. 185 */ 186void 187zcp_register_cleanup(lua_State *state, zcp_cleanup_t cleanfunc, void *cleanarg) 188{ 189 zcp_run_info_t *ri = zcp_run_info(state); 190 /* 191 * A cleanup function should always be explicitly removed before 192 * installing a new one to avoid accidental clobbering. 193 */ 194 ASSERT3P(ri->zri_cleanup, ==, NULL); 195 196 ri->zri_cleanup = cleanfunc; 197 ri->zri_cleanup_arg = cleanarg; 198} 199 200void 201zcp_clear_cleanup(lua_State *state) 202{ 203 zcp_run_info_t *ri = zcp_run_info(state); 204 205 ri->zri_cleanup = NULL; 206 ri->zri_cleanup_arg = NULL; 207} 208 209/* 210 * If it exists, execute the currently set cleanup function then unregister it. 211 */ 212void 213zcp_cleanup(lua_State *state) 214{ 215 zcp_run_info_t *ri = zcp_run_info(state); 216 217 if (ri->zri_cleanup != NULL) { 218 ri->zri_cleanup(ri->zri_cleanup_arg); 219 zcp_clear_cleanup(state); 220 } 221} 222 223#define ZCP_NVLIST_MAX_DEPTH 20 224 225/* 226 * Convert the lua table at the given index on the Lua stack to an nvlist 227 * and return it. 228 * 229 * If the table can not be converted for any reason, NULL is returned and 230 * an error message is pushed onto the Lua stack. 231 */ 232static nvlist_t * 233zcp_table_to_nvlist(lua_State *state, int index, int depth) 234{ 235 nvlist_t *nvl; 236 /* 237 * Converting a Lua table to an nvlist with key uniqueness checking is 238 * O(n^2) in the number of keys in the nvlist, which can take a long 239 * time when we return a large table from a channel program. 240 * Furthermore, Lua's table interface *almost* guarantees unique keys 241 * on its own (details below). Therefore, we don't use fnvlist_alloc() 242 * here to avoid the built-in uniqueness checking. 243 * 244 * The *almost* is because it's possible to have key collisions between 245 * e.g. the string "1" and the number 1, or the string "true" and the 246 * boolean true, so we explicitly check that when we're looking at a 247 * key which is an integer / boolean or a string that can be parsed as 248 * one of those types. In the worst case this could still devolve into 249 * O(n^2), so we only start doing these checks on boolean/integer keys 250 * once we've seen a string key which fits this weird usage pattern. 251 * 252 * Ultimately, we still want callers to know that the keys in this 253 * nvlist are unique, so before we return this we set the nvlist's 254 * flags to reflect that. 255 */ 256 VERIFY0(nvlist_alloc(&nvl, 0, KM_SLEEP)); 257 258 /* 259 * Push an empty stack slot where lua_next() will store each 260 * table key. 261 */ 262 lua_pushnil(state); 263 boolean_t saw_str_could_collide = B_FALSE; 264 while (lua_next(state, index) != 0) { 265 /* 266 * The next key-value pair from the table at index is 267 * now on the stack, with the key at stack slot -2 and 268 * the value at slot -1. 269 */ 270 int err = 0; 271 char buf[32]; 272 const char *key = NULL; 273 boolean_t key_could_collide = B_FALSE; 274 275 switch (lua_type(state, -2)) { 276 case LUA_TSTRING: 277 key = lua_tostring(state, -2); 278 279 /* check if this could collide with a number or bool */ 280 long long tmp; 281 int parselen; 282 if ((sscanf(key, "%lld%n", &tmp, &parselen) > 0 && 283 parselen == strlen(key)) || 284 strcmp(key, "true") == 0 || 285 strcmp(key, "false") == 0) { 286 key_could_collide = B_TRUE; 287 saw_str_could_collide = B_TRUE; 288 } 289 break; 290 case LUA_TBOOLEAN: 291 key = (lua_toboolean(state, -2) == B_TRUE ? 292 "true" : "false"); 293 if (saw_str_could_collide) { 294 key_could_collide = B_TRUE; 295 } 296 break; 297 case LUA_TNUMBER: 298 VERIFY3U(sizeof (buf), >, 299 snprintf(buf, sizeof (buf), "%lld", 300 (longlong_t)lua_tonumber(state, -2))); 301 key = buf; 302 if (saw_str_could_collide) { 303 key_could_collide = B_TRUE; 304 } 305 break; 306 default: 307 fnvlist_free(nvl); 308 (void) lua_pushfstring(state, "Invalid key " 309 "type '%s' in table", 310 lua_typename(state, lua_type(state, -2))); 311 return (NULL); 312 } 313 /* 314 * Check for type-mismatched key collisions, and throw an error. 315 */ 316 if (key_could_collide && nvlist_exists(nvl, key)) { 317 fnvlist_free(nvl); 318 (void) lua_pushfstring(state, "Collision of " 319 "key '%s' in table", key); 320 return (NULL); 321 } 322 /* 323 * Recursively convert the table value and insert into 324 * the new nvlist with the parsed key. To prevent 325 * stack overflow on circular or heavily nested tables, 326 * we track the current nvlist depth. 