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Member "memcached-1.6.15/vendor/lua/src/lauxlib.c" (1 Oct 2021, 32746 Bytes) of package /linux/www/memcached-1.6.15.tar.gz:


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    1 /*
    2 ** $Id: lauxlib.c $
    3 ** Auxiliary functions for building Lua libraries
    4 ** See Copyright Notice in lua.h
    5 */
    6 
    7 #define lauxlib_c
    8 #define LUA_LIB
    9 
   10 #include "lprefix.h"
   11 
   12 
   13 #include <errno.h>
   14 #include <stdarg.h>
   15 #include <stdio.h>
   16 #include <stdlib.h>
   17 #include <string.h>
   18 
   19 
   20 /*
   21 ** This file uses only the official API of Lua.
   22 ** Any function declared here could be written as an application function.
   23 */
   24 
   25 #include "lua.h"
   26 
   27 #include "lauxlib.h"
   28 
   29 
   30 #if !defined(MAX_SIZET)
   31 /* maximum value for size_t */
   32 #define MAX_SIZET   ((size_t)(~(size_t)0))
   33 #endif
   34 
   35 
   36 /*
   37 ** {======================================================
   38 ** Traceback
   39 ** =======================================================
   40 */
   41 
   42 
   43 #define LEVELS1 10  /* size of the first part of the stack */
   44 #define LEVELS2 11  /* size of the second part of the stack */
   45 
   46 
   47 
   48 /*
   49 ** Search for 'objidx' in table at index -1. ('objidx' must be an
   50 ** absolute index.) Return 1 + string at top if it found a good name.
   51 */
   52 static int findfield (lua_State *L, int objidx, int level) {
   53   if (level == 0 || !lua_istable(L, -1))
   54     return 0;  /* not found */
   55   lua_pushnil(L);  /* start 'next' loop */
   56   while (lua_next(L, -2)) {  /* for each pair in table */
   57     if (lua_type(L, -2) == LUA_TSTRING) {  /* ignore non-string keys */
   58       if (lua_rawequal(L, objidx, -1)) {  /* found object? */
   59         lua_pop(L, 1);  /* remove value (but keep name) */
   60         return 1;
   61       }
   62       else if (findfield(L, objidx, level - 1)) {  /* try recursively */
   63         /* stack: lib_name, lib_table, field_name (top) */
   64         lua_pushliteral(L, ".");  /* place '.' between the two names */
   65         lua_replace(L, -3);  /* (in the slot occupied by table) */
   66         lua_concat(L, 3);  /* lib_name.field_name */
   67         return 1;
   68       }
   69     }
   70     lua_pop(L, 1);  /* remove value */
   71   }
   72   return 0;  /* not found */
   73 }
   74 
   75 
   76 /*
   77 ** Search for a name for a function in all loaded modules
   78 */
   79 static int pushglobalfuncname (lua_State *L, lua_Debug *ar) {
   80   int top = lua_gettop(L);
   81   lua_getinfo(L, "f", ar);  /* push function */
   82   lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
   83   if (findfield(L, top + 1, 2)) {
   84     const char *name = lua_tostring(L, -1);
   85     if (strncmp(name, LUA_GNAME ".", 3) == 0) {  /* name start with '_G.'? */
   86       lua_pushstring(L, name + 3);  /* push name without prefix */
   87       lua_remove(L, -2);  /* remove original name */
   88     }
   89     lua_copy(L, -1, top + 1);  /* copy name to proper place */
   90     lua_settop(L, top + 1);  /* remove table "loaded" and name copy */
   91     return 1;
   92   }
   93   else {
   94     lua_settop(L, top);  /* remove function and global table */
   95     return 0;
   96   }
   97 }
   98 
   99 
  100 static void pushfuncname (lua_State *L, lua_Debug *ar) {
  101   if (pushglobalfuncname(L, ar)) {  /* try first a global name */
  102     lua_pushfstring(L, "function '%s'", lua_tostring(L, -1));
  103     lua_remove(L, -2);  /* remove name */
  104   }
  105   else if (*ar->namewhat != '\0')  /* is there a name from code? */
  106     lua_pushfstring(L, "%s '%s'", ar->namewhat, ar->name);  /* use it */
  107   else if (*ar->what == 'm')  /* main? */
  108       lua_pushliteral(L, "main chunk");
  109   else if (*ar->what != 'C')  /* for Lua functions, use <file:line> */
  110     lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
  111   else  /* nothing left... */
  112     lua_pushliteral(L, "?");
  113 }
  114 
  115 
  116 static int lastlevel (lua_State *L) {
  117   lua_Debug ar;
  118   int li = 1, le = 1;
  119   /* find an upper bound */
