1 | /* |
2 | ** $Id: ldo.c $ |
3 | ** Stack and Call structure of Lua |
4 | ** See Copyright Notice in lua.h |
5 | */ |
6 | |
7 | #define ldo_c |
8 | #define LUA_CORE |
9 | |
10 | #include "lprefix.h" |
11 | |
12 | |
13 | #include <setjmp.h> |
14 | #include <stdlib.h> |
15 | #include <string.h> |
16 | |
17 | #include "lua.h" |
18 | |
19 | #include "lapi.h" |
20 | #include "ldebug.h" |
21 | #include "ldo.h" |
22 | #include "lfunc.h" |
23 | #include "lgc.h" |
24 | #include "lmem.h" |
25 | #include "lobject.h" |
26 | #include "lopcodes.h" |
27 | #include "lparser.h" |
28 | #include "lstate.h" |
29 | #include "lstring.h" |
30 | #include "ltable.h" |
31 | #include "ltm.h" |
32 | #include "lundump.h" |
33 | #include "lvm.h" |
34 | #include "lzio.h" |
35 | |
36 | |
37 | |
38 | #define errorstatus(s) ((s) > LUA_YIELD) |
39 | |
40 | |
41 | /* |
42 | ** {====================================================== |
43 | ** Error-recovery functions |
44 | ** ======================================================= |
45 | */ |
46 | |
47 | /* |
48 | ** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By |
49 | ** default, Lua handles errors with exceptions when compiling as |
50 | ** C++ code, with _longjmp/_setjmp when asked to use them, and with |
51 | ** longjmp/setjmp otherwise. |
52 | */ |
53 | #if !defined(LUAI_THROW) /* { */ |
54 | |
55 | #if defined(__cplusplus) && !defined(LUA_USE_LONGJMP) /* { */ |
56 | |
57 | /* C++ exceptions */ |
58 | #define LUAI_THROW(L,c) throw(c) |
59 | #define LUAI_TRY(L,c,a) \ |
60 | try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; } |
61 | #define luai_jmpbuf int /* dummy variable */ |
62 | |
63 | #elif defined(LUA_USE_POSIX) /* }{ */ |
64 | |
65 | /* in POSIX, try _longjmp/_setjmp (more efficient) */ |
66 | #define LUAI_THROW(L,c) _longjmp((c)->b, 1) |
67 | #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a } |
68 | #define luai_jmpbuf jmp_buf |
69 | |
70 | #else /* }{ */ |
71 | |
72 | /* ISO C handling with long jumps */ |
73 | #define LUAI_THROW(L,c) longjmp((c)->b, 1) |
74 | #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a } |
75 | #define luai_jmpbuf jmp_buf |
76 | |
77 | #endif /* } */ |
78 | |
79 | #endif /* } */ |
80 | |
81 | |
82 | |
83 | /* chain list of long jump buffers */ |
84 | struct lua_longjmp { |
85 | struct lua_longjmp *previous; |
86 | luai_jmpbuf b; |
87 | volatile int status; /* error code */ |
88 | }; |
89 | |
90 | |
91 | void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) { |
92 | switch (errcode) { |
93 | case LUA_ERRMEM: { /* memory error? */ |
94 | setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */ |
95 | break; |
96 | } |
97 | case LUA_ERRERR: { |
98 | setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling" )); |
99 | break; |
100 | } |
101 | case CLOSEPROTECT: { |
102 | setnilvalue(s2v(oldtop)); /* no error message */ |
103 | break; |
104 | } |
105 | default: { |
106 | setobjs2s(L, oldtop, L->top - 1); /* error message on current top */ |
107 | break; |
108 | } |
109 | } |
110 | L->top = oldtop + 1; |
111 | } |
112 | |
113 | |
114 | l_noret luaD_throw (lua_State *L, int errcode) { |
115 | if (L->errorJmp) { /* thread has an error handler? */ |
116 | L->errorJmp->status = errcode; /* set status */ |
117 | LUAI_THROW(L, L->errorJmp); /* jump to it */ |
118 | } |
119 | else { /* thread has no error handler */ |
120 | global_State *g = G(L); |
121 | errcode = luaF_close(L, L->stack, errcode); /* close all upvalues */ |
122 | L->status = cast_byte(errcode); /* mark it as dead */ |
123 | if (g->mainthread->errorJmp) { /* main thread has a handler? */ |
124 | setobjs2s(L, g->mainthread->top++, L->top - 1); /* copy error obj. */ |
125 | luaD_throw(g->mainthread, errcode); /* re-throw in main thread */ |
126 | } |
127 | else { /* no handler at all; abort */ |
128 | if (g->panic) { /* panic function? */ |
129 | luaD_seterrorobj(L, errcode, L->top); /* assume EXTRA_STACK */ |
130 | if (L->ci->top < L->top) |
131 | L->ci->top = L->top; /* pushing msg. can break this invariant */ |