327 */ 328 if (depth >= ZCP_NVLIST_MAX_DEPTH) { 329 fnvlist_free(nvl); 330 (void) lua_pushfstring(state, "Maximum table " 331 "depth (%d) exceeded for table", 332 ZCP_NVLIST_MAX_DEPTH); 333 return (NULL); 334 } 335 err = zcp_lua_to_nvlist_impl(state, -1, nvl, key, 336 depth + 1); 337 if (err != 0) { 338 fnvlist_free(nvl); 339 /* 340 * Error message has been pushed to the lua 341 * stack by the recursive call. 342 */ 343 return (NULL); 344 } 345 /* 346 * Pop the value pushed by lua_next(). 347 */ 348 lua_pop(state, 1); 349 } 350 351 /* 352 * Mark the nvlist as having unique keys. This is a little ugly, but we 353 * ensured above that there are no duplicate keys in the nvlist. 354 */ 355 nvl->nvl_nvflag |= NV_UNIQUE_NAME; 356 357 return (nvl); 358} 359 360/* 361 * Convert a value from the given index into the lua stack to an nvpair, adding 362 * it to an nvlist with the given key. 363 * 364 * Values are converted as follows: 365 * 366 * string -> string 367 * number -> int64 368 * boolean -> boolean 369 * nil -> boolean (no value) 370 * 371 * Lua tables are converted to nvlists and then inserted. The table's keys 372 * are converted to strings then used as keys in the nvlist to store each table 373 * element. Keys are converted as follows: 374 * 375 * string -> no change 376 * number -> "%lld" 377 * boolean -> "true" | "false" 378 * nil -> error 379 * 380 * In the case of a key collision, an error is thrown. 381 * 382 * If an error is encountered, a nonzero error code is returned, and an error 383 * string will be pushed onto the Lua stack. 384 */ 385static int 386zcp_lua_to_nvlist_impl(lua_State *state, int index, nvlist_t *nvl, 387 const char *key, int depth) 388{ 389 /* 390 * Verify that we have enough remaining space in the lua stack to parse 391 * a key-value pair and push an error. 392 */ 393 if (!lua_checkstack(state, 3)) { 394 (void) lua_pushstring(state, "Lua stack overflow"); 395 return (1); 396 } 397 398 index = lua_absindex(state, index); 399 400 switch (lua_type(state, index)) { 401 case LUA_TNIL: 402 fnvlist_add_boolean(nvl, key); 403 break; 404 case LUA_TBOOLEAN: 405 fnvlist_add_boolean_value(nvl, key, 406 lua_toboolean(state, index)); 407 break; 408 case LUA_TNUMBER: 409 fnvlist_add_int64(nvl, key, lua_tonumber(state, index)); 410 break; 411 case LUA_TSTRING: 412 fnvlist_add_string(nvl, key, lua_tostring(state, index)); 413 break; 414 case LUA_TTABLE: { 415 nvlist_t *value_nvl = zcp_table_to_nvlist(state, index, depth); 416 if (value_nvl == NULL) 417 return (EINVAL); 418 419 fnvlist_add_nvlist(nvl, key, value_nvl); 420 fnvlist_free(value_nvl); 421 break; 422 } 423 default: 424 (void) lua_pushfstring(state, 425 "Invalid value type '%s' for key '%s'", 426 lua_typename(state, lua_type(state, index)), key); 427 return (EINVAL); 428 } 429 430 return (0); 431} 432 433/* 434 * Convert a lua value to an nvpair, adding it to an nvlist with the given key. 435 */ 436void 437zcp_lua_to_nvlist(lua_State *state, int index, nvlist_t *nvl, const char *key) 438{ 439 /* 440 * On error, zcp_lua_to_nvlist_impl pushes an error string onto the Lua 441 * stack before returning with a nonzero error code. If an error is 442 * returned, throw a fatal lua error with the given string. 443 */ 444 if (zcp_lua_to_nvlist_impl(state, index, nvl, key, 0) != 0) 445 (void) lua_error(state); 446} 447 448int 449zcp_lua_to_nvlist_helper(lua_State *state) 450{ 451 nvlist_t *nv = (nvlist_t *)lua_touserdata(state, 2); 452 const char *key = (const char *)lua_touserdata(state, 1); 453 zcp_lua_to_nvlist(state, 3, nv, key); 454 return (0); 455} 456 457void 458zcp_convert_return_values(lua_State *state, nvlist_t *nvl, 459 const char *key, zcp_eval_arg_t *evalargs) 460{ 461 int err; 462 lua_pushcfunction(state, zcp_lua_to_nvlist_helper); 463 lua_pushlightuserdata(state, (char *)key); 464 lua_pushlightuserdata(state, nvl); 465 lua_pushvalue(state, 1); 466 lua_remove(state, 1); 467 err = lua_pcall(state, 3, 0, 0); /* zcp_lua_to_nvlist_helper */ 468 if (err != 0) { 469 zcp_lua_to_nvlist(state, 1, nvl, ZCP_RET_ERROR); 470 evalargs->ea_result = SET_ERROR(ECHRNG); 471 } 472} 473 474/* 475 * Push a Lua table representing nvl onto the stack. If it can't be 476 * converted, return EINVAL, fill in errbuf, and push nothing. errbuf may 477 * be specified as NULL, in which case no error string will be output. 478 * 479 * Most nvlists are converted as simple key->value Lua tables, but we make 480 * an exception for the case where all nvlist entries are BOOLEANs (a string 481 * key without a value). In Lua, a table key pointing to a value of Nil 482 * (no value) is equivalent to the key not existing, so a BOOLEAN nvlist 483 * entry can't be directly converted to a Lua table entry. Nvlists of entirely 484 * BOOLEAN entries are frequently used to pass around lists of datasets, so for 485 * convenience we check for this case, and convert it to a simple Lua array of 486 * strings. 