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      1 /*
      2 ** $Id: lauxlib.c,v 1.248 2013/03/21 13:54:57 roberto Exp $
      3 ** Auxiliary functions for building Lua libraries
      4 ** See Copyright Notice in lua.h
      5 */
      6 
      7 
      8 #include <errno.h>
      9 #include <stdarg.h>
     10 #include <stdio.h>
     11 #include <stdlib.h>
     12 #include <string.h>
     13 
     14 
     15 /* This file uses only the official API of Lua.
     16 ** Any function declared here could be written as an application function.
     17 */
     18 
     19 #define lauxlib_c
     20 #define LUA_LIB
     21 
     22 #include "lua.h"
     23 
     24 #include "lauxlib.h"
     25 
     26 
     27 /*
     28 ** {======================================================
     29 ** Traceback
     30 ** =======================================================
     31 */
     32 
     33 
     34 #define LEVELS1	12	/* size of the first part of the stack */
     35 #define LEVELS2	10	/* size of the second part of the stack */
     36 
     37 
     38 
     39 /*
     40 ** search for 'objidx' in table at index -1.
     41 ** return 1 + string at top if find a good name.
     42 */
     43 static int findfield (lua_State *L, int objidx, int level) {
     44   if (level == 0 || !lua_istable(L, -1))
     45     return 0;  /* not found */
     46   lua_pushnil(L);  /* start 'next' loop */
     47   while (lua_next(L, -2)) {  /* for each pair in table */
     48     if (lua_type(L, -2) == LUA_TSTRING) {  /* ignore non-string keys */
     49       if (lua_rawequal(L, objidx, -1)) {  /* found object? */
     50         lua_pop(L, 1);  /* remove value (but keep name) */
     51         return 1;
     52       }
     53       else if (findfield(L, objidx, level - 1)) {  /* try recursively */
     54         lua_remove(L, -2);  /* remove table (but keep name) */
     55         lua_pushliteral(L, ".");
     56         lua_insert(L, -2);  /* place '.' between the two names */
     57         lua_concat(L, 3);
     58         return 1;
     59       }
     60     }
     61     lua_pop(L, 1);  /* remove value */
     62   }
     63   return 0;  /* not found */
     64 }
     65 
     66 
     67 static int pushglobalfuncname (lua_State *L, lua_Debug *ar) {
     68   int top = lua_gettop(L);
     69   lua_getinfo(L, "f", ar);  /* push function */
     70   lua_pushglobaltable(L);
     71   if (findfield(L, top + 1, 2)) {
     72     lua_copy(L, -1, top + 1);  /* move name to proper place */
     73     lua_pop(L, 2);  /* remove pushed values */
     74     return 1;
     75   }
     76   else {
     77     lua_settop(L, top);  /* remove function and global table */
     78     return 0;
     79   }
     80 }
     81 
     82 
     83 static void pushfuncname (lua_State *L, lua_Debug *ar) {
     84   if (*ar->namewhat != '\0')  /* is there a name? */
     85     lua_pushfstring(L, "function " LUA_QS, ar->name);
     86   else if (*ar->what == 'm')  /* main? */
     87       lua_pushliteral(L, "main chunk");
     88   else if (*ar->what == 'C') {
     89     if (pushglobalfuncname(L, ar)) {
     90       lua_pushfstring(L, "function " LUA_QS, lua_tostring(L, -1));
     91       lua_remove(L, -2);  /* remove name */
     92     }
     93     else
     94       lua_pushliteral(L, "?");
     95   }
     96   else
     97     lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
     98 }
     99 
    100 
    101 static int countlevels (lua_State *L) {
    102   lua_Debug ar;
    103   int li = 1, le = 1;
    104   /* find an upper bound */
    105   while (lua_getstack(L, le, &ar)) { li = le; le *= 2; }
    106   /* do a binary search */
    107   while (li < le) {
    108     int m = (li + le)/2;
    109     if (lua_getstack(L, m, &ar)) li = m + 1;
    110     else le = m;
    111   }
    112   return le - 1;
    113 }
    114 
    115 
    116 LUALIB_API void luaL_traceback (lua_State *L, lua_State *L1,
    117                                 const char *msg, int level) {
    118   lua_Debug ar;
    119   int top = lua_gettop(L);
    120   int numlevels = countlevels(L1);
    121   int mark = (numlevels > LEVELS1 + LEVELS2) ? LEVELS1 : 0;
    122   if (msg) lua_pushfstring(L, "%s\n", msg);
    123   lua_pushliteral(L, "stack traceback:");
    124   while (lua_getstack(L1, level++, &ar)) {