132 | lua_unlock(L); |
133 | g->panic(L); /* call panic function (last chance to jump out) */ |
134 | } |
135 | abort(); |
136 | } |
137 | } |
138 | } |
139 | |
140 | |
141 | int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) { |
142 | l_uint32 oldnCcalls = L->nCcalls; |
143 | struct lua_longjmp lj; |
144 | lj.status = LUA_OK; |
145 | lj.previous = L->errorJmp; /* chain new error handler */ |
146 | L->errorJmp = &lj; |
147 | LUAI_TRY(L, &lj, |
148 | (*f)(L, ud); |
149 | ); |
150 | L->errorJmp = lj.previous; /* restore old error handler */ |
151 | L->nCcalls = oldnCcalls; |
152 | return lj.status; |
153 | } |
154 | |
155 | /* }====================================================== */ |
156 | |
157 | |
158 | /* |
159 | ** {================================================================== |
160 | ** Stack reallocation |
161 | ** =================================================================== |
162 | */ |
163 | static void correctstack (lua_State *L, StkId oldstack, StkId newstack) { |
164 | CallInfo *ci; |
165 | UpVal *up; |
166 | if (oldstack == newstack) |
167 | return; /* stack address did not change */ |
168 | L->top = (L->top - oldstack) + newstack; |
169 | for (up = L->openupval; up != NULL; up = up->u.open.next) |
170 | up->v = s2v((uplevel(up) - oldstack) + newstack); |
171 | for (ci = L->ci; ci != NULL; ci = ci->previous) { |
172 | ci->top = (ci->top - oldstack) + newstack; |
173 | ci->func = (ci->func - oldstack) + newstack; |
174 | if (isLua(ci)) |
175 | ci->u.l.trap = 1; /* signal to update 'trap' in 'luaV_execute' */ |
176 | } |
177 | } |
178 | |
179 | |
180 | /* some space for error handling */ |
181 | #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200) |
182 | |
183 | |
184 | int luaD_reallocstack (lua_State *L, int newsize, int raiseerror) { |
185 | int lim = stacksize(L); |
186 | StkId newstack = luaM_reallocvector(L, L->stack, |
187 | lim + EXTRA_STACK, newsize + EXTRA_STACK, StackValue); |
188 | lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE); |
189 | if (unlikely(newstack == NULL)) { /* reallocation failed? */ |
190 | if (raiseerror) |
191 | luaM_error(L); |
192 | else return 0; /* do not raise an error */ |
193 | } |
194 | for (; lim < newsize; lim++) |
195 | setnilvalue(s2v(newstack + lim)); /* erase new segment */ |
196 | correctstack(L, L->stack, newstack); |
197 | L->stack = newstack; |
198 | L->stack_last = L->stack + newsize; |
199 | return 1; |
200 | } |
201 | |
202 | |
203 | /* |
204 | ** Try to grow the stack by at least 'n' elements. when 'raiseerror' |
205 | ** is true, raises any error; otherwise, return 0 in case of errors. |
206 | */ |
207 | int luaD_growstack (lua_State *L, int n, int raiseerror) { |
208 | int size = stacksize(L); |
209 | if (unlikely(size > LUAI_MAXSTACK)) { |
210 | /* if stack is larger than maximum, thread is already using the |
211 | extra space reserved for errors, that is, thread is handling |
212 | a stack error; cannot grow further than that. */ |
213 | lua_assert(stacksize(L) == ERRORSTACKSIZE); |
214 | if (raiseerror) |
215 | luaD_throw(L, LUA_ERRERR); /* error inside message handler */ |
216 | return 0; /* if not 'raiseerror', just signal it */ |
217 | } |
218 | else { |
219 | int newsize = 2 * size; /* tentative new size */ |
220 | int needed = cast_int(L->top - L->stack) + n; |
221 | if (newsize > LUAI_MAXSTACK) /* cannot cross the limit */ |
222 | newsize = LUAI_MAXSTACK; |
223 | if (newsize < needed) /* but must respect what was asked for */ |
224 | newsize = needed; |
225 | if (likely(newsize <= LUAI_MAXSTACK)) |
226 | return luaD_reallocstack(L, newsize, raiseerror); |
227 | else { /* stack overflow */ |
228 | /* add extra size to be able to handle the error message */ |
229 | luaD_reallocstack(L, ERRORSTACKSIZE, raiseerror); |
230 | if (raiseerror) |
231 | luaG_runerror(L, "stack overflow" ); |
232 | return 0; |
233 | } |
234 | } |
235 | } |
236 | |
237 | |
238 | static int stackinuse (lua_State *L) { |
239 | CallInfo *ci; |
240 | int res; |
