Home | History | Annotate | Download | only in src
      1 /*
      2 ** $Id: lapi.c,v 2.171 2013/03/16 21:10:18 roberto Exp $
      3 ** Lua API
      4 ** See Copyright Notice in lua.h
      5 */
      6 
      7 
      8 #include <stdarg.h>
      9 #include <string.h>
     10 
     11 #define lapi_c
     12 #define LUA_CORE
     13 
     14 #include "lua.h"
     15 
     16 #include "lapi.h"
     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 "lstate.h"
     24 #include "lstring.h"
     25 #include "ltable.h"
     26 #include "ltm.h"
     27 #include "lundump.h"
     28 #include "lvm.h"
     29 
     30 
     31 
     32 const char lua_ident[] =
     33   "$LuaVersion: " LUA_COPYRIGHT " $"
     34   "$LuaAuthors: " LUA_AUTHORS " $";
     35 
     36 
     37 /* value at a non-valid index */
     38 #define NONVALIDVALUE		cast(TValue *, luaO_nilobject)
     39 
     40 /* corresponding test */
     41 #define isvalid(o)	((o) != luaO_nilobject)
     42 
     43 /* test for pseudo index */
     44 #define ispseudo(i)		((i) <= LUA_REGISTRYINDEX)
     45 
     46 /* test for valid but not pseudo index */
     47 #define isstackindex(i, o)	(isvalid(o) && !ispseudo(i))
     48 
     49 #define api_checkvalidindex(L, o)  api_check(L, isvalid(o), "invalid index")
     50 
     51 #define api_checkstackindex(L, i, o)  \
     52 	api_check(L, isstackindex(i, o), "index not in the stack")
     53 
     54 
     55 static TValue *index2addr (lua_State *L, int idx) {
     56   CallInfo *ci = L->ci;
     57   if (idx > 0) {
     58     TValue *o = ci->func + idx;
     59     api_check(L, idx <= ci->top - (ci->func + 1), "unacceptable index");
     60     if (o >= L->top) return NONVALIDVALUE;
     61     else return o;
     62   }
     63   else if (!ispseudo(idx)) {  /* negative index */
     64     api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
     65     return L->top + idx;
     66   }
     67   else if (idx == LUA_REGISTRYINDEX)
     68     return &G(L)->l_registry;
     69   else {  /* upvalues */
     70     idx = LUA_REGISTRYINDEX - idx;
     71     api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large");
     72     if (ttislcf(ci->func))  /* light C function? */
     73       return NONVALIDVALUE;  /* it has no upvalues */
     74     else {
     75       CClosure *func = clCvalue(ci->func);
     76       return (idx <= func->nupvalues) ? &func->upvalue[idx-1] : NONVALIDVALUE;
     77     }
     78   }
     79 }
     80 
     81 
     82 /*
     83 ** to be called by 'lua_checkstack' in protected mode, to grow stack
     84 ** capturing memory errors
     85 */
     86 static void growstack (lua_State *L, void *ud) {
     87   int size = *(int *)ud;
     88   luaD_growstack(L, size);
     89 }
     90 
     91 
     92 LUA_API int lua_checkstack (lua_State *L, int size) {
     93   int res;
     94   CallInfo *ci = L->ci;
     95   lua_lock(L);
     96   if (L->stack_last - L->top > size)  /* stack large enough? */
     97     res = 1;  /* yes; check is OK */
     98   else {  /* no; need to grow stack */
     99     int inuse = cast_int(L->top - L->stack) + EXTRA_STACK;
    100     if (inuse > LUAI_MAXSTACK - size)  /* can grow without overflow? */
    101       res = 0;  /* no */
    102     else  /* try to grow stack */
    103       res = (luaD_rawrunprotected(L, &growstack, &size) == LUA_OK);
    104   }
    105   if (res && ci->top < L->top + size)
    106     ci->top = L->top + size;  /* adjust frame top */
    107   lua_unlock(L);
    108   return res;
    109 }
    110 
    111 
    112 LUA_API void lua_xmove (lua_State *from, lua_State *to, int n) {
    113   int i;
    114   if (from == to) return;
    115   lua_lock(to);
    116   api_checknelems(from, n);
    117   api_check(from, G(from) == G(to), "moving among independent states");
    118   api_check(from, to->ci->top - to->top >= n, "not enough elements to move");
    119   from->top -= n;
    120   for (i = 0; i < n; i++) {
    121     setobj2s(to, to->top++, from->top + i);
    122   }
    123   lua_unlock(to);
    124 }
    125 
    126 
    127 LUA_API lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf) {
    128   lua_CFunction old;
    129   lua_lock(L);
    130   old = G(L)->panic;
    131   G(L)->panic = panicf;
    132   lua_unlock(L);
    133   return old;
    134 }
    135 
    136 
    137 LUA_API const lua_Number *lua_version (lua_State *L) {
    138   static const lua_Number version = LUA_VERSION_NUM;
    139   if (L == NULL) return &version;
    140   else return G(L)->version;
    141 }
    142 
    143 
    144 
    145 /*
    146 ** basic stack manipulation
    147 */
    148 
    149 
    150 /*
    151 ** convert an acceptable stack index into an absolute index
    152 */
    153 LUA_API int lua_absindex (lua_State *L, int idx) {
    154   return (idx > 0 || ispseudo(idx))
    155          ? idx
    156          : cast_int(L->top - L->ci->func + idx);
    157 }
    158 
    159 
