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Root/lua/ldo.cc

1/*
2** $Id: ldo.c,v 2.38 2006/06/05 19:36:14 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 */
44struct lua_longjmp {
45 struct lua_longjmp *previous;
46 luai_jmpbuf b;
47 volatile int status; /* error code */
48};
49
50
51void 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
71static 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
81static 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 = 0;
87 L->allowhook = 1;
88 restore_stack_limit(L);
89 L->errfunc = 0;
90 L->errorJmp = NULL;
91}
92
93
94void 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
111int 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
126static 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
141void 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
152void 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
161void 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
169static 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
181void 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
208static 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 htab = luaH_new(L, nvar, 1); /* create `arg' table */
221 for (i=0; i<nvar; i++) /* put extra arguments into `arg' table */
222 setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);
223 /* store counter in field `n' */
224 setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));
225 }
226#endif
227 /* move fixed parameters to final position */
228 fixed = L->top - actual; /* first fixed argument */
229 base = L->top; /* final position of first argument */
230 for (i=0; i<nfixargs; i++) {
231 setobjs2s(L, L->top++, fixed+i);
232 setnilvalue(fixed+i);
233 }
234 /* add `arg' parameter */
235 if (htab) {
236 sethvalue(L, L->top++, htab);
237 lua_assert(iswhite(obj2gco(htab)));
238 }
239 return base;
240}
241
242
243static StkId tryfuncTM (lua_State *L, StkId func) {
244 const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
245 StkId p;
246 ptrdiff_t funcr = savestack(L, func);
247 if (!ttisfunction(tm))
248 luaG_typeerror(L, func, "call");
249 /* Open a hole inside the stack at `func' */
250 for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
251 incr_top(L);
252 func = restorestack(L, funcr); /* previous call may change stack */
253 setobj2s(L, func, tm); /* tag method is the new function to be called */
254 return func;
255}
256
257
258
259#define inc_ci(L) \
260 ((L->ci == L->end_ci) ? growCI(L) : \
261 (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))
262
263
264int luaD_precall (lua_State *L, StkId func, int nresults) {
265 LClosure *cl;
266 ptrdiff_t funcr;
267 if (!ttisfunction(func)) /* `func' is not a function? */
268 func = tryfuncTM(L, func); /* check the `function' tag method */
269 funcr = savestack(L, func);
270 cl = &clvalue(func)->l;
271 L->ci->savedpc = L->savedpc;
272 if (!cl->isC) { /* Lua function? prepare its call */
273 CallInfo *ci;
274 StkId st, base;
275 Proto *p = cl->p;
276 luaD_checkstack(L, p->maxstacksize);
277 func = restorestack(L, funcr);
278 if (!p->is_vararg) { /* no varargs? */
279 base = func + 1;
280 if (L->top > base + p->numparams)
281 L->top = base + p->numparams;
282 }
283 else { /* vararg function */
284 int nargs = cast_int(L->top - func) - 1;
285 base = adjust_varargs(L, p, nargs);
286 func = restorestack(L, funcr); /* previous call may change the stack */
287 }
288 ci = inc_ci(L); /* now `enter' new function */
289 ci->func = func;
290 L->base = ci->base = base;
291 ci->top = L->base + p->maxstacksize;
292 lua_assert(ci->top <= L->stack_last);
293 L->savedpc = p->code; /* starting point */
294 ci->tailcalls = 0;
295 ci->nresults = nresults;
296 for (st = L->top; st < ci->top; st++)
297 setnilvalue(st);
298 L->top = ci->top;
299 if (L->hookmask & LUA_MASKCALL) {
300 L->savedpc++; /* hooks assume 'pc' is already incremented */
301 luaD_callhook(L, LUA_HOOKCALL, -1);
302 L->savedpc--; /* correct 'pc' */
303 }
304 return PCRLUA;
305 }
306 else { /* if is a C function, call it */
307 CallInfo *ci;
308 int n;
309 luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
310 ci = inc_ci(L); /* now `enter' new function */
311 ci->func = restorestack(L, funcr);
312 L->base = ci->base = ci->func + 1;
313 ci->top = L->top + LUA_MINSTACK;
314 lua_assert(ci->top <= L->stack_last);
315 ci->nresults = nresults;
316 if (L->hookmask & LUA_MASKCALL)
317 luaD_callhook(L, LUA_HOOKCALL, -1);
318 lua_unlock(L);
319 n = (*curr_func(L)->c.f)(L); /* do the actual call */
320 lua_lock(L);
321 if (n < 0) /* yielding? */
322 return PCRYIELD;
323 else {
324 luaD_poscall(L, L->top - n);
325 return PCRC;
326 }
327 }
328}
329
330
331static StkId callrethooks (lua_State *L, StkId firstResult) {
332 ptrdiff_t fr = savestack(L, firstResult); /* next call may change stack */
333 luaD_callhook(L, LUA_HOOKRET, -1);
334 if (f_isLua(L->ci)) { /* Lua function? */
335 while (L->ci->tailcalls--) /* call hook for eventual tail calls */
336 luaD_callhook(L, LUA_HOOKTAILRET, -1);
337 }
338 return restorestack(L, fr);
339}
340
341
342int luaD_poscall (lua_State *L, StkId firstResult) {
343 StkId res;
344 int wanted, i;
345 CallInfo *ci;
346 if (L->hookmask & LUA_MASKRET)
347 firstResult = callrethooks(L, firstResult);
348 ci = L->ci--;
349 res = ci->func; /* res == final position of 1st result */
350 wanted = ci->nresults;
351 L->base = (ci - 1)->base; /* restore base */
352 L->savedpc = (ci - 1)->savedpc; /* restore savedpc */
353 /* move results to correct place */
354 for (i = wanted; i != 0 && firstResult < L->top; i--)
355 setobjs2s(L, res++, firstResult++);
356 while (i-- > 0)
357 setnilvalue(res++);
358 L->top = res;
359 return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
360}
361
362
363/*
364** Call a function (C or Lua). The function to be called is at *func.