  120   while (lua_getstack(L, le, &ar)) { li = le; le *= 2; }
  121   /* do a binary search */
  122   while (li < le) {
  123     int m = (li + le)/2;
  124     if (lua_getstack(L, m, &ar)) li = m + 1;
  125     else le = m;
  126   }
  127   return le - 1;
  128 }
  129 
  130 
  131 LUALIB_API void luaL_traceback (lua_State *L, lua_State *L1,
  132                                 const char *msg, int level) {
  133   luaL_Buffer b;
  134   lua_Debug ar;
  135   int last = lastlevel(L1);
  136   int limit2show = (last - level > LEVELS1 + LEVELS2) ? LEVELS1 : -1;
  137   luaL_buffinit(L, &b);
  138   if (msg) {
  139     luaL_addstring(&b, msg);
  140     luaL_addchar(&b, '\n');
  141   }
  142   luaL_addstring(&b, "stack traceback:");
  143   while (lua_getstack(L1, level++, &ar)) {
  144     if (limit2show-- == 0) {  /* too many levels? */
  145       int n = last - level - LEVELS2 + 1;  /* number of levels to skip */
  146       lua_pushfstring(L, "\n\t...\t(skipping %d levels)", n);
  147       luaL_addvalue(&b);  /* add warning about skip */
  148       level += n;  /* and skip to last levels */
  149     }
  150     else {
  151       lua_getinfo(L1, "Slnt", &ar);
  152       if (ar.currentline <= 0)
  153         lua_pushfstring(L, "\n\t%s: in ", ar.short_src);
  154       else
  155         lua_pushfstring(L, "\n\t%s:%d: in ", ar.short_src, ar.currentline);
  156       luaL_addvalue(&b);
  157       pushfuncname(L, &ar);
  158       luaL_addvalue(&b);
  159       if (ar.istailcall)
  160         luaL_addstring(&b, "\n\t(...tail calls...)");
  161     }
  162   }
  163   luaL_pushresult(&b);
  164 }
  165 
  166 /* }====================================================== */
  167 
  168 
  169 /*
  170 ** {======================================================
  171 ** Error-report functions
  172 ** =======================================================
  173 */
  174 
  175 LUALIB_API int luaL_argerror (lua_State *L, int arg, const char *extramsg) {
  176   lua_Debug ar;
  177   if (!lua_getstack(L, 0, &ar))  /* no stack frame? */
  178     return luaL_error(L, "bad argument #%d (%s)", arg, extramsg);
  179   lua_getinfo(L, "n", &ar);
  180   if (strcmp(ar.namewhat, "method") == 0) {
  181     arg--;  /* do not count 'self' */
  182     if (arg == 0)  /* error is in the self argument itself? */
  183       return luaL_error(L, "calling '%s' on bad self (%s)",
  184                            ar.name, extramsg);
  185   }
  186   if (ar.name == NULL)
  187     ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?";
  188   return luaL_error(L, "bad argument #%d to '%s' (%s)",
  189                         arg, ar.name, extramsg);
  190 }
  191 
  192 
  193 LUALIB_API int luaL_typeerror (lua_State *L, int arg, const char *tname) {
  194   const char *msg;
  195   const char *typearg;  /* name for the type of the actual argument */
  196   if (luaL_getmetafield(L, arg, "__name") == LUA_TSTRING)
  197     typearg = lua_tostring(L, -1);  /* use the given type name */
  198   else if (lua_type(L, arg) == LUA_TLIGHTUSERDATA)
  199     typearg = "light userdata";  /* special name for messages */
  200   else
  201     typearg = luaL_typename(L, arg);  /* standard name */
  202   msg = lua_pushfstring(L, "%s expected, got %s", tname, typearg);
  203   return luaL_argerror(L, arg, msg);
  204 }
  205 
  206 
  207 static void tag_error (lua_State *L, int arg, int tag) {
  208   luaL_typeerror(L, arg, lua_typename(L, tag));
  209 }
  210 
  211 
  212 /*
  213 ** The use of 'lua_pushfstring' ensures this function does not
  214 ** need reserved stack space when called.
  215 */
  216 LUALIB_API void luaL_where (lua_State *L, int level) {
  217   lua_Debug ar;
  218   if (lua_getstack(L, level, &ar)) {  /* check function at level */
  219     lua_getinfo(L, "Sl", &ar);  /* get info about it */
  220     if (ar.currentline > 0) {  /* is there info? */
  221       lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline);
  222       return;
  223     }
  224   }
  225   lua_pushfstring(L, "");  /* else, no information available... */
  226 }
  227 
  228 
  229 /*
  230 ** Again, the use of 'lua_pushvfstring' ensures this function does
  231 ** not need reserved stack space when called. (At worst, it generates
  232 ** an error with "stack overflow" instead of the given message.)