241 | StkId lim = L->top; |
242 | for (ci = L->ci; ci != NULL; ci = ci->previous) { |
243 | if (lim < ci->top) lim = ci->top; |
244 | } |
245 | lua_assert(lim <= L->stack_last); |
246 | res = cast_int(lim - L->stack) + 1; /* part of stack in use */ |
247 | if (res < LUA_MINSTACK) |
248 | res = LUA_MINSTACK; /* ensure a minimum size */ |
249 | return res; |
250 | } |
251 | |
252 | |
253 | /* |
254 | ** If stack size is more than 3 times the current use, reduce that size |
255 | ** to twice the current use. (So, the final stack size is at most 2/3 the |
256 | ** previous size, and half of its entries are empty.) |
257 | ** As a particular case, if stack was handling a stack overflow and now |
258 | ** it is not, 'max' (limited by LUAI_MAXSTACK) will be smaller than |
259 | ** stacksize (equal to ERRORSTACKSIZE in this case), and so the stack |
260 | ** will be reduced to a "regular" size. |
261 | */ |
262 | void luaD_shrinkstack (lua_State *L) { |
263 | int inuse = stackinuse(L); |
264 | int nsize = inuse * 2; /* proposed new size */ |
265 | int max = inuse * 3; /* maximum "reasonable" size */ |
266 | if (max > LUAI_MAXSTACK) { |
267 | max = LUAI_MAXSTACK; /* respect stack limit */ |
268 | if (nsize > LUAI_MAXSTACK) |
269 | nsize = LUAI_MAXSTACK; |
270 | } |
271 | /* if thread is currently not handling a stack overflow and its |
272 | size is larger than maximum "reasonable" size, shrink it */ |
273 | if (inuse <= LUAI_MAXSTACK && stacksize(L) > max) |
274 | luaD_reallocstack(L, nsize, 0); /* ok if that fails */ |
275 | else /* don't change stack */ |
276 | condmovestack(L,{},{}); /* (change only for debugging) */ |
277 | luaE_shrinkCI(L); /* shrink CI list */ |
278 | } |
279 | |
280 | |
281 | void luaD_inctop (lua_State *L) { |
282 | luaD_checkstack(L, 1); |
283 | L->top++; |
284 | } |
285 | |
286 | /* }================================================================== */ |
287 | |
288 | |
289 | /* |
290 | ** Call a hook for the given event. Make sure there is a hook to be |
291 | ** called. (Both 'L->hook' and 'L->hookmask', which trigger this |
292 | ** function, can be changed asynchronously by signals.) |
293 | */ |
294 | void luaD_hook (lua_State *L, int event, int line, |
295 | int ftransfer, int ntransfer) { |
296 | lua_Hook hook = L->hook; |
297 | if (hook && L->allowhook) { /* make sure there is a hook */ |
298 | int mask = CIST_HOOKED; |
299 | CallInfo *ci = L->ci; |
300 | ptrdiff_t top = savestack(L, L->top); |
301 | ptrdiff_t ci_top = savestack(L, ci->top); |
302 | lua_Debug ar; |
303 | ar.event = event; |
304 | ar.currentline = line; |
305 | ar.i_ci = ci; |
306 | if (ntransfer != 0) { |
307 | mask |= CIST_TRAN; /* 'ci' has transfer information */ |
308 | ci->u2.transferinfo.ftransfer = ftransfer; |
309 | ci->u2.transferinfo.ntransfer = ntransfer; |
310 | } |
311 | luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ |
312 | if (L->top + LUA_MINSTACK > ci->top) |
313 | ci->top = L->top + LUA_MINSTACK; |
314 | L->allowhook = 0; /* cannot call hooks inside a hook */ |
315 | ci->callstatus |= mask; |
316 | lua_unlock(L); |
317 | (*hook)(L, &ar); |
318 | lua_lock(L); |
319 | lua_assert(!L->allowhook); |
320 | L->allowhook = 1; |
321 | ci->top = restorestack(L, ci_top); |
322 | L->top = restorestack(L, top); |
323 | ci->callstatus &= ~mask; |
324 | } |
325 | } |
326 | |
327 | |
328 | /* |
329 | ** Executes a call hook for Lua functions. This function is called |
330 | ** whenever 'hookmask' is not zero, so it checks whether call hooks are |
331 | ** active. |
332 | */ |
333 | void luaD_hookcall (lua_State *L, CallInfo *ci) { |
334 | int hook = (ci->callstatus & CIST_TAIL) ? LUA_HOOKTAILCALL : LUA_HOOKCALL; |
335 | Proto *p; |
336 | if (!(L->hookmask & LUA_MASKCALL)) /* some other hook? */ |
337 | return; /* don't call hook */ |
338 | p = clLvalue(s2v(ci->func))->p; |
339 | L->top = ci->top; /* prepare top */ |
340 | ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */ |
341 | luaD_hook(L, hook, -1, 1, p->numparams); |