    125     if (level == mark) {  /* too many levels? */
    126       lua_pushliteral(L, "\n\t...");  /* add a '...' */
    127       level = numlevels - LEVELS2;  /* and skip to last ones */
    128     }
    129     else {
    130       lua_getinfo(L1, "Slnt", &ar);
    131       lua_pushfstring(L, "\n\t%s:", ar.short_src);
    132       if (ar.currentline > 0)
    133         lua_pushfstring(L, "%d:", ar.currentline);
    134       lua_pushliteral(L, " in ");
    135       pushfuncname(L, &ar);
    136       if (ar.istailcall)
    137         lua_pushliteral(L, "\n\t(...tail calls...)");
    138       lua_concat(L, lua_gettop(L) - top);
    139     }
    140   }
    141   lua_concat(L, lua_gettop(L) - top);
    142 }
    143 
    144 /* }====================================================== */
    145 
    146 
    147 /*
    148 ** {======================================================
    149 ** Error-report functions
    150 ** =======================================================
    151 */
    152 
    153 LUALIB_API int luaL_argerror (lua_State *L, int narg, const char *extramsg) {
    154   lua_Debug ar;
    155   if (!lua_getstack(L, 0, &ar))  /* no stack frame? */
    156     return luaL_error(L, "bad argument #%d (%s)", narg, extramsg);
    157   lua_getinfo(L, "n", &ar);
    158   if (strcmp(ar.namewhat, "method") == 0) {
    159     narg--;  /* do not count `self' */
    160     if (narg == 0)  /* error is in the self argument itself? */
    161       return luaL_error(L, "calling " LUA_QS " on bad self (%s)",
    162                            ar.name, extramsg);
    163   }
    164   if (ar.name == NULL)
    165     ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?";
    166   return luaL_error(L, "bad argument #%d to " LUA_QS " (%s)",
    167                         narg, ar.name, extramsg);
    168 }
    169 
    170 
    171 static int typeerror (lua_State *L, int narg, const char *tname) {
    172   const char *msg = lua_pushfstring(L, "%s expected, got %s",
    173                                     tname, luaL_typename(L, narg));
    174   return luaL_argerror(L, narg, msg);
    175 }
    176 
    177 
    178 static void tag_error (lua_State *L, int narg, int tag) {
    179   typeerror(L, narg, lua_typename(L, tag));
    180 }
    181 
    182 
    183 LUALIB_API void luaL_where (lua_State *L, int level) {
    184   lua_Debug ar;
    185   if (lua_getstack(L, level, &ar)) {  /* check function at level */
    186     lua_getinfo(L, "Sl", &ar);  /* get info about it */
    187     if (ar.currentline > 0) {  /* is there info? */
    188       lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline);
    189       return;
    190     }
    191   }
    192   lua_pushliteral(L, "");  /* else, no information available... */
    193 }
    194 
    195 
    196 LUALIB_API int luaL_error (lua_State *L, const char *fmt, ...) {
    197   va_list argp;
    198   va_start(argp, fmt);
    199   luaL_where(L, 1);
    200   lua_pushvfstring(L, fmt, argp);
    201   va_end(argp);
    202   lua_concat(L, 2);
    203   return lua_error(L);
    204 }
    205 
    206 
    207 LUALIB_API int luaL_fileresult (lua_State *L, int stat, const char *fname) {
    208   int en = errno;  /* calls to Lua API may change this value */
    209   if (stat) {
    210     lua_pushboolean(L, 1);
    211     return 1;
    212   }
    213   else {
    214     lua_pushnil(L);
    215     if (fname)
    216       lua_pushfstring(L, "%s: %s", fname, strerror(en));
    217     else
    218       lua_pushstring(L, strerror(en));
    219     lua_pushinteger(L, en);
    220     return 3;
    221   }
    222 }
    223 
    224 
    225 #if !defined(inspectstat)	/* { */
    226 
    227 #if defined(LUA_USE_POSIX)
    228 
    229 #include <sys/wait.h>
    230 
    231 /*
    232 ** use appropriate macros to interpret 'pclose' return status
    233 */
    234 #define inspectstat(stat,what)  \
    235    if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
    236    else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }
    237 
    238 #else
    239 
    240 #define inspectstat(stat,what)  /* no op */
    241 
    242 #endif
    243 
    244 #endif				/* } */
    245 
    246 
    247 LUALIB_API int luaL_execresult (lua_State *L, int stat) {
    248   const char *what = "exit";  /* type of termination */
    249   if (stat == -1)  /* error? */
