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, 2017 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 #include <util/sscanf.h>
104
105 #define ZCP_NVLIST_MAX_DEPTH 20
106
107 uint64_t zfs_lua_check_instrlimit_interval = 100;
108 uint64_t zfs_lua_max_instrlimit = ZCP_MAX_INSTRLIMIT;
109 uint64_t zfs_lua_max_memlimit = ZCP_MAX_MEMLIMIT;
110
111 /*
112 * Forward declarations for mutually recursive functions
113 */
114 static int zcp_nvpair_value_to_lua(lua_State *, nvpair_t *, char *, int);
115 static int zcp_lua_to_nvlist_impl(lua_State *, int, nvlist_t *, const char *,
116 int);
117
118 /*
119 * The outer-most error callback handler for use with lua_pcall(). On
120 * error Lua will call this callback with a single argument that
121 * represents the error value. In most cases this will be a string
122 * containing an error message, but channel programs can use Lua's
123 * error() function to return arbitrary objects as errors. This callback
124 * returns (on the Lua stack) the original error object along with a traceback.
125 *
126 * Fatal Lua errors can occur while resources are held, so we also call any
127 * registered cleanup function here.
128 */
129 static int
130 zcp_error_handler(lua_State *state)
131 {
132 const char *msg;
133
134 zcp_cleanup(state);
135
136 VERIFY3U(1, ==, lua_gettop(state));
137 msg = lua_tostring(state, 1);
138 luaL_traceback(state, state, msg, 1);
139 return (1);
140 }
141
142 int
143 zcp_argerror(lua_State *state, int narg, const char *msg, ...)
144 {
145 va_list alist;
146
147 va_start(alist, msg);
148 const char *buf = lua_pushvfstring(state, msg, alist);
149 va_end(alist);
150
151 return (luaL_argerror(state, narg, buf));
152 }
153
154 /*
155 * Install a new cleanup function, which will be invoked with the given
156 * opaque argument if a fatal error causes the Lua interpreter to longjump out
157 * of a function call.
158 *
159 * If an error occurs, the cleanup function will be invoked exactly once and
160 * then unreigstered.
161 *
162 * Returns the registered cleanup handler so the caller can deregister it
163 * if no error occurs.
164 */
165 zcp_cleanup_handler_t *
166 zcp_register_cleanup(lua_State *state, zcp_cleanup_t cleanfunc, void *cleanarg)
167 {
168 zcp_run_info_t *ri = zcp_run_info(state);
169
170 zcp_cleanup_handler_t *zch = kmem_alloc(sizeof (*zch), KM_SLEEP);
171 zch->zch_cleanup_func = cleanfunc;
172 zch->zch_cleanup_arg = cleanarg;
173 list_insert_head(&ri->zri_cleanup_handlers, zch);
174
175 return (zch);
176 }
177
178 void
179 zcp_deregister_cleanup(lua_State *state, zcp_cleanup_handler_t *zch)
180 {
181 zcp_run_info_t *ri = zcp_run_info(state);
182 list_remove(&ri->zri_cleanup_handlers, zch);
183 kmem_free(zch, sizeof (*zch));
184 }
185
186 /*
187 * Execute the currently registered cleanup handlers then free them and
188 * destroy the handler list.
189 */
190 void
191 zcp_cleanup(lua_State *state)
192 {
193 zcp_run_info_t *ri = zcp_run_info(state);
194
195 for (zcp_cleanup_handler_t *zch =
196 list_remove_head(&ri->zri_cleanup_handlers); zch != NULL;
197 zch = list_remove_head(&ri->zri_cleanup_handlers)) {
198 zch->zch_cleanup_func(zch->zch_cleanup_arg);
199 kmem_free(zch, sizeof (*zch));
200 }
201 }
202
203 /*
204 * Convert the lua table at the given index on the Lua stack to an nvlist
205 * and return it.
206 *
207 * If the table can not be converted for any reason, NULL is returned and
208 * an error message is pushed onto the Lua stack.
209 */
210 static nvlist_t *
211 zcp_table_to_nvlist(lua_State *state, int index, int depth)
212 {
213 nvlist_t *nvl;
214 /*
215 * Converting a Lua table to an nvlist with key uniqueness checking is
216 * O(n^2) in the number of keys in the nvlist, which can take a long
217 * time when we return a large table from a channel program.
218 * Furthermore, Lua's table interface *almost* guarantees unique keys
219 * on its own (details below). Therefore, we don't use fnvlist_alloc()
220 * here to avoid the built-in uniqueness checking.
221 *
222 * The *almost* is because it's possible to have key collisions between
223 * e.g. the string "1" and the number 1, or the string "true" and the
224 * boolean true, so we explicitly check that when we're looking at a
225 * key which is an integer / boolean or a string that can be parsed as
226 * one of those types. In the worst case this could still devolve into
227 * O(n^2), so we only start doing these checks on boolean/integer keys
228 * once we've seen a string key which fits this weird usage pattern.
229 *
230 * Ultimately, we still want callers to know that the keys in this
231 * nvlist are unique, so before we return this we set the nvlist's
232 * flags to reflect that.
233 */
234 VERIFY0(nvlist_alloc(&nvl, 0, KM_SLEEP));
235
236 /*
237 * Push an empty stack slot where lua_next() will store each
238 * table key.
239 */
240 lua_pushnil(state);
241 boolean_t saw_str_could_collide = B_FALSE;
242 while (lua_next(state, index) != 0) {
243 /*
244 * The next key-value pair from the table at index is
245 * now on the stack, with the key at stack slot -2 and
246 * the value at slot -1.
247 */
248 int err = 0;
249 char buf[32];
250 const char *key = NULL;
251 boolean_t key_could_collide = B_FALSE;
252
253 switch (lua_type(state, -2)) {
254 case LUA_TSTRING:
255 key = lua_tostring(state, -2);
256
257 /* check if this could collide with a number or bool */
258 long long tmp;
259 int parselen;
260 if ((sscanf(key, "%lld%n", &tmp, &parselen) > 0 &&
261 parselen == strlen(key)) ||
262 strcmp(key, "true") == 0 ||
263 strcmp(key, "false") == 0) {
264 key_could_collide = B_TRUE;
265 saw_str_could_collide = B_TRUE;
266 }
267 break;
268 case LUA_TBOOLEAN:
269 key = (lua_toboolean(state, -2) == B_TRUE ?
