text: /*
  ** $Id: lauxlib.c,v 1.289.1.1 2017/04/19 17:20:42 roberto Exp $
  ** Auxiliary functions for building Lua libraries
  ** See Copyright Notice in lua.h
  */
  
  #define lauxlib_c
  #define LUA_LIB
  
  #include "lprefix.h"
  
  
  #include <errno.h>
  #include <stdarg.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  
  /*
  ** This file uses only the official API of Lua.
  ** Any function declared here could be written as an application function.
  */
  
  #include "lua.h"
  
  #include "lauxlib.h"
  
  
  /*
  ** {======================================================
  ** Traceback
  ** =======================================================
  */
  
  
  #define LEVELS1	10	/* size of the first part of the stack */
  #define LEVELS2	11	/* size of the second part of the stack */
  
  
  
  /*
  ** search for 'objidx' in table at index -1.
  ** return 1 + string at top if find a good name.
  */
  static int findfield (lua_State *L, int objidx, int level) {
    if (level == 0 || !lua_istable(L, -1))
      return 0;  /* not found */
    lua_pushnil(L);  /* start 'next' loop */
    while (lua_next(L, -2)) {  /* for each pair in table */
      if (lua_type(L, -2) == LUA_TSTRING) {  /* ignore non-string keys */
        if (lua_rawequal(L, objidx, -1)) {  /* found object? */
          lua_pop(L, 1);  /* remove value (but keep name) */
          return 1;
        }
        else if (findfield(L, objidx, level - 1)) {  /* try recursively */
          lua_remove(L, -2);  /* remove table (but keep name) */
          lua_pushliteral(L, ".");
          lua_insert(L, -2);  /* place '.' between the two names */
          lua_concat(L, 3);
          return 1;
        }
      }
      lua_pop(L, 1);  /* remove value */
    }
    return 0;  /* not found */
  }
  
  
  /*
  ** Search for a name for a function in all loaded modules
  */
  static int pushglobalfuncname (lua_State *L, lua_Debug *ar) {
    int top = lua_gettop(L);
    lua_getinfo(L, "f", ar);  /* push function */
    lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
    if (findfield(L, top + 1, 2)) {
      const char *name = lua_tostring(L, -1);
      if (strncmp(name, "_G.", 3) == 0) {  /* name start with '_G.'? */
        lua_pushstring(L, name + 3);  /* push name without prefix */
        lua_remove(L, -2);  /* remove original name */
      }
      lua_copy(L, -1, top + 1);  /* move name to proper place */
      lua_pop(L, 2);  /* remove pushed values */
      return 1;
    }
    else {
      lua_settop(L, top);  /* remove function and global table */
      return 0;
    }
  }
  
  
  static void pushfuncname (lua_State *L, lua_Debug *ar) {
    if (pushglobalfuncname(L, ar)) {  /* try first a global name */
      lua_pushfstring(L, "function '%s'", lua_tostring(L, -1));
      lua_remove(L, -2);  /* remove name */
    }
    else if (*ar->namewhat != '\0')  /* is there a name from code? */
      lua_pushfstring(L, "%s '%s'", ar->namewhat, ar->name);  /* use it */
    else if (*ar->what == 'm')  /* main? */
        lua_pushliteral(L, "main chunk");
    else if (*ar->what != 'C')  /* for Lua functions, use <file:line> */
      lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
    else  /* nothing left... */
      lua_pushliteral(L, "?");
  }
  
  
  static int lastlevel (lua_State *L) {
    lua_Debug ar;
    int li = 1, le = 1;
    /* find an upper bound */
    while (lua_getstack(L, le, &ar)) { li = le; le *= 2; }
    /* do a binary search */
    while (li < le) {
      int m = (li + le)/2;
      if (lua_getstack(L, m, &ar)) li = m + 1;
      else le = m;
    }
    return le - 1;
  }
  