    250     return luaL_fileresult(L, 0, NULL);
    251   else {
    252     inspectstat(stat, what);  /* interpret result */
    253     if (*what == 'e' && stat == 0)  /* successful termination? */
    254       lua_pushboolean(L, 1);
    255     else
    256       lua_pushnil(L);
    257     lua_pushstring(L, what);
    258     lua_pushinteger(L, stat);
    259     return 3;  /* return true/nil,what,code */
    260   }
    261 }
    262 
    263 /* }====================================================== */
    264 
    265 
    266 /*
    267 ** {======================================================
    268 ** Userdata's metatable manipulation
    269 ** =======================================================
    270 */
    271 
    272 LUALIB_API int luaL_newmetatable (lua_State *L, const char *tname) {
    273   luaL_getmetatable(L, tname);  /* try to get metatable */
    274   if (!lua_isnil(L, -1))  /* name already in use? */
    275     return 0;  /* leave previous value on top, but return 0 */
    276   lua_pop(L, 1);
    277   lua_newtable(L);  /* create metatable */
    278   lua_pushvalue(L, -1);
    279   lua_setfield(L, LUA_REGISTRYINDEX, tname);  /* registry.name = metatable */
    280   return 1;
    281 }
    282 
    283 
    284 LUALIB_API void luaL_setmetatable (lua_State *L, const char *tname) {
    285   luaL_getmetatable(L, tname);
    286   lua_setmetatable(L, -2);
    287 }
    288 
    289 
    290 LUALIB_API void *luaL_testudata (lua_State *L, int ud, const char *tname) {
    291   void *p = lua_touserdata(L, ud);
    292   if (p != NULL) {  /* value is a userdata? */
    293     if (lua_getmetatable(L, ud)) {  /* does it have a metatable? */
    294       luaL_getmetatable(L, tname);  /* get correct metatable */
    295       if (!lua_rawequal(L, -1, -2))  /* not the same? */
    296         p = NULL;  /* value is a userdata with wrong metatable */
    297       lua_pop(L, 2);  /* remove both metatables */
    298       return p;
    299     }
    300   }
    301   return NULL;  /* value is not a userdata with a metatable */
    302 }
    303 
    304 
    305 LUALIB_API void *luaL_checkudata (lua_State *L, int ud, const char *tname) {
    306   void *p = luaL_testudata(L, ud, tname);
    307   if (p == NULL) typeerror(L, ud, tname);
    308   return p;
    309 }
    310 
    311 /* }====================================================== */
    312 
    313 
    314 /*
    315 ** {======================================================
    316 ** Argument check functions
    317 ** =======================================================
    318 */
    319 
    320 LUALIB_API int luaL_checkoption (lua_State *L, int narg, const char *def,
    321                                  const char *const lst[]) {
    322   const char *name = (def) ? luaL_optstring(L, narg, def) :
    323                              luaL_checkstring(L, narg);
    324   int i;
    325   for (i=0; lst[i]; i++)
    326     if (strcmp(lst[i], name) == 0)
    327       return i;
    328   return luaL_argerror(L, narg,
    329                        lua_pushfstring(L, "invalid option " LUA_QS, name));
    330 }
    331 
    332 
    333 LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *msg) {
    334   /* keep some extra space to run error routines, if needed */
    335   const int extra = LUA_MINSTACK;
    336   if (!lua_checkstack(L, space + extra)) {
    337     if (msg)
    338       luaL_error(L, "stack overflow (%s)", msg);
    339     else
    340       luaL_error(L, "stack overflow");
    341   }
    342 }
    343 
    344 
    345 LUALIB_API void luaL_checktype (lua_State *L, int narg, int t) {
    346   if (lua_type(L, narg) != t)
    347     tag_error(L, narg, t);
    348 }
    349 
    350 
    351 LUALIB_API void luaL_checkany (lua_State *L, int narg) {
    352   if (lua_type(L, narg) == LUA_TNONE)
    353     luaL_argerror(L, narg, "value expected");
    354 }
    355 
    356 
    357 LUALIB_API const char *luaL_checklstring (lua_State *L, int narg, size_t *len) {
    358   const char *s = lua_tolstring(L, narg, len);
    359   if (!s) tag_error(L, narg, LUA_TSTRING);
    360   return s;
    361 }
    362 
    363 
    364 LUALIB_API const char *luaL_optlstring (lua_State *L, int narg,
    365                                         const char *def, size_t *len) {
    366   if (lua_isnoneornil(L, narg)) {