  233 */
  234 LUALIB_API int luaL_error (lua_State *L, const char *fmt, ...) {
  235   va_list argp;
  236   va_start(argp, fmt);
  237   luaL_where(L, 1);
  238   lua_pushvfstring(L, fmt, argp);
  239   va_end(argp);
  240   lua_concat(L, 2);
  241   return lua_error(L);
  242 }
  243 
  244 
  245 LUALIB_API int luaL_fileresult (lua_State *L, int stat, const char *fname) {
  246   int en = errno;  /* calls to Lua API may change this value */
  247   if (stat) {
  248     lua_pushboolean(L, 1);
  249     return 1;
  250   }
  251   else {
  252     luaL_pushfail(L);
  253     if (fname)
  254       lua_pushfstring(L, "%s: %s", fname, strerror(en));
  255     else
  256       lua_pushstring(L, strerror(en));
  257     lua_pushinteger(L, en);
  258     return 3;
  259   }
  260 }
  261 
  262 
  263 #if !defined(l_inspectstat) /* { */
  264 
  265 #if defined(LUA_USE_POSIX)
  266 
  267 #include <sys/wait.h>
  268 
  269 /*
  270 ** use appropriate macros to interpret 'pclose' return status
  271 */
  272 #define l_inspectstat(stat,what)  \
  273    if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
  274    else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }
  275 
  276 #else
  277 
  278 #define l_inspectstat(stat,what)  /* no op */
  279 
  280 #endif
  281 
  282 #endif              /* } */
  283 
  284 
  285 LUALIB_API int luaL_execresult (lua_State *L, int stat) {
  286   if (stat != 0 && errno != 0)  /* error with an 'errno'? */
  287     return luaL_fileresult(L, 0, NULL);
  288   else {
  289     const char *what = "exit";  /* type of termination */
  290     l_inspectstat(stat, what);  /* interpret result */
  291     if (*what == 'e' && stat == 0)  /* successful termination? */
  292       lua_pushboolean(L, 1);
  293     else
  294       luaL_pushfail(L);
  295     lua_pushstring(L, what);
  296     lua_pushinteger(L, stat);
  297     return 3;  /* return true/fail,what,code */
  298   }
  299 }
  300 
  301 /* }====================================================== */
  302 
  303 
  304 
  305 /*
  306 ** {======================================================
  307 ** Userdata's metatable manipulation
  308 ** =======================================================
  309 */
  310 
  311 LUALIB_API int luaL_newmetatable (lua_State *L, const char *tname) {
  312   if (luaL_getmetatable(L, tname) != LUA_TNIL)  /* name already in use? */
  313     return 0;  /* leave previous value on top, but return 0 */
  314   lua_pop(L, 1);
  315   lua_createtable(L, 0, 2);  /* create metatable */
  316   lua_pushstring(L, tname);
  317   lua_setfield(L, -2, "__name");  /* metatable.__name = tname */
  318   lua_pushvalue(L, -1);
  319   lua_setfield(L, LUA_REGISTRYINDEX, tname);  /* registry.name = metatable */
  320   return 1;
  321 }
  322 
  323 
  324 LUALIB_API void luaL_setmetatable (lua_State *L, const char *tname) {
  325   luaL_getmetatable(L, tname);
  326   lua_setmetatable(L, -2);
  327 }
  328 
  329 
  330 LUALIB_API void *luaL_testudata (lua_State *L, int ud, const char *tname) {
  331   void *p = lua_touserdata(L, ud);
  332   if (p != NULL) {  /* value is a userdata? */
  333     if (lua_getmetatable(L, ud)) {  /* does it have a metatable? */
  334       luaL_getmetatable(L, tname);  /* get correct metatable */
  335       if (!lua_rawequal(L, -1, -2))  /* not the same? */
  336         p = NULL;  /* value is a userdata with wrong metatable */
  337       lua_pop(L, 2);  /* remove both metatables */
  338       return p;
  339     }
  340   }
  341   return NULL;  /* value is not a userdata with a metatable */
  342 }
  343 
  344 
  345 LUALIB_API void *luaL_checkudata (lua_State *L, int ud, const char *tname) {
  346   void *p = luaL_testudata(L, ud, tname);
  347   luaL_argexpected(L, p != NULL, ud, tname);
  348   return p;
  349 }
  350 
  351 /* }====================================================== */
  352 
  353 
  354 /*
  355 ** {======================================================
  356 ** Argument check functions
  357 ** =======================================================
  358 */
  359 
  360 LUALIB_API int luaL_checkoption (lua_State *L, int arg, const char *def,
  361                                  const char *const lst[]) {
  362   const char *name = (def) ? luaL_optstring(L, arg, def) :
  363                              luaL_checkstring(L, arg);
  364   int i;
  365   for (i=0; lst[i]; i++)
  366     if (strcmp(lst[i], name) == 0)
  367       return i;
  368   return luaL_argerror(L, arg,
  369                        lua_pushfstring(L, "invalid option '%s'", name));
  370 }
  371 
  372 
  373 /*
  374 ** Ensures the stack has at least 'space' extra slots, raising an error
  375 ** if it cannot fulfill the request. (The error handling needs a few
  376 ** extra slots to format the error message. In case of an error without
  377 ** this extra space, Lua will generate the same 'stack overflow' error,
  378 ** but without 'msg'.)