    160 LUA_API int lua_gettop (lua_State *L) {
    161   return cast_int(L->top - (L->ci->func + 1));
    162 }
    163 
    164 
    165 LUA_API void lua_settop (lua_State *L, int idx) {
    166   StkId func = L->ci->func;
    167   lua_lock(L);
    168   if (idx >= 0) {
    169     api_check(L, idx <= L->stack_last - (func + 1), "new top too large");
    170     while (L->top < (func + 1) + idx)
    171       setnilvalue(L->top++);
    172     L->top = (func + 1) + idx;
    173   }
    174   else {
    175     api_check(L, -(idx+1) <= (L->top - (func + 1)), "invalid new top");
    176     L->top += idx+1;  /* `subtract' index (index is negative) */
    177   }
    178   lua_unlock(L);
    179 }
    180 
    181 
    182 LUA_API void lua_remove (lua_State *L, int idx) {
    183   StkId p;
    184   lua_lock(L);
    185   p = index2addr(L, idx);
    186   api_checkstackindex(L, idx, p);
    187   while (++p < L->top) setobjs2s(L, p-1, p);
    188   L->top--;
    189   lua_unlock(L);
    190 }
    191 
    192 
    193 LUA_API void lua_insert (lua_State *L, int idx) {
    194   StkId p;
    195   StkId q;
    196   lua_lock(L);
    197   p = index2addr(L, idx);
    198   api_checkstackindex(L, idx, p);
    199   for (q = L->top; q > p; q--)  /* use L->top as a temporary */
    200     setobjs2s(L, q, q - 1);
    201   setobjs2s(L, p, L->top);
    202   lua_unlock(L);
    203 }
    204 
    205 
    206 static void moveto (lua_State *L, TValue *fr, int idx) {
    207   TValue *to = index2addr(L, idx);
    208   api_checkvalidindex(L, to);
    209   setobj(L, to, fr);
    210   if (idx < LUA_REGISTRYINDEX)  /* function upvalue? */
    211     luaC_barrier(L, clCvalue(L->ci->func), fr);
    212   /* LUA_REGISTRYINDEX does not need gc barrier
    213      (collector revisits it before finishing collection) */
    214 }
    215 
    216 
    217 LUA_API void lua_replace (lua_State *L, int idx) {
    218   lua_lock(L);
    219   api_checknelems(L, 1);
    220   moveto(L, L->top - 1, idx);
    221   L->top--;
    222   lua_unlock(L);
    223 }
    224 
    225 
    226 LUA_API void lua_copy (lua_State *L, int fromidx, int toidx) {
    227   TValue *fr;
    228   lua_lock(L);
    229   fr = index2addr(L, fromidx);
    230   moveto(L, fr, toidx);
    231   lua_unlock(L);
    232 }
    233 
    234 
    235 LUA_API void lua_pushvalue (lua_State *L, int idx) {
    236   lua_lock(L);
    237   setobj2s(L, L->top, index2addr(L, idx));
    238   api_incr_top(L);
    239   lua_unlock(L);
    240 }
    241 
    242 
    243 
    244 /*
    245 ** access functions (stack -> C)
    246 */
    247 
    248 
    249 LUA_API int lua_type (lua_State *L, int idx) {
    250   StkId o = index2addr(L, idx);
    251   return (isvalid(o) ? ttypenv(o) : LUA_TNONE);
    252 }
    253 
    254 
    255 LUA_API const char *lua_typename (lua_State *L, int t) {
    256   UNUSED(L);
    257   return ttypename(t);
    258 }
    259 
    260 
    261 LUA_API int lua_iscfunction (lua_State *L, int idx) {
    262   StkId o = index2addr(L, idx);
    263   return (ttislcf(o) || (ttisCclosure(o)));
    264 }
    265 
    266 
    267 LUA_API int lua_isnumber (lua_State *L, int idx) {
    268   TValue n;
    269   const TValue *o = index2addr(L, idx);
    270   return tonumber(o, &n);
    271 }
    272 
    273 
    274 LUA_API int lua_isstring (lua_State *L, int idx) {
    275   int t = lua_type(L, idx);
    276   return (t == LUA_TSTRING || t == LUA_TNUMBER);
    277 }
    278 
    279 
    280 LUA_API int lua_isuserdata (lua_State *L, int idx) {
    281   const TValue *o = index2addr(L, idx);
    282   return (ttisuserdata(o) || ttislightuserdata(o));
    283 }
    284 
    285 
    286 LUA_API int lua_rawequal (lua_State *L, int index1, int index2) {
    287   StkId o1 = index2addr(L, index1);
    288   StkId o2 = index2addr(L, index2);
    289   return (isvalid(o1) && isvalid(o2)) ? luaV_rawequalobj(o1, o2) : 0;
    290 }
    291 
    292 
    293 LUA_API void lua_arith (lua_State *L, int op) {
    294   StkId o1;  /* 1st operand */
    295   StkId o2;  /* 2nd operand */
    296   lua_lock(L);
    297   if (op != LUA_OPUNM) /* all other operations expect two operands */
    298     api_checknelems(L, 2);
    299   else {  /* for unary minus, add fake 2nd operand */
    300     api_checknelems(L, 1);
    301     setobjs2s(L, L->top, L->top - 1);
    302     L->top++;
    303   }
    304   o1 = L->top - 2;
    305   o2 = L->top - 1;
    306   if (ttisnumber(o1) && ttisnumber(o2)) {
    307     setnvalue(o1, luaO_arith(op, nvalue(o1), nvalue(o2)));
    308   }
    309   else
    310     luaV_arith(L, o1, o1, o2, cast(TMS, op - LUA_OPADD + TM_ADD));
    311   L->top--;
    312   lua_unlock(L);
    313 }
    314 
    315 
    316 LUA_API int lua_compare (lua_State *L, int index1, int index2, int op) {
    317   StkId o1, o2;
    318   int i = 0;
    319   lua_lock(L);  /* may call tag method */
    320   o1 = index2addr(L, index1);
    321   o2 = index2addr(L, index2);