    367     if (len)
    368       *len = (def ? strlen(def) : 0);
    369     return def;
    370   }
    371   else return luaL_checklstring(L, narg, len);
    372 }
    373 
    374 
    375 LUALIB_API lua_Number luaL_checknumber (lua_State *L, int narg) {
    376   int isnum;
    377   lua_Number d = lua_tonumberx(L, narg, &isnum);
    378   if (!isnum)
    379     tag_error(L, narg, LUA_TNUMBER);
    380   return d;
    381 }
    382 
    383 
    384 LUALIB_API lua_Number luaL_optnumber (lua_State *L, int narg, lua_Number def) {
    385   return luaL_opt(L, luaL_checknumber, narg, def);
    386 }
    387 
    388 
    389 LUALIB_API lua_Integer luaL_checkinteger (lua_State *L, int narg) {
    390   int isnum;
    391   lua_Integer d = lua_tointegerx(L, narg, &isnum);
    392   if (!isnum)
    393     tag_error(L, narg, LUA_TNUMBER);
    394   return d;
    395 }
    396 
    397 
    398 LUALIB_API lua_Unsigned luaL_checkunsigned (lua_State *L, int narg) {
    399   int isnum;
    400   lua_Unsigned d = lua_tounsignedx(L, narg, &isnum);
    401   if (!isnum)
    402     tag_error(L, narg, LUA_TNUMBER);
    403   return d;
    404 }
    405 
    406 
    407 LUALIB_API lua_Integer luaL_optinteger (lua_State *L, int narg,
    408                                                       lua_Integer def) {
    409   return luaL_opt(L, luaL_checkinteger, narg, def);
    410 }
    411 
    412 
    413 LUALIB_API lua_Unsigned luaL_optunsigned (lua_State *L, int narg,
    414                                                         lua_Unsigned def) {
    415   return luaL_opt(L, luaL_checkunsigned, narg, def);
    416 }
    417 
    418 /* }====================================================== */
    419 
    420 
    421 /*
    422 ** {======================================================
    423 ** Generic Buffer manipulation
    424 ** =======================================================
    425 */
    426 
    427 /*
    428 ** check whether buffer is using a userdata on the stack as a temporary
    429 ** buffer
    430 */
    431 #define buffonstack(B)	((B)->b != (B)->initb)
    432 
    433 
    434 /*
    435 ** returns a pointer to a free area with at least 'sz' bytes
    436 */
    437 LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) {
    438   lua_State *L = B->L;
    439   if (B->size - B->n < sz) {  /* not enough space? */
    440     char *newbuff;
    441     size_t newsize = B->size * 2;  /* double buffer size */
    442     if (newsize - B->n < sz)  /* not big enough? */
    443       newsize = B->n + sz;
    444     if (newsize < B->n || newsize - B->n < sz)
    445       luaL_error(L, "buffer too large");
    446     /* create larger buffer */
    447     newbuff = (char *)lua_newuserdata(L, newsize * sizeof(char));
    448     /* move content to new buffer */
    449     memcpy(newbuff, B->b, B->n * sizeof(char));
    450     if (buffonstack(B))
    451       lua_remove(L, -2);  /* remove old buffer */
    452     B->b = newbuff;
    453     B->size = newsize;
    454   }
    455   return &B->b[B->n];
    456 }
    457 
    458 
    459 LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {
    460   char *b = luaL_prepbuffsize(B, l);
    461   memcpy(b, s, l * sizeof(char));
    462   luaL_addsize(B, l);
    463 }
    464 
    465 
    466 LUALIB_API void luaL_addstring (luaL_Buffer *B, const char *s) {
    467   luaL_addlstring(B, s, strlen(s));
    468 }
    469 
    470 
    471 LUALIB_API void luaL_pushresult (luaL_Buffer *B) {
    472   lua_State *L = B->L;
    473   lua_pushlstring(L, B->b, B->n);
    474   if (buffonstack(B))
    475     lua_remove(L, -2);  /* remove old buffer */
    476 }
    477 
    478 
    479 LUALIB_API void luaL_pushresultsize (luaL_Buffer *B, size_t sz) {
    480   luaL_addsize(B, sz);
    481   luaL_pushresult(B);
    482 }
    483 
    484 
    485 LUALIB_API void luaL_addvalue (luaL_Buffer *B) {
    486   lua_State *L = B->L;
    487   size_t l;
    488   const char *s = lua_tolstring(L, -1, &l);
    489   if (buffonstack(B))
    490     lua_insert(L, -2);  /* put value below buffer */
    491   luaL_addlstring(B, s, l);
    492   lua_remove(L, (buffonstack(B)) ? -2 : -1);  /* remove value */
    493 }
    494 
    495 
    496 LUALIB_API void luaL_buffinit (lua_State *L, luaL_Buffer *B) {
    497   B->L = L;
    498   B->b = B->initb;
