root/src/lua-5.1.3/src/ldo.c

Revision 5c8778c4361d2ad3adc94ef98d804c6fa9e6ba7c, 14.5 kB (checked in by Theo Schlossnagle <jesus@omniti.com>, 10 years ago)

import lua... I'd like to write checkers in lua

  • Property mode set to 100644
Line 
1 /*
2 ** $Id: ldo.c,v 2.38.1.3 2008/01/18 22:31:22 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     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
243 static 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
264 int 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
331 static 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->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */
336       luaD_callhook(L, LUA_HOOKTAILRET, -1);
337   }
338   return restorestack(L, fr);
339 }
340
341
342 int 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 */
369 void 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
383 static 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
408 static 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
417 LUA_API int lua_resume (lua_State *L, int nargs) {
418   int status;
419   lua_lock(L);
420   if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))
421       return resume_error(L, "cannot resume non-suspended coroutine");
422   if (L->nCcalls >= LUAI_MAXCCALLS)
423     return resume_error(L, "C stack overflow");
424   luai_userstateresume(L, nargs);
425   lua_assert(L->errfunc == 0);
426   L->baseCcalls = ++L->nCcalls;
427   status = luaD_rawrunprotected(L, resume, L->top - nargs);
428   if (status != 0) {  /* error? */
429     L->status = cast_byte(status);  /* mark thread as `dead' */
430     luaD_seterrorobj(L, status, L->top);
431     L->ci->top = L->top;
432   }
433   else {
434     lua_assert(L->nCcalls == L->baseCcalls);
435     status = L->status;
436   }
437   --L->nCcalls;
438   lua_unlock(L);
439   return status;
440 }
441
442
443 LUA_API int lua_yield (lua_State *L, int nresults) {
444   luai_userstateyield(L, nresults);
445   lua_lock(L);
446   if (L->nCcalls > L->baseCcalls)
447     luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
448   L->base = L->top - nresults;  /* protect stack slots below */
449   L->status = LUA_YIELD;
450   lua_unlock(L);
451   return -1;
452 }
453
454
455 int luaD_pcall (lua_State *L, Pfunc func, void *u,
456                 ptrdiff_t old_top, ptrdiff_t ef) {
457   int status;
458   unsigned short oldnCcalls = L->nCcalls;
459   ptrdiff_t old_ci = saveci(L, L->ci);
460   lu_byte old_allowhooks = L->allowhook;
461   ptrdiff_t old_errfunc = L->errfunc;
462   L->errfunc = ef;
463   status = luaD_rawrunprotected(L, func, u);
464   if (status != 0) {  /* an error occurred? */
465     StkId oldtop = restorestack(L, old_top);
466     luaF_close(L, oldtop);  /* close eventual pending closures */
467     luaD_seterrorobj(L, status, oldtop);
468     L->nCcalls = oldnCcalls;
469     L->ci = restoreci(L, old_ci);
470     L->base = L->ci->base;
471     L->savedpc = L->ci->savedpc;
472     L->allowhook = old_allowhooks;
473     restore_stack_limit(L);
474   }
475   L->errfunc = old_errfunc;
476   return status;
477 }
478
479
480
481 /*
482 ** Execute a protected parser.
483 */
484 struct SParser {  /* data to `f_parser' */
485   ZIO *z;
486   Mbuffer buff;  /* buffer to be used by the scanner */
487   const char *name;
488 };
489
490 static void f_parser (lua_State *L, void *ud) {
491   int i;
492   Proto *tf;
493   Closure *cl;
494   struct SParser *p = cast(struct SParser *, ud);
495   int c = luaZ_lookahead(p->z);
496   luaC_checkGC(L);
497   tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,
498                                                              &p->buff, p->name);
499   cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));
500   cl->l.p = tf;
501   for (i = 0; i < tf->nups; i++)  /* initialize eventual upvalues */
502     cl->l.upvals[i] = luaF_newupval(L);
503   setclvalue(L, L->top, cl);
504   incr_top(L);
505 }
506
507
508 int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {
509   struct SParser p;
510   int status;
511   p.z = z; p.name = name;
512   luaZ_initbuffer(L, &p.buff);
513   status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
514   luaZ_freebuffer(L, &p.buff);
515   return status;
516 }
517
518
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