    322   if (isvalid(o1) && isvalid(o2)) {
    323     switch (op) {
    324       case LUA_OPEQ: i = equalobj(L, o1, o2); break;
    325       case LUA_OPLT: i = luaV_lessthan(L, o1, o2); break;
    326       case LUA_OPLE: i = luaV_lessequal(L, o1, o2); break;
    327       default: api_check(L, 0, "invalid option");
    328     }
    329   }
    330   lua_unlock(L);
    331   return i;
    332 }
    333 
    334 
    335 LUA_API lua_Number lua_tonumberx (lua_State *L, int idx, int *isnum) {
    336   TValue n;
    337   const TValue *o = index2addr(L, idx);
    338   if (tonumber(o, &n)) {
    339     if (isnum) *isnum = 1;
    340     return nvalue(o);
    341   }
    342   else {
    343     if (isnum) *isnum = 0;
    344     return 0;
    345   }
    346 }
    347 
    348 
    349 LUA_API lua_Integer lua_tointegerx (lua_State *L, int idx, int *isnum) {
    350   TValue n;
    351   const TValue *o = index2addr(L, idx);
    352   if (tonumber(o, &n)) {
    353     lua_Integer res;
    354     lua_Number num = nvalue(o);
    355     lua_number2integer(res, num);
    356     if (isnum) *isnum = 1;
    357     return res;
    358   }
    359   else {
    360     if (isnum) *isnum = 0;
    361     return 0;
    362   }
    363 }
    364 
    365 
    366 LUA_API lua_Unsigned lua_tounsignedx (lua_State *L, int idx, int *isnum) {
    367   TValue n;
    368   const TValue *o = index2addr(L, idx);
    369   if (tonumber(o, &n)) {
    370     lua_Unsigned res;
    371     lua_Number num = nvalue(o);
    372     lua_number2unsigned(res, num);
    373     if (isnum) *isnum = 1;
    374     return res;
    375   }
    376   else {
    377     if (isnum) *isnum = 0;
    378     return 0;
    379   }
    380 }
    381 
    382 
    383 LUA_API int lua_toboolean (lua_State *L, int idx) {
    384   const TValue *o = index2addr(L, idx);
    385   return !l_isfalse(o);
    386 }
    387 
    388 
    389 LUA_API const char *lua_tolstring (lua_State *L, int idx, size_t *len) {
    390   StkId o = index2addr(L, idx);
    391   if (!ttisstring(o)) {
    392     lua_lock(L);  /* `luaV_tostring' may create a new string */
    393     if (!luaV_tostring(L, o)) {  /* conversion failed? */
    394       if (len != NULL) *len = 0;
    395       lua_unlock(L);
    396       return NULL;
    397     }
    398     luaC_checkGC(L);
    399     o = index2addr(L, idx);  /* previous call may reallocate the stack */
    400     lua_unlock(L);
    401   }
    402   if (len != NULL) *len = tsvalue(o)->len;
    403   return svalue(o);
    404 }
    405 
    406 
    407 LUA_API size_t lua_rawlen (lua_State *L, int idx) {
    408   StkId o = index2addr(L, idx);
    409   switch (ttypenv(o)) {
    410     case LUA_TSTRING: return tsvalue(o)->len;
    411     case LUA_TUSERDATA: return uvalue(o)->len;
    412     case LUA_TTABLE: return luaH_getn(hvalue(o));
    413     default: return 0;
    414   }
    415 }
    416 
    417 
    418 LUA_API lua_CFunction lua_tocfunction (lua_State *L, int idx) {
    419   StkId o = index2addr(L, idx);
    420   if (ttislcf(o)) return fvalue(o);
    421   else if (ttisCclosure(o))
    422     return clCvalue(o)->f;
    423   else return NULL;  /* not a C function */
    424 }
    425 
    426 
    427 LUA_API void *lua_touserdata (lua_State *L, int idx) {
    428   StkId o = index2addr(L, idx);
    429   switch (ttypenv(o)) {
    430     case LUA_TUSERDATA: return (rawuvalue(o) + 1);
    431     case LUA_TLIGHTUSERDATA: return pvalue(o);
    432     default: return NULL;
    433   }
    434 }
    435 
    436 
    437 LUA_API lua_State *lua_tothread (lua_State *L, int idx) {
    438   StkId o = index2addr(L, idx);
    439   return (!ttisthread(o)) ? NULL : thvalue(o);
    440 }
    441 
    442 
    443 LUA_API const void *lua_topointer (lua_State *L, int idx) {
    444   StkId o = index2addr(L, idx);
    445   switch (ttype(o)) {
    446     case LUA_TTABLE: return hvalue(o);
    447     case LUA_TLCL: return clLvalue(o);
    448     case LUA_TCCL: return clCvalue(o);
    449     case LUA_TLCF: return cast(void *, cast(size_t, fvalue(o)));
    450     case LUA_TTHREAD: return thvalue(o);
    451     case LUA_TUSERDATA:
    452     case LUA_TLIGHTUSERDATA:
    453       return lua_touserdata(L, idx);
    454     default: return NULL;
    455   }
    456 }
    457 
    458 
    459 
    460 /*
    461 ** push functions (C -> stack)
    462 */
    463 
    464 
    465 LUA_API void lua_pushnil (lua_State *L) {
    466   lua_lock(L);
    467   setnilvalue(L->top);
    468   api_incr_top(L);
    469   lua_unlock(L);
    470 }
    471 
    472 
    473 LUA_API void lua_pushnumber (lua_State *L, lua_Number n) {
    474   lua_lock(L);
    475   setnvalue(L->top, n);
    476   luai_checknum(L, L->top,
    477     luaG_runerror(L, "C API - attempt to push a signaling NaN"));
    478   api_incr_top(L);
    479   lua_unlock(L);
    480 }
    481 
    482 
    483 LUA_API void lua_pushinteger (lua_State *L, lua_Integer n) {