270 "true" : "false");
271 if (saw_str_could_collide) {
272 key_could_collide = B_TRUE;
273 }
274 break;
275 case LUA_TNUMBER:
276 VERIFY3U(sizeof (buf), >,
277 snprintf(buf, sizeof (buf), "%lld",
278 (longlong_t)lua_tonumber(state, -2)));
279 key = buf;
280 if (saw_str_could_collide) {
281 key_could_collide = B_TRUE;
282 }
283 break;
284 default:
285 fnvlist_free(nvl);
286 (void) lua_pushfstring(state, "Invalid key "
287 "type '%s' in table",
288 lua_typename(state, lua_type(state, -2)));
289 return (NULL);
290 }
291 /*
292 * Check for type-mismatched key collisions, and throw an error.
293 */
294 if (key_could_collide && nvlist_exists(nvl, key)) {
295 fnvlist_free(nvl);
296 (void) lua_pushfstring(state, "Collision of "
297 "key '%s' in table", key);
298 return (NULL);
299 }
300 /*
301 * Recursively convert the table value and insert into
302 * the new nvlist with the parsed key. To prevent
303 * stack overflow on circular or heavily nested tables,
304 * we track the current nvlist depth.
305 */
306 if (depth >= ZCP_NVLIST_MAX_DEPTH) {
307 fnvlist_free(nvl);
308 (void) lua_pushfstring(state, "Maximum table "
309 "depth (%d) exceeded for table",
310 ZCP_NVLIST_MAX_DEPTH);
311 return (NULL);
312 }
313 err = zcp_lua_to_nvlist_impl(state, -1, nvl, key,
314 depth + 1);
315 if (err != 0) {
316 fnvlist_free(nvl);
317 /*
318 * Error message has been pushed to the lua
319 * stack by the recursive call.
320 */
321 return (NULL);
322 }
323 /*
324 * Pop the value pushed by lua_next().
325 */
326 lua_pop(state, 1);
327 }
328
329 /*
330 * Mark the nvlist as having unique keys. This is a little ugly, but we
331 * ensured above that there are no duplicate keys in the nvlist.
332 */
333 nvl->nvl_nvflag |= NV_UNIQUE_NAME;
334
335 return (nvl);
336 }
337
338 /*
339 * Convert a value from the given index into the lua stack to an nvpair, adding
340 * it to an nvlist with the given key.
341 *
342 * Values are converted as follows:
343 *
344 * string -> string
345 * number -> int64
346 * boolean -> boolean
347 * nil -> boolean (no value)
348 *
349 * Lua tables are converted to nvlists and then inserted. The table's keys
350 * are converted to strings then used as keys in the nvlist to store each table
351 * element. Keys are converted as follows:
352 *
353 * string -> no change
354 * number -> "%lld"
355 * boolean -> "true" | "false"
356 * nil -> error
357 *
358 * In the case of a key collision, an error is thrown.
359 *
360 * If an error is encountered, a nonzero error code is returned, and an error
361 * string will be pushed onto the Lua stack.
362 */
363 static int
364 zcp_lua_to_nvlist_impl(lua_State *state, int index, nvlist_t *nvl,
365 const char *key, int depth)
366 {
367 /*
368 * Verify that we have enough remaining space in the lua stack to parse
369 * a key-value pair and push an error.
370 */
371 if (!lua_checkstack(state, 3)) {
372 (void) lua_pushstring(state, "Lua stack overflow");
373 return (1);
374 }
375
376 index = lua_absindex(state, index);
377
378 switch (lua_type(state, index)) {
379 case LUA_TNIL:
380 fnvlist_add_boolean(nvl, key);
381 break;
382 case LUA_TBOOLEAN:
383 fnvlist_add_boolean_value(nvl, key,
384 lua_toboolean(state, index));
385 break;
386 case LUA_TNUMBER:
387 fnvlist_add_int64(nvl, key, lua_tonumber(state, index));
388 break;
389 case LUA_TSTRING:
390 fnvlist_add_string(nvl, key, lua_tostring(state, index));
391 break;
392 case LUA_TTABLE: {
393 nvlist_t *value_nvl = zcp_table_to_nvlist(state, index, depth);
394 if (value_nvl == NULL)
395 return (EINVAL);
396
397 fnvlist_add_nvlist(nvl, key, value_nvl);
398 fnvlist_free(value_nvl);
399 break;
400 }
401 default:
402 (void) lua_pushfstring(state,
403 "Invalid value type '%s' for key '%s'",
404 lua_typename(state, lua_type(state, index)), key);
405 return (EINVAL);
406 }
407
408 return (0);
409 }
410
411 /*
412 * Convert a lua value to an nvpair, adding it to an nvlist with the given key.
413 */
414 static void
415 zcp_lua_to_nvlist(lua_State *state, int index, nvlist_t *nvl, const char *key)
416 {
417 /*
418 * On error, zcp_lua_to_nvlist_impl pushes an error string onto the Lua
419 * stack before returning with a nonzero error code. If an error is
420 * returned, throw a fatal lua error with the given string.
421 */
422 if (zcp_lua_to_nvlist_impl(state, index, nvl, key, 0) != 0)
423 (void) lua_error(state);
424 }
425
426 static int
427 zcp_lua_to_nvlist_helper(lua_State *state)
428 {
429 nvlist_t *nv = (nvlist_t *)lua_touserdata(state, 2);
430 const char *key = (const char *)lua_touserdata(state, 1);
431 zcp_lua_to_nvlist(state, 3, nv, key);
432 return (0);
433 }
434
435 static void
436 zcp_convert_return_values(lua_State *state, nvlist_t *nvl,
437 const char *key, int *result)
438 {
439 int err;
440 VERIFY3U(1, ==, lua_gettop(state));
441 lua_pushcfunction(state, zcp_lua_to_nvlist_helper);
442 lua_pushlightuserdata(state, (char *)key);
443 lua_pushlightuserdata(state, nvl);
444 lua_pushvalue(state, 1);
445 lua_remove(state, 1);
446 err = lua_pcall(state, 3, 0, 0); /* zcp_lua_to_nvlist_helper */
447 if (err != 0) {
448 zcp_lua_to_nvlist(state, 1, nvl, ZCP_RET_ERROR);
449 *result = SET_ERROR(ECHRNG);
450 }
451 }
452
453 /*
454 * Push a Lua table representing nvl onto the stack. If it can't be
455 * converted, return EINVAL, fill in errbuf, and push nothing. errbuf may
456 * be specified as NULL, in which case no error string will be output.
