1 | /* |
2 | ** $Id: ldo.c,v 2.38.1.4 2012/01/18 02:27:10 roberto Exp $ |
3 | ** Stack and Call structure of Lua |
4 | ** See Copyright Notice in lua.h |
5 | */ |
6 | |
7 | |
8 | #include <setjmp.h> |
9 | #include <stdlib.h> |
10 | #include <string.h> |
11 | |
12 | #define ldo_c |
13 | #define LUA_CORE |
14 | |
15 | #include "lua.h" |
16 | |
17 | #include "ldebug.h" |
18 | #include "ldo.h" |
19 | #include "lfunc.h" |
20 | #include "lgc.h" |
21 | #include "lmem.h" |
22 | #include "lobject.h" |
23 | #include "lopcodes.h" |
24 | #include "lparser.h" |
25 | #include "lstate.h" |
26 | #include "lstring.h" |
27 | #include "ltable.h" |
28 | #include "ltm.h" |
29 | #include "lundump.h" |
30 | #include "lvm.h" |
31 | #include "lzio.h" |
32 | |
33 | |
34 | |
35 | |
36 | /* |
37 | ** {====================================================== |
38 | ** Error-recovery functions |
39 | ** ======================================================= |
40 | */ |
41 | |
42 | |
43 | /* chain list of long jump buffers */ |
44 | struct lua_longjmp { |
45 | struct lua_longjmp *previous; |
46 | luai_jmpbuf b; |
47 | volatile int status; /* error code */ |
48 | }; |
49 | |
50 | |
51 | void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) { |
52 | switch (errcode) { |
53 | case LUA_ERRMEM: { |
54 | setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG)); |
55 | break; |
56 | } |
57 | case LUA_ERRERR: { |
58 | setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling" )); |
59 | break; |
60 | } |
61 | case LUA_ERRSYNTAX: |
62 | case LUA_ERRRUN: { |
63 | setobjs2s(L, oldtop, L->top - 1); /* error message on current top */ |
64 | break; |
65 | } |
66 | } |
67 | L->top = oldtop + 1; |
68 | } |
69 | |
70 | |
71 | static void restore_stack_limit (lua_State *L) { |
72 | lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1); |
73 | if (L->size_ci > LUAI_MAXCALLS) { /* there was an overflow? */ |
74 | int inuse = cast_int(L->ci - L->base_ci); |
75 | if (inuse + 1 < LUAI_MAXCALLS) /* can `undo' overflow? */ |
76 | luaD_reallocCI(L, LUAI_MAXCALLS); |
77 | } |
78 | } |
79 | |
80 | |
81 | static void resetstack (lua_State *L, int status) { |
82 | L->ci = L->base_ci; |
83 | L->base = L->ci->base; |
84 | luaF_close(L, L->base); /* close eventual pending closures */ |
85 | luaD_seterrorobj(L, status, L->base); |
86 | L->nCcalls = L->baseCcalls; |
87 | L->allowhook = 1; |
88 | restore_stack_limit(L); |
89 | L->errfunc = 0; |
90 | L->errorJmp = NULL; |
91 | } |
92 | |
93 | |
94 | void luaD_throw (lua_State *L, int errcode) { |
95 | if (L->errorJmp) { |
96 | L->errorJmp->status = errcode; |
97 | LUAI_THROW(L, L->errorJmp); |
98 | } |
99 | else { |
100 | L->status = cast_byte(errcode); |
101 | if (G(L)->panic) { |
102 | resetstack(L, errcode); |
103 | lua_unlock(L); |
104 | G(L)->panic(L); |
105 | } |
106 | exit(EXIT_FAILURE); |
107 | } |
108 | } |
109 | |
110 | |
111 | int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) { |
112 | struct lua_longjmp lj; |
113 | lj.status = 0; |
114 | lj.previous = L->errorJmp; /* chain new error handler */ |
115 | L->errorJmp = &lj; |
116 | LUAI_TRY(L, &lj, |
117 | (*f)(L, ud); |
118 | ); |
119 | L->errorJmp = lj.previous; /* restore old error handler */ |
120 | return lj.status; |
121 | } |
122 | |
123 | /* }====================================================== */ |
124 | |
125 | |
126 | static void correctstack (lua_State *L, TValue *oldstack) { |
127 | CallInfo *ci; |
128 | GCObject *up; |
129 | L->top = (L->top - oldstack) + L->stack; |