    484   lua_lock(L);
    485   setnvalue(L->top, cast_num(n));
    486   api_incr_top(L);
    487   lua_unlock(L);
    488 }
    489 
    490 
    491 LUA_API void lua_pushunsigned (lua_State *L, lua_Unsigned u) {
    492   lua_Number n;
    493   lua_lock(L);
    494   n = lua_unsigned2number(u);
    495   setnvalue(L->top, n);
    496   api_incr_top(L);
    497   lua_unlock(L);
    498 }
    499 
    500 
    501 LUA_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) {
    502   TString *ts;
    503   lua_lock(L);
    504   luaC_checkGC(L);
    505   ts = luaS_newlstr(L, s, len);
    506   setsvalue2s(L, L->top, ts);
    507   api_incr_top(L);
    508   lua_unlock(L);
    509   return getstr(ts);
    510 }
    511 
    512 
    513 LUA_API const char *lua_pushstring (lua_State *L, const char *s) {
    514   if (s == NULL) {
    515     lua_pushnil(L);
    516     return NULL;
    517   }
    518   else {
    519     TString *ts;
    520     lua_lock(L);
    521     luaC_checkGC(L);
    522     ts = luaS_new(L, s);
    523     setsvalue2s(L, L->top, ts);
    524     api_incr_top(L);
    525     lua_unlock(L);
    526     return getstr(ts);
    527   }
    528 }
    529 
    530 
    531 LUA_API const char *lua_pushvfstring (lua_State *L, const char *fmt,
    532                                       va_list argp) {
    533   const char *ret;
    534   lua_lock(L);
    535   luaC_checkGC(L);
    536   ret = luaO_pushvfstring(L, fmt, argp);
    537   lua_unlock(L);
    538   return ret;
    539 }
    540 
    541 
    542 LUA_API const char *lua_pushfstring (lua_State *L, const char *fmt, ...) {
    543   const char *ret;
    544   va_list argp;
    545   lua_lock(L);
    546   luaC_checkGC(L);
    547   va_start(argp, fmt);
    548   ret = luaO_pushvfstring(L, fmt, argp);
    549   va_end(argp);
    550   lua_unlock(L);
    551   return ret;
    552 }
    553 
    554 
    555 LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
    556   lua_lock(L);
    557   if (n == 0) {
    558     setfvalue(L->top, fn);
    559   }
    560   else {
    561     Closure *cl;
    562     api_checknelems(L, n);
    563     api_check(L, n <= MAXUPVAL, "upvalue index too large");
    564     luaC_checkGC(L);
    565     cl = luaF_newCclosure(L, n);
    566     cl->c.f = fn;
    567     L->top -= n;
    568     while (n--)
    569       setobj2n(L, &cl->c.upvalue[n], L->top + n);
    570     setclCvalue(L, L->top, cl);
    571   }
    572   api_incr_top(L);
    573   lua_unlock(L);
    574 }
    575 
    576 
    577 LUA_API void lua_pushboolean (lua_State *L, int b) {
    578   lua_lock(L);
    579   setbvalue(L->top, (b != 0));  /* ensure that true is 1 */
    580   api_incr_top(L);
    581   lua_unlock(L);
    582 }
    583 
    584 
    585 LUA_API void lua_pushlightuserdata (lua_State *L, void *p) {
    586   lua_lock(L);
    587   setpvalue(L->top, p);
    588   api_incr_top(L);
    589   lua_unlock(L);
    590 }
    591 
    592 
    593 LUA_API int lua_pushthread (lua_State *L) {
    594   lua_lock(L);
    595   setthvalue(L, L->top, L);
    596   api_incr_top(L);
    597   lua_unlock(L);
    598   return (G(L)->mainthread == L);
    599 }
    600 
    601 
    602 
    603 /*
    604 ** get functions (Lua -> stack)
    605 */
    606 
    607 
    608 LUA_API void lua_getglobal (lua_State *L, const char *var) {
    609   Table *reg = hvalue(&G(L)->l_registry);
    610   const TValue *gt;  /* global table */
    611   lua_lock(L);
    612   gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
    613   setsvalue2s(L, L->top++, luaS_new(L, var));
    614   luaV_gettable(L, gt, L->top - 1, L->top - 1);
    615   lua_unlock(L);
    616 }
    617 
    618 
    619 LUA_API void lua_gettable (lua_State *L, int idx) {
    620   StkId t;
    621   lua_lock(L);
    622   t = index2addr(L, idx);
    623   luaV_gettable(L, t, L->top - 1, L->top - 1);
    624   lua_unlock(L);
    625 }
    626 
    627 
    628 LUA_API void lua_getfield (lua_State *L, int idx, const char *k) {
    629   StkId t;
    630   lua_lock(L);
    631   t = index2addr(L, idx);
    632   setsvalue2s(L, L->top, luaS_new(L, k));
    633   api_incr_top(L);
    634   luaV_gettable(L, t, L->top - 1, L->top - 1);
    635   lua_unlock(L);
    636 }
    637 
    638 
    639 LUA_API void lua_rawget (lua_State *L, int idx) {
    640   StkId t;
    641   lua_lock(L);
    642   t = index2addr(L, idx);
    643   api_check(L, ttistable(t), "table expected");
    644   setobj2s(L, L->top - 1, luaH_get(hvalue(t), L->top - 1));
    645   lua_unlock(L);
    646 }
    647 
    648 
    649 LUA_API void lua_rawgeti (lua_State *L, int idx, int n) {
    650   StkId t;
    651   lua_lock(L);
    652   t = index2addr(L, idx);
    653   api_check(L, ttistable(t), "table expected");
    654   setobj2s(L, L->top, luaH_getint(hvalue(t), n));
    655   api_incr_top(L);
    656   lua_unlock(L);
    657 }
    658 
    659 
    660 LUA_API void lua_rawgetp (lua_State *L, int idx, const void *p) {