342 | ci->u.l.savedpc--; /* correct 'pc' */ |
343 | } |
344 | |
345 | |
346 | static StkId rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) { |
347 | ptrdiff_t oldtop = savestack(L, L->top); /* hook may change top */ |
348 | int delta = 0; |
349 | if (isLuacode(ci)) { |
350 | Proto *p = ci_func(ci)->p; |
351 | if (p->is_vararg) |
352 | delta = ci->u.l.nextraargs + p->numparams + 1; |
353 | if (L->top < ci->top) |
354 | L->top = ci->top; /* correct top to run hook */ |
355 | } |
356 | if (L->hookmask & LUA_MASKRET) { /* is return hook on? */ |
357 | int ftransfer; |
358 | ci->func += delta; /* if vararg, back to virtual 'func' */ |
359 | ftransfer = cast(unsigned short, firstres - ci->func); |
360 | luaD_hook(L, LUA_HOOKRET, -1, ftransfer, nres); /* call it */ |
361 | ci->func -= delta; |
362 | } |
363 | if (isLua(ci = ci->previous)) |
364 | L->oldpc = pcRel(ci->u.l.savedpc, ci_func(ci)->p); /* update 'oldpc' */ |
365 | return restorestack(L, oldtop); |
366 | } |
367 | |
368 | |
369 | /* |
370 | ** Check whether 'func' has a '__call' metafield. If so, put it in the |
371 | ** stack, below original 'func', so that 'luaD_precall' can call it. Raise |
372 | ** an error if there is no '__call' metafield. |
373 | */ |
374 | void luaD_tryfuncTM (lua_State *L, StkId func) { |
375 | const TValue *tm = luaT_gettmbyobj(L, s2v(func), TM_CALL); |
376 | StkId p; |
377 | if (unlikely(ttisnil(tm))) |
378 | luaG_typeerror(L, s2v(func), "call" ); /* nothing to call */ |
379 | for (p = L->top; p > func; p--) /* open space for metamethod */ |
380 | setobjs2s(L, p, p-1); |
381 | L->top++; /* stack space pre-allocated by the caller */ |
382 | setobj2s(L, func, tm); /* metamethod is the new function to be called */ |
383 | } |
384 | |
385 | |
386 | /* |
387 | ** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'. |
388 | ** Handle most typical cases (zero results for commands, one result for |
389 | ** expressions, multiple results for tail calls/single parameters) |
390 | ** separated. |
391 | */ |
392 | static void moveresults (lua_State *L, StkId res, int nres, int wanted) { |
393 | StkId firstresult; |
394 | int i; |
395 | switch (wanted) { /* handle typical cases separately */ |
396 | case 0: /* no values needed */ |
397 | L->top = res; |
398 | return; |
399 | case 1: /* one value needed */ |
400 | if (nres == 0) /* no results? */ |
401 | setnilvalue(s2v(res)); /* adjust with nil */ |
402 | else |
403 | setobjs2s(L, res, L->top - nres); /* move it to proper place */ |
404 | L->top = res + 1; |
405 | return; |
406 | case LUA_MULTRET: |
407 | wanted = nres; /* we want all results */ |
408 | break; |
409 | default: /* multiple results (or to-be-closed variables) */ |
410 | if (hastocloseCfunc(wanted)) { /* to-be-closed variables? */ |
411 | ptrdiff_t savedres = savestack(L, res); |
412 | luaF_close(L, res, LUA_OK); /* may change the stack */ |
413 | res = restorestack(L, savedres); |
414 | wanted = codeNresults(wanted); /* correct value */ |
415 | if (wanted == LUA_MULTRET) |
416 | wanted = nres; |
417 | } |
418 | break; |
419 | } |
420 | firstresult = L->top - nres; /* index of first result */ |
421 | /* move all results to correct place */ |
422 | for (i = 0; i < nres && i < wanted; i++) |
423 | setobjs2s(L, res + i, firstresult + i); |
424 | for (; i < wanted; i++) /* complete wanted number of results */ |
425 | setnilvalue(s2v(res + i)); |
426 | L->top = res + wanted; /* top points after the last result */ |
427 | } |
428 | |
429 | |
430 | /* |
431 | ** Finishes a function call: calls hook if necessary, removes CallInfo, |
432 | ** moves current number of results to proper place. |
433 | */ |
434 | void luaD_poscall (lua_State *L, CallInfo *ci, int nres) { |
435 | if (L->hookmask) |
436 | L->top = rethook(L, ci, L->top - nres, nres); |
437 | L->ci = ci->previous; /* back to caller */ |
438 | /* move results to proper place */ |
439 | moveresults(L, ci->func, nres, ci->nresults); |
440 | } |
441 | |
442 | |
443 | |
444 | #define next_ci(L) (L->ci->next ? L->ci->next : luaE_extendCI(L)) |