130 | for (up = L->openupval; up != NULL; up = up->gch.next) |
131 | gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack; |
132 | for (ci = L->base_ci; ci <= L->ci; ci++) { |
133 | ci->top = (ci->top - oldstack) + L->stack; |
134 | ci->base = (ci->base - oldstack) + L->stack; |
135 | ci->func = (ci->func - oldstack) + L->stack; |
136 | } |
137 | L->base = (L->base - oldstack) + L->stack; |
138 | } |
139 | |
140 | |
141 | void luaD_reallocstack (lua_State *L, int newsize) { |
142 | TValue *oldstack = L->stack; |
143 | int realsize = newsize + 1 + EXTRA_STACK; |
144 | lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1); |
145 | luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue); |
146 | L->stacksize = realsize; |
147 | L->stack_last = L->stack+newsize; |
148 | correctstack(L, oldstack); |
149 | } |
150 | |
151 | |
152 | void luaD_reallocCI (lua_State *L, int newsize) { |
153 | CallInfo *oldci = L->base_ci; |
154 | luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo); |
155 | L->size_ci = newsize; |
156 | L->ci = (L->ci - oldci) + L->base_ci; |
157 | L->end_ci = L->base_ci + L->size_ci - 1; |
158 | } |
159 | |
160 | |
161 | void luaD_growstack (lua_State *L, int n) { |
162 | if (n <= L->stacksize) /* double size is enough? */ |
163 | luaD_reallocstack(L, 2*L->stacksize); |
164 | else |
165 | luaD_reallocstack(L, L->stacksize + n); |
166 | } |
167 | |
168 | |
169 | static CallInfo *growCI (lua_State *L) { |
170 | if (L->size_ci > LUAI_MAXCALLS) /* overflow while handling overflow? */ |
171 | luaD_throw(L, LUA_ERRERR); |
172 | else { |
173 | luaD_reallocCI(L, 2*L->size_ci); |
174 | if (L->size_ci > LUAI_MAXCALLS) |
175 | luaG_runerror(L, "stack overflow" ); |
176 | } |
177 | return ++L->ci; |
178 | } |
179 | |
180 | |
181 | void luaD_callhook (lua_State *L, int event, int line) { |
182 | lua_Hook hook = L->hook; |
183 | if (hook && L->allowhook) { |
184 | ptrdiff_t top = savestack(L, L->top); |
185 | ptrdiff_t ci_top = savestack(L, L->ci->top); |
186 | lua_Debug ar; |
187 | ar.event = event; |
188 | ar.currentline = line; |
189 | if (event == LUA_HOOKTAILRET) |
190 | ar.i_ci = 0; /* tail call; no debug information about it */ |
191 | else |
192 | ar.i_ci = cast_int(L->ci - L->base_ci); |
193 | luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ |
194 | L->ci->top = L->top + LUA_MINSTACK; |
195 | lua_assert(L->ci->top <= L->stack_last); |
196 | L->allowhook = 0; /* cannot call hooks inside a hook */ |
197 | lua_unlock(L); |
198 | (*hook)(L, &ar); |
199 | lua_lock(L); |
200 | lua_assert(!L->allowhook); |
201 | L->allowhook = 1; |
202 | L->ci->top = restorestack(L, ci_top); |
203 | L->top = restorestack(L, top); |
204 | } |
205 | } |
206 | |
207 | |
208 | static StkId adjust_varargs (lua_State *L, Proto *p, int actual) { |
209 | int i; |
210 | int nfixargs = p->numparams; |
211 | Table *htab = NULL; |
212 | StkId base, fixed; |
213 | for (; actual < nfixargs; ++actual) |
214 | setnilvalue(L->top++); |
215 | #if defined(LUA_COMPAT_VARARG) |
216 | if (p->is_vararg & VARARG_NEEDSARG) { /* compat. with old-style vararg? */ |
217 | int nvar = actual - nfixargs; /* number of extra arguments */ |
218 | lua_assert(p->is_vararg & VARARG_HASARG); |
219 | luaC_checkGC(L); |
220 | luaD_checkstack(L, p->maxstacksize); |
221 | htab = luaH_new(L, nvar, 1); /* create `arg' table */ |
222 | for (i=0; i<nvar; i++) /* put extra arguments into `arg' table */ |
223 | setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i); |