    661   StkId t;
    662   TValue k;
    663   lua_lock(L);
    664   t = index2addr(L, idx);
    665   api_check(L, ttistable(t), "table expected");
    666   setpvalue(&k, cast(void *, p));
    667   setobj2s(L, L->top, luaH_get(hvalue(t), &k));
    668   api_incr_top(L);
    669   lua_unlock(L);
    670 }
    671 
    672 
    673 LUA_API void lua_createtable (lua_State *L, int narray, int nrec) {
    674   Table *t;
    675   lua_lock(L);
    676   luaC_checkGC(L);
    677   t = luaH_new(L);
    678   sethvalue(L, L->top, t);
    679   api_incr_top(L);
    680   if (narray > 0 || nrec > 0)
    681     luaH_resize(L, t, narray, nrec);
    682   lua_unlock(L);
    683 }
    684 
    685 
    686 LUA_API int lua_getmetatable (lua_State *L, int objindex) {
    687   const TValue *obj;
    688   Table *mt = NULL;
    689   int res;
    690   lua_lock(L);
    691   obj = index2addr(L, objindex);
    692   switch (ttypenv(obj)) {
    693     case LUA_TTABLE:
    694       mt = hvalue(obj)->metatable;
    695       break;
    696     case LUA_TUSERDATA:
    697       mt = uvalue(obj)->metatable;
    698       break;
    699     default:
    700       mt = G(L)->mt[ttypenv(obj)];
    701       break;
    702   }
    703   if (mt == NULL)
    704     res = 0;
    705   else {
    706     sethvalue(L, L->top, mt);
    707     api_incr_top(L);
    708     res = 1;
    709   }
    710   lua_unlock(L);
    711   return res;
    712 }
    713 
    714 
    715 LUA_API void lua_getuservalue (lua_State *L, int idx) {
    716   StkId o;
    717   lua_lock(L);
    718   o = index2addr(L, idx);
    719   api_check(L, ttisuserdata(o), "userdata expected");
    720   if (uvalue(o)->env) {
    721     sethvalue(L, L->top, uvalue(o)->env);
    722   } else
    723     setnilvalue(L->top);
    724   api_incr_top(L);
    725   lua_unlock(L);
    726 }
    727 
    728 
    729 /*
    730 ** set functions (stack -> Lua)
    731 */
    732 
    733 
    734 LUA_API void lua_setglobal (lua_State *L, const char *var) {
    735   Table *reg = hvalue(&G(L)->l_registry);
    736   const TValue *gt;  /* global table */
    737   lua_lock(L);
    738   api_checknelems(L, 1);
    739   gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
    740   setsvalue2s(L, L->top++, luaS_new(L, var));
    741   luaV_settable(L, gt, L->top - 1, L->top - 2);
    742   L->top -= 2;  /* pop value and key */
    743   lua_unlock(L);
    744 }
    745 
    746 
    747 LUA_API void lua_settable (lua_State *L, int idx) {
    748   StkId t;
    749   lua_lock(L);
    750   api_checknelems(L, 2);
    751   t = index2addr(L, idx);
    752   luaV_settable(L, t, L->top - 2, L->top - 1);
    753   L->top -= 2;  /* pop index and value */
    754   lua_unlock(L);
    755 }
    756 
    757 
    758 LUA_API void lua_setfield (lua_State *L, int idx, const char *k) {
    759   StkId t;
    760   lua_lock(L);
    761   api_checknelems(L, 1);
    762   t = index2addr(L, idx);
    763   setsvalue2s(L, L->top++, luaS_new(L, k));
    764   luaV_settable(L, t, L->top - 1, L->top - 2);
    765   L->top -= 2;  /* pop value and key */
    766   lua_unlock(L);
    767 }
    768 
    769 
    770 LUA_API void lua_rawset (lua_State *L, int idx) {
    771   StkId t;
    772   lua_lock(L);
    773   api_checknelems(L, 2);
    774   t = index2addr(L, idx);
    775   api_check(L, ttistable(t), "table expected");
    776   setobj2t(L, luaH_set(L, hvalue(t), L->top-2), L->top-1);
    777   invalidateTMcache(hvalue(t));
    778   luaC_barrierback(L, gcvalue(t), L->top-1);
    779   L->top -= 2;
    780   lua_unlock(L);
    781 }
    782 
    783 
    784 LUA_API void lua_rawseti (lua_State *L, int idx, int n) {
    785   StkId t;
    786   lua_lock(L);
    787   api_checknelems(L, 1);
    788   t = index2addr(L, idx);
    789   api_check(L, ttistable(t), "table expected");
    790   luaH_setint(L, hvalue(t), n, L->top - 1);
    791   luaC_barrierback(L, gcvalue(t), L->top-1);
    792   L->top--;
    793   lua_unlock(L);
    794 }
    795 
    796 
    797 LUA_API void lua_rawsetp (lua_State *L, int idx, const void *p) {
    798   StkId t;
    799   TValue k;
    800   lua_lock(L);
    801   api_checknelems(L, 1);
    802   t = index2addr(L, idx);
    803   api_check(L, ttistable(t), "table expected");
    804   setpvalue(&k, cast(void *, p));
    805   setobj2t(L, luaH_set(L, hvalue(t), &k), L->top - 1);
    806   luaC_barrierback(L, gcvalue(t), L->top - 1);
    807   L->top--;
    808   lua_unlock(L);
    809 }
    810 
    811 
    812 LUA_API int lua_setmetatable (lua_State *L, int objindex) {
    813   TValue *obj;
    814   Table *mt;
    815   lua_lock(L);
    816   api_checknelems(L, 1);
    817   obj = index2addr(L, objindex);
    818   if (ttisnil(L->top - 1))
    819     mt = NULL;
    820   else {
    821     api_check(L, ttistable(L->top - 1), "table expected");
    822     mt = hvalue(L->top - 1);
    823   }
    824   switch (ttypenv(obj)) {
    825     case LUA_TTABLE: {