    499   B->n = 0;
    500   B->size = LUAL_BUFFERSIZE;
    501 }
    502 
    503 
    504 LUALIB_API char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz) {
    505   luaL_buffinit(L, B);
    506   return luaL_prepbuffsize(B, sz);
    507 }
    508 
    509 /* }====================================================== */
    510 
    511 
    512 /*
    513 ** {======================================================
    514 ** Reference system
    515 ** =======================================================
    516 */
    517 
    518 /* index of free-list header */
    519 #define freelist	0
    520 
    521 
    522 LUALIB_API int luaL_ref (lua_State *L, int t) {
    523   int ref;
    524   if (lua_isnil(L, -1)) {
    525     lua_pop(L, 1);  /* remove from stack */
    526     return LUA_REFNIL;  /* `nil' has a unique fixed reference */
    527   }
    528   t = lua_absindex(L, t);
    529   lua_rawgeti(L, t, freelist);  /* get first free element */
    530   ref = (int)lua_tointeger(L, -1);  /* ref = t[freelist] */
    531   lua_pop(L, 1);  /* remove it from stack */
    532   if (ref != 0) {  /* any free element? */
    533     lua_rawgeti(L, t, ref);  /* remove it from list */
    534     lua_rawseti(L, t, freelist);  /* (t[freelist] = t[ref]) */
    535   }
    536   else  /* no free elements */
    537     ref = (int)lua_rawlen(L, t) + 1;  /* get a new reference */
    538   lua_rawseti(L, t, ref);
    539   return ref;
    540 }
    541 
    542 
    543 LUALIB_API void luaL_unref (lua_State *L, int t, int ref) {
    544   if (ref >= 0) {
    545     t = lua_absindex(L, t);
    546     lua_rawgeti(L, t, freelist);
    547     lua_rawseti(L, t, ref);  /* t[ref] = t[freelist] */
    548     lua_pushinteger(L, ref);
    549     lua_rawseti(L, t, freelist);  /* t[freelist] = ref */
    550   }
    551 }
    552 
    553 /* }====================================================== */
    554 
    555 
    556 /*
    557 ** {======================================================
    558 ** Load functions
    559 ** =======================================================
    560 */
    561 
    562 typedef struct LoadF {
    563   int n;  /* number of pre-read characters */
    564   FILE *f;  /* file being read */
    565   char buff[LUAL_BUFFERSIZE];  /* area for reading file */
    566 } LoadF;
    567 
    568 
    569 static const char *getF (lua_State *L, void *ud, size_t *size) {
    570   LoadF *lf = (LoadF *)ud;
    571   (void)L;  /* not used */
    572   if (lf->n > 0) {  /* are there pre-read characters to be read? */
    573     *size = lf->n;  /* return them (chars already in buffer) */
    574     lf->n = 0;  /* no more pre-read characters */
    575   }
    576   else {  /* read a block from file */
    577     /* 'fread' can return > 0 *and* set the EOF flag. If next call to
    578        'getF' called 'fread', it might still wait for user input.
    579        The next check avoids this problem. */
    580     if (feof(lf->f)) return NULL;
    581     *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);  /* read block */
    582   }
    583   return lf->buff;
    584 }
    585 
    586 
    587 static int errfile (lua_State *L, const char *what, int fnameindex) {
    588   const char *serr = strerror(errno);
    589   const char *filename = lua_tostring(L, fnameindex) + 1;
    590   lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
    591   lua_remove(L, fnameindex);
    592   return LUA_ERRFILE;
    593 }
    594 
    595 
    596 static int skipBOM (LoadF *lf) {
    597   const char *p = "\xEF\xBB\xBF";  /* Utf8 BOM mark */
    598   int c;
    599   lf->n = 0;
    600   do {
    601     c = getc(lf->f);
    602     if (c == EOF || c != *(const unsigned char *)p++) return c;
    603     lf->buff[lf->n++] = c;  /* to be read by the parser */
    604   } while (*p != '\0');
    605   lf->n = 0;  /* prefix matched; discard it */
    606   return getc(lf->f);  /* return next character */
    607 }
    608 
    609 
    610 /*
    611 ** reads the first character of file 'f' and skips an optional BOM mark
    612 ** in its beginning plus its first line if it starts with '#'. Returns
    613 ** true if it skipped the first line.  In any case, '*cp' has the
    614 ** first "valid" character of the file (after the optional BOM and
    615 ** a first-line comment).