224 | /* store counter in field `n' */ |
225 | setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n" )), cast_num(nvar)); |
226 | } |
227 | #endif |
228 | /* move fixed parameters to final position */ |
229 | fixed = L->top - actual; /* first fixed argument */ |
230 | base = L->top; /* final position of first argument */ |
231 | for (i=0; i<nfixargs; i++) { |
232 | setobjs2s(L, L->top++, fixed+i); |
233 | setnilvalue(fixed+i); |
234 | } |
235 | /* add `arg' parameter */ |
236 | if (htab) { |
237 | sethvalue(L, L->top++, htab); |
238 | lua_assert(iswhite(obj2gco(htab))); |
239 | } |
240 | return base; |
241 | } |
242 | |
243 | |
244 | static StkId tryfuncTM (lua_State *L, StkId func) { |
245 | const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL); |
246 | StkId p; |
247 | ptrdiff_t funcr = savestack(L, func); |
248 | if (!ttisfunction(tm)) |
249 | luaG_typeerror(L, func, "call" ); |
250 | /* Open a hole inside the stack at `func' */ |
251 | for (p = L->top; p > func; p--) setobjs2s(L, p, p-1); |
252 | incr_top(L); |
253 | func = restorestack(L, funcr); /* previous call may change stack */ |
254 | setobj2s(L, func, tm); /* tag method is the new function to be called */ |
255 | return func; |
256 | } |
257 | |
258 | |
259 | |
260 | #define inc_ci(L) \ |
261 | ((L->ci == L->end_ci) ? growCI(L) : \ |
262 | (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci)) |
263 | |
264 | |
265 | int luaD_precall (lua_State *L, StkId func, int nresults) { |
266 | LClosure *cl; |
267 | ptrdiff_t funcr; |
268 | if (!ttisfunction(func)) /* `func' is not a function? */ |
269 | func = tryfuncTM(L, func); /* check the `function' tag method */ |
270 | funcr = savestack(L, func); |
271 | cl = &clvalue(func)->l; |
272 | L->ci->savedpc = L->savedpc; |
273 | if (!cl->isC) { /* Lua function? prepare its call */ |
274 | CallInfo *ci; |
275 | StkId st, base; |
276 | Proto *p = cl->p; |
277 | luaD_checkstack(L, p->maxstacksize + p->numparams); |
278 | func = restorestack(L, funcr); |
279 | if (!p->is_vararg) { /* no varargs? */ |
280 | base = func + 1; |
281 | if (L->top > base + p->numparams) |
282 | L->top = base + p->numparams; |
283 | } |
284 | else { /* vararg function */ |
285 | int nargs = cast_int(L->top - func) - 1; |
286 | base = adjust_varargs(L, p, nargs); |
287 | func = restorestack(L, funcr); /* previous call may change the stack */ |
288 | } |
289 | ci = inc_ci(L); /* now `enter' new function */ |
290 | ci->func = func; |
291 | L->base = ci->base = base; |
292 | ci->top = L->base + p->maxstacksize; |
293 | lua_assert(ci->top <= L->stack_last); |
294 | L->savedpc = p->code; /* starting point */ |
295 | ci->tailcalls = 0; |
296 | ci->nresults = nresults; |
297 | for (st = L->top; st < ci->top; st++) |
298 | setnilvalue(st); |
299 | L->top = ci->top; |
300 | if (L->hookmask & LUA_MASKCALL) { |
301 | L->savedpc++; /* hooks assume 'pc' is already incremented */ |
302 | luaD_callhook(L, LUA_HOOKCALL, -1); |
303 | L->savedpc--; /* correct 'pc' */ |
304 | } |
305 | return PCRLUA; |
306 | } |
307 | else { /* if is a C function, call it */ |
308 | CallInfo *ci; |
309 | int n; |
310 | luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ |
311 | ci = inc_ci(L); /* now `enter' new function */ |
312 | ci->func = restorestack(L, funcr); |
313 | L->base = ci->base = ci->func + 1; |
314 | ci->top = L->top + LUA_MINSTACK; |
315 | lua_assert(ci->top <= L->stack_last); |
316 | ci->nresults = nresults; |
317 | if (L->hookmask & LUA_MASKCALL) |