    826       hvalue(obj)->metatable = mt;
    827       if (mt) {
    828         luaC_objbarrierback(L, gcvalue(obj), mt);
    829         luaC_checkfinalizer(L, gcvalue(obj), mt);
    830       }
    831       break;
    832     }
    833     case LUA_TUSERDATA: {
    834       uvalue(obj)->metatable = mt;
    835       if (mt) {
    836         luaC_objbarrier(L, rawuvalue(obj), mt);
    837         luaC_checkfinalizer(L, gcvalue(obj), mt);
    838       }
    839       break;
    840     }
    841     default: {
    842       G(L)->mt[ttypenv(obj)] = mt;
    843       break;
    844     }
    845   }
    846   L->top--;
    847   lua_unlock(L);
    848   return 1;
    849 }
    850 
    851 
    852 LUA_API void lua_setuservalue (lua_State *L, int idx) {
    853   StkId o;
    854   lua_lock(L);
    855   api_checknelems(L, 1);
    856   o = index2addr(L, idx);
    857   api_check(L, ttisuserdata(o), "userdata expected");
    858   if (ttisnil(L->top - 1))
    859     uvalue(o)->env = NULL;
    860   else {
    861     api_check(L, ttistable(L->top - 1), "table expected");
    862     uvalue(o)->env = hvalue(L->top - 1);
    863     luaC_objbarrier(L, gcvalue(o), hvalue(L->top - 1));
    864   }
    865   L->top--;
    866   lua_unlock(L);
    867 }
    868 
    869 
    870 /*
    871 ** `load' and `call' functions (run Lua code)
    872 */
    873 
    874 
    875 #define checkresults(L,na,nr) \
    876      api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)), \
    877 	"results from function overflow current stack size")
    878 
    879 
    880 LUA_API int lua_getctx (lua_State *L, int *ctx) {
    881   if (L->ci->callstatus & CIST_YIELDED) {
    882     if (ctx) *ctx = L->ci->u.c.ctx;
    883     return L->ci->u.c.status;
    884   }
    885   else return LUA_OK;
    886 }
    887 
    888 
    889 LUA_API void lua_callk (lua_State *L, int nargs, int nresults, int ctx,
    890                         lua_CFunction k) {
    891   StkId func;
    892   lua_lock(L);
    893   api_check(L, k == NULL || !isLua(L->ci),
    894     "cannot use continuations inside hooks");
    895   api_checknelems(L, nargs+1);
    896   api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
    897   checkresults(L, nargs, nresults);
    898   func = L->top - (nargs+1);
    899   if (k != NULL && L->nny == 0) {  /* need to prepare continuation? */
    900     L->ci->u.c.k = k;  /* save continuation */
    901     L->ci->u.c.ctx = ctx;  /* save context */
    902     luaD_call(L, func, nresults, 1);  /* do the call */
    903   }
    904   else  /* no continuation or no yieldable */
    905     luaD_call(L, func, nresults, 0);  /* just do the call */
    906   adjustresults(L, nresults);
    907   lua_unlock(L);
    908 }
    909 
    910 
    911 
    912 /*
    913 ** Execute a protected call.
    914 */
    915 struct CallS {  /* data to `f_call' */
    916   StkId func;
    917   int nresults;
    918 };
    919 
    920 
    921 static void f_call (lua_State *L, void *ud) {
    922   struct CallS *c = cast(struct CallS *, ud);
    923   luaD_call(L, c->func, c->nresults, 0);
    924 }
    925 
    926 
    927 
    928 LUA_API int lua_pcallk (lua_State *L, int nargs, int nresults, int errfunc,
    929                         int ctx, lua_CFunction k) {
    930   struct CallS c;
    931   int status;
    932   ptrdiff_t func;
    933   lua_lock(L);
    934   api_check(L, k == NULL || !isLua(L->ci),
    935     "cannot use continuations inside hooks");
    936   api_checknelems(L, nargs+1);
    937   api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
    938   checkresults(L, nargs, nresults);
    939   if (errfunc == 0)
    940     func = 0;
    941   else {
    942     StkId o = index2addr(L, errfunc);
    943     api_checkstackindex(L, errfunc, o);
    944     func = savestack(L, o);
    945   }
    946   c.func = L->top - (nargs+1);  /* function to be called */
    947   if (k == NULL || L->nny > 0) {  /* no continuation or no yieldable? */
    948     c.nresults = nresults;  /* do a 'conventional' protected call */
    949     status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func);
    950   }
    951   else {  /* prepare continuation (call is already protected by 'resume') */
    952     CallInfo *ci = L->ci;
    953     ci->u.c.k = k;  /* save continuation */
    954     ci->u.c.ctx = ctx;  /* save context */
    955     /* save information for error recovery */
    956     ci->extra = savestack(L, c.func);
    957     ci->u.c.old_allowhook = L->allowhook;
    958     ci->u.c.old_errfunc = L->errfunc;
    959     L->errfunc = func;
    960     /* mark that function may do error recovery */
    961     ci->callstatus |= CIST_YPCALL;
    962     luaD_call(L, c.func, nresults, 1);  /* do the call */
    963     ci->callstatus &= ~CIST_YPCALL;
    964     L->errfunc = ci->u.c.old_errfunc;
    965     status = LUA_OK;  /* if it is here, there were no errors */
    966   }