487 */ 488int 489zcp_nvlist_to_lua(lua_State *state, nvlist_t *nvl, 490 char *errbuf, int errbuf_len) 491{ 492 nvpair_t *pair; 493 lua_newtable(state); 494 boolean_t has_values = B_FALSE; 495 /* 496 * If the list doesn't have any values, just convert it to a string 497 * array. 498 */ 499 for (pair = nvlist_next_nvpair(nvl, NULL); 500 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) { 501 if (nvpair_type(pair) != DATA_TYPE_BOOLEAN) { 502 has_values = B_TRUE; 503 break; 504 } 505 } 506 if (!has_values) { 507 int i = 1; 508 for (pair = nvlist_next_nvpair(nvl, NULL); 509 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) { 510 (void) lua_pushinteger(state, i); 511 (void) lua_pushstring(state, nvpair_name(pair)); 512 (void) lua_settable(state, -3); 513 i++; 514 } 515 } else { 516 for (pair = nvlist_next_nvpair(nvl, NULL); 517 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) { 518 int err = zcp_nvpair_value_to_lua(state, pair, 519 errbuf, errbuf_len); 520 if (err != 0) { 521 lua_pop(state, 1); 522 return (err); 523 } 524 (void) lua_setfield(state, -2, nvpair_name(pair)); 525 } 526 } 527 return (0); 528} 529 530/* 531 * Push a Lua object representing the value of "pair" onto the stack. 532 * 533 * Only understands boolean_value, string, int64, nvlist, 534 * string_array, and int64_array type values. For other 535 * types, returns EINVAL, fills in errbuf, and pushes nothing. 536 */ 537static int 538zcp_nvpair_value_to_lua(lua_State *state, nvpair_t *pair, 539 char *errbuf, int errbuf_len) 540{ 541 int err = 0; 542 543 if (pair == NULL) { 544 lua_pushnil(state); 545 return (0); 546 } 547 548 switch (nvpair_type(pair)) { 549 case DATA_TYPE_BOOLEAN_VALUE: 550 (void) lua_pushboolean(state, 551 fnvpair_value_boolean_value(pair)); 552 break; 553 case DATA_TYPE_STRING: 554 (void) lua_pushstring(state, fnvpair_value_string(pair)); 555 break; 556 case DATA_TYPE_INT64: 557 (void) lua_pushinteger(state, fnvpair_value_int64(pair)); 558 break; 559 case DATA_TYPE_NVLIST: 560 err = zcp_nvlist_to_lua(state, 561 fnvpair_value_nvlist(pair), errbuf, errbuf_len); 562 break; 563 case DATA_TYPE_STRING_ARRAY: { 564 char **strarr; 565 uint_t nelem; 566 (void) nvpair_value_string_array(pair, &strarr, &nelem); 567 lua_newtable(state); 568 for (int i = 0; i < nelem; i++) { 569 (void) lua_pushinteger(state, i + 1); 570 (void) lua_pushstring(state, strarr[i]); 571 (void) lua_settable(state, -3); 572 } 573 break; 574 } 575 case DATA_TYPE_UINT64_ARRAY: { 576 uint64_t *intarr; 577 uint_t nelem; 578 (void) nvpair_value_uint64_array(pair, &intarr, &nelem); 579 lua_newtable(state); 580 for (int i = 0; i < nelem; i++) { 581 (void) lua_pushinteger(state, i + 1); 582 (void) lua_pushinteger(state, intarr[i]); 583 (void) lua_settable(state, -3); 584 } 585 break; 586 } 587 case DATA_TYPE_INT64_ARRAY: { 588 int64_t *intarr; 589 uint_t nelem; 590 (void) nvpair_value_int64_array(pair, &intarr, &nelem); 591 lua_newtable(state); 592 for (int i = 0; i < nelem; i++) { 593 (void) lua_pushinteger(state, i + 1); 594 (void) lua_pushinteger(state, intarr[i]); 595 (void) lua_settable(state, -3); 596 } 597 break; 598 } 599 default: { 600 if (errbuf != NULL) { 601 (void) snprintf(errbuf, errbuf_len, 602 "Unhandled nvpair type %d for key '%s'", 603 nvpair_type(pair), nvpair_name(pair)); 604 } 605 return (EINVAL); 606 } 607 } 608 return (err); 609} 610 611int 612zcp_dataset_hold_error(lua_State *state, dsl_pool_t *dp, const char *dsname, 613 int error) 614{ 615 if (error == ENOENT) { 616 (void) zcp_argerror(state, 1, "no such dataset '%s'", dsname); 617 return (0); /* not reached; zcp_argerror will longjmp */ 618 } else if (error == EXDEV) { 619 (void) zcp_argerror(state, 1, 620 "dataset '%s' is not in the target pool '%s'", 621 dsname, spa_name(dp->dp_spa)); 622 return (0); /* not reached; zcp_argerror will longjmp */ 623 } else if (error == EIO) { 624 (void) luaL_error(state, 625 "I/O error while accessing dataset '%s'", dsname); 626 return (0); /* not reached; luaL_error will longjmp */ 627 } else if (error != 0) { 628 (void) luaL_error(state, 629 "unexpected error %d while accessing dataset '%s'", 630 error, dsname); 631 return (0); /* not reached; luaL_error will longjmp */ 632 } 633 return (0); 634} 635 636/* 637 * Note: will longjmp (via lua_error()) on error. 