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  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);
  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.   int c = luaZ_lookahead(p->z);
  497.   luaC_checkGC(L);
  498.   tf = ((c == LUA_SIGNATURE[0]) ? luaU_undump : 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.