    967   adjustresults(L, nresults);
    968   lua_unlock(L);
    969   return status;
    970 }
    971 
    972 
    973 LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data,
    974                       const char *chunkname, const char *mode) {
    975   ZIO z;
    976   int status;
    977   lua_lock(L);
    978   if (!chunkname) chunkname = "?";
    979   luaZ_init(L, &z, reader, data);
    980   status = luaD_protectedparser(L, &z, chunkname, mode);
    981   if (status == LUA_OK) {  /* no errors? */
    982     LClosure *f = clLvalue(L->top - 1);  /* get newly created function */
    983     if (f->nupvalues == 1) {  /* does it have one upvalue? */
    984       /* get global table from registry */
    985       Table *reg = hvalue(&G(L)->l_registry);
    986       const TValue *gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
    987       /* set global table as 1st upvalue of 'f' (may be LUA_ENV) */
    988       setobj(L, f->upvals[0]->v, gt);
    989       luaC_barrier(L, f->upvals[0], gt);
    990     }
    991   }
    992   lua_unlock(L);
    993   return status;
    994 }
    995 
    996 
    997 LUA_API int lua_dump (lua_State *L, lua_Writer writer, void *data) {
    998   int status;
    999   TValue *o;
   1000   lua_lock(L);
   1001   api_checknelems(L, 1);
   1002   o = L->top - 1;
   1003   if (isLfunction(o))
   1004     status = luaU_dump(L, getproto(o), writer, data, 0);
   1005   else
   1006     status = 1;
   1007   lua_unlock(L);
   1008   return status;
   1009 }
   1010 
   1011 
   1012 LUA_API int lua_status (lua_State *L) {
   1013   return L->status;
   1014 }
   1015 
   1016 
   1017 /*
   1018 ** Garbage-collection function
   1019 */
   1020 
   1021 LUA_API int lua_gc (lua_State *L, int what, int data) {
   1022   int res = 0;
   1023   global_State *g;
   1024   lua_lock(L);
   1025   g = G(L);
   1026   switch (what) {
   1027     case LUA_GCSTOP: {
   1028       g->gcrunning = 0;
   1029       break;
   1030     }
   1031     case LUA_GCRESTART: {
   1032       luaE_setdebt(g, 0);
   1033       g->gcrunning = 1;
   1034       break;
   1035     }
   1036     case LUA_GCCOLLECT: {
   1037       luaC_fullgc(L, 0);
   1038       break;
   1039     }
   1040     case LUA_GCCOUNT: {
   1041       /* GC values are expressed in Kbytes: #bytes/2^10 */
   1042       res = cast_int(gettotalbytes(g) >> 10);
   1043       break;
   1044     }
   1045     case LUA_GCCOUNTB: {
   1046       res = cast_int(gettotalbytes(g) & 0x3ff);
   1047       break;
   1048     }
   1049     case LUA_GCSTEP: {
   1050       if (g->gckind == KGC_GEN) {  /* generational mode? */
   1051         res = (g->GCestimate == 0);  /* true if it will do major collection */
   1052         luaC_forcestep(L);  /* do a single step */
   1053       }
   1054       else {
   1055        lu_mem debt = cast(lu_mem, data) * 1024 - GCSTEPSIZE;
   1056        if (g->gcrunning)
   1057          debt += g->GCdebt;  /* include current debt */
   1058        luaE_setdebt(g, debt);
   1059        luaC_forcestep(L);
   1060        if (g->gcstate == GCSpause)  /* end of cycle? */
   1061          res = 1;  /* signal it */
   1062       }
   1063       break;
   1064     }
   1065     case LUA_GCSETPAUSE: {
   1066       res = g->gcpause;
   1067       g->gcpause = data;
   1068       break;
   1069     }
   1070     case LUA_GCSETMAJORINC: {
   1071       res = g->gcmajorinc;
   1072       g->gcmajorinc = data;
   1073       break;
   1074     }
   1075     case LUA_GCSETSTEPMUL: {
   1076       res = g->gcstepmul;
   1077       g->gcstepmul = data;
   1078       break;
   1079     }
   1080     case LUA_GCISRUNNING: {
   1081       res = g->gcrunning;
   1082       break;
   1083     }
   1084     case LUA_GCGEN: {  /* change collector to generational mode */
   1085       luaC_changemode(L, KGC_GEN);
   1086       break;
   1087     }
   1088     case LUA_GCINC: {  /* change collector to incremental mode */
   1089       luaC_changemode(L, KGC_NORMAL);
   1090       break;
   1091     }
   1092     default: res = -1;  /* invalid option */
   1093   }
   1094   lua_unlock(L);
   1095   return res;
   1096 }
   1097 
   1098 
   1099 
   1100 /*
   1101 ** miscellaneous functions
   1102 */
   1103 
   1104 
   1105 LUA_API int lua_error (lua_State *L) {
   1106   lua_lock(L);
   1107   api_checknelems(L, 1);
   1108   luaG_errormsg(L);
   1109   /* code unreachable; will unlock when control actually leaves the kernel */
   1110   return 0;  /* to avoid warnings */
   1111 }
   1112 
   1113 
   1114 LUA_API int lua_next (lua_State *L, int idx) {
   1115   StkId t;
   1116   int more;
   1117   lua_lock(L);
   1118   t = index2addr(L, idx);
   1119   api_check(L, ttistable(t), "table expected");
   1120   more = luaH_next(L, hvalue(t), L->top - 1);
   1121   if (more) {
   1122     api_incr_top(L);
   1123   }
   1124   else  /* no more elements */
   1125     L->top -= 1;  /* remove key */
   1126   lua_unlock(L);