457 *
458 * Most nvlists are converted as simple key->value Lua tables, but we make
459 * an exception for the case where all nvlist entries are BOOLEANs (a string
460 * key without a value). In Lua, a table key pointing to a value of Nil
461 * (no value) is equivalent to the key not existing, so a BOOLEAN nvlist
462 * entry can't be directly converted to a Lua table entry. Nvlists of entirely
463 * BOOLEAN entries are frequently used to pass around lists of datasets, so for
464 * convenience we check for this case, and convert it to a simple Lua array of
465 * strings.
466 */
467 int
468 zcp_nvlist_to_lua(lua_State *state, nvlist_t *nvl,
469 char *errbuf, int errbuf_len)
470 {
471 nvpair_t *pair;
472 lua_newtable(state);
473 boolean_t has_values = B_FALSE;
474 /*
475 * If the list doesn't have any values, just convert it to a string
476 * array.
477 */
478 for (pair = nvlist_next_nvpair(nvl, NULL);
479 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) {
480 if (nvpair_type(pair) != DATA_TYPE_BOOLEAN) {
481 has_values = B_TRUE;
482 break;
483 }
484 }
485 if (!has_values) {
486 int i = 1;
487 for (pair = nvlist_next_nvpair(nvl, NULL);
488 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) {
489 (void) lua_pushinteger(state, i);
490 (void) lua_pushstring(state, nvpair_name(pair));
491 (void) lua_settable(state, -3);
492 i++;
493 }
494 } else {
495 for (pair = nvlist_next_nvpair(nvl, NULL);
496 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) {
497 int err = zcp_nvpair_value_to_lua(state, pair,
498 errbuf, errbuf_len);
499 if (err != 0) {
500 lua_pop(state, 1);
501 return (err);
502 }
503 (void) lua_setfield(state, -2, nvpair_name(pair));
504 }
505 }
506 return (0);
507 }
508
509 /*
510 * Push a Lua object representing the value of "pair" onto the stack.
511 *
512 * Only understands boolean_value, string, int64, nvlist,
513 * string_array, and int64_array type values. For other
514 * types, returns EINVAL, fills in errbuf, and pushes nothing.
515 */
516 static int
517 zcp_nvpair_value_to_lua(lua_State *state, nvpair_t *pair,
518 char *errbuf, int errbuf_len)
519 {
520 int err = 0;
521
522 if (pair == NULL) {
523 lua_pushnil(state);
524 return (0);
525 }
526
527 switch (nvpair_type(pair)) {
528 case DATA_TYPE_BOOLEAN_VALUE:
529 (void) lua_pushboolean(state,
530 fnvpair_value_boolean_value(pair));
531 break;
532 case DATA_TYPE_STRING:
533 (void) lua_pushstring(state, fnvpair_value_string(pair));
534 break;
535 case DATA_TYPE_INT64:
536 (void) lua_pushinteger(state, fnvpair_value_int64(pair));
537 break;
538 case DATA_TYPE_NVLIST:
539 err = zcp_nvlist_to_lua(state,
540 fnvpair_value_nvlist(pair), errbuf, errbuf_len);
541 break;
542 case DATA_TYPE_STRING_ARRAY: {
543 char **strarr;
544 uint_t nelem;
545 (void) nvpair_value_string_array(pair, &strarr, &nelem);
546 lua_newtable(state);
547 for (int i = 0; i < nelem; i++) {
548 (void) lua_pushinteger(state, i + 1);
549 (void) lua_pushstring(state, strarr[i]);
550 (void) lua_settable(state, -3);
551 }
552 break;
553 }
554 case DATA_TYPE_UINT64_ARRAY: {
555 uint64_t *intarr;
556 uint_t nelem;
557 (void) nvpair_value_uint64_array(pair, &intarr, &nelem);
558 lua_newtable(state);
559 for (int i = 0; i < nelem; i++) {
560 (void) lua_pushinteger(state, i + 1);
561 (void) lua_pushinteger(state, intarr[i]);
562 (void) lua_settable(state, -3);
563 }
564 break;
565 }
566 case DATA_TYPE_INT64_ARRAY: {
567 int64_t *intarr;
568 uint_t nelem;
569 (void) nvpair_value_int64_array(pair, &intarr, &nelem);
570 lua_newtable(state);
571 for (int i = 0; i < nelem; i++) {
572 (void) lua_pushinteger(state, i + 1);
573 (void) lua_pushinteger(state, intarr[i]);
574 (void) lua_settable(state, -3);
575 }
576 break;
577 }
578 default: {
579 if (errbuf != NULL) {
580 (void) snprintf(errbuf, errbuf_len,
581 "Unhandled nvpair type %d for key '%s'",
582 nvpair_type(pair), nvpair_name(pair));
583 }
584 return (EINVAL);
585 }
586 }
587 return (err);
588 }
589
590 int
591 zcp_dataset_hold_error(lua_State *state, dsl_pool_t *dp, const char *dsname,
592 int error)
593 {
594 if (error == ENOENT) {
595 (void) zcp_argerror(state, 1, "no such dataset '%s'", dsname);
596 return (0); /* not reached; zcp_argerror will longjmp */
597 } else if (error == EXDEV) {
598 (void) zcp_argerror(state, 1,
599 "dataset '%s' is not in the target pool '%s'",
600 dsname, spa_name(dp->dp_spa));
601 return (0); /* not reached; zcp_argerror will longjmp */
602 } else if (error == EIO) {
603 (void) luaL_error(state,
604 "I/O error while accessing dataset '%s'", dsname);
605 return (0); /* not reached; luaL_error will longjmp */
606 } else if (error != 0) {
607 (void) luaL_error(state,
608 "unexpected error %d while accessing dataset '%s'",
609 error, dsname);
610 return (0); /* not reached; luaL_error will longjmp */
611 }
612 return (0);
613 }
614
615 /*
616 * Note: will longjmp (via lua_error()) on error.