445 | |
446 | |
447 | /* |
448 | ** Prepare a function for a tail call, building its call info on top |
449 | ** of the current call info. 'narg1' is the number of arguments plus 1 |
450 | ** (so that it includes the function itself). |
451 | */ |
452 | void luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func, int narg1) { |
453 | Proto *p = clLvalue(s2v(func))->p; |
454 | int fsize = p->maxstacksize; /* frame size */ |
455 | int nfixparams = p->numparams; |
456 | int i; |
457 | for (i = 0; i < narg1; i++) /* move down function and arguments */ |
458 | setobjs2s(L, ci->func + i, func + i); |
459 | checkstackGC(L, fsize); |
460 | func = ci->func; /* moved-down function */ |
461 | for (; narg1 <= nfixparams; narg1++) |
462 | setnilvalue(s2v(func + narg1)); /* complete missing arguments */ |
463 | ci->top = func + 1 + fsize; /* top for new function */ |
464 | lua_assert(ci->top <= L->stack_last); |
465 | ci->u.l.savedpc = p->code; /* starting point */ |
466 | ci->callstatus |= CIST_TAIL; |
467 | L->top = func + narg1; /* set top */ |
468 | } |
469 | |
470 | |
471 | /* |
472 | ** Prepares the call to a function (C or Lua). For C functions, also do |
473 | ** the call. The function to be called is at '*func'. The arguments |
474 | ** are on the stack, right after the function. Returns the CallInfo |
475 | ** to be executed, if it was a Lua function. Otherwise (a C function) |
476 | ** returns NULL, with all the results on the stack, starting at the |
477 | ** original function position. |
478 | */ |
479 | CallInfo *luaD_precall (lua_State *L, StkId func, int nresults) { |
480 | lua_CFunction f; |
481 | retry: |
482 | switch (ttypetag(s2v(func))) { |
483 | case LUA_VCCL: /* C closure */ |
484 | f = clCvalue(s2v(func))->f; |
485 | goto Cfunc; |
486 | case LUA_VLCF: /* light C function */ |
487 | f = fvalue(s2v(func)); |
488 | Cfunc: { |
489 | int n; /* number of returns */ |
490 | CallInfo *ci; |
491 | checkstackGCp(L, LUA_MINSTACK, func); /* ensure minimum stack size */ |
492 | L->ci = ci = next_ci(L); |
493 | ci->nresults = nresults; |
494 | ci->callstatus = CIST_C; |
495 | ci->top = L->top + LUA_MINSTACK; |
496 | ci->func = func; |
497 | lua_assert(ci->top <= L->stack_last); |
498 | if (L->hookmask & LUA_MASKCALL) { |
499 | int narg = cast_int(L->top - func) - 1; |
500 | luaD_hook(L, LUA_HOOKCALL, -1, 1, narg); |
501 | } |
502 | lua_unlock(L); |
503 | n = (*f)(L); /* do the actual call */ |
504 | lua_lock(L); |
505 | api_checknelems(L, n); |
506 | luaD_poscall(L, ci, n); |
507 | return NULL; |
508 | } |
509 | case LUA_VLCL: { /* Lua function */ |
510 | CallInfo *ci; |
511 | Proto *p = clLvalue(s2v(func))->p; |
512 | int narg = cast_int(L->top - func) - 1; /* number of real arguments */ |
513 | int nfixparams = p->numparams; |
514 | int fsize = p->maxstacksize; /* frame size */ |
515 | checkstackGCp(L, fsize, func); |
516 | L->ci = ci = next_ci(L); |
517 | ci->nresults = nresults; |
518 | ci->u.l.savedpc = p->code; /* starting point */ |
519 | ci->top = func + 1 + fsize; |
520 | ci->func = func; |
521 | L->ci = ci; |
522 | for (; narg < nfixparams; narg++) |
523 | setnilvalue(s2v(L->top++)); /* complete missing arguments */ |
524 | lua_assert(ci->top <= L->stack_last); |
525 | return ci; |
526 | } |
527 | default: { /* not a function */ |
528 | checkstackGCp(L, 1, func); /* space for metamethod */ |
529 | luaD_tryfuncTM(L, func); /* try to get '__call' metamethod */ |
530 | goto retry; /* try again with metamethod */ |
531 | } |
532 | } |
533 | } |
534 | |
535 | |
536 | /* |
537 | ** Call a function (C or Lua). 'inc' can be 1 (increment number |
538 | ** of recursive invocations in the C stack) or nyci (the same plus |
539 | ** increment number of non-yieldable calls). |
540 | */ |
541 | static void docall (lua_State *L, StkId func, int nResults, int inc) { |
542 | CallInfo *ci; |
543 | L->nCcalls += inc; |
544 | if (unlikely(getCcalls(L) >= LUAI_MAXCCALLS)) |
545 | luaE_checkcstack(L); |