    616 */
    617 static int skipcomment (LoadF *lf, int *cp) {
    618   int c = *cp = skipBOM(lf);
    619   if (c == '#') {  /* first line is a comment (Unix exec. file)? */
    620     do {  /* skip first line */
    621       c = getc(lf->f);
    622     } while (c != EOF && c != '\n') ;
    623     *cp = getc(lf->f);  /* skip end-of-line, if present */
    624     return 1;  /* there was a comment */
    625   }
    626   else return 0;  /* no comment */
    627 }
    628 
    629 
    630 LUALIB_API int luaL_loadfilex (lua_State *L, const char *filename,
    631                                              const char *mode) {
    632   LoadF lf;
    633   int status, readstatus;
    634   int c;
    635   int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */
    636   if (filename == NULL) {
    637     lua_pushliteral(L, "=stdin");
    638     lf.f = stdin;
    639   }
    640   else {
    641     lua_pushfstring(L, "@%s", filename);
    642     lf.f = fopen(filename, "r");
    643     if (lf.f == NULL) return errfile(L, "open", fnameindex);
    644   }
    645   if (skipcomment(&lf, &c))  /* read initial portion */
    646     lf.buff[lf.n++] = '\n';  /* add line to correct line numbers */
    647   if (c == LUA_SIGNATURE[0] && filename) {  /* binary file? */
    648     lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */
    649     if (lf.f == NULL) return errfile(L, "reopen", fnameindex);
    650     skipcomment(&lf, &c);  /* re-read initial portion */
    651   }
    652   if (c != EOF)
    653     lf.buff[lf.n++] = c;  /* 'c' is the first character of the stream */
    654   status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode);
    655   readstatus = ferror(lf.f);
    656   if (filename) fclose(lf.f);  /* close file (even in case of errors) */
    657   if (readstatus) {
    658     lua_settop(L, fnameindex);  /* ignore results from `lua_load' */
    659     return errfile(L, "read", fnameindex);
    660   }
    661   lua_remove(L, fnameindex);
    662   return status;
    663 }
    664 
    665 
    666 typedef struct LoadS {
    667   const char *s;
    668   size_t size;
    669 } LoadS;
    670 
    671 
    672 static const char *getS (lua_State *L, void *ud, size_t *size) {
    673   LoadS *ls = (LoadS *)ud;
    674   (void)L;  /* not used */
    675   if (ls->size == 0) return NULL;
    676   *size = ls->size;
    677   ls->size = 0;
    678   return ls->s;
    679 }
    680 
    681 
    682 LUALIB_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t size,
    683                                  const char *name, const char *mode) {
    684   LoadS ls;
    685   ls.s = buff;
    686   ls.size = size;
    687   return lua_load(L, getS, &ls, name, mode);
    688 }
    689 
    690 
    691 LUALIB_API int luaL_loadstring (lua_State *L, const char *s) {
    692   return luaL_loadbuffer(L, s, strlen(s), s);
    693 }
    694 
    695 /* }====================================================== */
    696 
    697 
    698 
    699 LUALIB_API int luaL_getmetafield (lua_State *L, int obj, const char *event) {
    700   if (!lua_getmetatable(L, obj))  /* no metatable? */
    701     return 0;
    702   lua_pushstring(L, event);
    703   lua_rawget(L, -2);
    704   if (lua_isnil(L, -1)) {
    705     lua_pop(L, 2);  /* remove metatable and metafield */
    706     return 0;
    707   }
    708   else {
    709     lua_remove(L, -2);  /* remove only metatable */
    710     return 1;
    711   }
    712 }
    713 
    714 
    715 LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) {
    716   obj = lua_absindex(L, obj);
    717   if (!luaL_getmetafield(L, obj, event))  /* no metafield? */
    718     return 0;
    719   lua_pushvalue(L, obj);
    720   lua_call(L, 1, 1);
    721   return 1;
    722 }
    723 
    724 
    725 LUALIB_API int luaL_len (lua_State *L, int idx) {
    726   int l;
    727   int isnum;
    728   lua_len(L, idx);
    729   l = (int)lua_tointegerx(L, -1, &isnum);
    730   if (!isnum)
    731     luaL_error(L, "object length is not a number");
    732   lua_pop(L, 1);  /* remove object */
    733   return l;
    734 }
    735 
    736 
    737 LUALIB_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {
    738   if (!luaL_callmeta(L, idx, "__tostring")) {  /* no metafield? */