318 | luaD_callhook(L, LUA_HOOKCALL, -1); |
319 | lua_unlock(L); |
320 | n = (*curr_func(L)->c.f)(L); /* do the actual call */ |
321 | lua_lock(L); |
322 | if (n < 0) /* yielding? */ |
323 | return PCRYIELD; |
324 | else { |
325 | luaD_poscall(L, L->top - n); |
326 | return PCRC; |
327 | } |
328 | } |
329 | } |
330 | |
331 | |
332 | static StkId callrethooks (lua_State *L, StkId firstResult) { |
333 | ptrdiff_t fr = savestack(L, firstResult); /* next call may change stack */ |
334 | luaD_callhook(L, LUA_HOOKRET, -1); |
335 | if (f_isLua(L->ci)) { /* Lua function? */ |
336 | while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */ |
337 | luaD_callhook(L, LUA_HOOKTAILRET, -1); |
338 | } |
339 | return restorestack(L, fr); |
340 | } |
341 | |
342 | |
343 | int luaD_poscall (lua_State *L, StkId firstResult) { |
344 | StkId res; |
345 | int wanted, i; |
346 | CallInfo *ci; |
347 | if (L->hookmask & LUA_MASKRET) |
348 | firstResult = callrethooks(L, firstResult); |
349 | ci = L->ci--; |
350 | res = ci->func; /* res == final position of 1st result */ |
351 | wanted = ci->nresults; |
352 | L->base = (ci - 1)->base; /* restore base */ |
353 | L->savedpc = (ci - 1)->savedpc; /* restore savedpc */ |
354 | /* move results to correct place */ |
355 | for (i = wanted; i != 0 && firstResult < L->top; i--) |
356 | setobjs2s(L, res++, firstResult++); |
357 | while (i-- > 0) |
358 | setnilvalue(res++); |
359 | L->top = res; |
360 | return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */ |
361 | } |
362 | |
363 | |
364 | /* |
365 | ** Call a function (C or Lua). The function to be called is at *func. |
366 | ** The arguments are on the stack, right after the function. |
367 | ** When returns, all the results are on the stack, starting at the original |
368 | ** function position. |
369 | */ |
370 | void luaD_call (lua_State *L, StkId func, int nResults) { |
371 | if (++L->nCcalls >= LUAI_MAXCCALLS) { |
372 | if (L->nCcalls == LUAI_MAXCCALLS) |
373 | luaG_runerror(L, "C stack overflow" ); |
374 | else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3))) |
375 | luaD_throw(L, LUA_ERRERR); /* error while handing stack error */ |
376 | } |
377 | if (luaD_precall(L, func, nResults) == PCRLUA) /* is a Lua function? */ |
378 | luaV_execute(L, 1); /* call it */ |
379 | L->nCcalls--; |
380 | luaC_checkGC(L); |
381 | } |
382 | |
383 | |
384 | static void resume (lua_State *L, void *ud) { |
385 | StkId firstArg = cast(StkId, ud); |
386 | CallInfo *ci = L->ci; |
387 | if (L->status == 0) { /* start coroutine? */ |
388 | lua_assert(ci == L->base_ci && firstArg > L->base); |
389 | if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA) |
390 | return; |
391 | } |
392 | else { /* resuming from previous yield */ |
393 | lua_assert(L->status == LUA_YIELD); |
394 | L->status = 0; |
395 | if (!f_isLua(ci)) { /* `common' yield? */ |
396 | /* finish interrupted execution of `OP_CALL' */ |
397 | lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL || |
398 | GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL); |
399 | if (luaD_poscall(L, firstArg)) /* complete it... */ |
400 | L->top = L->ci->top; /* and correct top if not multiple results */ |
401 | } |
402 | else /* yielded inside a hook: just continue its execution */ |
403 | L->base = L->ci->base; |
404 | } |
405 | luaV_execute(L, cast_int(L->ci - L->base_ci)); |
406 | } |
407 | |
408 | |
409 | static int resume_error (lua_State *L, const char *msg) { |
410 | L->top = L->ci->base; |
411 | setsvalue2s(L, L->top, luaS_new(L, msg)); |