  379 */
  380 LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *msg) {
  381   if (l_unlikely(!lua_checkstack(L, space))) {
  382     if (msg)
  383       luaL_error(L, "stack overflow (%s)", msg);
  384     else
  385       luaL_error(L, "stack overflow");
  386   }
  387 }
  388 
  389 
  390 LUALIB_API void luaL_checktype (lua_State *L, int arg, int t) {
  391   if (l_unlikely(lua_type(L, arg) != t))
  392     tag_error(L, arg, t);
  393 }
  394 
  395 
  396 LUALIB_API void luaL_checkany (lua_State *L, int arg) {
  397   if (l_unlikely(lua_type(L, arg) == LUA_TNONE))
  398     luaL_argerror(L, arg, "value expected");
  399 }
  400 
  401 
  402 LUALIB_API const char *luaL_checklstring (lua_State *L, int arg, size_t *len) {
  403   const char *s = lua_tolstring(L, arg, len);
  404   if (l_unlikely(!s)) tag_error(L, arg, LUA_TSTRING);
  405   return s;
  406 }
  407 
  408 
  409 LUALIB_API const char *luaL_optlstring (lua_State *L, int arg,
  410                                         const char *def, size_t *len) {
  411   if (lua_isnoneornil(L, arg)) {
  412     if (len)
  413       *len = (def ? strlen(def) : 0);
  414     return def;
  415   }
  416   else return luaL_checklstring(L, arg, len);
  417 }
  418 
  419 
  420 LUALIB_API lua_Number luaL_checknumber (lua_State *L, int arg) {
  421   int isnum;
  422   lua_Number d = lua_tonumberx(L, arg, &isnum);
  423   if (l_unlikely(!isnum))
  424     tag_error(L, arg, LUA_TNUMBER);
  425   return d;
  426 }
  427 
  428 
  429 LUALIB_API lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number def) {
  430   return luaL_opt(L, luaL_checknumber, arg, def);
  431 }
  432 
  433 
  434 static void interror (lua_State *L, int arg) {
  435   if (lua_isnumber(L, arg))
  436     luaL_argerror(L, arg, "number has no integer representation");
  437   else
  438     tag_error(L, arg, LUA_TNUMBER);
  439 }
  440 
  441 
  442 LUALIB_API lua_Integer luaL_checkinteger (lua_State *L, int arg) {
  443   int isnum;
  444   lua_Integer d = lua_tointegerx(L, arg, &isnum);
  445   if (l_unlikely(!isnum)) {
  446     interror(L, arg);
  447   }
  448   return d;
  449 }
  450 
  451 
  452 LUALIB_API lua_Integer luaL_optinteger (lua_State *L, int arg,
  453                                                       lua_Integer def) {
  454   return luaL_opt(L, luaL_checkinteger, arg, def);
  455 }
  456 
  457 /* }====================================================== */
  458 
  459 
  460 /*
  461 ** {======================================================
  462 ** Generic Buffer manipulation
  463 ** =======================================================
  464 */
  465 
  466 /* userdata to box arbitrary data */
  467 typedef struct UBox {
  468   void *box;
  469   size_t bsize;
  470 } UBox;
  471 
  472 
  473 static void *resizebox (lua_State *L, int idx, size_t newsize) {
  474   void *ud;
  475   lua_Alloc allocf = lua_getallocf(L, &ud);
  476   UBox *box = (UBox *)lua_touserdata(L, idx);
  477   void *temp = allocf(ud, box->box, box->bsize, newsize);
  478   if (l_unlikely(temp == NULL && newsize > 0)) {  /* allocation error? */
  479     lua_pushliteral(L, "not enough memory");
  480     lua_error(L);  /* raise a memory error */
  481   }
  482   box->box = temp;
  483   box->bsize = newsize;
  484   return temp;
  485 }
  486 
  487 
  488 static int boxgc (lua_State *L) {
  489   resizebox(L, 1, 0);
  490   return 0;
  491 }
  492 
  493 
  494 static const luaL_Reg boxmt[] = {  /* box metamethods */
  495   {"__gc", boxgc},
  496   {"__close", boxgc},
  497   {NULL, NULL}
  498 };
  499 
  500 
  501 static void newbox (lua_State *L) {
  502   UBox *box = (UBox *)lua_newuserdatauv(L, sizeof(UBox), 0);
  503   box->box = NULL;
  504   box->bsize = 0;
  505   if (luaL_newmetatable(L, "_UBOX*"))  /* creating metatable? */
  506     luaL_setfuncs(L, boxmt, 0);  /* set its metamethods */
  507   lua_setmetatable(L, -2);
  508 }
  509 
  510 
  511 /*
  512 ** check whether buffer is using a userdata on the stack as a temporary
  513 ** buffer
  514 */
  515 #define buffonstack(B)  ((B)->b != (B)->init.b)
  516 
  517 
  518 /*
  519 ** Whenever buffer is accessed, slot 'idx' must either be a box (which
  520 ** cannot be NULL) or it is a placeholder for the buffer.
  521 */
  522 #define checkbufferlevel(B,idx)  \
  523   lua_assert(buffonstack(B) ? lua_touserdata(B->L, idx) != NULL  \
  524                             : lua_touserdata(B->L, idx) == (void*)B)
  525 
  526 
  527 /*
  528 ** Compute new size for buffer 'B', enough to accommodate extra 'sz'
  529 ** bytes.
  530 */
  531 static size_t newbuffsize (luaL_Buffer *B, size_t sz) {
  532   size_t newsize = B->size * 2;  /* double buffer size */
  533   if (l_unlikely(MAX_SIZET - sz < B->n))  /* overflow in (B->n + sz)? */
  534     return luaL_error(B->L, "buffer too large");
  535   if (newsize < B->n + sz)  /* double is not big enough? */
  536     newsize = B->n + sz;
  537   return newsize;
  538 }
  539 
  540 
  541 /*
  542 ** Returns a pointer to a free area with at least 'sz' bytes in buffer
  543 ** 'B'. 'boxidx' is the relative position in the stack where is the
  544 ** buffer's box or its placeholder.
