1/*	$NetBSD$	*/
2
3/*
4** Id: ldo.c,v 2.38.1.3 2008/01/18 22:31:22 roberto Exp
5** Stack and Call structure of Lua
6** See Copyright Notice in lua.h
7*/
8
9
10#include <setjmp.h>
11#include <stdlib.h>
12#include <string.h>
13
14#define ldo_c
15#define LUA_CORE
16
17#include "lua.h"
18
19#include "ldebug.h"
20#include "ldo.h"
21#include "lfunc.h"
22#include "lgc.h"
23#include "lmem.h"
24#include "lobject.h"
25#include "lopcodes.h"
26#include "lparser.h"
27#include "lstate.h"
28#include "lstring.h"
29#include "ltable.h"
30#include "ltm.h"
31#include "lundump.h"
32#include "lvm.h"
33#include "lzio.h"
34
35
36
37
38/*
39** {======================================================
40** Error-recovery functions
41** =======================================================
42*/
43
44
45/* chain list of long jump buffers */
46struct lua_longjmp {
47  struct lua_longjmp *previous;
48  luai_jmpbuf b;
49  volatile int status;  /* error code */
50};
51
52
53void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {
54  switch (errcode) {
55    case LUA_ERRMEM: {
56      setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));
57      break;
58    }
59    case LUA_ERRERR: {
60      setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
61      break;
62    }
63    case LUA_ERRSYNTAX:
64    case LUA_ERRRUN: {
65      setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
66      break;
67    }
68  }
69  L->top = oldtop + 1;
70}
71
72
73static void restore_stack_limit (lua_State *L) {
74  lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
75  if (L->size_ci > LUAI_MAXCALLS) {  /* there was an overflow? */
76    int inuse = cast_int(L->ci - L->base_ci);
77    if (inuse + 1 < LUAI_MAXCALLS)  /* can `undo' overflow? */
78      luaD_reallocCI(L, LUAI_MAXCALLS);
79  }
80}
81
82
83static void resetstack (lua_State *L, int status) {
84  L->ci = L->base_ci;
85  L->base = L->ci->base;
86  luaF_close(L, L->base);  /* close eventual pending closures */
87  luaD_seterrorobj(L, status, L->base);
88  L->nCcalls = L->baseCcalls;
89  L->allowhook = 1;
90  restore_stack_limit(L);
91  L->errfunc = 0;
92  L->errorJmp = NULL;
93}
94
95
96void luaD_throw (lua_State *L, int errcode) {
97  if (L->errorJmp) {
98    L->errorJmp->status = errcode;
99    LUAI_THROW(L, L->errorJmp);
100  }
101  else {
102    L->status = cast_byte(errcode);
103    if (G(L)->panic) {
104      resetstack(L, errcode);
105      lua_unlock(L);
106      G(L)->panic(L);
107    }
108    exit(EXIT_FAILURE);
109  }
110}
111
112
113int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
114  struct lua_longjmp lj;
115  lj.status = 0;
116  lj.previous = L->errorJmp;  /* chain new error handler */
117  L->errorJmp = &lj;
118  LUAI_TRY(L, &lj,
119    (*f)(L, ud);
120  );
121  L->errorJmp = lj.previous;  /* restore old error handler */
122  return lj.status;
123}
124
125/* }====================================================== */
126
127
128static void correctstack (lua_State *L, TValue *oldstack) {
129  CallInfo *ci;
130  GCObject *up;
131  L->top = (L->top - oldstack) + L->stack;
132  for (up = L->openupval; up != NULL; up = up->gch.next)
133    gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
134  for (ci = L->base_ci; ci <= L->ci; ci++) {
135    ci->top = (ci->top - oldstack) + L->stack;
136    ci->base = (ci->base - oldstack) + L->stack;
137    ci->func = (ci->func - oldstack) + L->stack;
138  }
139  L->base = (L->base - oldstack) + L->stack;
140}
141
142
143void luaD_reallocstack (lua_State *L, int newsize) {
144  TValue *oldstack = L->stack;
145  int realsize = newsize + 1 + EXTRA_STACK;
146  lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
147  luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);
148  L->stacksize = realsize;