  
  LUALIB_API void luaL_traceback (lua_State *L, lua_State *L1,
                                  const char *msg, int level) {
    lua_Debug ar;
    int top = lua_gettop(L);
    int last = lastlevel(L1);
    int n1 = (last - level > LEVELS1 + LEVELS2) ? LEVELS1 : -1;
    if (msg)
      lua_pushfstring(L, "%s\n", msg);
    luaL_checkstack(L, 10, NULL);
    lua_pushliteral(L, "stack traceback:");
    while (lua_getstack(L1, level++, &ar)) {
      if (n1-- == 0) {  /* too many levels? */
        lua_pushliteral(L, "\n\t...");  /* add a '...' */
        level = last - LEVELS2 + 1;  /* and skip to last ones */
      }
      else {
        lua_getinfo(L1, "Slnt", &ar);
        lua_pushfstring(L, "\n\t%s:", ar.short_src);
        if (ar.currentline > 0)
          lua_pushfstring(L, "%d:", ar.currentline);
        lua_pushliteral(L, " in ");
        pushfuncname(L, &ar);
        if (ar.istailcall)
          lua_pushliteral(L, "\n\t(...tail calls...)");
        lua_concat(L, lua_gettop(L) - top);
      }
    }
    lua_concat(L, lua_gettop(L) - top);
  }
  
  /* }====================================================== */
  
  
  /*
  ** {======================================================
  ** Error-report functions
  ** =======================================================
  */
  
  LUALIB_API int luaL_argerror (lua_State *L, int arg, const char *extramsg) {
    lua_Debug ar;
    if (!lua_getstack(L, 0, &ar))  /* no stack frame? */
      return luaL_error(L, "bad argument #%d (%s)", arg, extramsg);
    lua_getinfo(L, "n", &ar);
    if (strcmp(ar.namewhat, "method") == 0) {
      arg--;  /* do not count 'self' */
      if (arg == 0)  /* error is in the self argument itself? */
        return luaL_error(L, "calling '%s' on bad self (%s)",
                             ar.name, extramsg);
    }
    if (ar.name == NULL)
      ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?";
    return luaL_error(L, "bad argument #%d to '%s' (%s)",
                          arg, ar.name, extramsg);
  }
  
  
  static int typeerror (lua_State *L, int arg, const char *tname) {
    const char *msg;
    const char *typearg;  /* name for the type of the actual argument */
    if (luaL_getmetafield(L, arg, "__name") == LUA_TSTRING)
      typearg = lua_tostring(L, -1);  /* use the given type name */
    else if (lua_type(L, arg) == LUA_TLIGHTUSERDATA)
      typearg = "light userdata";  /* special name for messages */
    else
      typearg = luaL_typename(L, arg);  /* standard name */
    msg = lua_pushfstring(L, "%s expected, got %s", tname, typearg);
    return luaL_argerror(L, arg, msg);
  }
  
  
  static void tag_error (lua_State *L, int arg, int tag) {
    typeerror(L, arg, lua_typename(L, tag));
  }
  
  
  /*
  ** The use of 'lua_pushfstring' ensures this function does not
  ** need reserved stack space when called.
  */
  LUALIB_API void luaL_where (lua_State *L, int level) {
    lua_Debug ar;
    if (lua_getstack(L, level, &ar)) {  /* check function at level */
      lua_getinfo(L, "Sl", &ar);  /* get info about it */
      if (ar.currentline > 0) {  /* is there info? */
        lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline);
        return;
      }
    }
    lua_pushfstring(L, "");  /* else, no information available... */
  }
  
  
  /*
  ** Again, the use of 'lua_pushvfstring' ensures this function does
  ** not need reserved stack space when called. (At worst, it generates
  ** an error with "stack overflow" instead of the given message.)
  */
  LUALIB_API int luaL_error (lua_State *L, const char *fmt, ...) {
    va_list argp;
    va_start(argp, fmt);
    luaL_where(L, 1);
    lua_pushvfstring(L, fmt, argp);
    va_end(argp);
    lua_concat(L, 2);
    return lua_error(L);
  }
  
  
  LUALIB_API int luaL_fileresult (lua_State *L, int stat, const char *fname) {
    int en = errno;  /* calls to Lua API may change this value */
    if (stat) {
      lua_pushboolean(L, 1);
      return 1;
    }
    else {
      lua_pushnil(L);
      if (fname)
        lua_pushfstring(L, "%s: %s", fname, strerror(en));
      else
        lua_pushstring(L, strerror(en));
      lua_pushinteger(L, en);
      return 3;
    }
  }
  
  
  #if !defined(l_inspectstat)	/* { */
  
  #if defined(LUA_USE_POSIX)
  
  #include <sys/wait.h>
  
  /*
  ** use appropriate macros to interpret 'pclose' return status
  */
  #define l_inspectstat(stat,what)  \
     if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
     else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }
  