  545 */
  546 static char *prepbuffsize (luaL_Buffer *B, size_t sz, int boxidx) {
  547   checkbufferlevel(B, boxidx);
  548   if (B->size - B->n >= sz)  /* enough space? */
  549     return B->b + B->n;
  550   else {
  551     lua_State *L = B->L;
  552     char *newbuff;
  553     size_t newsize = newbuffsize(B, sz);
  554     /* create larger buffer */
  555     if (buffonstack(B))  /* buffer already has a box? */
  556       newbuff = (char *)resizebox(L, boxidx, newsize);  /* resize it */
  557     else {  /* no box yet */
  558       lua_remove(L, boxidx);  /* remove placeholder */
  559       newbox(L);  /* create a new box */
  560       lua_insert(L, boxidx);  /* move box to its intended position */
  561       lua_toclose(L, boxidx);
  562       newbuff = (char *)resizebox(L, boxidx, newsize);
  563       memcpy(newbuff, B->b, B->n * sizeof(char));  /* copy original content */
  564     }
  565     B->b = newbuff;
  566     B->size = newsize;
  567     return newbuff + B->n;
  568   }
  569 }
  570 
  571 /*
  572 ** returns a pointer to a free area with at least 'sz' bytes
  573 */
  574 LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) {
  575   return prepbuffsize(B, sz, -1);
  576 }
  577 
  578 
  579 LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {
  580   if (l > 0) {  /* avoid 'memcpy' when 's' can be NULL */
  581     char *b = prepbuffsize(B, l, -1);
  582     memcpy(b, s, l * sizeof(char));
  583     luaL_addsize(B, l);
  584   }
  585 }
  586 
  587 
  588 LUALIB_API void luaL_addstring (luaL_Buffer *B, const char *s) {
  589   luaL_addlstring(B, s, strlen(s));
  590 }
  591 
  592 
  593 LUALIB_API void luaL_pushresult (luaL_Buffer *B) {
  594   lua_State *L = B->L;
  595   checkbufferlevel(B, -1);
  596   lua_pushlstring(L, B->b, B->n);
  597   if (buffonstack(B))
  598     lua_closeslot(L, -2);  /* close the box */
  599   lua_remove(L, -2);  /* remove box or placeholder from the stack */
  600 }
  601 
  602 
  603 LUALIB_API void luaL_pushresultsize (luaL_Buffer *B, size_t sz) {
  604   luaL_addsize(B, sz);
  605   luaL_pushresult(B);
  606 }
  607 
  608 
  609 /*
  610 ** 'luaL_addvalue' is the only function in the Buffer system where the
  611 ** box (if existent) is not on the top of the stack. So, instead of
  612 ** calling 'luaL_addlstring', it replicates the code using -2 as the
  613 ** last argument to 'prepbuffsize', signaling that the box is (or will
  614 ** be) bellow the string being added to the buffer. (Box creation can
  615 ** trigger an emergency GC, so we should not remove the string from the
  616 ** stack before we have the space guaranteed.)
  617 */
  618 LUALIB_API void luaL_addvalue (luaL_Buffer *B) {
  619   lua_State *L = B->L;
  620   size_t len;
  621   const char *s = lua_tolstring(L, -1, &len);
  622   char *b = prepbuffsize(B, len, -2);
  623   memcpy(b, s, len * sizeof(char));
  624   luaL_addsize(B, len);
  625   lua_pop(L, 1);  /* pop string */
  626 }
  627 
  628 
  629 LUALIB_API void luaL_buffinit (lua_State *L, luaL_Buffer *B) {
  630   B->L = L;
  631   B->b = B->init.b;
  632   B->n = 0;
  633   B->size = LUAL_BUFFERSIZE;
  634   lua_pushlightuserdata(L, (void*)B);  /* push placeholder */
  635 }
  636 
  637 
  638 LUALIB_API char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz) {
  639   luaL_buffinit(L, B);
  640   return prepbuffsize(B, sz, -1);
  641 }
  642 
  643 /* }====================================================== */
  644 
  645 
  646 /*
  647 ** {======================================================
  648 ** Reference system
  649 ** =======================================================
  650 */
  651 
  652 /* index of free-list header (after the predefined values) */
  653 #define freelist    (LUA_RIDX_LAST + 1)
  654 
  655 /*
  656 ** The previously freed references form a linked list:
  657 ** t[freelist] is the index of a first free index, or zero if list is
  658 ** empty; t[t[freelist]] is the index of the second element; etc.
  659 */
  660 LUALIB_API int luaL_ref (lua_State *L, int t) {
  661   int ref;
  662   if (lua_isnil(L, -1)) {
  663     lua_pop(L, 1);  /* remove from stack */
  664     return LUA_REFNIL;  /* 'nil' has a unique fixed reference */
  665   }
  666   t = lua_absindex(L, t);
  667   if (lua_rawgeti(L, t, freelist) == LUA_TNIL) {  /* first access? */
  668     ref = 0;  /* list is empty */
  669     lua_pushinteger(L, 0);  /* initialize as an empty list */
  670     lua_rawseti(L, t, freelist);  /* ref = t[freelist] = 0 */
  671   }
  672   else {  /* already initialized */
  673     lua_assert(lua_isinteger(L, -1));
  674     ref = (int)lua_tointeger(L, -1);  /* ref = t[freelist] */
  675   }
  676   lua_pop(L, 1);  /* remove element from stack */
  677   if (ref != 0) {  /* any free element? */
  678     lua_rawgeti(L, t, ref);  /* remove it from list */
  679     lua_rawseti(L, t, freelist);  /* (t[freelist] = t[ref]) */
  680   }
  681   else  /* no free elements */
  682     ref = (int)lua_rawlen(L, t) + 1;  /* get a new reference */
  683   lua_rawseti(L, t, ref);
  684   return ref;
  685 }
  686 
  687 
  688 LUALIB_API void luaL_unref (lua_State *L, int t, int ref) {
  689   if (ref >= 0) {
  690     t = lua_absindex(L, t);
  691     lua_rawgeti(L, t, freelist);
  692     lua_assert(lua_isinteger(L, -1));
  693     lua_rawseti(L, t, ref);  /* t[ref] = t[freelist] */
  694     lua_pushinteger(L, ref);
  695     lua_rawseti(L, t, freelist);  /* t[freelist] = ref */
  696   }
  697 }
  698 
  699 /* }====================================================== */
  700 
  701 
  702 /*
  703 ** {======================================================
  704 ** Load functions
  705 ** =======================================================
  706 */
  707 
  708 typedef struct LoadF {
  709   int n;  /* number of pre-read characters */
  710   FILE *f;  /* file being read */
  711   char buff[BUFSIZ];  /* area for reading file */
  712 } LoadF;
  713 
  714 
  715 static const char *getF (lua_State *L, void *ud, size_t *size) {
  716   LoadF *lf = (LoadF *)ud;
  717   (void)L;  /* not used */
  718   if (lf->n > 0) {  /* are there pre-read characters to be read? */
  719     *size = lf->n;  /* return them (chars already in buffer) */
  720     lf->n = 0;  /* no more pre-read characters */
  721   }
  722   else {  /* read a block from file */
  723     /* 'fread' can return > 0 *and* set the EOF flag. If next call to
  724        'getF' called 'fread', it might still wait for user input.