638 * Assumes that the dsname is argument #1 (for error reporting purposes). 639 */ 640dsl_dataset_t * 641zcp_dataset_hold(lua_State *state, dsl_pool_t *dp, const char *dsname, 642 void *tag) 643{ 644 dsl_dataset_t *ds; 645 int error = dsl_dataset_hold(dp, dsname, tag, &ds); 646 (void) zcp_dataset_hold_error(state, dp, dsname, error); 647 return (ds); 648} 649 650static int zcp_debug(lua_State *); 651static zcp_lib_info_t zcp_debug_info = { 652 .name = "debug", 653 .func = zcp_debug, 654 .pargs = { 655 { .za_name = "debug string", .za_lua_type = LUA_TSTRING}, 656 {NULL, 0} 657 }, 658 .kwargs = { 659 {NULL, 0} 660 } 661}; 662 663static int 664zcp_debug(lua_State *state) 665{ 666 const char *dbgstring; 667 zcp_run_info_t *ri = zcp_run_info(state); 668 zcp_lib_info_t *libinfo = &zcp_debug_info; 669 670 zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs); 671 672 dbgstring = lua_tostring(state, 1); 673 674 zfs_dbgmsg("txg %lld ZCP: %s", ri->zri_tx->tx_txg, dbgstring); 675 676 return (0); 677} 678 679static int zcp_exists(lua_State *); 680static zcp_lib_info_t zcp_exists_info = { 681 .name = "exists", 682 .func = zcp_exists, 683 .pargs = { 684 { .za_name = "dataset", .za_lua_type = LUA_TSTRING}, 685 {NULL, 0} 686 }, 687 .kwargs = { 688 {NULL, 0} 689 } 690}; 691 692static int 693zcp_exists(lua_State *state) 694{ 695 zcp_run_info_t *ri = zcp_run_info(state); 696 dsl_pool_t *dp = ri->zri_pool; 697 zcp_lib_info_t *libinfo = &zcp_exists_info; 698 699 zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs); 700 701 const char *dsname = lua_tostring(state, 1); 702 703 dsl_dataset_t *ds; 704 int error = dsl_dataset_hold(dp, dsname, FTAG, &ds); 705 if (error == 0) { 706 dsl_dataset_rele(ds, FTAG); 707 lua_pushboolean(state, B_TRUE); 708 } else if (error == ENOENT) { 709 lua_pushboolean(state, B_FALSE); 710 } else if (error == EXDEV) { 711 return (luaL_error(state, "dataset '%s' is not in the " 712 "target pool", dsname)); 713 } else if (error == EIO) { 714 return (luaL_error(state, "I/O error opening dataset '%s'", 715 dsname)); 716 } else if (error != 0) { 717 return (luaL_error(state, "unexpected error %d", error)); 718 } 719 720 return (1); 721} 722 723/* 724 * Allocate/realloc/free a buffer for the lua interpreter. 725 * 726 * When nsize is 0, behaves as free() and returns NULL. 727 * 728 * If ptr is NULL, behaves as malloc() and returns an allocated buffer of size 729 * at least nsize. 730 * 731 * Otherwise, behaves as realloc(), changing the allocation from osize to nsize. 732 * Shrinking the buffer size never fails. 733 * 734 * The original allocated buffer size is stored as a uint64 at the beginning of 735 * the buffer to avoid actually reallocating when shrinking a buffer, since lua 736 * requires that this operation never fail. 737 */ 738static void * 739zcp_lua_alloc(void *ud, void *ptr, size_t osize, size_t nsize) 740{ 741 zcp_alloc_arg_t *allocargs = ud; 742 int flags = (allocargs->aa_must_succeed) ? 743 KM_SLEEP : (KM_NOSLEEP | KM_NORMALPRI); 744 745 if (nsize == 0) { 746 if (ptr != NULL) { 747 int64_t *allocbuf = (int64_t *)ptr - 1; 748 int64_t allocsize = *allocbuf; 749 ASSERT3S(allocsize, >, 0); 750 ASSERT3S(allocargs->aa_alloc_remaining + allocsize, <=, 751 allocargs->aa_alloc_limit); 752 allocargs->aa_alloc_remaining += allocsize; 753 kmem_free(allocbuf, allocsize); 754 } 755 return (NULL); 756 } else if (ptr == NULL) { 757 int64_t *allocbuf; 758 int64_t allocsize = nsize + sizeof (int64_t); 759 760 if (!allocargs->aa_must_succeed && 761 (allocsize <= 0 || 762 allocsize > allocargs->aa_alloc_remaining)) { 763 return (NULL); 764 } 765 766 allocbuf = kmem_alloc(allocsize, flags); 767 if (allocbuf == NULL) { 768 return (NULL); 769 } 770 allocargs->aa_alloc_remaining -= allocsize; 771 772 *allocbuf = allocsize; 773 return (allocbuf + 1); 774 } else if (nsize <= osize) { 775 /* 776 * If shrinking the buffer, lua requires that the reallocation 777 * never fail. 778 */ 779 return (ptr); 780 } else { 781 ASSERT3U(nsize, >, osize); 782 783 uint64_t *luabuf = zcp_lua_alloc(ud, NULL, 0, nsize); 784 if (luabuf == NULL) { 785 return (NULL); 786 } 787 (void) memcpy(luabuf, ptr, osize); 788 VERIFY3P(zcp_lua_alloc(ud, ptr, osize, 0), ==, NULL); 789 return (luabuf); 790 } 791} 792 793/* ARGSUSED */ 794static void 795zcp_lua_counthook(lua_State *state, lua_Debug *ar) 796{ 797 /* 798 * If we're called, check how many instructions the channel program has 799 * executed so far, and compare against the limit. 