  #else
  
  #define l_inspectstat(stat,what)  /* no op */
  
  #endif
  
  #endif				/* } */
  
  
  LUALIB_API int luaL_execresult (lua_State *L, int stat) {
    const char *what = "exit";  /* type of termination */
    if (stat == -1)  /* error? */
      return luaL_fileresult(L, 0, NULL);
    else {
      l_inspectstat(stat, what);  /* interpret result */
      if (*what == 'e' && stat == 0)  /* successful termination? */
        lua_pushboolean(L, 1);
      else
        lua_pushnil(L);
      lua_pushstring(L, what);
      lua_pushinteger(L, stat);
      return 3;  /* return true/nil,what,code */
    }
  }
  
  /* }====================================================== */
  
  
  /*
  ** {======================================================
  ** Userdata's metatable manipulation
  ** =======================================================
  */
  
  LUALIB_API int luaL_newmetatable (lua_State *L, const char *tname) {
    if (luaL_getmetatable(L, tname) != LUA_TNIL)  /* name already in use? */
      return 0;  /* leave previous value on top, but return 0 */
    lua_pop(L, 1);
    lua_createtable(L, 0, 2);  /* create metatable */
    lua_pushstring(L, tname);
    lua_setfield(L, -2, "__name");  /* metatable.__name = tname */
    lua_pushvalue(L, -1);
    lua_setfield(L, LUA_REGISTRYINDEX, tname);  /* registry.name = metatable */
    return 1;
  }
  
  
  LUALIB_API void luaL_setmetatable (lua_State *L, const char *tname) {
    luaL_getmetatable(L, tname);
    lua_setmetatable(L, -2);
  }
  
  
  LUALIB_API void *luaL_testudata (lua_State *L, int ud, const char *tname) {
    void *p = lua_touserdata(L, ud);
    if (p != NULL) {  /* value is a userdata? */
      if (lua_getmetatable(L, ud)) {  /* does it have a metatable? */
        luaL_getmetatable(L, tname);  /* get correct metatable */
        if (!lua_rawequal(L, -1, -2))  /* not the same? */
          p = NULL;  /* value is a userdata with wrong metatable */
        lua_pop(L, 2);  /* remove both metatables */
        return p;
      }
    }
    return NULL;  /* value is not a userdata with a metatable */
  }
  
  
  LUALIB_API void *luaL_checkudata (lua_State *L, int ud, const char *tname) {
    void *p = luaL_testudata(L, ud, tname);
    if (p == NULL) typeerror(L, ud, tname);
    return p;
  }
  
  /* }====================================================== */
  
  
  /*
  ** {======================================================
  ** Argument check functions
  ** =======================================================
  */
  
  LUALIB_API int luaL_checkoption (lua_State *L, int arg, const char *def,
                                   const char *const lst[]) {
    const char *name = (def) ? luaL_optstring(L, arg, def) :
                               luaL_checkstring(L, arg);
    int i;
    for (i=0; lst[i]; i++)
      if (strcmp(lst[i], name) == 0)
        return i;
    return luaL_argerror(L, arg,
                         lua_pushfstring(L, "invalid option '%s'", name));
  }
  
  
  /*
  ** Ensures the stack has at least 'space' extra slots, raising an error
  ** if it cannot fulfill the request. (The error handling needs a few
  ** extra slots to format the error message. In case of an error without
  ** this extra space, Lua will generate the same 'stack overflow' error,
  ** but without 'msg'.)
  */
  LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *msg) {
    if (!lua_checkstack(L, space)) {
      if (msg)
        luaL_error(L, "stack overflow (%s)", msg);
      else
        luaL_error(L, "stack overflow");
    }
  }
  
  
  LUALIB_API void luaL_checktype (lua_State *L, int arg, int t) {
    if (lua_type(L, arg) != t)
      tag_error(L, arg, t);
  }
  
  
  LUALIB_API void luaL_checkany (lua_State *L, int arg) {
    if (lua_type(L, arg) == LUA_TNONE)
      luaL_argerror(L, arg, "value expected");
  }
  
  
  LUALIB_API const char *luaL_checklstring (lua_State *L, int arg, size_t *len) {
    const char *s = lua_tolstring(L, arg, len);
    if (!s) tag_error(L, arg, LUA_TSTRING);
    return s;
  }
  
  
  LUALIB_API const char *luaL_optlstring (lua_State *L, int arg,
                                          const char *def, size_t *len) {
    if (lua_isnoneornil(L, arg)) {
      if (len)
        *len = (def ? strlen(def) : 0);
      return def;
    }
    else return luaL_checklstring(L, arg, len);
  }
  