  725        The next check avoids this problem. */
  726     if (feof(lf->f)) return NULL;
  727     *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);  /* read block */
  728   }
  729   return lf->buff;
  730 }
  731 
  732 
  733 static int errfile (lua_State *L, const char *what, int fnameindex) {
  734   const char *serr = strerror(errno);
  735   const char *filename = lua_tostring(L, fnameindex) + 1;
  736   lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
  737   lua_remove(L, fnameindex);
  738   return LUA_ERRFILE;
  739 }
  740 
  741 
  742 static int skipBOM (LoadF *lf) {
  743   const char *p = "\xEF\xBB\xBF";  /* UTF-8 BOM mark */
  744   int c;
  745   lf->n = 0;
  746   do {
  747     c = getc(lf->f);
  748     if (c == EOF || c != *(const unsigned char *)p++) return c;
  749     lf->buff[lf->n++] = c;  /* to be read by the parser */
  750   } while (*p != '\0');
  751   lf->n = 0;  /* prefix matched; discard it */
  752   return getc(lf->f);  /* return next character */
  753 }
  754 
  755 
  756 /*
  757 ** reads the first character of file 'f' and skips an optional BOM mark
  758 ** in its beginning plus its first line if it starts with '#'. Returns
  759 ** true if it skipped the first line.  In any case, '*cp' has the
  760 ** first "valid" character of the file (after the optional BOM and
  761 ** a first-line comment).
  762 */
  763 static int skipcomment (LoadF *lf, int *cp) {
  764   int c = *cp = skipBOM(lf);
  765   if (c == '#') {  /* first line is a comment (Unix exec. file)? */
  766     do {  /* skip first line */
  767       c = getc(lf->f);
  768     } while (c != EOF && c != '\n');
  769     *cp = getc(lf->f);  /* skip end-of-line, if present */
  770     return 1;  /* there was a comment */
  771   }
  772   else return 0;  /* no comment */
  773 }
  774 
  775 
  776 LUALIB_API int luaL_loadfilex (lua_State *L, const char *filename,
  777                                              const char *mode) {
  778   LoadF lf;
  779   int status, readstatus;
  780   int c;
  781   int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */
  782   if (filename == NULL) {
  783     lua_pushliteral(L, "=stdin");
  784     lf.f = stdin;
  785   }
  786   else {
  787     lua_pushfstring(L, "@%s", filename);
  788     lf.f = fopen(filename, "r");
  789     if (lf.f == NULL) return errfile(L, "open", fnameindex);
  790   }
  791   if (skipcomment(&lf, &c))  /* read initial portion */
  792     lf.buff[lf.n++] = '\n';  /* add line to correct line numbers */
  793   if (c == LUA_SIGNATURE[0] && filename) {  /* binary file? */
  794     lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */
  795     if (lf.f == NULL) return errfile(L, "reopen", fnameindex);
  796     skipcomment(&lf, &c);  /* re-read initial portion */
  797   }
  798   if (c != EOF)
  799     lf.buff[lf.n++] = c;  /* 'c' is the first character of the stream */
  800   status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode);
  801   readstatus = ferror(lf.f);
  802   if (filename) fclose(lf.f);  /* close file (even in case of errors) */
  803   if (readstatus) {
  804     lua_settop(L, fnameindex);  /* ignore results from 'lua_load' */
  805     return errfile(L, "read", fnameindex);
  806   }
  807   lua_remove(L, fnameindex);
  808   return status;
  809 }
  810 
  811 
  812 typedef struct LoadS {
  813   const char *s;
  814   size_t size;
  815 } LoadS;
  816 
  817 
  818 static const char *getS (lua_State *L, void *ud, size_t *size) {
  819   LoadS *ls = (LoadS *)ud;
  820   (void)L;  /* not used */
  821   if (ls->size == 0) return NULL;
  822   *size = ls->size;
  823   ls->size = 0;
  824   return ls->s;
  825 }
  826 
  827 
  828 LUALIB_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t size,
  829                                  const char *name, const char *mode) {
  830   LoadS ls;
  831   ls.s = buff;
  832   ls.size = size;
  833   return lua_load(L, getS, &ls, name, mode);
  834 }
  835 
  836 
  837 LUALIB_API int luaL_loadstring (lua_State *L, const char *s) {
  838   return luaL_loadbuffer(L, s, strlen(s), s);
  839 }
  840 
  841 /* }====================================================== */
  842 
  843 
  844 
  845 LUALIB_API int luaL_getmetafield (lua_State *L, int obj, const char *event) {