800 */ 801 lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY); 802 zcp_run_info_t *ri = lua_touserdata(state, -1); 803 804 ri->zri_curinstrs += zfs_lua_check_instrlimit_interval; 805 if (ri->zri_maxinstrs != 0 && ri->zri_curinstrs > ri->zri_maxinstrs) { 806 ri->zri_timed_out = B_TRUE; 807 (void) lua_pushstring(state, 808 "Channel program timed out."); 809 (void) lua_error(state); 810 } 811} 812 813static int 814zcp_panic_cb(lua_State *state) 815{ 816 panic("unprotected error in call to Lua API (%s)\n", 817 lua_tostring(state, -1)); 818 return (0); 819} 820 821static void 822zcp_eval_sync(void *arg, dmu_tx_t *tx) 823{ 824 int err; 825 zcp_run_info_t ri; 826 zcp_eval_arg_t *evalargs = arg; 827 lua_State *state = evalargs->ea_state; 828 829 /* 830 * Open context should have setup the stack to contain: 831 * 1: Error handler callback 832 * 2: Script to run (converted to a Lua function) 833 * 3: nvlist input to function (converted to Lua table or nil) 834 */ 835 VERIFY3U(3, ==, lua_gettop(state)); 836 837 /* 838 * Store the zcp_run_info_t struct for this run in the Lua registry. 839 * Registry entries are not directly accessible by the Lua scripts but 840 * can be accessed by our callbacks. 841 */ 842 ri.zri_space_used = 0; 843 ri.zri_pool = dmu_tx_pool(tx); 844 ri.zri_cred = evalargs->ea_cred; 845 ri.zri_tx = tx; 846 ri.zri_timed_out = B_FALSE; 847 ri.zri_cleanup = NULL; 848 ri.zri_cleanup_arg = NULL; 849 ri.zri_curinstrs = 0; 850 ri.zri_maxinstrs = evalargs->ea_instrlimit; 851 852 lua_pushlightuserdata(state, &ri); 853 lua_setfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY); 854 VERIFY3U(3, ==, lua_gettop(state)); 855 856 /* 857 * Tell the Lua interpreter to call our handler every count 858 * instructions. Channel programs that execute too many instructions 859 * should die with ETIMEDOUT. 860 */ 861 (void) lua_sethook(state, zcp_lua_counthook, LUA_MASKCOUNT, 862 zfs_lua_check_instrlimit_interval); 863 864 /* 865 * Tell the Lua memory allocator to stop using KM_SLEEP before handing 866 * off control to the channel program. Channel programs that use too 867 * much memory should die with ENOSPC. 868 */ 869 evalargs->ea_allocargs->aa_must_succeed = B_FALSE; 870 871 /* 872 * Call the Lua function that open-context passed us. This pops the 873 * function and its input from the stack and pushes any return 874 * or error values. 875 */ 876 err = lua_pcall(state, 1, LUA_MULTRET, 1); 877 878 /* 879 * Let Lua use KM_SLEEP while we interpret the return values. 880 */ 881 evalargs->ea_allocargs->aa_must_succeed = B_TRUE; 882 883 /* 884 * Remove the error handler callback from the stack. At this point, 885 * if there is a cleanup function registered, then it was registered 886 * but never run or removed, which should never occur. 887 */ 888 ASSERT3P(ri.zri_cleanup, ==, NULL); 889 lua_remove(state, 1); 890 891 switch (err) { 892 case LUA_OK: { 893 /* 894 * Lua supports returning multiple values in a single return 895 * statement. Return values will have been pushed onto the 896 * stack: 897 * 1: Return value 1 898 * 2: Return value 2 899 * 3: etc... 900 * To simplify the process of retrieving a return value from a 901 * channel program, we disallow returning more than one value 902 * to ZFS from the Lua script, yielding a singleton return 903 * nvlist of the form { "return": Return value 1 }. 904 */ 905 int return_count = lua_gettop(state); 906 907 if (return_count == 1) { 908 evalargs->ea_result = 0; 909 zcp_convert_return_values(state, evalargs->ea_outnvl, 910 ZCP_RET_RETURN, evalargs); 911 } else if (return_count > 1) { 912 evalargs->ea_result = SET_ERROR(ECHRNG); 913 (void) lua_pushfstring(state, "Multiple return " 914 "values not supported"); 915 zcp_convert_return_values(state, evalargs->ea_outnvl, 916 ZCP_RET_ERROR, evalargs); 917 } 918 break; 919 } 920 case LUA_ERRRUN: 921 case LUA_ERRGCMM: { 922 /* 923 * The channel program encountered a fatal error within the 924 * script, such as failing an assertion, or calling a function 925 * with incompatible arguments. The error value and the 926 * traceback generated by zcp_error_handler() should be on the 927 * stack. 928 */ 929 VERIFY3U(1, ==, lua_gettop(state)); 930 if (ri.zri_timed_out) { 931 evalargs->ea_result = SET_ERROR(ETIME); 932 } else { 933 evalargs->ea_result = SET_ERROR(ECHRNG); 934 } 935 936 zcp_convert_return_values(state, evalargs->ea_outnvl, 937 ZCP_RET_ERROR, evalargs); 938 break; 939 } 940 case LUA_ERRERR: { 941 /* 942 * The channel program encountered a fatal error within the 943 * script, and we encountered another error while trying to 944 * compute the traceback in zcp_error_handler(). We can only 945 * return the error message. 