149  L->stack_last = L->stack+newsize;
150  correctstack(L, oldstack);
151}
152
153
154void luaD_reallocCI (lua_State *L, int newsize) {
155  CallInfo *oldci = L->base_ci;
156  luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo);
157  L->size_ci = newsize;
158  L->ci = (L->ci - oldci) + L->base_ci;
159  L->end_ci = L->base_ci + L->size_ci - 1;
160}
161
162
163void luaD_growstack (lua_State *L, int n) {
164  if (n <= L->stacksize)  /* double size is enough? */
165    luaD_reallocstack(L, 2*L->stacksize);
166  else
167    luaD_reallocstack(L, L->stacksize + n);
168}
169
170
171static CallInfo *growCI (lua_State *L) {
172  if (L->size_ci > LUAI_MAXCALLS)  /* overflow while handling overflow? */
173    luaD_throw(L, LUA_ERRERR);
174  else {
175    luaD_reallocCI(L, 2*L->size_ci);
176    if (L->size_ci > LUAI_MAXCALLS)
177      luaG_runerror(L, "stack overflow");
178  }
179  return ++L->ci;
180}
181
182
183void luaD_callhook (lua_State *L, int event, int line) {
184  lua_Hook hook = L->hook;
185  if (hook && L->allowhook) {
186    ptrdiff_t top = savestack(L, L->top);
187    ptrdiff_t ci_top = savestack(L, L->ci->top);
188    lua_Debug ar;
189    ar.event = event;
190    ar.currentline = line;
191    if (event == LUA_HOOKTAILRET)
192      ar.i_ci = 0;  /* tail call; no debug information about it */
193    else
194      ar.i_ci = cast_int(L->ci - L->base_ci);
195    luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
196    L->ci->top = L->top + LUA_MINSTACK;
197    lua_assert(L->ci->top <= L->stack_last);
198    L->allowhook = 0;  /* cannot call hooks inside a hook */
199    lua_unlock(L);
200    (*hook)(L, &ar);
201    lua_lock(L);
202    lua_assert(!L->allowhook);
203    L->allowhook = 1;
204    L->ci->top = restorestack(L, ci_top);
205    L->top = restorestack(L, top);
206  }
207}
208
209
210static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
211  int i;
212  int nfixargs = p->numparams;
213  Table *htab = NULL;
214  StkId base, fixed;
215  for (; actual < nfixargs; ++actual)
216    setnilvalue(L->top++);
217#if defined(LUA_COMPAT_VARARG)
218  if (p->is_vararg & VARARG_NEEDSARG) { /* compat. with old-style vararg? */
219    int nvar = actual - nfixargs;  /* number of extra arguments */
220    lua_assert(p->is_vararg & VARARG_HASARG);
221    luaC_checkGC(L);
222    htab = luaH_new(L, nvar, 1);  /* create `arg' table */
223    for (i=0; i<nvar; i++)  /* put extra arguments into `arg' table */
224      setobj2n(L, luaH_setnum(L, htab, i+1), L->top - nvar + i);
225    /* store counter in field `n' */
226    setnvalue(luaH_setstr(L, htab, luaS_newliteral(L, "n")), cast_num(nvar));
227  }
228#endif
229  /* move fixed parameters to final position */
230  fixed = L->top - actual;  /* first fixed argument */
231  base = L->top;  /* final position of first argument */
232  for (i=0; i<nfixargs; i++) {
233    setobjs2s(L, L->top++, fixed+i);
234    setnilvalue(fixed+i);
235  }
236  /* add `arg' parameter */
237  if (htab) {
238    sethvalue(L, L->top++, htab);
239    lua_assert(iswhite(obj2gco(htab)));
240  }
241  return base;
242}
243
244
245static StkId tryfuncTM (lua_State *L, StkId func) {
246  const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
247  StkId p;
248  ptrdiff_t funcr = savestack(L, func);
249  if (!ttisfunction(tm))
250    luaG_typeerror(L, func, "call");
251  /* Open a hole inside the stack at `func' */
252  for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
253  incr_top(L);
254  func = restorestack(L, funcr);  /* previous call may change stack */
255  setobj2s(L, func, tm);  /* tag method is the new function to be called */
256  return func;
257}
258
259
260
261#define inc_ci(L) \
262  ((L->ci == L->end_ci) ? growCI(L) : \