  
  LUALIB_API lua_Number luaL_checknumber (lua_State *L, int arg) {
    int isnum;
    lua_Number d = lua_tonumberx(L, arg, &isnum);
    if (!isnum)
      tag_error(L, arg, LUA_TNUMBER);
    return d;
  }
  
  
  LUALIB_API lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number def) {
    return luaL_opt(L, luaL_checknumber, arg, def);
  }
  
  
  static void interror (lua_State *L, int arg) {
    if (lua_isnumber(L, arg))
      luaL_argerror(L, arg, "number has no integer representation");
    else
      tag_error(L, arg, LUA_TNUMBER);
  }
  
  
  LUALIB_API lua_Integer luaL_checkinteger (lua_State *L, int arg) {
    int isnum;
    lua_Integer d = lua_tointegerx(L, arg, &isnum);
    if (!isnum) {
      interror(L, arg);
    }
    return d;
  }
  
  
  LUALIB_API lua_Integer luaL_optinteger (lua_State *L, int arg,
                                                        lua_Integer def) {
    return luaL_opt(L, luaL_checkinteger, arg, def);
  }
  
  /* }====================================================== */
  
  
  /*
  ** {======================================================
  ** Generic Buffer manipulation
  ** =======================================================
  */
  
  /* userdata to box arbitrary data */
  typedef struct UBox {
    void *box;
    size_t bsize;
  } UBox;
  
  
  static void *resizebox (lua_State *L, int idx, size_t newsize) {
    void *ud;
    lua_Alloc allocf = lua_getallocf(L, &ud);
    UBox *box = (UBox *)lua_touserdata(L, idx);
    void *temp = allocf(ud, box->box, box->bsize, newsize);
    if (temp == NULL && newsize > 0) {  /* allocation error? */
      resizebox(L, idx, 0);  /* free buffer */
      luaL_error(L, "not enough memory for buffer allocation");
    }
    box->box = temp;
    box->bsize = newsize;
    return temp;
  }
  
  
  static int boxgc (lua_State *L) {
    resizebox(L, 1, 0);
    return 0;
  }
  
  
  static void *newbox (lua_State *L, size_t newsize) {
    UBox *box = (UBox *)lua_newuserdata(L, sizeof(UBox));
    box->box = NULL;
    box->bsize = 0;
    if (luaL_newmetatable(L, "LUABOX")) {  /* creating metatable? */
      lua_pushcfunction(L, boxgc);
      lua_setfield(L, -2, "__gc");  /* metatable.__gc = boxgc */
    }
    lua_setmetatable(L, -2);
    return resizebox(L, -1, newsize);
  }
  
  
  /*
  ** check whether buffer is using a userdata on the stack as a temporary
  ** buffer
  */
  #define buffonstack(B)	((B)->b != (B)->initb)
  
  
  /*
  ** returns a pointer to a free area with at least 'sz' bytes
  */
  LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) {
    lua_State *L = B->L;
    if (B->size - B->n < sz) {  /* not enough space? */
      char *newbuff;
      size_t newsize = B->size * 2;  /* double buffer size */
      if (newsize - B->n < sz)  /* not big enough? */
        newsize = B->n + sz;
      if (newsize < B->n || newsize - B->n < sz)
        luaL_error(L, "buffer too large");
      /* create larger buffer */
      if (buffonstack(B))
        newbuff = (char *)resizebox(L, -1, newsize);
      else {  /* no buffer yet */
        newbuff = (char *)newbox(L, newsize);
        memcpy(newbuff, B->b, B->n * sizeof(char));  /* copy original content */
      }
      B->b = newbuff;
      B->size = newsize;
    }
    return &B->b[B->n];
  }
  
  
  LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {
    if (l > 0) {  /* avoid 'memcpy' when 's' can be NULL */
      char *b = luaL_prepbuffsize(B, l);
      memcpy(b, s, l * sizeof(char));
      luaL_addsize(B, l);
    }
  }
  
  
  LUALIB_API void luaL_addstring (luaL_Buffer *B, const char *s) {
    luaL_addlstring(B, s, strlen(s));
  }
  
  
  LUALIB_API void luaL_pushresult (luaL_Buffer *B) {
    lua_State *L = B->L;
    lua_pushlstring(L, B->b, B->n);
    if (buffonstack(B)) {
      resizebox(L, -2, 0);  /* delete old buffer */
      lua_remove(L, -2);  /* remove its header from the stack */
    }
  }
  
  
  LUALIB_API void luaL_pushresultsize (luaL_Buffer *B, size_t sz) {
    luaL_addsize(B, sz);
    luaL_pushresult(B);
  }
  