617 * Assumes that the dsname is argument #1 (for error reporting purposes).
618 */
619 dsl_dataset_t *
620 zcp_dataset_hold(lua_State *state, dsl_pool_t *dp, const char *dsname,
621 void *tag)
622 {
623 dsl_dataset_t *ds;
624 int error = dsl_dataset_hold(dp, dsname, tag, &ds);
625 (void) zcp_dataset_hold_error(state, dp, dsname, error);
626 return (ds);
627 }
628
629 static int zcp_debug(lua_State *);
630 static zcp_lib_info_t zcp_debug_info = {
631 .name = "debug",
632 .func = zcp_debug,
633 .pargs = {
634 { .za_name = "debug string", .za_lua_type = LUA_TSTRING},
635 {NULL, 0}
636 },
637 .kwargs = {
638 {NULL, 0}
639 }
640 };
641
642 static int
643 zcp_debug(lua_State *state)
644 {
645 const char *dbgstring;
646 zcp_run_info_t *ri = zcp_run_info(state);
647 zcp_lib_info_t *libinfo = &zcp_debug_info;
648
649 zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs);
650
651 dbgstring = lua_tostring(state, 1);
652
653 zfs_dbgmsg("txg %lld ZCP: %s", ri->zri_tx->tx_txg, dbgstring);
654
655 return (0);
656 }
657
658 static int zcp_exists(lua_State *);
659 static zcp_lib_info_t zcp_exists_info = {
660 .name = "exists",
661 .func = zcp_exists,
662 .pargs = {
663 { .za_name = "dataset", .za_lua_type = LUA_TSTRING},
664 {NULL, 0}
665 },
666 .kwargs = {
667 {NULL, 0}
668 }
669 };
670
671 static int
672 zcp_exists(lua_State *state)
673 {
674 zcp_run_info_t *ri = zcp_run_info(state);
675 dsl_pool_t *dp = ri->zri_pool;
676 zcp_lib_info_t *libinfo = &zcp_exists_info;
677
678 zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs);
679
680 const char *dsname = lua_tostring(state, 1);
681
682 dsl_dataset_t *ds;
683 int error = dsl_dataset_hold(dp, dsname, FTAG, &ds);
684 if (error == 0) {
685 dsl_dataset_rele(ds, FTAG);
686 lua_pushboolean(state, B_TRUE);
687 } else if (error == ENOENT) {
688 lua_pushboolean(state, B_FALSE);
689 } else if (error == EXDEV) {
690 return (luaL_error(state, "dataset '%s' is not in the "
691 "target pool", dsname));
692 } else if (error == EIO) {
693 return (luaL_error(state, "I/O error opening dataset '%s'",
694 dsname));
695 } else if (error != 0) {
696 return (luaL_error(state, "unexpected error %d", error));
697 }
698
699 return (1);
700 }
701
702 /*
703 * Allocate/realloc/free a buffer for the lua interpreter.
704 *
705 * When nsize is 0, behaves as free() and returns NULL.
706 *
707 * If ptr is NULL, behaves as malloc() and returns an allocated buffer of size
708 * at least nsize.
709 *
710 * Otherwise, behaves as realloc(), changing the allocation from osize to nsize.
711 * Shrinking the buffer size never fails.
712 *
713 * The original allocated buffer size is stored as a uint64 at the beginning of
714 * the buffer to avoid actually reallocating when shrinking a buffer, since lua
715 * requires that this operation never fail.
716 */
717 static void *
718 zcp_lua_alloc(void *ud, void *ptr, size_t osize, size_t nsize)
719 {
720 zcp_alloc_arg_t *allocargs = ud;
721 int flags = (allocargs->aa_must_succeed) ? KM_SLEEP : KM_NOSLEEP_LAZY;
722
723 if (nsize == 0) {
724 if (ptr != NULL) {
725 int64_t *allocbuf = (int64_t *)ptr - 1;
726 int64_t allocsize = *allocbuf;
727 ASSERT3S(allocsize, >, 0);
728 ASSERT3S(allocargs->aa_alloc_remaining + allocsize, <=,
729 allocargs->aa_alloc_limit);
730 allocargs->aa_alloc_remaining += allocsize;
731 kmem_free(allocbuf, allocsize);
732 }
733 return (NULL);
734 } else if (ptr == NULL) {
735 int64_t *allocbuf;
736 int64_t allocsize = nsize + sizeof (int64_t);
737
738 if (!allocargs->aa_must_succeed &&
739 (allocsize <= 0 ||
740 allocsize > allocargs->aa_alloc_remaining)) {
741 return (NULL);
742 }
743
744 allocbuf = kmem_alloc(allocsize, flags);
745 if (allocbuf == NULL) {
746 return (NULL);
747 }
748 allocargs->aa_alloc_remaining -= allocsize;
749
750 *allocbuf = allocsize;
751 return (allocbuf + 1);
752 } else if (nsize <= osize) {
753 /*
754 * If shrinking the buffer, lua requires that the reallocation
755 * never fail.
756 */
757 return (ptr);
758 } else {
759 ASSERT3U(nsize, >, osize);
760
761 uint64_t *luabuf = zcp_lua_alloc(ud, NULL, 0, nsize);
762 if (luabuf == NULL) {
763 return (NULL);
764 }
765 (void) memcpy(luabuf, ptr, osize);
766 VERIFY3P(zcp_lua_alloc(ud, ptr, osize, 0), ==, NULL);
767 return (luabuf);
768 }
769 }
770
771 /* ARGSUSED */
772 static void
773 zcp_lua_counthook(lua_State *state, lua_Debug *ar)
774 {
775 lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);
776 zcp_run_info_t *ri = lua_touserdata(state, -1);
777
778 /*
779 * Check if we were canceled while waiting for the
780 * txg to sync or from our open context thread
781 */
782 if (ri->zri_canceled ||
783 (!ri->zri_sync && issig(JUSTLOOKING) && issig(FORREAL))) {
784 ri->zri_canceled = B_TRUE;
785 (void) lua_pushstring(state, "Channel program was canceled.");
786 (void) lua_error(state);
787 }
788
789 /*
790 * Check how many instructions the channel program has
791 * executed so far, and compare against the limit.