412 | incr_top(L); |
413 | lua_unlock(L); |
414 | return LUA_ERRRUN; |
415 | } |
416 | |
417 | |
418 | LUA_API int lua_resume (lua_State *L, int nargs) { |
419 | int status; |
420 | lua_lock(L); |
421 | if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci)) |
422 | return resume_error(L, "cannot resume non-suspended coroutine" ); |
423 | if (L->nCcalls >= LUAI_MAXCCALLS) |
424 | return resume_error(L, "C stack overflow" ); |
425 | luai_userstateresume(L, nargs); |
426 | lua_assert(L->errfunc == 0); |
427 | L->baseCcalls = ++L->nCcalls; |
428 | status = luaD_rawrunprotected(L, resume, L->top - nargs); |
429 | if (status != 0) { /* error? */ |
430 | L->status = cast_byte(status); /* mark thread as `dead' */ |
431 | luaD_seterrorobj(L, status, L->top); |
432 | L->ci->top = L->top; |
433 | } |
434 | else { |
435 | lua_assert(L->nCcalls == L->baseCcalls); |
436 | status = L->status; |
437 | } |
438 | --L->nCcalls; |
439 | lua_unlock(L); |
440 | return status; |
441 | } |
442 | |
443 | |
444 | LUA_API int lua_yield (lua_State *L, int nresults) { |
445 | luai_userstateyield(L, nresults); |
446 | lua_lock(L); |
447 | if (L->nCcalls > L->baseCcalls) |
448 | luaG_runerror(L, "attempt to yield across metamethod/C-call boundary" ); |
449 | L->base = L->top - nresults; /* protect stack slots below */ |
450 | L->status = LUA_YIELD; |
451 | lua_unlock(L); |
452 | return -1; |
453 | } |
454 | |
455 | |
456 | int luaD_pcall (lua_State *L, Pfunc func, void *u, |
457 | ptrdiff_t old_top, ptrdiff_t ef) { |
458 | int status; |
459 | unsigned short oldnCcalls = L->nCcalls; |
460 | ptrdiff_t old_ci = saveci(L, L->ci); |
461 | lu_byte old_allowhooks = L->allowhook; |
462 | ptrdiff_t old_errfunc = L->errfunc; |
463 | L->errfunc = ef; |
464 | status = luaD_rawrunprotected(L, func, u); |
465 | if (status != 0) { /* an error occurred? */ |
466 | StkId oldtop = restorestack(L, old_top); |
467 | luaF_close(L, oldtop); /* close eventual pending closures */ |
468 | luaD_seterrorobj(L, status, oldtop); |
469 | L->nCcalls = oldnCcalls; |
470 | L->ci = restoreci(L, old_ci); |
471 | L->base = L->ci->base; |
472 | L->savedpc = L->ci->savedpc; |
473 | L->allowhook = old_allowhooks; |
474 | restore_stack_limit(L); |
475 | } |
476 | L->errfunc = old_errfunc; |
477 | return status; |
478 | } |
479 | |
480 | |
481 | |
482 | /* |
483 | ** Execute a protected parser. |
484 | */ |
485 | struct SParser { /* data to `f_parser' */ |
486 | ZIO *z; |
487 | Mbuffer buff; /* buffer to be used by the scanner */ |
488 | const char *name; |
489 | }; |
490 | |
491 | static void f_parser (lua_State *L, void *ud) { |
492 | int i; |
493 | Proto *tf; |
494 | Closure *cl; |
495 | struct SParser *p = cast(struct SParser *, ud); |
496 | luaZ_lookahead(p->z); |
497 | luaC_checkGC(L); |
498 | tf = (luaY_parser)(L, p->z, |
499 | &p->buff, p->name); |
500 | cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L))); |
501 | cl->l.p = tf; |
502 | for (i = 0; i < tf->nups; i++) /* initialize eventual upvalues */ |
503 | cl->l.upvals[i] = luaF_newupval(L); |
504 | setclvalue(L, L->top, cl); |
505 | incr_top(L); |
506 | } |
507 | |
508 | |
509 | int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) { |
510 | struct SParser p; |
511 | int status; |
512 | p.z = z; p.name = name; |
513 | luaZ_initbuffer(L, &p.buff); |
514 | status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc); |
515 | luaZ_freebuffer(L, &p.buff); |
516 | return status; |
517 | } |
518 | |
519 | |
520 | |