  846   if (!lua_getmetatable(L, obj))  /* no metatable? */
  847     return LUA_TNIL;
  848   else {
  849     int tt;
  850     lua_pushstring(L, event);
  851     tt = lua_rawget(L, -2);
  852     if (tt == LUA_TNIL)  /* is metafield nil? */
  853       lua_pop(L, 2);  /* remove metatable and metafield */
  854     else
  855       lua_remove(L, -2);  /* remove only metatable */
  856     return tt;  /* return metafield type */
  857   }
  858 }
  859 
  860 
  861 LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) {
  862   obj = lua_absindex(L, obj);
  863   if (luaL_getmetafield(L, obj, event) == LUA_TNIL)  /* no metafield? */
  864     return 0;
  865   lua_pushvalue(L, obj);
  866   lua_call(L, 1, 1);
  867   return 1;
  868 }
  869 
  870 
  871 LUALIB_API lua_Integer luaL_len (lua_State *L, int idx) {
  872   lua_Integer l;
  873   int isnum;
  874   lua_len(L, idx);
  875   l = lua_tointegerx(L, -1, &isnum);
  876   if (l_unlikely(!isnum))
  877     luaL_error(L, "object length is not an integer");
  878   lua_pop(L, 1);  /* remove object */
  879   return l;
  880 }
  881 
  882 
  883 LUALIB_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {
  884   if (luaL_callmeta(L, idx, "__tostring")) {  /* metafield? */
  885     if (!lua_isstring(L, -1))
  886       luaL_error(L, "'__tostring' must return a string");
  887   }
  888   else {
  889     switch (lua_type(L, idx)) {
  890       case LUA_TNUMBER: {
  891         if (lua_isinteger(L, idx))
  892           lua_pushfstring(L, "%I", (LUAI_UACINT)lua_tointeger(L, idx));
  893         else
  894           lua_pushfstring(L, "%f", (LUAI_UACNUMBER)lua_tonumber(L, idx));
  895         break;
  896       }
  897       case LUA_TSTRING:
  898         lua_pushvalue(L, idx);
  899         break;
  900       case LUA_TBOOLEAN:
  901         lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false"));
  902         break;
  903       case LUA_TNIL:
  904         lua_pushliteral(L, "nil");
  905         break;
  906       default: {
  907         int tt = luaL_getmetafield(L, idx, "__name");  /* try name */
  908         const char *kind = (tt == LUA_TSTRING) ? lua_tostring(L, -1) :
  909                                                  luaL_typename(L, idx);
  910         lua_pushfstring(L, "%s: %p", kind, lua_topointer(L, idx));
  911         if (tt != LUA_TNIL)
  912           lua_remove(L, -2);  /* remove '__name' */
  913         break;
  914       }
  915     }
  916   }
  917   return lua_tolstring(L, -1, len);
  918 }
  919 
  920 
  921 /*
  922 ** set functions from list 'l' into table at top - 'nup'; each
  923 ** function gets the 'nup' elements at the top as upvalues.
  924 ** Returns with only the table at the stack.
  925 */
  926 LUALIB_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
  927   luaL_checkstack(L, nup, "too many upvalues");
  928   for (; l->name != NULL; l++) {  /* fill the table with given functions */
  929     if (l->func == NULL)  /* place holder? */
  930       lua_pushboolean(L, 0);
  931     else {
  932       int i;
  933       for (i = 0; i < nup; i++)  /* copy upvalues to the top */
  934         lua_pushvalue(L, -nup);
  935       lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
  936     }
  937     lua_setfield(L, -(nup + 2), l->name);
  938   }
  939   lua_pop(L, nup);  /* remove upvalues */
  940 }
  941 
  942 
  943 /*
  944 ** ensure that stack[idx][fname] has a table and push that table
  945 ** into the stack
  946 */
  947 LUALIB_API int luaL_getsubtable (lua_State *L, int idx, const char *fname) {
  948   if (lua_getfield(L, idx, fname) == LUA_TTABLE)
  949     return 1;  /* table already there */
  950   else {
  951     lua_pop(L, 1);  /* remove previous result */
  952     idx = lua_absindex(L, idx);
  953     lua_newtable(L);
  954     lua_pushvalue(L, -1);  /* copy to be left at top */
  955     lua_setfield(L, idx, fname);  /* assign new table to field */
  956     return 0;  /* false, because did not find table there */
  957   }
  958 }
  959 
  960 
  961 /*
  962 ** Stripped-down 'require': After checking "loaded" table, calls 'openf'
  963 ** to open a module, registers the result in 'package.loaded' table and,
  964 ** if 'glb' is true, also registers the result in the global table.
  965 ** Leaves resulting module on the top.