792 */
793 ri->zri_curinstrs += zfs_lua_check_instrlimit_interval;
794 if (ri->zri_maxinstrs != 0 && ri->zri_curinstrs > ri->zri_maxinstrs) {
795 ri->zri_timed_out = B_TRUE;
796 (void) lua_pushstring(state,
797 "Channel program timed out.");
798 (void) lua_error(state);
799 }
800 }
801
802 static int
803 zcp_panic_cb(lua_State *state)
804 {
805 panic("unprotected error in call to Lua API (%s)\n",
806 lua_tostring(state, -1));
807 return (0);
808 }
809
810 static void
811 zcp_eval_impl(dmu_tx_t *tx, zcp_run_info_t *ri)
812 {
813 int err;
814 lua_State *state = ri->zri_state;
815
816 VERIFY3U(3, ==, lua_gettop(state));
817
818 /* finish initializing our runtime state */
819 ri->zri_pool = dmu_tx_pool(tx);
820 ri->zri_tx = tx;
821 list_create(&ri->zri_cleanup_handlers, sizeof (zcp_cleanup_handler_t),
822 offsetof(zcp_cleanup_handler_t, zch_node));
823
824 /*
825 * Store the zcp_run_info_t struct for this run in the Lua registry.
826 * Registry entries are not directly accessible by the Lua scripts but
827 * can be accessed by our callbacks.
828 */
829 lua_pushlightuserdata(state, ri);
830 lua_setfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);
831 VERIFY3U(3, ==, lua_gettop(state));
832
833 /*
834 * Tell the Lua interpreter to call our handler every count
835 * instructions. Channel programs that execute too many instructions
836 * should die with ETIME.
837 */
838 (void) lua_sethook(state, zcp_lua_counthook, LUA_MASKCOUNT,
839 zfs_lua_check_instrlimit_interval);
840
841 /*
842 * Tell the Lua memory allocator to stop using KM_SLEEP before handing
843 * off control to the channel program. Channel programs that use too
844 * much memory should die with ENOSPC.
845 */
846 ri->zri_allocargs->aa_must_succeed = B_FALSE;
847
848 /*
849 * Call the Lua function that open-context passed us. This pops the
850 * function and its input from the stack and pushes any return
851 * or error values.
852 */
853 err = lua_pcall(state, 1, LUA_MULTRET, 1);
854
855 /*
856 * Let Lua use KM_SLEEP while we interpret the return values.
857 */
858 ri->zri_allocargs->aa_must_succeed = B_TRUE;
859
860 /*
861 * Remove the error handler callback from the stack. At this point,
862 * there shouldn't be any cleanup handler registered in the handler
863 * list (zri_cleanup_handlers), regardless of whether it ran or not.
864 */
865 list_destroy(&ri->zri_cleanup_handlers);
866 lua_remove(state, 1);
867
868 switch (err) {
869 case LUA_OK: {
870 /*
871 * Lua supports returning multiple values in a single return
872 * statement. Return values will have been pushed onto the
873 * stack:
874 * 1: Return value 1
875 * 2: Return value 2
876 * 3: etc...
877 * To simplify the process of retrieving a return value from a
878 * channel program, we disallow returning more than one value
879 * to ZFS from the Lua script, yielding a singleton return
880 * nvlist of the form { "return": Return value 1 }.
881 */
882 int return_count = lua_gettop(state);
883
884 if (return_count == 1) {
885 ri->zri_result = 0;
886 zcp_convert_return_values(state, ri->zri_outnvl,
887 ZCP_RET_RETURN, &ri->zri_result);
888 } else if (return_count > 1) {
889 ri->zri_result = SET_ERROR(ECHRNG);
890 lua_settop(state, 0);
891 (void) lua_pushfstring(state, "Multiple return "
892 "values not supported");
893 zcp_convert_return_values(state, ri->zri_outnvl,
894 ZCP_RET_ERROR, &ri->zri_result);
895 }
896 break;
897 }
898 case LUA_ERRRUN:
899 case LUA_ERRGCMM: {
900 /*
901 * The channel program encountered a fatal error within the
902 * script, such as failing an assertion, or calling a function
903 * with incompatible arguments. The error value and the
904 * traceback generated by zcp_error_handler() should be on the
905 * stack.
906 */
907 VERIFY3U(1, ==, lua_gettop(state));
908 if (ri->zri_timed_out) {
909 ri->zri_result = SET_ERROR(ETIME);
910 } else if (ri->zri_canceled) {
911 ri->zri_result = SET_ERROR(EINTR);
912 } else {
913 ri->zri_result = SET_ERROR(ECHRNG);
914 }
915
916 zcp_convert_return_values(state, ri->zri_outnvl,
917 ZCP_RET_ERROR, &ri->zri_result);
918 break;
919 }
920 case LUA_ERRERR: {
921 /*
922 * The channel program encountered a fatal error within the
923 * script, and we encountered another error while trying to
924 * compute the traceback in zcp_error_handler(). We can only
925 * return the error message.
926 */
927 VERIFY3U(1, ==, lua_gettop(state));
928 if (ri->zri_timed_out) {
929 ri->zri_result = SET_ERROR(ETIME);
930 } else if (ri->zri_canceled) {
931 ri->zri_result = SET_ERROR(EINTR);
932 } else {
933 ri->zri_result = SET_ERROR(ECHRNG);
934 }
935
936 zcp_convert_return_values(state, ri->zri_outnvl,
937 ZCP_RET_ERROR, &ri->zri_result);
938 break;
939 }
940 case LUA_ERRMEM:
941 /*
942 * Lua ran out of memory while running the channel program.
943 * There's not much we can do.
944 */
945 ri->zri_result = SET_ERROR(ENOSPC);
946 break;
947 default:
948 VERIFY0(err);
949 }
950 }
951
952 static void
953 zcp_pool_error(zcp_run_info_t *ri, const char *poolname)
954 {
955 ri->zri_result = SET_ERROR(ECHRNG);
956 lua_settop(ri->zri_state, 0);
957 (void) lua_pushfstring(ri->zri_state, "Could not open pool: %s",
958 poolname);
959 zcp_convert_return_values(ri->zri_state, ri->zri_outnvl,
960 ZCP_RET_ERROR, &ri->zri_result);
961
962 }
963
964 /*
965 * This callback is called when txg_wait_synced_sig encountered a signal.