   1127   return more;
   1128 }
   1129 
   1130 
   1131 LUA_API void lua_concat (lua_State *L, int n) {
   1132   lua_lock(L);
   1133   api_checknelems(L, n);
   1134   if (n >= 2) {
   1135     luaC_checkGC(L);
   1136     luaV_concat(L, n);
   1137   }
   1138   else if (n == 0) {  /* push empty string */
   1139     setsvalue2s(L, L->top, luaS_newlstr(L, "", 0));
   1140     api_incr_top(L);
   1141   }
   1142   /* else n == 1; nothing to do */
   1143   lua_unlock(L);
   1144 }
   1145 
   1146 
   1147 LUA_API void lua_len (lua_State *L, int idx) {
   1148   StkId t;
   1149   lua_lock(L);
   1150   t = index2addr(L, idx);
   1151   luaV_objlen(L, L->top, t);
   1152   api_incr_top(L);
   1153   lua_unlock(L);
   1154 }
   1155 
   1156 
   1157 LUA_API lua_Alloc lua_getallocf (lua_State *L, void **ud) {
   1158   lua_Alloc f;
   1159   lua_lock(L);
   1160   if (ud) *ud = G(L)->ud;
   1161   f = G(L)->frealloc;
   1162   lua_unlock(L);
   1163   return f;
   1164 }
   1165 
   1166 
   1167 LUA_API void lua_setallocf (lua_State *L, lua_Alloc f, void *ud) {
   1168   lua_lock(L);
   1169   G(L)->ud = ud;
   1170   G(L)->frealloc = f;
   1171   lua_unlock(L);
   1172 }
   1173 
   1174 
   1175 LUA_API void *lua_newuserdata (lua_State *L, size_t size) {
   1176   Udata *u;
   1177   lua_lock(L);
   1178   luaC_checkGC(L);
   1179   u = luaS_newudata(L, size, NULL);
   1180   setuvalue(L, L->top, u);
   1181   api_incr_top(L);
   1182   lua_unlock(L);
   1183   return u + 1;
   1184 }
   1185 
   1186 
   1187 
   1188 static const char *aux_upvalue (StkId fi, int n, TValue **val,
   1189                                 GCObject **owner) {
   1190   switch (ttype(fi)) {
   1191     case LUA_TCCL: {  /* C closure */
   1192       CClosure *f = clCvalue(fi);
   1193       if (!(1 <= n && n <= f->nupvalues)) return NULL;
   1194       *val = &f->upvalue[n-1];
   1195       if (owner) *owner = obj2gco(f);
   1196       return "";
   1197     }
   1198     case LUA_TLCL: {  /* Lua closure */
   1199       LClosure *f = clLvalue(fi);
   1200       TString *name;
   1201       Proto *p = f->p;
   1202       if (!(1 <= n && n <= p->sizeupvalues)) return NULL;
   1203       *val = f->upvals[n-1]->v;
   1204       if (owner) *owner = obj2gco(f->upvals[n - 1]);
   1205       name = p->upvalues[n-1].name;
   1206       return (name == NULL) ? "" : getstr(name);
   1207     }
   1208     default: return NULL;  /* not a closure */
   1209   }
   1210 }
   1211 
   1212 
   1213 LUA_API const char *lua_getupvalue (lua_State *L, int funcindex, int n) {
   1214   const char *name;
   1215   TValue *val = NULL;  /* to avoid warnings */
   1216   lua_lock(L);
   1217   name = aux_upvalue(index2addr(L, funcindex), n, &val, NULL);
   1218   if (name) {
   1219     setobj2s(L, L->top, val);
   1220     api_incr_top(L);
   1221   }
   1222   lua_unlock(L);
   1223   return name;
   1224 }
   1225 
   1226 
   1227 LUA_API const char *lua_setupvalue (lua_State *L, int funcindex, int n) {
   1228   const char *name;
   1229   TValue *val = NULL;  /* to avoid warnings */
   1230   GCObject *owner = NULL;  /* to avoid warnings */
   1231   StkId fi;
   1232   lua_lock(L);
   1233   fi = index2addr(L, funcindex);
   1234   api_checknelems(L, 1);
   1235   name = aux_upvalue(fi, n, &val, &owner);
   1236   if (name) {
   1237     L->top--;
   1238     setobj(L, val, L->top);
   1239     luaC_barrier(L, owner, L->top);
   1240   }
   1241   lua_unlock(L);
   1242   return name;
   1243 }
   1244 
   1245 
   1246 static UpVal **getupvalref (lua_State *L, int fidx, int n, LClosure **pf) {
   1247   LClosure *f;
   1248   StkId fi = index2addr(L, fidx);
   1249   api_check(L, ttisLclosure(fi), "Lua function expected");
   1250   f = clLvalue(fi);
   1251   api_check(L, (1 <= n && n <= f->p->sizeupvalues), "invalid upvalue index");
   1252   if (pf) *pf = f;
   1253   return &f->upvals[n - 1];  /* get its upvalue pointer */
   1254 }
   1255 
   1256 
   1257 LUA_API void *lua_upvalueid (lua_State *L, int fidx, int n) {
   1258   StkId fi = index2addr(L, fidx);
   1259   switch (ttype(fi)) {
   1260     case LUA_TLCL: {  /* lua closure */
   1261       return *getupvalref(L, fidx, n, NULL);
   1262     }
   1263     case LUA_TCCL: {  /* C closure */
   1264       CClosure *f = clCvalue(fi);
   1265       api_check(L, 1 <= n && n <= f->nupvalues, "invalid upvalue index");
   1266       return &f->upvalue[n - 1];
   1267     }
   1268     default: {
   1269       api_check(L, 0, "closure expected");
   1270       return NULL;
   1271     }
   1272   }
   1273 }
   1274 
   1275 
   1276 LUA_API void lua_upvaluejoin (lua_State *L, int fidx1, int n1,
   1277                                             int fidx2, int n2) {
   1278   LClosure *f1;
   1279   UpVal **up1 = getupvalref(L, fidx1, n1, &f1);
   1280   UpVal **up2 = getupvalref(L, fidx2, n2, NULL);
   1281   *up1 = *up2;
   1282   luaC_objbarrier(L, f1, *up2);
   1283 }
   1284 
   1285