546 | if ((ci = luaD_precall(L, func, nResults)) != NULL) { /* Lua function? */ |
547 | ci->callstatus = CIST_FRESH; /* mark that it is a "fresh" execute */ |
548 | luaV_execute(L, ci); /* call it */ |
549 | } |
550 | L->nCcalls -= inc; |
551 | } |
552 | |
553 | |
554 | /* |
555 | ** External interface for 'docall' |
556 | */ |
557 | void luaD_call (lua_State *L, StkId func, int nResults) { |
558 | return docall(L, func, nResults, 1); |
559 | } |
560 | |
561 | |
562 | /* |
563 | ** Similar to 'luaD_call', but does not allow yields during the call. |
564 | */ |
565 | void luaD_callnoyield (lua_State *L, StkId func, int nResults) { |
566 | return docall(L, func, nResults, nyci); |
567 | } |
568 | |
569 | |
570 | /* |
571 | ** Completes the execution of an interrupted C function, calling its |
572 | ** continuation function. |
573 | */ |
574 | static void finishCcall (lua_State *L, int status) { |
575 | CallInfo *ci = L->ci; |
576 | int n; |
577 | /* must have a continuation and must be able to call it */ |
578 | lua_assert(ci->u.c.k != NULL && yieldable(L)); |
579 | /* error status can only happen in a protected call */ |
580 | lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD); |
581 | if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */ |
582 | ci->callstatus &= ~CIST_YPCALL; /* continuation is also inside it */ |
583 | L->errfunc = ci->u.c.old_errfunc; /* with the same error function */ |
584 | } |
585 | /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already |
586 | handled */ |
587 | adjustresults(L, ci->nresults); |
588 | lua_unlock(L); |
589 | n = (*ci->u.c.k)(L, status, ci->u.c.ctx); /* call continuation function */ |
590 | lua_lock(L); |
591 | api_checknelems(L, n); |
592 | luaD_poscall(L, ci, n); /* finish 'luaD_call' */ |
593 | } |
594 | |
595 | |
596 | /* |
597 | ** Executes "full continuation" (everything in the stack) of a |
598 | ** previously interrupted coroutine until the stack is empty (or another |
599 | ** interruption long-jumps out of the loop). If the coroutine is |
600 | ** recovering from an error, 'ud' points to the error status, which must |
601 | ** be passed to the first continuation function (otherwise the default |
602 | ** status is LUA_YIELD). |
603 | */ |
604 | static void unroll (lua_State *L, void *ud) { |
605 | CallInfo *ci; |
606 | if (ud != NULL) /* error status? */ |
607 | finishCcall(L, *(int *)ud); /* finish 'lua_pcallk' callee */ |
608 | while ((ci = L->ci) != &L->base_ci) { /* something in the stack */ |
609 | if (!isLua(ci)) /* C function? */ |
610 | finishCcall(L, LUA_YIELD); /* complete its execution */ |
611 | else { /* Lua function */ |
612 | luaV_finishOp(L); /* finish interrupted instruction */ |
613 | luaV_execute(L, ci); /* execute down to higher C 'boundary' */ |
614 | } |
615 | } |
616 | } |
617 | |
618 | |
619 | /* |
620 | ** Try to find a suspended protected call (a "recover point") for the |
621 | ** given thread. |
622 | */ |
623 | static CallInfo *findpcall (lua_State *L) { |
624 | CallInfo *ci; |
625 | for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */ |
626 | if (ci->callstatus & CIST_YPCALL) |
627 | return ci; |
628 | } |
629 | return NULL; /* no pending pcall */ |
630 | } |
631 | |
632 | |
633 | /* |
634 | ** Recovers from an error in a coroutine. Finds a recover point (if |
635 | ** there is one) and completes the execution of the interrupted |
636 | ** 'luaD_pcall'. If there is no recover point, returns zero. |
637 | */ |
638 | static int recover (lua_State *L, int status) { |
639 | StkId oldtop; |
640 | CallInfo *ci = findpcall(L); |
641 | if (ci == NULL) return 0; /* no recovery point */ |
642 | /* "finish" luaD_pcall */ |
643 | oldtop = restorestack(L, ci->u2.funcidx); |
644 | L->ci = ci; |
645 | L->allowhook = getoah(ci->callstatus); /* restore original 'allowhook' */ |
646 | status = luaF_close(L, oldtop, status); /* may change the stack */ |
647 | oldtop = restorestack(L, ci->u2.funcidx); |
648 | luaD_seterrorobj(L, status, oldtop); |
649 | luaD_shrinkstack(L); /* restore stack size in case of overflow */ |