  966 */
  967 LUALIB_API void luaL_requiref (lua_State *L, const char *modname,
  968                                lua_CFunction openf, int glb) {
  969   luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
  970   lua_getfield(L, -1, modname);  /* LOADED[modname] */
  971   if (!lua_toboolean(L, -1)) {  /* package not already loaded? */
  972     lua_pop(L, 1);  /* remove field */
  973     lua_pushcfunction(L, openf);
  974     lua_pushstring(L, modname);  /* argument to open function */
  975     lua_call(L, 1, 1);  /* call 'openf' to open module */
  976     lua_pushvalue(L, -1);  /* make copy of module (call result) */
  977     lua_setfield(L, -3, modname);  /* LOADED[modname] = module */
  978   }
  979   lua_remove(L, -2);  /* remove LOADED table */
  980   if (glb) {
  981     lua_pushvalue(L, -1);  /* copy of module */
  982     lua_setglobal(L, modname);  /* _G[modname] = module */
  983   }
  984 }
  985 
  986 
  987 LUALIB_API void luaL_addgsub (luaL_Buffer *b, const char *s,
  988                                      const char *p, const char *r) {
  989   const char *wild;
  990   size_t l = strlen(p);
  991   while ((wild = strstr(s, p)) != NULL) {
  992     luaL_addlstring(b, s, wild - s);  /* push prefix */
  993     luaL_addstring(b, r);  /* push replacement in place of pattern */
  994     s = wild + l;  /* continue after 'p' */
  995   }
  996   luaL_addstring(b, s);  /* push last suffix */
  997 }
  998 
  999 
 1000 LUALIB_API const char *luaL_gsub (lua_State *L, const char *s,
 1001                                   const char *p, const char *r) {
 1002   luaL_Buffer b;
 1003   luaL_buffinit(L, &b);
 1004   luaL_addgsub(&b, s, p, r);
 1005   luaL_pushresult(&b);
 1006   return lua_tostring(L, -1);
 1007 }
 1008 
 1009 
 1010 static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
 1011   (void)ud; (void)osize;  /* not used */
 1012   if (nsize == 0) {
 1013     free(ptr);
 1014     return NULL;
 1015   }
 1016   else
 1017     return realloc(ptr, nsize);
 1018 }
 1019 
 1020 
 1021 static int panic (lua_State *L) {
 1022   const char *msg = lua_tostring(L, -1);
 1023   if (msg == NULL) msg = "error object is not a string";
 1024   lua_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n",
 1025                         msg);
 1026   return 0;  /* return to Lua to abort */
 1027 }
 1028 
 1029 
 1030 /*
 1031 ** Warning functions:
 1032 ** warnfoff: warning system is off
 1033 ** warnfon: ready to start a new message
 1034 ** warnfcont: previous message is to be continued
 1035 */
 1036 static void warnfoff (void *ud, const char *message, int tocont);
 1037 static void warnfon (void *ud, const char *message, int tocont);
 1038 static void warnfcont (void *ud, const char *message, int tocont);
 1039 
 1040 
 1041 /*
 1042 ** Check whether message is a control message. If so, execute the
 1043 ** control or ignore it if unknown.
 1044 */
 1045 static int checkcontrol (lua_State *L, const char *message, int tocont) {
 1046   if (tocont || *(message++) != '@')  /* not a control message? */
 1047     return 0;
 1048   else {
 1049     if (strcmp(message, "off") == 0)
 1050       lua_setwarnf(L, warnfoff, L);  /* turn warnings off */
 1051     else if (strcmp(message, "on") == 0)
 1052       lua_setwarnf(L, warnfon, L);   /* turn warnings on */
 1053     return 1;  /* it was a control message */
 1054   }
 1055 }
 1056 
 1057 
 1058 static void warnfoff (void *ud, const char *message, int tocont) {
 1059   checkcontrol((lua_State *)ud, message, tocont);
 1060 }
 1061 
 1062 
 1063 /*
 1064 ** Writes the message and handle 'tocont', finishing the message
 1065 ** if needed and setting the next warn function.
 1066 */
 1067 static void warnfcont (void *ud, const char *message, int tocont) {
 1068   lua_State *L = (lua_State *)ud;
 1069   lua_writestringerror("%s", message);  /* write message */
 1070   if (tocont)  /* not the last part? */
 1071     lua_setwarnf(L, warnfcont, L);  /* to be continued */
 1072   else {  /* last part */
 1073     lua_writestringerror("%s", "\n");  /* finish message with end-of-line */
 1074     lua_setwarnf(L, warnfon, L);  /* next call is a new message */
 1075   }
 1076 }
 1077 
 1078 
 1079 static void warnfon (void *ud, const char *message, int tocont) {
 1080   if (checkcontrol((lua_State *)ud, message, tocont))  /* control message? */
 1081     return;  /* nothing else to be done */
 1082   lua_writestringerror("%s", "Lua warning: ");  /* start a new warning */
 1083   warnfcont(ud, message, tocont);  /* finish processing */
 1084 }
 1085 
 1086 
 1087 LUALIB_API lua_State *luaL_newstate (void) {
 1088   lua_State *L = lua_newstate(l_alloc, NULL);
 1089   if (l_likely(L)) {
 1090     lua_atpanic(L, &panic);
 1091     lua_setwarnf(L, warnfoff, L);  /* default is warnings off */
 1092   }
 1093   return L;
 1094 }
 1095 
 1096 
 1097 LUALIB_API void luaL_checkversion_ (lua_State *L, lua_Number ver, size_t sz) {
 1098   lua_Number v = lua_version(L);
 1099   if (sz != LUAL_NUMSIZES)  /* check numeric types */
 1100     luaL_error(L, "core and library have incompatible numeric types");
 1101   else if (v != ver)
 1102     luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f",
 1103                   (LUAI_UACNUMBER)ver, (LUAI_UACNUMBER)v);
 1104 }
 1105