    739     switch (lua_type(L, idx)) {
    740       case LUA_TNUMBER:
    741       case LUA_TSTRING:
    742         lua_pushvalue(L, idx);
    743         break;
    744       case LUA_TBOOLEAN:
    745         lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false"));
    746         break;
    747       case LUA_TNIL:
    748         lua_pushliteral(L, "nil");
    749         break;
    750       default:
    751         lua_pushfstring(L, "%s: %p", luaL_typename(L, idx),
    752                                             lua_topointer(L, idx));
    753         break;
    754     }
    755   }
    756   return lua_tolstring(L, -1, len);
    757 }
    758 
    759 
    760 /*
    761 ** {======================================================
    762 ** Compatibility with 5.1 module functions
    763 ** =======================================================
    764 */
    765 #if defined(LUA_COMPAT_MODULE)
    766 
    767 static const char *luaL_findtable (lua_State *L, int idx,
    768                                    const char *fname, int szhint) {
    769   const char *e;
    770   if (idx) lua_pushvalue(L, idx);
    771   do {
    772     e = strchr(fname, '.');
    773     if (e == NULL) e = fname + strlen(fname);
    774     lua_pushlstring(L, fname, e - fname);
    775     lua_rawget(L, -2);
    776     if (lua_isnil(L, -1)) {  /* no such field? */
    777       lua_pop(L, 1);  /* remove this nil */
    778       lua_createtable(L, 0, (*e == '.' ? 1 : szhint)); /* new table for field */
    779       lua_pushlstring(L, fname, e - fname);
    780       lua_pushvalue(L, -2);
    781       lua_settable(L, -4);  /* set new table into field */
    782     }
    783     else if (!lua_istable(L, -1)) {  /* field has a non-table value? */
    784       lua_pop(L, 2);  /* remove table and value */
    785       return fname;  /* return problematic part of the name */
    786     }
    787     lua_remove(L, -2);  /* remove previous table */
    788     fname = e + 1;
    789   } while (*e == '.');
    790   return NULL;
    791 }
    792 
    793 
    794 /*
    795 ** Count number of elements in a luaL_Reg list.
    796 */
    797 static int libsize (const luaL_Reg *l) {
    798   int size = 0;
    799   for (; l && l->name; l++) size++;
    800   return size;
    801 }
    802 
    803 
    804 /*
    805 ** Find or create a module table with a given name. The function
    806 ** first looks at the _LOADED table and, if that fails, try a
    807 ** global variable with that name. In any case, leaves on the stack
    808 ** the module table.
    809 */
    810 LUALIB_API void luaL_pushmodule (lua_State *L, const char *modname,
    811                                  int sizehint) {
    812   luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 1);  /* get _LOADED table */
    813   lua_getfield(L, -1, modname);  /* get _LOADED[modname] */
    814   if (!lua_istable(L, -1)) {  /* not found? */
    815     lua_pop(L, 1);  /* remove previous result */
    816     /* try global variable (and create one if it does not exist) */
    817     lua_pushglobaltable(L);
    818     if (luaL_findtable(L, 0, modname, sizehint) != NULL)
    819       luaL_error(L, "name conflict for module " LUA_QS, modname);
    820     lua_pushvalue(L, -1);
    821     lua_setfield(L, -3, modname);  /* _LOADED[modname] = new table */
    822   }
    823   lua_remove(L, -2);  /* remove _LOADED table */
    824 }
    825 
    826 
    827 LUALIB_API void luaL_openlib (lua_State *L, const char *libname,
    828                                const luaL_Reg *l, int nup) {
    829   luaL_checkversion(L);
    830   if (libname) {
    831     luaL_pushmodule(L, libname, libsize(l));  /* get/create library table */
    832     lua_insert(L, -(nup + 1));  /* move library table to below upvalues */
    833   }
    834   if (l)
    835     luaL_setfuncs(L, l, nup);
    836   else
    837     lua_pop(L, nup);  /* remove upvalues */
    838 }
    839 
    840 #endif
    841 /* }====================================================== */
    842 
    843 /*
    844 ** set functions from list 'l' into table at top - 'nup'; each
    845 ** function gets the 'nup' elements at the top as upvalues.
    846 ** Returns with only the table at the stack.