946 */ 947 VERIFY3U(1, ==, lua_gettop(state)); 948 if (ri.zri_timed_out) { 949 evalargs->ea_result = SET_ERROR(ETIME); 950 } else { 951 evalargs->ea_result = SET_ERROR(ECHRNG); 952 } 953 954 zcp_convert_return_values(state, evalargs->ea_outnvl, 955 ZCP_RET_ERROR, evalargs); 956 break; 957 } 958 case LUA_ERRMEM: 959 /* 960 * Lua ran out of memory while running the channel program. 961 * There's not much we can do. 962 */ 963 evalargs->ea_result = SET_ERROR(ENOSPC); 964 break; 965 default: 966 VERIFY0(err); 967 } 968} 969 970int 971zcp_eval(const char *poolname, const char *program, uint64_t instrlimit, 972 uint64_t memlimit, nvpair_t *nvarg, nvlist_t *outnvl) 973{ 974 int err; 975 lua_State *state; 976 zcp_eval_arg_t evalargs; 977 978 if (instrlimit > zfs_lua_max_instrlimit) 979 return (SET_ERROR(EINVAL)); 980 if (memlimit == 0 || memlimit > zfs_lua_max_memlimit) 981 return (SET_ERROR(EINVAL)); 982 983 zcp_alloc_arg_t allocargs = { 984 .aa_must_succeed = B_TRUE, 985 .aa_alloc_remaining = (int64_t)memlimit, 986 .aa_alloc_limit = (int64_t)memlimit, 987 }; 988 989 /* 990 * Creates a Lua state with a memory allocator that uses KM_SLEEP. 991 * This should never fail. 992 */ 993 state = lua_newstate(zcp_lua_alloc, &allocargs); 994 VERIFY(state != NULL); 995 (void) lua_atpanic(state, zcp_panic_cb); 996 997 /* 998 * Load core Lua libraries we want access to. 999 */ 1000 VERIFY3U(1, ==, luaopen_base(state)); 1001 lua_pop(state, 1); 1002 VERIFY3U(1, ==, luaopen_coroutine(state)); 1003 lua_setglobal(state, LUA_COLIBNAME); 1004 VERIFY0(lua_gettop(state)); 1005 VERIFY3U(1, ==, luaopen_string(state)); 1006 lua_setglobal(state, LUA_STRLIBNAME); 1007 VERIFY0(lua_gettop(state)); 1008 VERIFY3U(1, ==, luaopen_table(state)); 1009 lua_setglobal(state, LUA_TABLIBNAME); 1010 VERIFY0(lua_gettop(state)); 1011 1012 /* 1013 * Load globally visible variables such as errno aliases. 1014 */ 1015 zcp_load_globals(state); 1016 VERIFY0(lua_gettop(state)); 1017 1018 /* 1019 * Load ZFS-specific modules. 1020 */ 1021 lua_newtable(state); 1022 VERIFY3U(1, ==, zcp_load_list_lib(state)); 1023 lua_setfield(state, -2, "list"); 1024 VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_FALSE)); 1025 lua_setfield(state, -2, "check"); 1026 VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_TRUE)); 1027 lua_setfield(state, -2, "sync"); 1028 VERIFY3U(1, ==, zcp_load_get_lib(state)); 1029 lua_pushcclosure(state, zcp_debug_info.func, 0); 1030 lua_setfield(state, -2, zcp_debug_info.name); 1031 lua_pushcclosure(state, zcp_exists_info.func, 0); 1032 lua_setfield(state, -2, zcp_exists_info.name); 1033 lua_setglobal(state, "zfs"); 1034 VERIFY0(lua_gettop(state)); 1035 1036 /* 1037 * Push the error-callback that calculates Lua stack traces on 1038 * unexpected failures. 1039 */ 1040 lua_pushcfunction(state, zcp_error_handler); 1041 VERIFY3U(1, ==, lua_gettop(state)); 1042 1043 /* 1044 * Load the actual script as a function onto the stack as text ("t"). 1045 * The only valid error condition is a syntax error in the script. 1046 * ERRMEM should not be possible because our allocator is using 1047 * KM_SLEEP. ERRGCMM should not be possible because we have not added 1048 * any objects with __gc metamethods to the interpreter that could 1049 * fail. 1050 */ 1051 err = luaL_loadbufferx(state, program, strlen(program), 1052 "channel program", "t"); 1053 if (err == LUA_ERRSYNTAX) { 1054 fnvlist_add_string(outnvl, ZCP_RET_ERROR, 1055 lua_tostring(state, -1)); 1056 lua_close(state); 1057 return (SET_ERROR(EINVAL)); 1058 } 1059 VERIFY0(err); 1060 VERIFY3U(2, ==, lua_gettop(state)); 1061 1062 /* 1063 * Convert the input nvlist to a Lua object and put it on top of the 1064 * stack. 1065 */ 1066 char errmsg[128]; 1067 err = zcp_nvpair_value_to_lua(state, nvarg, 1068 errmsg, sizeof (errmsg)); 1069 if (err != 0) { 1070 fnvlist_add_string(outnvl, ZCP_RET_ERROR, errmsg); 1071 lua_close(state); 1072 return (SET_ERROR(EINVAL)); 1073 } 1074 VERIFY3U(3, ==, lua_gettop(state)); 1075 1076 evalargs.ea_state = state; 1077 evalargs.ea_allocargs = &allocargs; 1078 evalargs.ea_instrlimit = instrlimit; 1079 evalargs.ea_cred = CRED(); 1080 evalargs.ea_outnvl = outnvl; 1081 evalargs.ea_result = 0; 1082 1083 VERIFY0(dsl_sync_task(poolname, zcp_eval_check, 1084 zcp_eval_sync, &evalargs, 0, ZFS_SPACE_CHECK_NONE)); 1085 1086 lua_close(state); 1087 1088 return (evalargs.ea_result); 1089} 1090 1091/* 1092 * Retrieve metadata about the currently running channel program. 