263   (condhardstacktests(luaD_reallocCI(L, L->size_ci)), ++L->ci))
264
265
266int luaD_precall (lua_State *L, StkId func, int nresults) {
267  LClosure *cl;
268  ptrdiff_t funcr;
269  if (!ttisfunction(func)) /* `func' is not a function? */
270    func = tryfuncTM(L, func);  /* check the `function' tag method */
271  funcr = savestack(L, func);
272  cl = &clvalue(func)->l;
273  L->ci->savedpc = L->savedpc;
274  if (!cl->isC) {  /* Lua function? prepare its call */
275    CallInfo *ci;
276    StkId st, base;
277    Proto *p = cl->p;
278    luaD_checkstack(L, p->maxstacksize);
279    func = restorestack(L, funcr);
280    if (!p->is_vararg) {  /* no varargs? */
281      base = func + 1;
282      if (L->top > base + p->numparams)
283        L->top = base + p->numparams;
284    }
285    else {  /* vararg function */
286      int nargs = cast_int(L->top - func) - 1;
287      base = adjust_varargs(L, p, nargs);
288      func = restorestack(L, funcr);  /* previous call may change the stack */
289    }
290    ci = inc_ci(L);  /* now `enter' new function */
291    ci->func = func;
292    L->base = ci->base = base;
293    ci->top = L->base + p->maxstacksize;
294    lua_assert(ci->top <= L->stack_last);
295    L->savedpc = p->code;  /* starting point */
296    ci->tailcalls = 0;
297    ci->nresults = nresults;
298    for (st = L->top; st < ci->top; st++)
299      setnilvalue(st);
300    L->top = ci->top;
301    if (L->hookmask & LUA_MASKCALL) {
302      L->savedpc++;  /* hooks assume 'pc' is already incremented */
303      luaD_callhook(L, LUA_HOOKCALL, -1);
304      L->savedpc--;  /* correct 'pc' */
305    }
306    return PCRLUA;
307  }
308  else {  /* if is a C function, call it */
309    CallInfo *ci;
310    int n;
311    luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
312    ci = inc_ci(L);  /* now `enter' new function */
313    ci->func = restorestack(L, funcr);
314    L->base = ci->base = ci->func + 1;
315    ci->top = L->top + LUA_MINSTACK;
316    lua_assert(ci->top <= L->stack_last);
317    ci->nresults = nresults;
318    if (L->hookmask & LUA_MASKCALL)
319      luaD_callhook(L, LUA_HOOKCALL, -1);
320    lua_unlock(L);
321    n = (*curr_func(L)->c.f)(L);  /* do the actual call */
322    lua_lock(L);
323    if (n < 0)  /* yielding? */
324      return PCRYIELD;
325    else {
326      luaD_poscall(L, L->top - n);
327      return PCRC;
328    }
329  }
330}
331
332
333static StkId callrethooks (lua_State *L, StkId firstResult) {
334  ptrdiff_t fr = savestack(L, firstResult);  /* next call may change stack */
335  luaD_callhook(L, LUA_HOOKRET, -1);
336  if (f_isLua(L->ci)) {  /* Lua function? */
337    while ((L->hookmask & LUA_MASKRET) && L->ci->tailcalls--) /* tail calls */
338      luaD_callhook(L, LUA_HOOKTAILRET, -1);
339  }
340  return restorestack(L, fr);
341}
342
343
344int luaD_poscall (lua_State *L, StkId firstResult) {
345  StkId res;
346  int wanted, i;
347  CallInfo *ci;
348  if (L->hookmask & LUA_MASKRET)
349    firstResult = callrethooks(L, firstResult);
350  ci = L->ci--;
351  res = ci->func;  /* res == final position of 1st result */
352  wanted = ci->nresults;
353  L->base = (ci - 1)->base;  /* restore base */
354  L->savedpc = (ci - 1)->savedpc;  /* restore savedpc */
355  /* move results to correct place */
356  for (i = wanted; i != 0 && firstResult < L->top; i--)
357    setobjs2s(L, res++, firstResult++);
358  while (i-- > 0)
359    setnilvalue(res++);
360  L->top = res;
361  return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
362}
363
364
365/*
366** Call a function (C or Lua). The function to be called is at *func.
367** The arguments are on the stack, right after the function.
368** When returns, all the results are on the stack, starting at the original
369** function position.