  
  LUALIB_API void luaL_addvalue (luaL_Buffer *B) {
    lua_State *L = B->L;
    size_t l;
    const char *s = lua_tolstring(L, -1, &l);
    if (buffonstack(B))
      lua_insert(L, -2);  /* put value below buffer */
    luaL_addlstring(B, s, l);
    lua_remove(L, (buffonstack(B)) ? -2 : -1);  /* remove value */
  }
  
  
  LUALIB_API void luaL_buffinit (lua_State *L, luaL_Buffer *B) {
    B->L = L;
    B->b = B->initb;
    B->n = 0;
    B->size = LUAL_BUFFERSIZE;
  }
  
  
  LUALIB_API char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz) {
    luaL_buffinit(L, B);
    return luaL_prepbuffsize(B, sz);
  }
  
  /* }====================================================== */
  
  
  /*
  ** {======================================================
  ** Reference system
  ** =======================================================
  */
  
  /* index of free-list header */
  #define freelist	0
  
  
  LUALIB_API int luaL_ref (lua_State *L, int t) {
    int ref;
    if (lua_isnil(L, -1)) {
      lua_pop(L, 1);  /* remove from stack */
      return LUA_REFNIL;  /* 'nil' has a unique fixed reference */
    }
    t = lua_absindex(L, t);
    lua_rawgeti(L, t, freelist);  /* get first free element */
    ref = (int)lua_tointeger(L, -1);  /* ref = t[freelist] */
    lua_pop(L, 1);  /* remove it from stack */
    if (ref != 0) {  /* any free element? */
      lua_rawgeti(L, t, ref);  /* remove it from list */
      lua_rawseti(L, t, freelist);  /* (t[freelist] = t[ref]) */
    }
    else  /* no free elements */
      ref = (int)lua_rawlen(L, t) + 1;  /* get a new reference */
    lua_rawseti(L, t, ref);
    return ref;
  }
  
  
  LUALIB_API void luaL_unref (lua_State *L, int t, int ref) {
    if (ref >= 0) {
      t = lua_absindex(L, t);
      lua_rawgeti(L, t, freelist);
      lua_rawseti(L, t, ref);  /* t[ref] = t[freelist] */
      lua_pushinteger(L, ref);
      lua_rawseti(L, t, freelist);  /* t[freelist] = ref */
    }
  }
  
  /* }====================================================== */
  
  
  /*
  ** {======================================================
  ** Load functions
  ** =======================================================
  */
  
  typedef struct LoadF {
    int n;  /* number of pre-read characters */
    FILE *f;  /* file being read */
    char buff[BUFSIZ];  /* area for reading file */
  } LoadF;
  
  
  static const char *getF (lua_State *L, void *ud, size_t *size) {
    LoadF *lf = (LoadF *)ud;
    (void)L;  /* not used */
    if (lf->n > 0) {  /* are there pre-read characters to be read? */
      *size = lf->n;  /* return them (chars already in buffer) */
      lf->n = 0;  /* no more pre-read characters */
    }
    else {  /* read a block from file */
      /* 'fread' can return > 0 *and* set the EOF flag. If next call to
         'getF' called 'fread', it might still wait for user input.
         The next check avoids this problem. */
      if (feof(lf->f)) return NULL;
      *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);  /* read block */
    }
    return lf->buff;
  }
  
  
  static int errfile (lua_State *L, const char *what, int fnameindex) {
    const char *serr = strerror(errno);
    const char *filename = lua_tostring(L, fnameindex) + 1;
    lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);
    lua_remove(L, fnameindex);
    return LUA_ERRFILE;
  }
  
  
  static int skipBOM (LoadF *lf) {
    const char *p = "\xEF\xBB\xBF";  /* UTF-8 BOM mark */
    int c;
    lf->n = 0;
    do {
      c = getc(lf->f);
      if (c == EOF || c != *(const unsigned char *)p++) return c;
      lf->buff[lf->n++] = c;  /* to be read by the parser */
    } while (*p != '\0');
    lf->n = 0;  /* prefix matched; discard it */
    return getc(lf->f);  /* return next character */
  }
  
  
  /*
  ** reads the first character of file 'f' and skips an optional BOM mark
  ** in its beginning plus its first line if it starts with '#'. Returns
  ** true if it skipped the first line.  In any case, '*cp' has the
  ** first "valid" character of the file (after the optional BOM and
  ** a first-line comment).
  */
  static int skipcomment (LoadF *lf, int *cp) {
    int c = *cp = skipBOM(lf);
    if (c == '#') {  /* first line is a comment (Unix exec. file)? */
      do {  /* skip first line */
        c = getc(lf->f);
      } while (c != EOF && c != '\n');
      *cp = getc(lf->f);  /* skip end-of-line, if present */
      return 1;  /* there was a comment */
    }
    else return 0;  /* no comment */
  }
  