1093 */ 1094zcp_run_info_t * 1095zcp_run_info(lua_State *state) 1096{ 1097 zcp_run_info_t *ri; 1098 1099 lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY); 1100 ri = lua_touserdata(state, -1); 1101 lua_pop(state, 1); 1102 return (ri); 1103} 1104 1105/* 1106 * Argument Parsing 1107 * ================ 1108 * 1109 * The Lua language allows methods to be called with any number 1110 * of arguments of any type. When calling back into ZFS we need to sanitize 1111 * arguments from channel programs to make sure unexpected arguments or 1112 * arguments of the wrong type result in clear error messages. To do this 1113 * in a uniform way all callbacks from channel programs should use the 1114 * zcp_parse_args() function to interpret inputs. 1115 * 1116 * Positional vs Keyword Arguments 1117 * =============================== 1118 * 1119 * Every callback function takes a fixed set of required positional arguments 1120 * and optional keyword arguments. For example, the destroy function takes 1121 * a single positional string argument (the name of the dataset to destroy) 1122 * and an optional "defer" keyword boolean argument. When calling lua functions 1123 * with parentheses, only positional arguments can be used: 1124 * 1125 * zfs.sync.snapshot("rpool@snap") 1126 * 1127 * To use keyword arguments functions should be called with a single argument 1128 * that is a lua table containing mappings of integer -> positional arguments 1129 * and string -> keyword arguments: 1130 * 1131 * zfs.sync.snapshot({1="rpool@snap", defer=true}) 1132 * 1133 * The lua language allows curly braces to be used in place of parenthesis as 1134 * syntactic sugar for this calling convention: 1135 * 1136 * zfs.sync.snapshot{"rpool@snap", defer=true} 1137 */ 1138 1139/* 1140 * Throw an error and print the given arguments. If there are too many 1141 * arguments to fit in the output buffer, only the error format string is 1142 * output. 1143 */ 1144static void 1145zcp_args_error(lua_State *state, const char *fname, const zcp_arg_t *pargs, 1146 const zcp_arg_t *kwargs, const char *fmt, ...) 1147{ 1148 int i; 1149 char errmsg[512]; 1150 size_t len = sizeof (errmsg); 1151 size_t msglen = 0; 1152 va_list argp; 1153 1154 va_start(argp, fmt); 1155 VERIFY3U(len, >, vsnprintf(errmsg, len, fmt, argp)); 1156 va_end(argp); 1157 1158 /* 1159 * Calculate the total length of the final string, including extra 1160 * formatting characters. If the argument dump would be too large, 1161 * only print the error string. 1162 */ 1163 msglen = strlen(errmsg); 1164 msglen += strlen(fname) + 4; /* : + {} + null terminator */ 1165 for (i = 0; pargs[i].za_name != NULL; i++) { 1166 msglen += strlen(pargs[i].za_name); 1167 msglen += strlen(lua_typename(state, pargs[i].za_lua_type)); 1168 if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL) 1169 msglen += 5; /* < + ( + )> + , */ 1170 else 1171 msglen += 4; /* < + ( + )> */ 1172 } 1173 for (i = 0; kwargs[i].za_name != NULL; i++) { 1174 msglen += strlen(kwargs[i].za_name); 1175 msglen += strlen(lua_typename(state, kwargs[i].za_lua_type)); 1176 if (kwargs[i + 1].za_name != NULL) 1177 msglen += 4; /* =( + ) + , */ 1178 else 1179 msglen += 3; /* =( + ) */ 1180 } 1181 1182 if (msglen >= len) 1183 (void) luaL_error(state, errmsg); 1184 1185 VERIFY3U(len, >, strlcat(errmsg, ": ", len)); 1186 VERIFY3U(len, >, strlcat(errmsg, fname, len)); 1187 VERIFY3U(len, >, strlcat(errmsg, "{", len)); 1188 for (i = 0; pargs[i].za_name != NULL; i++) { 1189 VERIFY3U(len, >, strlcat(errmsg, "<", len)); 1190 VERIFY3U(len, >, strlcat(errmsg, pargs[i].za_name, len)); 1191 VERIFY3U(len, >, strlcat(errmsg, "(", len)); 1192 VERIFY3U(len, >, strlcat(errmsg, 1193 lua_typename(state, pargs[i].za_lua_type), len)); 1194 VERIFY3U(len, >, strlcat(errmsg, ")>", len)); 1195 if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL) { 1196 VERIFY3U(len, >, strlcat(errmsg, ", ", len)); 1197 } 1198 } 1199 for (i = 0; kwargs[i].za_name != NULL; i++) { 1200 VERIFY3U(len, >, strlcat(errmsg, kwargs[i].za_name, len)); 1201 VERIFY3U(len, >, strlcat(errmsg, "=(", len)); 1202 VERIFY3U(len, >, strlcat(errmsg, 1203 lua_typename(state, kwargs[i].za_lua_type), len)); 1204 VERIFY3U(len, >, strlcat(errmsg, ")", len)); 1205 if (kwargs[i + 1].za_name != NULL) { 1206 VERIFY3U(len, >, strlcat(errmsg, ", ", len)); 1207 } 1208 } 1209 VERIFY3U(len, >, strlcat(errmsg, "}", len)); 1210 1211 (void) luaL_error(state, errmsg); 1212 panic("unreachable code"); 1213} 1214 1215static void 1216zcp_parse_table_args(lua_State *state, const char *fname, 1217 const zcp_arg_t *pargs, const