    847 */
    848 LUALIB_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
    849   luaL_checkversion(L);
    850   luaL_checkstack(L, nup, "too many upvalues");
    851   for (; l->name != NULL; l++) {  /* fill the table with given functions */
    852     int i;
    853     for (i = 0; i < nup; i++)  /* copy upvalues to the top */
    854       lua_pushvalue(L, -nup);
    855     lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
    856     lua_setfield(L, -(nup + 2), l->name);
    857   }
    858   lua_pop(L, nup);  /* remove upvalues */
    859 }
    860 
    861 
    862 /*
    863 ** ensure that stack[idx][fname] has a table and push that table
    864 ** into the stack
    865 */
    866 LUALIB_API int luaL_getsubtable (lua_State *L, int idx, const char *fname) {
    867   lua_getfield(L, idx, fname);
    868   if (lua_istable(L, -1)) return 1;  /* table already there */
    869   else {
    870     lua_pop(L, 1);  /* remove previous result */
    871     idx = lua_absindex(L, idx);
    872     lua_newtable(L);
    873     lua_pushvalue(L, -1);  /* copy to be left at top */
    874     lua_setfield(L, idx, fname);  /* assign new table to field */
    875     return 0;  /* false, because did not find table there */
    876   }
    877 }
    878 
    879 
    880 /*
    881 ** stripped-down 'require'. Calls 'openf' to open a module,
    882 ** registers the result in 'package.loaded' table and, if 'glb'
    883 ** is true, also registers the result in the global table.
    884 ** Leaves resulting module on the top.
    885 */
    886 LUALIB_API void luaL_requiref (lua_State *L, const char *modname,
    887                                lua_CFunction openf, int glb) {
    888   lua_pushcfunction(L, openf);
    889   lua_pushstring(L, modname);  /* argument to open function */
    890   lua_call(L, 1, 1);  /* open module */
    891   luaL_getsubtable(L, LUA_REGISTRYINDEX, "_LOADED");
    892   lua_pushvalue(L, -2);  /* make copy of module (call result) */
    893   lua_setfield(L, -2, modname);  /* _LOADED[modname] = module */
    894   lua_pop(L, 1);  /* remove _LOADED table */
    895   if (glb) {
    896     lua_pushvalue(L, -1);  /* copy of 'mod' */
    897     lua_setglobal(L, modname);  /* _G[modname] = module */
    898   }
    899 }
    900 
    901 
    902 LUALIB_API const char *luaL_gsub (lua_State *L, const char *s, const char *p,
    903                                                                const char *r) {
    904   const char *wild;
    905   size_t l = strlen(p);
    906   luaL_Buffer b;
    907   luaL_buffinit(L, &b);
    908   while ((wild = strstr(s, p)) != NULL) {
    909     luaL_addlstring(&b, s, wild - s);  /* push prefix */
    910     luaL_addstring(&b, r);  /* push replacement in place of pattern */
    911     s = wild + l;  /* continue after `p' */
    912   }
    913   luaL_addstring(&b, s);  /* push last suffix */
    914   luaL_pushresult(&b);
    915   return lua_tostring(L, -1);
    916 }
    917 
    918 
    919 static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
    920   (void)ud; (void)osize;  /* not used */
    921   if (nsize == 0) {
    922     free(ptr);
    923     return NULL;
    924   }
    925   else
    926     return realloc(ptr, nsize);
    927 }
    928 
    929 
    930 static int panic (lua_State *L) {
    931   luai_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n",
    932                    lua_tostring(L, -1));
    933   return 0;  /* return to Lua to abort */
    934 }
    935 
    936 
    937 LUALIB_API lua_State *luaL_newstate (void) {
    938   lua_State *L = lua_newstate(l_alloc, NULL);
    939   if (L) lua_atpanic(L, &panic);
    940   return L;
    941 }
    942 
    943 
    944 LUALIB_API void luaL_checkversion_ (lua_State *L, lua_Number ver) {
    945   const lua_Number *v = lua_version(L);
    946   if (v != lua_version(NULL))
    947     luaL_error(L, "multiple Lua VMs detected");
    948   else if (*v != ver)
    949     luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f",
    950                   ver, *v);
    951   /* check conversions number -> integer types */
    952   lua_pushnumber(L, -(lua_Number)0x1234);
    953   if (lua_tointeger(L, -1) != -0x1234 ||
    954       lua_tounsigned(L, -1) != (lua_Unsigned)-0x1234)
    955     luaL_error(L, "bad conversion number->int;"
    956                   " must recompile Lua with proper settings");
    957   lua_pop(L, 1);
    958 }
    959 
    960