966 * The txg_wait_synced_sig will continue to wait for the txg to complete
967 * after calling this callback.
968 */
969 /* ARGSUSED */
970 static void
971 zcp_eval_sig(void *arg, dmu_tx_t *tx)
972 {
973 zcp_run_info_t *ri = arg;
974
975 ri->zri_canceled = B_TRUE;
976 }
977
978 static void
979 zcp_eval_sync(void *arg, dmu_tx_t *tx)
980 {
981 zcp_run_info_t *ri = arg;
982
983 /*
984 * Open context should have setup the stack to contain:
985 * 1: Error handler callback
986 * 2: Script to run (converted to a Lua function)
987 * 3: nvlist input to function (converted to Lua table or nil)
988 */
989 VERIFY3U(3, ==, lua_gettop(ri->zri_state));
990
991 zcp_eval_impl(tx, ri);
992 }
993
994 static void
995 zcp_eval_open(zcp_run_info_t *ri, const char *poolname)
996 {
997 int error;
998 dsl_pool_t *dp;
999 dmu_tx_t *tx;
1000
1001 /*
1002 * See comment from the same assertion in zcp_eval_sync().
1003 */
1004 VERIFY3U(3, ==, lua_gettop(ri->zri_state));
1005
1006 error = dsl_pool_hold(poolname, FTAG, &dp);
1007 if (error != 0) {
1008 zcp_pool_error(ri, poolname);
1009 return;
1010 }
1011
1012 /*
1013 * As we are running in open-context, we have no transaction associated
1014 * with the channel program. At the same time, functions from the
1015 * zfs.check submodule need to be associated with a transaction as
1016 * they are basically dry-runs of their counterparts in the zfs.sync
1017 * submodule. These functions should be able to run in open-context.
1018 * Therefore we create a new transaction that we later abort once
1019 * the channel program has been evaluated.
1020 */
1021 tx = dmu_tx_create_dd(dp->dp_mos_dir);
1022
1023 zcp_eval_impl(tx, ri);
1024
1025 dmu_tx_abort(tx);
1026
1027 dsl_pool_rele(dp, FTAG);
1028 }
1029
1030 int
1031 zcp_eval(const char *poolname, const char *program, boolean_t sync,
1032 uint64_t instrlimit, uint64_t memlimit, nvpair_t *nvarg, nvlist_t *outnvl)
1033 {
1034 int err;
1035 lua_State *state;
1036 zcp_run_info_t runinfo;
1037
1038 if (instrlimit > zfs_lua_max_instrlimit)
1039 return (SET_ERROR(EINVAL));
1040 if (memlimit == 0 || memlimit > zfs_lua_max_memlimit)
1041 return (SET_ERROR(EINVAL));
1042
1043 zcp_alloc_arg_t allocargs = {
1044 .aa_must_succeed = B_TRUE,
1045 .aa_alloc_remaining = (int64_t)memlimit,
1046 .aa_alloc_limit = (int64_t)memlimit,
1047 };
1048
1049 /*
1050 * Creates a Lua state with a memory allocator that uses KM_SLEEP.
1051 * This should never fail.
1052 */
1053 state = lua_newstate(zcp_lua_alloc, &allocargs);
1054 VERIFY(state != NULL);
1055 (void) lua_atpanic(state, zcp_panic_cb);
1056
1057 /*
1058 * Load core Lua libraries we want access to.
1059 */
1060 VERIFY3U(1, ==, luaopen_base(state));
1061 lua_pop(state, 1);
1062 VERIFY3U(1, ==, luaopen_coroutine(state));
1063 lua_setglobal(state, LUA_COLIBNAME);
1064 VERIFY0(lua_gettop(state));
1065 VERIFY3U(1, ==, luaopen_string(state));
1066 lua_setglobal(state, LUA_STRLIBNAME);
1067 VERIFY0(lua_gettop(state));
1068 VERIFY3U(1, ==, luaopen_table(state));
1069 lua_setglobal(state, LUA_TABLIBNAME);
1070 VERIFY0(lua_gettop(state));
1071
1072 /*
1073 * Load globally visible variables such as errno aliases.
1074 */
1075 zcp_load_globals(state);
1076 VERIFY0(lua_gettop(state));
1077
1078 /*
1079 * Load ZFS-specific modules.
1080 */
1081 lua_newtable(state);
1082 VERIFY3U(1, ==, zcp_load_list_lib(state));
1083 lua_setfield(state, -2, "list");
1084 VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_FALSE));
1085 lua_setfield(state, -2, "check");
1086 VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_TRUE));
1087 lua_setfield(state, -2, "sync");
1088 VERIFY3U(1, ==, zcp_load_get_lib(state));
1089 lua_pushcclosure(state, zcp_debug_info.func, 0);
1090 lua_setfield(state, -2, zcp_debug_info.name);
1091 lua_pushcclosure(state, zcp_exists_info.func, 0);
1092 lua_setfield(state, -2, zcp_exists_info.name);
1093 lua_setglobal(state, "zfs");
1094 VERIFY0(lua_gettop(state));
1095
1096 /*
1097 * Push the error-callback that calculates Lua stack traces on
1098 * unexpected failures.
1099 */
1100 lua_pushcfunction(state, zcp_error_handler);
1101 VERIFY3U(1, ==, lua_gettop(state));
1102
1103 /*
1104 * Load the actual script as a function onto the stack as text ("t").
1105 * The only valid error condition is a syntax error in the script.
1106 * ERRMEM should not be possible because our allocator is using
1107 * KM_SLEEP. ERRGCMM should not be possible because we have not added
1108 * any objects with __gc metamethods to the interpreter that could
1109 * fail.
1110 */
1111 err = luaL_loadbufferx(state, program, strlen(program),
1112 "channel program", "t");
1113 if (err == LUA_ERRSYNTAX) {
1114 fnvlist_add_string(outnvl, ZCP_RET_ERROR,
1115 lua_tostring(state, -1));
1116 lua_close(state);
1117 return (SET_ERROR(EINVAL));
1118 }
1119 VERIFY0(err);
1120 VERIFY3U(2, ==, lua_gettop(state));
1121
1122 /*
1123 * Convert the input nvlist to a Lua object and put it on top of the
1124 * stack.