  LUA_API void luaS_expandshr(int n);
  
  static int luaL_loadfilex_ (lua_State *L, const char *filename,
                                               const char *mode) {
    LoadF lf;
    int status, readstatus;
    int c;
    int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */
    if (filename == NULL) {
      lua_pushliteral(L, "=stdin");
      lf.f = stdin;
    }
    else {
      lua_pushfstring(L, "@%s", filename);
      lf.f = fopen(filename, "r");
      if (lf.f == NULL) return errfile(L, "open", fnameindex);
    }
    if (skipcomment(&lf, &c))  /* read initial portion */
      lf.buff[lf.n++] = '\n';  /* add line to correct line numbers */
    if (c == LUA_SIGNATURE[0] && filename) {  /* binary file? */
      lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */
      if (lf.f == NULL) return errfile(L, "reopen", fnameindex);
      skipcomment(&lf, &c);  /* re-read initial portion */
    }
    if (c != EOF)
      lf.buff[lf.n++] = c;  /* 'c' is the first character of the stream */
    luaS_expandshr(4096);
    status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode);
    luaS_expandshr(-4096);
    readstatus = ferror(lf.f);
    if (filename) fclose(lf.f);  /* close file (even in case of errors) */
    if (readstatus) {
      lua_settop(L, fnameindex);  /* ignore results from 'lua_load' */
      return errfile(L, "read", fnameindex);
    }
    lua_remove(L, fnameindex);
    return status;
  }
  
  
  typedef struct LoadS {
    const char *s;
    size_t size;
  } LoadS;
  
  
  static const char *getS (lua_State *L, void *ud, size_t *size) {
    LoadS *ls = (LoadS *)ud;
    (void)L;  /* not used */
    if (ls->size == 0) return NULL;
    *size = ls->size;
    ls->size = 0;
    return ls->s;
  }
  
  
  LUALIB_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t size,
                                   const char *name, const char *mode) {
    LoadS ls;
    ls.s = buff;
    ls.size = size;
    return lua_load(L, getS, &ls, name, mode);
  }
  
  
  LUALIB_API int luaL_loadstring (lua_State *L, const char *s) {
    return luaL_loadbuffer(L, s, strlen(s), s);
  }
  
  /* }====================================================== */
  
  
  
  LUALIB_API int luaL_getmetafield (lua_State *L, int obj, const char *event) {
    if (!lua_getmetatable(L, obj))  /* no metatable? */
      return LUA_TNIL;
    else {
      int tt;
      lua_pushstring(L, event);
      tt = lua_rawget(L, -2);
      if (tt == LUA_TNIL)  /* is metafield nil? */
        lua_pop(L, 2);  /* remove metatable and metafield */
      else
        lua_remove(L, -2);  /* remove only metatable */
      return tt;  /* return metafield type */
    }
  }
  
  
  LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) {
    obj = lua_absindex(L, obj);
    if (luaL_getmetafield(L, obj, event) == LUA_TNIL)  /* no metafield? */
      return 0;
    lua_pushvalue(L, obj);
    lua_call(L, 1, 1);
    return 1;
  }
  
  
  LUALIB_API lua_Integer luaL_len (lua_State *L, int idx) {
    lua_Integer l;
    int isnum;
    lua_len(L, idx);
    l = lua_tointegerx(L, -1, &isnum);
    if (!isnum)
      luaL_error(L, "object length is not an integer");
    lua_pop(L, 1);  /* remove object */
    return l;
  }
  