370*/
371void luaD_call (lua_State *L, StkId func, int nResults) {
372  if (++L->nCcalls >= LUAI_MAXCCALLS) {
373    if (L->nCcalls == LUAI_MAXCCALLS)
374      luaG_runerror(L, "C stack overflow");
375    else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
376      luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
377  }
378  if (luaD_precall(L, func, nResults) == PCRLUA)  /* is a Lua function? */
379    luaV_execute(L, 1);  /* call it */
380  L->nCcalls--;
381  luaC_checkGC(L);
382}
383
384
385static void resume (lua_State *L, void *ud) {
386  StkId firstArg = cast(StkId, ud);
387  CallInfo *ci = L->ci;
388  if (L->status == 0) {  /* start coroutine? */
389    lua_assert(ci == L->base_ci && firstArg > L->base);
390    if (luaD_precall(L, firstArg - 1, LUA_MULTRET) != PCRLUA)
391      return;
392  }
393  else {  /* resuming from previous yield */
394    lua_assert(L->status == LUA_YIELD);
395    L->status = 0;
396    if (!f_isLua(ci)) {  /* `common' yield? */
397      /* finish interrupted execution of `OP_CALL' */
398      lua_assert(GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_CALL ||
399                 GET_OPCODE(*((ci-1)->savedpc - 1)) == OP_TAILCALL);
400      if (luaD_poscall(L, firstArg))  /* complete it... */
401        L->top = L->ci->top;  /* and correct top if not multiple results */
402    }
403    else  /* yielded inside a hook: just continue its execution */
404      L->base = L->ci->base;
405  }
406  luaV_execute(L, cast_int(L->ci - L->base_ci));
407}
408
409
410static int resume_error (lua_State *L, const char *msg) {
411  L->top = L->ci->base;
412  setsvalue2s(L, L->top, luaS_new(L, msg));
413  incr_top(L);
414  lua_unlock(L);
415  return LUA_ERRRUN;
416}
417
418
419LUA_API int lua_resume (lua_State *L, int nargs) {
420  int status;
421  lua_lock(L);
422  if (L->status != LUA_YIELD && (L->status != 0 || L->ci != L->base_ci))
423      return resume_error(L, "cannot resume non-suspended coroutine");
424  if (L->nCcalls >= LUAI_MAXCCALLS)
425    return resume_error(L, "C stack overflow");
426  luai_userstateresume(L, nargs);
427  lua_assert(L->errfunc == 0);
428  L->baseCcalls = ++L->nCcalls;
429  status = luaD_rawrunprotected(L, resume, L->top - nargs);
430  if (status != 0) {  /* error? */
431    L->status = cast_byte(status);  /* mark thread as `dead' */
432    luaD_seterrorobj(L, status, L->top);
433    L->ci->top = L->top;
434  }
435  else {
436    lua_assert(L->nCcalls == L->baseCcalls);
437    status = L->status;
438  }
439  --L->nCcalls;
440  lua_unlock(L);
441  return status;
442}
443
444
445LUA_API int lua_yield (lua_State *L, int nresults) {
446  luai_userstateyield(L, nresults);
447  lua_lock(L);
448  if (L->nCcalls > L->baseCcalls)
449    luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
450  L->base = L->top - nresults;  /* protect stack slots below */
451  L->status = LUA_YIELD;
452  lua_unlock(L);
453  return -1;
454}
455
456
457int luaD_pcall (lua_State *L, Pfunc func, void *u,
458                ptrdiff_t old_top, ptrdiff_t ef) {
459  int status;
460  unsigned short oldnCcalls = L->nCcalls;
461  ptrdiff_t old_ci = saveci(L, L->ci);
462  lu_byte old_allowhooks = L->allowhook;
463  ptrdiff_t old_errfunc = L->errfunc;
464  L->errfunc = ef;
465  status = luaD_rawrunprotected(L, func, u);
466  if (status != 0) {  /* an error occurred? */
467    StkId oldtop = restorestack(L, old_top);
468    luaF_close(L, oldtop);  /* close eventual pending closures */
469    luaD_seterrorobj(L, status, oldtop);
470    L->nCcalls = oldnCcalls;
471    L->ci = restoreci(L, old_ci);
472    L->base = L->ci->base;
473    L->savedpc = L->ci->savedpc;
474    L->allowhook = old_allowhooks;
475    restore_stack_limit(L);
476  }
477  L->errfunc = old_errfunc;
478  return status;
479}
480
481
482
483/*
484** Execute a protected parser.
485*/
486struct SParser {  /* data to `f_parser' */
487  ZIO *z;
488  Mbuffer buff;  /* buffer to be used by the scanner */
489  const char *name;
490};
491
492static void f_parser (lua_State *L, void *ud) {
493  int i;
494  Proto *tf;
495  Closure *cl;
496  struct SParser *p = cast(struct SParser *, ud);
497  int c = luaZ_lookahead(p->z);
498  luaC_checkGC(L);
499  tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : luaY_parser)(L, p->z,
500                                                             &p->buff, p->name);
501  cl = luaF_newLclosure(L, tf->nups, hvalue(gt(L)));
502  cl->l.p = tf;
503  for (i = 0; i < tf->nups; i++)  /* initialize eventual upvalues */
504    cl->l.upvals[i] = luaF_newupval(L);
505  setclvalue(L, L->top, cl);
506  incr_top(L);
507}
508
509
510int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) {
511  struct SParser p;
512  int status;
513  p.z = z; p.name = name;
514  luaZ_initbuffer(L, &p.buff);
515  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
516  luaZ_freebuffer(L, &p.buff);
517  return status;
518}
519
520
521