1125 */
1126 char errmsg[128];
1127 err = zcp_nvpair_value_to_lua(state, nvarg,
1128 errmsg, sizeof (errmsg));
1129 if (err != 0) {
1130 fnvlist_add_string(outnvl, ZCP_RET_ERROR, errmsg);
1131 lua_close(state);
1132 return (SET_ERROR(EINVAL));
1133 }
1134 VERIFY3U(3, ==, lua_gettop(state));
1135
1136 runinfo.zri_state = state;
1137 runinfo.zri_allocargs = &allocargs;
1138 runinfo.zri_outnvl = outnvl;
1139 runinfo.zri_result = 0;
1140 runinfo.zri_cred = CRED();
1141 runinfo.zri_timed_out = B_FALSE;
1142 runinfo.zri_canceled = B_FALSE;
1143 runinfo.zri_sync = sync;
1144 runinfo.zri_space_used = 0;
1145 runinfo.zri_curinstrs = 0;
1146 runinfo.zri_maxinstrs = instrlimit;
1147
1148 if (sync) {
1149 err = dsl_sync_task_sig(poolname, NULL, zcp_eval_sync,
1150 zcp_eval_sig, &runinfo, 0, ZFS_SPACE_CHECK_ZCP_EVAL);
1151 if (err != 0)
1152 zcp_pool_error(&runinfo, poolname);
1153 } else {
1154 zcp_eval_open(&runinfo, poolname);
1155 }
1156 lua_close(state);
1157
1158 return (runinfo.zri_result);
1159 }
1160
1161 /*
1162 * Retrieve metadata about the currently running channel program.
1163 */
1164 zcp_run_info_t *
1165 zcp_run_info(lua_State *state)
1166 {
1167 zcp_run_info_t *ri;
1168
1169 lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);
1170 ri = lua_touserdata(state, -1);
1171 lua_pop(state, 1);
1172 return (ri);
1173 }
1174
1175 /*
1176 * Argument Parsing
1177 * ================
1178 *
1179 * The Lua language allows methods to be called with any number
1180 * of arguments of any type. When calling back into ZFS we need to sanitize
1181 * arguments from channel programs to make sure unexpected arguments or
1182 * arguments of the wrong type result in clear error messages. To do this
1183 * in a uniform way all callbacks from channel programs should use the
1184 * zcp_parse_args() function to interpret inputs.
1185 *
1186 * Positional vs Keyword Arguments
1187 * ===============================
1188 *
1189 * Every callback function takes a fixed set of required positional arguments
1190 * and optional keyword arguments. For example, the destroy function takes
1191 * a single positional string argument (the name of the dataset to destroy)
1192 * and an optional "defer" keyword boolean argument. When calling lua functions
1193 * with parentheses, only positional arguments can be used:
1194 *
1195 * zfs.sync.snapshot("rpool@snap")
1196 *
1197 * To use keyword arguments functions should be called with a single argument
1198 * that is a lua table containing mappings of integer -> positional arguments
1199 * and string -> keyword arguments:
1200 *
1201 * zfs.sync.snapshot({1="rpool@snap", defer=true})
1202 *
1203 * The lua language allows curly braces to be used in place of parenthesis as
1204 * syntactic sugar for this calling convention:
1205 *
1206 * zfs.sync.snapshot{"rpool@snap", defer=true}
1207 */
1208
1209 /*
1210 * Throw an error and print the given arguments. If there are too many
1211 * arguments to fit in the output buffer, only the error format string is
1212 * output.
1213 */
1214 static void
1215 zcp_args_error(lua_State *state, const char *fname, const zcp_arg_t *pargs,
1216 const zcp_arg_t *kwargs, const char *fmt, ...)
1217 {
1218 int i;
1219 char errmsg[512];
1220 size_t len = sizeof (errmsg);
1221 size_t msglen = 0;
1222 va_list argp;
1223
1224 va_start(argp, fmt);
1225 VERIFY3U(len, >, vsnprintf(errmsg, len, fmt, argp));
1226 va_end(argp);
1227
1228 /*
1229 * Calculate the total length of the final string, including extra
1230 * formatting characters. If the argument dump would be too large,
1231 * only print the error string.
1232 */
1233 msglen = strlen(errmsg);
1234 msglen += strlen(fname) + 4; /* : + {} + null terminator */
1235 for (i = 0; pargs[i].za_name != NULL; i++) {
1236 msglen += strlen(pargs[i].za_name);
1237 msglen += strlen(lua_typename(state, pargs[i].za_lua_type));
1238 if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL)
1239 msglen += 5; /* < + ( + )> + , */
1240 else
1241 msglen += 4; /* < + ( + )> */
1242 }
1243 for (i = 0; kwargs[i].za_name != NULL; i++) {
1244 msglen += strlen(kwargs[i].za_name);
1245 msglen += strlen(lua_typename(state, kwargs[i].za_lua_type));
1246 if (kwargs[i + 1].za_name != NULL)
1247 msglen += 4; /* =( + ) + , */
1248 else
1249 msglen += 3; /* =( + ) */
1250 }
1251
1252 if (msglen >= len)
1253 (void) luaL_error(state, errmsg);
1254
1255 VERIFY3U(len, >, strlcat(errmsg, ": ", len));
1256 VERIFY3U(len, >, strlcat(errmsg, fname, len));
1257 VERIFY3U(len, >, strlcat(errmsg, "{", len));
1258 for (i = 0; pargs[i].za_name != NULL; i++) {
1259 VERIFY3U(len, >, strlcat(errmsg, "<", len));
1260 VERIFY3U(len, >, strlcat(errmsg, pargs[i].za_name, len));
1261 VERIFY3U(len, >, strlcat(errmsg, "(", len));
1262 VERIFY3U(len, >, strlcat(errmsg,
1263 lua_typename(state, pargs[i].za_lua_type), len));
1264 VERIFY3U(len, >, strlcat(errmsg, ")>", len));
1265 if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL) {
1266 VERIFY3U(len, >, strlcat(errmsg, ", ", len));
1267 }
1268 }
1269 for (i = 0; kwargs[i].za_name != NULL; i++) {
1270 VERIFY3U(len, >, strlcat(errmsg, kwargs[i].za_name, len));
1271 VERIFY3U(len, >, strlcat(errmsg, "=(", len));
1272 VERIFY3U(len, >, strlcat(errmsg,
1273 lua_typename(state, kwargs[i].za_lua_type), len));
1274 VERIFY3U(len, >, strlcat(errmsg, ")", len));
1275 if (kwargs[i + 1].za_name != NULL) {
1276 VERIFY3U(len, >, strlcat(errmsg, ", ", len));
1277 }
1278 }
1279 VERIFY3U(len, >, strlcat(errmsg, "}", len));
1280
1281 (void) luaL_error(state, errmsg);
1282 panic("unreachable code");
1283 }
1284
1285 static void
1286 zcp_parse_table_args(lua_State *state, const char *fname,
1287 const zcp_arg_t *pargs, const zcp_arg_t *kwargs)
1288 {
1289 int i;
1290 int type;
1291
1292 for (i = 0; pargs[i].za_name != NULL; i++) {
1293 /*
1294 * Check the table for this positional argument, leaving it
1295 * on the top of the stack once we finish validating it.