  
  LUALIB_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {
    if (luaL_callmeta(L, idx, "__tostring")) {  /* metafield? */
      if (!lua_isstring(L, -1))
        luaL_error(L, "'__tostring' must return a string");
    }
    else {
      switch (lua_type(L, idx)) {
        case LUA_TNUMBER: {
          if (lua_isinteger(L, idx))
            lua_pushfstring(L, "%I", (LUAI_UACINT)lua_tointeger(L, idx));
          else
            lua_pushfstring(L, "%f", (LUAI_UACNUMBER)lua_tonumber(L, idx));
          break;
        }
        case LUA_TSTRING:
          lua_pushvalue(L, idx);
          break;
        case LUA_TBOOLEAN:
          lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false"));
          break;
        case LUA_TNIL:
          lua_pushliteral(L, "nil");
          break;
        default: {
          int tt = luaL_getmetafield(L, idx, "__name");  /* try name */
          const char *kind = (tt == LUA_TSTRING) ? lua_tostring(L, -1) :
                                                   luaL_typename(L, idx);
          lua_pushfstring(L, "%s: %p", kind, lua_topointer(L, idx));
          if (tt != LUA_TNIL)
            lua_remove(L, -2);  /* remove '__name' */
          break;
        }
      }
    }
    return lua_tolstring(L, -1, len);
  }
  
  
  /*
  ** {======================================================
  ** Compatibility with 5.1 module functions
  ** =======================================================
  */
  #if defined(LUA_COMPAT_MODULE)
  
  static const char *luaL_findtable (lua_State *L, int idx,
                                     const char *fname, int szhint) {
    const char *e;
    if (idx) lua_pushvalue(L, idx);
    do {
      e = strchr(fname, '.');
      if (e == NULL) e = fname + strlen(fname);
      lua_pushlstring(L, fname, e - fname);
      if (lua_rawget(L, -2) == LUA_TNIL) {  /* no such field? */
        lua_pop(L, 1);  /* remove this nil */
        lua_createtable(L, 0, (*e == '.' ? 1 : szhint)); /* new table for field */
        lua_pushlstring(L, fname, e - fname);
        lua_pushvalue(L, -2);
        lua_settable(L, -4);  /* set new table into field */
      }
      else if (!lua_istable(L, -1)) {  /* field has a non-table value? */
        lua_pop(L, 2);  /* remove table and value */
        return fname;  /* return problematic part of the name */
      }
      lua_remove(L, -2);  /* remove previous table */
      fname = e + 1;
    } while (*e == '.');
    return NULL;
  }
  
  
  /*
  ** Count number of elements in a luaL_Reg list.
  */
  static int libsize (const luaL_Reg *l) {
    int size = 0;
    for (; l && l->name; l++) size++;
    return size;
  }
  
  
  /*
  ** Find or create a module table with a given name. The function
  ** first looks at the LOADED table and, if that fails, try a
  ** global variable with that name. In any case, leaves on the stack
  ** the module table.
  */
  LUALIB_API void luaL_pushmodule (lua_State *L, const char *modname,
                                   int sizehint) {
    luaL_findtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE, 1);
    if (lua_getfield(L, -1, modname) != LUA_TTABLE) {  /* no LOADED[modname]? */
      lua_pop(L, 1);  /* remove previous result */
      /* try global variable (and create one if it does not exist) */
      lua_pushglobaltable(L);
      if (luaL_findtable(L, 0, modname, sizehint) != NULL)
        luaL_error(L, "name conflict for module '%s'", modname);
      lua_pushvalue(L, -1);
      lua_setfield(L, -3, modname);  /* LOADED[modname] = new table */
    }
    lua_remove(L, -2);  /* remove LOADED table */
  }
  
  
  LUALIB_API void luaL_openlib (lua_State *L, const char *libname,
                                 const luaL_Reg *l, int nup) {
    luaL_checkversion(L);
    if (libname) {
      luaL_pushmodule(L, libname, libsize(l));  /* get/create library table */
      lua_insert(L, -(nup + 1));  /* move library table to below upvalues */
    }
    if (l)
      luaL_setfuncs(L, l, nup);
    else
      lua_pop(L, nup);  /* remove upvalues */
  }
  
  #endif
  /* }====================================================== */
  
  /*
  ** set functions from list 'l' into table at top - 'nup'; each
  ** function gets the 'nup' elements at the top as upvalues.
  ** Returns with only the table at the stack.
  */
  LUALIB_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
    luaL_checkstack(L, nup, "too many upvalues");
    for (; l->name != NULL; l++) {  /* fill the table with given functions */
      int i;
      for (i = 0; i < nup; i++)  /* copy upvalues to the top */
        lua_pushvalue(L, -nup);
      lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
      lua_setfield(L, -(nup + 2), l->name);
    }
    lua_pop(L, nup);  /* remove upvalues */
  }
  