650 | L->errfunc = ci->u.c.old_errfunc; |
651 | return 1; /* continue running the coroutine */ |
652 | } |
653 | |
654 | |
655 | /* |
656 | ** Signal an error in the call to 'lua_resume', not in the execution |
657 | ** of the coroutine itself. (Such errors should not be handled by any |
658 | ** coroutine error handler and should not kill the coroutine.) |
659 | */ |
660 | static int resume_error (lua_State *L, const char *msg, int narg) { |
661 | L->top -= narg; /* remove args from the stack */ |
662 | setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */ |
663 | api_incr_top(L); |
664 | lua_unlock(L); |
665 | return LUA_ERRRUN; |
666 | } |
667 | |
668 | |
669 | /* |
670 | ** Do the work for 'lua_resume' in protected mode. Most of the work |
671 | ** depends on the status of the coroutine: initial state, suspended |
672 | ** inside a hook, or regularly suspended (optionally with a continuation |
673 | ** function), plus erroneous cases: non-suspended coroutine or dead |
674 | ** coroutine. |
675 | */ |
676 | static void resume (lua_State *L, void *ud) { |
677 | int n = *(cast(int*, ud)); /* number of arguments */ |
678 | StkId firstArg = L->top - n; /* first argument */ |
679 | CallInfo *ci = L->ci; |
680 | if (L->status == LUA_OK) /* starting a coroutine? */ |
681 | docall(L, firstArg - 1, LUA_MULTRET, 1); /* just call its body */ |
682 | else { /* resuming from previous yield */ |
683 | lua_assert(L->status == LUA_YIELD); |
684 | L->status = LUA_OK; /* mark that it is running (again) */ |
685 | luaE_incCstack(L); /* control the C stack */ |
686 | if (isLua(ci)) /* yielded inside a hook? */ |
687 | luaV_execute(L, ci); /* just continue running Lua code */ |
688 | else { /* 'common' yield */ |
689 | if (ci->u.c.k != NULL) { /* does it have a continuation function? */ |
690 | lua_unlock(L); |
691 | n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */ |
692 | lua_lock(L); |
693 | api_checknelems(L, n); |
694 | } |
695 | luaD_poscall(L, ci, n); /* finish 'luaD_call' */ |
696 | } |
697 | unroll(L, NULL); /* run continuation */ |
698 | } |
699 | } |
700 | |
701 | LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs, |
702 | int *nresults) { |
703 | int status; |
704 | lua_lock(L); |
705 | if (L->status == LUA_OK) { /* may be starting a coroutine */ |
706 | if (L->ci != &L->base_ci) /* not in base level? */ |
707 | return resume_error(L, "cannot resume non-suspended coroutine" , nargs); |
708 | else if (L->top - (L->ci->func + 1) == nargs) /* no function? */ |
709 | return resume_error(L, "cannot resume dead coroutine" , nargs); |
710 | } |
711 | else if (L->status != LUA_YIELD) /* ended with errors? */ |
712 | return resume_error(L, "cannot resume dead coroutine" , nargs); |
713 | L->nCcalls = (from) ? getCcalls(from) : 0; |
714 | luai_userstateresume(L, nargs); |
715 | api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs); |
716 | status = luaD_rawrunprotected(L, resume, &nargs); |
717 | /* continue running after recoverable errors */ |
718 | while (errorstatus(status) && recover(L, status)) { |
719 | /* unroll continuation */ |
720 | status = luaD_rawrunprotected(L, unroll, &status); |
721 | } |
722 | if (likely(!errorstatus(status))) |
723 | lua_assert(status == L->status); /* normal end or yield */ |
724 | else { /* unrecoverable error */ |
725 | L->status = cast_byte(status); /* mark thread as 'dead' */ |
726 | luaD_seterrorobj(L, status, L->top); /* push error message */ |
727 | L->ci->top = L->top; |
728 | } |
729 | *nresults = (status == LUA_YIELD) ? L->ci->u2.nyield |
730 | : cast_int(L->top - (L->ci->func + 1)); |
731 | lua_unlock(L); |
732 | return status; |
733 | } |
734 | |
735 | |
736 | LUA_API int lua_isyieldable (lua_State *L) { |
737 | return yieldable(L); |
738 | } |
739 | |
740 | |
741 | LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx, |
742 | lua_KFunction k) { |
743 | CallInfo *ci; |
744 | luai_userstateyield(L, nresults); |
745 | lua_lock(L); |
746 | ci = L->ci; |