365** The arguments are on the stack, right after the function.
366** When returns, all the results are on the stack, starting at the original
367** function position.
368*/
369void luaD_call (lua_State *L, StkId func, int nResults) {
370 if (++L->nCcalls >= LUAI_MAXCCALLS) {
371 if (L->nCcalls == LUAI_MAXCCALLS)
372 luaG_runerror(L, "C stack overflow");
373 else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
374 luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
375 }
376 if (luaD_precall(L, func, nResults) == PCRLUA) /* is a Lua function? */
377 luaV_execute(L, 1); /* call it */
378 L->nCcalls--;
379 luaC_checkGC(L);
380}
381
382
383static void resume (lua_State *L, void *ud) {
384 StkId firstArg = cast(StkId, ud);
385 CallInfo *ci = L->ci;
386 if (L->status == 0) { /* start coroutine? */
387 lua_assert(ci == L->base_ci && firstArg > L->base);
388 if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)
389 return;
390 }
391 else { /* resuming from previous yield */
392 lua_assert(L->status == LUA_YIELD);
393 L->status = 0;
394 if (!f_isLua(ci)) { /* `common' yield? */
395 /* finish interrupted execution of `OP_CALL' */
396 lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||
397 GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);
398 if (luaD_poscall(L, firstArg)) /* complete it... */
399 L->top = L->ci->top; /* and correct top if not multiple results */
400 }
401 else /* yielded inside a hook: just continue its execution */
402 L->base = L->ci->base;
403 }
404 luaV_execute(L, cast_int(L->ci - L->base_ci));
405}
406
407
408static int resume_error (lua_State *L, const char *msg) {
409 L->top = L->ci->base;
410 setsvalue2s(L, L->top, luaS_new(L, msg));
411 incr_top(L);
412 lua_unlock(L);
413 return LUA_ERRRUN;
414}
415
416
417LUA_API int lua_resume (lua_State *L, int nargs) {
418 int status;
419 lua_lock(L);
420 if (L->status != LUA_YIELD) {
421 if (L->status != 0)
422 return resume_error(L, "cannot resume dead coroutine");
423 else if (L->ci != L->base_ci)
424 return resume_error(L, "cannot resume non-suspended coroutine");
425 }
426 luai_userstateresume(L, nargs);
427 lua_assert(L->errfunc == 0 && L->nCcalls == 0);
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 status = L->status;
436 lua_unlock(L);
437 return status;
438}
439
440
441LUA_API int lua_yield (lua_State *L, int nresults) {
442 luai_userstateyield(L, nresults);
443 lua_lock(L);
444 if (L->nCcalls > 0)
445 luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
446 L->base = L->top - nresults; /* protect stack slots below */
447 L->status = LUA_YIELD;
448 lua_unlock(L);
449 return -1;
450}
451
452
453int luaD_pcall (lua_State *L, Pfunc func, void *u,
454 ptrdiff_t old_top, ptrdiff_t ef) {
455 int status;
456 unsigned short oldnCcalls = L->nCcalls;
457 ptrdiff_t old_ci = saveci(L, L->ci);
458 lu_byte old_allowhooks = L->allowhook;
459 ptrdiff_t old_errfunc = L->errfunc;
460 L->errfunc = ef;
461 status = luaD_rawrunprotected(L, func, u);
462 if (status != 0) { /* an error occurred? */
463 StkId oldtop = restorestack(L, old_top);
464 luaF_close(L, oldtop); /* close eventual pending closures */
465 luaD_seterrorobj(L, status, oldtop);
466 L->nCcalls = oldnCcalls;
467 L->ci = restoreci(L, old_ci);
468 L->base = L->ci->base;
469 L->savedpc = L->ci->savedpc;
470 L->allowhook = old_allowhooks;
471 restore_stack_limit(L);
472 }
473 L->errfunc = old_errfunc;
474 return status;
475}
476
477
478
479/*
480** Execute a protected parser.
481*/
482struct SParser { /* data to `f_parser' */
483 ZIO *z;
484 Mbuffer buff; /* buffer to be used by the scanner */
485 const char *name;
486};
487
488static void f_parser (lua_State *L, void *ud) {
489 int i;
490 Proto *tf;
491 Closure *cl;
492 struct SParser *p = cast(struct SParser *, ud);
493 int c = luaZ_lookahead(p->z);
494 luaC_checkGC(L);
495 tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,
496 &p->buff, p->name);
497 cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));
498 cl->l.p = tf;
499 for (i = 0; i < tf->nups; i++) /* initialize eventual upvalues */
500 cl->l.upvals[i] = luaF_newupval(L);
501 setclvalue(L, L->top, cl);
502 incr_top(L);
503}
504
505
506int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {
507 struct SParser p;
508 int status;
509 p.z = z; p.name = name;
510 luaZ_initbuffer(L, &p.buff);
511 status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
512 luaZ_freebuffer(L, &p.buff);
513 return status;
514}
515
516

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