zcp_arg_t *kwargs) 1218{ 1219 int i; 1220 int type; 1221 1222 for (i = 0; pargs[i].za_name != NULL; i++) { 1223 /* 1224 * Check the table for this positional argument, leaving it 1225 * on the top of the stack once we finish validating it. 1226 */ 1227 lua_pushinteger(state, i + 1); 1228 lua_gettable(state, 1); 1229 1230 type = lua_type(state, -1); 1231 if (type == LUA_TNIL) { 1232 zcp_args_error(state, fname, pargs, kwargs, 1233 "too few arguments"); 1234 panic("unreachable code"); 1235 } else if (type != pargs[i].za_lua_type) { 1236 zcp_args_error(state, fname, pargs, kwargs, 1237 "arg %d wrong type (is '%s', expected '%s')", 1238 i + 1, lua_typename(state, type), 1239 lua_typename(state, pargs[i].za_lua_type)); 1240 panic("unreachable code"); 1241 } 1242 1243 /* 1244 * Remove the positional argument from the table. 1245 */ 1246 lua_pushinteger(state, i + 1); 1247 lua_pushnil(state); 1248 lua_settable(state, 1); 1249 } 1250 1251 for (i = 0; kwargs[i].za_name != NULL; i++) { 1252 /* 1253 * Check the table for this keyword argument, which may be 1254 * nil if it was omitted. Leave the value on the top of 1255 * the stack after validating it. 1256 */ 1257 lua_getfield(state, 1, kwargs[i].za_name); 1258 1259 type = lua_type(state, -1); 1260 if (type != LUA_TNIL && type != kwargs[i].za_lua_type) { 1261 zcp_args_error(state, fname, pargs, kwargs, 1262 "kwarg '%s' wrong type (is '%s', expected '%s')", 1263 kwargs[i].za_name, lua_typename(state, type), 1264 lua_typename(state, kwargs[i].za_lua_type)); 1265 panic("unreachable code"); 1266 } 1267 1268 /* 1269 * Remove the keyword argument from the table. 1270 */ 1271 lua_pushnil(state); 1272 lua_setfield(state, 1, kwargs[i].za_name); 1273 } 1274 1275 /* 1276 * Any entries remaining in the table are invalid inputs, print 1277 * an error message based on what the entry is. 1278 */ 1279 lua_pushnil(state); 1280 if (lua_next(state, 1)) { 1281 if (lua_isnumber(state, -2) && lua_tointeger(state, -2) > 0) { 1282 zcp_args_error(state, fname, pargs, kwargs, 1283 "too many positional arguments"); 1284 } else if (lua_isstring(state, -2)) { 1285 zcp_args_error(state, fname, pargs, kwargs, 1286 "invalid kwarg '%s'", lua_tostring(state, -2)); 1287 } else { 1288 zcp_args_error(state, fname, pargs, kwargs, 1289 "kwarg keys must be strings"); 1290 } 1291 panic("unreachable code"); 1292 } 1293 1294 lua_remove(state, 1); 1295} 1296 1297static void 1298zcp_parse_pos_args(lua_State *state, const char *fname, const zcp_arg_t *pargs, 1299 const zcp_arg_t *kwargs) 1300{ 1301 int i; 1302 int type; 1303 1304 for (i = 0; pargs[i].za_name != NULL; i++) { 1305 type = lua_type(state, i + 1); 1306 if (type == LUA_TNONE) { 1307 zcp_args_error(state, fname, pargs, kwargs, 1308 "too few arguments"); 1309 panic("unreachable code"); 1310 } else if (type != pargs[i].za_lua_type) { 1311 zcp_args_error(state, fname, pargs, kwargs, 1312 "arg %d wrong type (is '%s', expected '%s')", 1313 i + 1, lua_typename(state, type), 1314 lua_typename(state, pargs[i].za_lua_type)); 1315 panic("unreachable code"); 1316 } 1317 } 1318 if (lua_gettop(state) != i) { 1319 zcp_args_error(state, fname, pargs, kwargs, 1320 "too many positional arguments"); 1321 panic("unreachable code"); 1322 } 1323 1324 for (i = 0; kwargs[i].za_name != NULL; i++) { 1325 lua_pushnil(state); 1326 } 1327} 1328 1329/* 1330 * Checks the current Lua stack against an expected set of positional and 1331 * keyword arguments. If the stack does not match the expected arguments 1332 * aborts the current channel program with a useful error message, otherwise 1333 * it re-arranges the stack so that it contains the positional arguments 1334 * followed by the keyword argument values in declaration order. Any missing 1335 * keyword argument will be represented by a nil value on the stack. 1336 * 1337 * If the stack contains exactly one argument of type LUA_TTABLE the curly 1338 * braces calling convention is assumed, otherwise the stack is parsed for 1339 * positional arguments only. 1340 * 1341 * This function should be used by every function callback. It should be called 1342 * before the callback manipulates the Lua stack as it assumes the stack 1343 * represents the function arguments. 1344 */ 1345void 1346zcp_parse_args(lua_State *state, const char *fname, const zcp_arg_t *pargs, 1347 const zcp_arg_t *kwargs) 1348{ 1349 if (lua_gettop(state) == 1 && lua_istable(state, 1)) { 1350 zcp_parse_table_args(state, fname, pargs, kwargs); 1351 } else { 1352 zcp_parse_pos_args(state, fname, pargs, kwargs); 1353 } 1354} 1355