747 | api_checknelems(L, nresults); |
748 | if (unlikely(!yieldable(L))) { |
749 | if (L != G(L)->mainthread) |
750 | luaG_runerror(L, "attempt to yield across a C-call boundary" ); |
751 | else |
752 | luaG_runerror(L, "attempt to yield from outside a coroutine" ); |
753 | } |
754 | L->status = LUA_YIELD; |
755 | if (isLua(ci)) { /* inside a hook? */ |
756 | lua_assert(!isLuacode(ci)); |
757 | api_check(L, k == NULL, "hooks cannot continue after yielding" ); |
758 | ci->u2.nyield = 0; /* no results */ |
759 | } |
760 | else { |
761 | if ((ci->u.c.k = k) != NULL) /* is there a continuation? */ |
762 | ci->u.c.ctx = ctx; /* save context */ |
763 | ci->u2.nyield = nresults; /* save number of results */ |
764 | luaD_throw(L, LUA_YIELD); |
765 | } |
766 | lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */ |
767 | lua_unlock(L); |
768 | return 0; /* return to 'luaD_hook' */ |
769 | } |
770 | |
771 | |
772 | /* |
773 | ** Call the C function 'func' in protected mode, restoring basic |
774 | ** thread information ('allowhook', etc.) and in particular |
775 | ** its stack level in case of errors. |
776 | */ |
777 | int luaD_pcall (lua_State *L, Pfunc func, void *u, |
778 | ptrdiff_t old_top, ptrdiff_t ef) { |
779 | int status; |
780 | CallInfo *old_ci = L->ci; |
781 | lu_byte old_allowhooks = L->allowhook; |
782 | ptrdiff_t old_errfunc = L->errfunc; |
783 | L->errfunc = ef; |
784 | status = luaD_rawrunprotected(L, func, u); |
785 | if (unlikely(status != LUA_OK)) { /* an error occurred? */ |
786 | StkId oldtop = restorestack(L, old_top); |
787 | L->ci = old_ci; |
788 | L->allowhook = old_allowhooks; |
789 | status = luaF_close(L, oldtop, status); |
790 | oldtop = restorestack(L, old_top); /* previous call may change stack */ |
791 | luaD_seterrorobj(L, status, oldtop); |
792 | luaD_shrinkstack(L); /* restore stack size in case of overflow */ |
793 | } |
794 | L->errfunc = old_errfunc; |
795 | return status; |
796 | } |
797 | |
798 | |
799 | |
800 | /* |
801 | ** Execute a protected parser. |
802 | */ |
803 | struct SParser { /* data to 'f_parser' */ |
804 | ZIO *z; |
805 | Mbuffer buff; /* dynamic structure used by the scanner */ |
806 | Dyndata dyd; /* dynamic structures used by the parser */ |
807 | const char *mode; |
808 | const char *name; |
809 | }; |
810 | |
811 | |
812 | static void checkmode (lua_State *L, const char *mode, const char *x) { |
813 | if (mode && strchr(mode, x[0]) == NULL) { |
814 | luaO_pushfstring(L, |
815 | "attempt to load a %s chunk (mode is '%s')" , x, mode); |
816 | luaD_throw(L, LUA_ERRSYNTAX); |
817 | } |
818 | } |
819 | |
820 | |
821 | static void f_parser (lua_State *L, void *ud) { |
822 | LClosure *cl; |
823 | struct SParser *p = cast(struct SParser *, ud); |
824 | int c = zgetc(p->z); /* read first character */ |
825 | if (c == LUA_SIGNATURE[0]) { |
826 | checkmode(L, p->mode, "binary" ); |
827 | cl = luaU_undump(L, p->z, p->name); |
828 | } |
829 | else { |
830 | checkmode(L, p->mode, "text" ); |
831 | cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c); |
832 | } |
833 | lua_assert(cl->nupvalues == cl->p->sizeupvalues); |
834 | luaF_initupvals(L, cl); |
835 | } |
836 | |
837 | |
838 | int luaD_protectedparser (lua_State *L, ZIO *z, const char *name, |
839 | const char *mode) { |
840 | struct SParser p; |
841 | int status; |
842 | incnny(L); /* cannot yield during parsing */ |
843 | p.z = z; p.name = name; p.mode = mode; |
844 | p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0; |
845 | p.dyd.gt.arr = NULL; p.dyd.gt.size = 0; |
846 | p.dyd.label.arr = NULL; p.dyd.label.size = 0; |
847 | luaZ_initbuffer(L, &p.buff); |
848 | status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc); |
849 | luaZ_freebuffer(L, &p.buff); |
850 | luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size); |
851 | luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size); |
852 | luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size); |
853 | decnny(L); |
854 | return status; |
855 | } |
856 | |
857 | |
858 | |