1296 */
1297 lua_pushinteger(state, i + 1);
1298 lua_gettable(state, 1);
1299
1300 type = lua_type(state, -1);
1301 if (type == LUA_TNIL) {
1302 zcp_args_error(state, fname, pargs, kwargs,
1303 "too few arguments");
1304 panic("unreachable code");
1305 } else if (type != pargs[i].za_lua_type) {
1306 zcp_args_error(state, fname, pargs, kwargs,
1307 "arg %d wrong type (is '%s', expected '%s')",
1308 i + 1, lua_typename(state, type),
1309 lua_typename(state, pargs[i].za_lua_type));
1310 panic("unreachable code");
1311 }
1312
1313 /*
1314 * Remove the positional argument from the table.
1315 */
1316 lua_pushinteger(state, i + 1);
1317 lua_pushnil(state);
1318 lua_settable(state, 1);
1319 }
1320
1321 for (i = 0; kwargs[i].za_name != NULL; i++) {
1322 /*
1323 * Check the table for this keyword argument, which may be
1324 * nil if it was omitted. Leave the value on the top of
1325 * the stack after validating it.
1326 */
1327 lua_getfield(state, 1, kwargs[i].za_name);
1328
1329 type = lua_type(state, -1);
1330 if (type != LUA_TNIL && type != kwargs[i].za_lua_type) {
1331 zcp_args_error(state, fname, pargs, kwargs,
1332 "kwarg '%s' wrong type (is '%s', expected '%s')",
1333 kwargs[i].za_name, lua_typename(state, type),
1334 lua_typename(state, kwargs[i].za_lua_type));
1335 panic("unreachable code");
1336 }
1337
1338 /*
1339 * Remove the keyword argument from the table.
1340 */
1341 lua_pushnil(state);
1342 lua_setfield(state, 1, kwargs[i].za_name);
1343 }
1344
1345 /*
1346 * Any entries remaining in the table are invalid inputs, print
1347 * an error message based on what the entry is.
1348 */
1349 lua_pushnil(state);
1350 if (lua_next(state, 1)) {
1351 if (lua_isnumber(state, -2) && lua_tointeger(state, -2) > 0) {
1352 zcp_args_error(state, fname, pargs, kwargs,
1353 "too many positional arguments");
1354 } else if (lua_isstring(state, -2)) {
1355 zcp_args_error(state, fname, pargs, kwargs,
1356 "invalid kwarg '%s'", lua_tostring(state, -2));
1357 } else {
1358 zcp_args_error(state, fname, pargs, kwargs,
1359 "kwarg keys must be strings");
1360 }
1361 panic("unreachable code");
1362 }
1363
1364 lua_remove(state, 1);
1365 }
1366
1367 static void
1368 zcp_parse_pos_args(lua_State *state, const char *fname, const zcp_arg_t *pargs,
1369 const zcp_arg_t *kwargs)
1370 {
1371 int i;
1372 int type;
1373
1374 for (i = 0; pargs[i].za_name != NULL; i++) {
1375 type = lua_type(state, i + 1);
1376 if (type == LUA_TNONE) {
1377 zcp_args_error(state, fname, pargs, kwargs,
1378 "too few arguments");
1379 panic("unreachable code");
1380 } else if (type != pargs[i].za_lua_type) {
1381 zcp_args_error(state, fname, pargs, kwargs,
1382 "arg %d wrong type (is '%s', expected '%s')",
1383 i + 1, lua_typename(state, type),
1384 lua_typename(state, pargs[i].za_lua_type));
1385 panic("unreachable code");
1386 }
1387 }
1388 if (lua_gettop(state) != i) {
1389 zcp_args_error(state, fname, pargs, kwargs,
1390 "too many positional arguments");
1391 panic("unreachable code");
1392 }
1393
1394 for (i = 0; kwargs[i].za_name != NULL; i++) {
1395 lua_pushnil(state);
1396 }
1397 }
1398
1399 /*
1400 * Checks the current Lua stack against an expected set of positional and
1401 * keyword arguments. If the stack does not match the expected arguments
1402 * aborts the current channel program with a useful error message, otherwise
1403 * it re-arranges the stack so that it contains the positional arguments
1404 * followed by the keyword argument values in declaration order. Any missing
1405 * keyword argument will be represented by a nil value on the stack.
1406 *
1407 * If the stack contains exactly one argument of type LUA_TTABLE the curly
1408 * braces calling convention is assumed, otherwise the stack is parsed for
1409 * positional arguments only.
1410 *
1411 * This function should be used by every function callback. It should be called
1412 * before the callback manipulates the Lua stack as it assumes the stack
1413 * represents the function arguments.
1414 */
1415 void
1416 zcp_parse_args(lua_State *state, const char *fname, const zcp_arg_t *pargs,
1417 const zcp_arg_t *kwargs)
1418 {
1419 if (lua_gettop(state) == 1 && lua_istable(state, 1)) {
1420 zcp_parse_table_args(state, fname, pargs, kwargs);
1421 } else {
1422 zcp_parse_pos_args(state, fname, pargs, kwargs);
1423 }
1424 }