  
  /*
  ** ensure that stack[idx][fname] has a table and push that table
  ** into the stack
  */
  LUALIB_API int luaL_getsubtable (lua_State *L, int idx, const char *fname) {
    if (lua_getfield(L, idx, fname) == LUA_TTABLE)
      return 1;  /* table already there */
    else {
      lua_pop(L, 1);  /* remove previous result */
      idx = lua_absindex(L, idx);
      lua_newtable(L);
      lua_pushvalue(L, -1);  /* copy to be left at top */
      lua_setfield(L, idx, fname);  /* assign new table to field */
      return 0;  /* false, because did not find table there */
    }
  }
  
  
  /*
  ** Stripped-down 'require': After checking "loaded" table, calls 'openf'
  ** to open a module, registers the result in 'package.loaded' table and,
  ** if 'glb' is true, also registers the result in the global table.
  ** Leaves resulting module on the top.
  */
  LUALIB_API void luaL_requiref (lua_State *L, const char *modname,
                                 lua_CFunction openf, int glb) {
    luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
    lua_getfield(L, -1, modname);  /* LOADED[modname] */
    if (!lua_toboolean(L, -1)) {  /* package not already loaded? */
      lua_pop(L, 1);  /* remove field */
      lua_pushcfunction(L, openf);
      lua_pushstring(L, modname);  /* argument to open function */
      lua_call(L, 1, 1);  /* call 'openf' to open module */
      lua_pushvalue(L, -1);  /* make copy of module (call result) */
      lua_setfield(L, -3, modname);  /* LOADED[modname] = module */
    }
    lua_remove(L, -2);  /* remove LOADED table */
    if (glb) {
      lua_pushvalue(L, -1);  /* copy of module */
      lua_setglobal(L, modname);  /* _G[modname] = module */
    }
  }
  
  
  LUALIB_API const char *luaL_gsub (lua_State *L, const char *s, const char *p,
                                                                 const char *r) {
    const char *wild;
    size_t l = strlen(p);
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    while ((wild = strstr(s, p)) != NULL) {
      luaL_addlstring(&b, s, wild - s);  /* push prefix */
      luaL_addstring(&b, r);  /* push replacement in place of pattern */
      s = wild + l;  /* continue after 'p' */
    }
    luaL_addstring(&b, s);  /* push last suffix */
    luaL_pushresult(&b);
    return lua_tostring(L, -1);
  }
  
  
  static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
    (void)ud; (void)osize;  /* not used */
    if (nsize == 0) {
      free(ptr);
      return NULL;
    }
    else
      return realloc(ptr, nsize);
  }
  
  
  static int panic (lua_State *L) {
    lua_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n",
                          lua_tostring(L, -1));
    return 0;  /* return to Lua to abort */
  }
  
  
  LUALIB_API lua_State *luaL_newstate (void) {
    lua_State *L = lua_newstate(l_alloc, NULL);
    if (L) lua_atpanic(L, &panic);
    return L;
  }
  
  
  LUALIB_API void luaL_checkversion_ (lua_State *L, lua_Number ver, size_t sz) {
    const lua_Number *v = lua_version(L);
    if (sz != LUAL_NUMSIZES)  /* check numeric types */
      luaL_error(L, "core and library have incompatible numeric types");
    if (v != lua_version(NULL))
      luaL_error(L, "multiple Lua VMs detected");
    else if (*v != ver)
      luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f",
                    (LUAI_UACNUMBER)ver, (LUAI_UACNUMBER)*v);
  }
  
  // use clonefunction
  
  #include "spinlock.h"
  
  struct codecache {
  	struct spinlock lock;
  	lua_State *L;
  };
  
  static struct codecache CC;
  
  static void
  clearcache() {
  	if (CC.L == NULL)
  		return;
  	SPIN_LOCK(&CC)
  		lua_close(CC.L);
  		CC.L = luaL_newstate();
  	SPIN_UNLOCK(&CC)
  }
  
  static void
  init() {
  	SPIN_INIT(&CC);
  	CC.L = luaL_newstate();
  }
  
  static const void *
  load(const char *key) {
    if (CC.L == NULL)
      return NULL;
    SPIN_LOCK(&CC)
      lua_State *L = CC.L;
      lua_pushstring(L, key);
      lua_rawget(L, LUA_REGISTRYINDEX);
      const void * result = lua_touserdata(L, -1);
      lua_pop(L, 1);
    SPIN_UNLOCK(&CC)
  
    return result;
  }
  
  static const void *
  save(const char *key, const void * proto) {
    lua_State *L;
    const void * result = NULL;
  
    SPIN_LOCK(&CC)
      if (CC.L == NULL) {
        init();
      }
      L = CC.L;
      lua_pushstring(L, key);
      lua_pushvalue(L, -1);
      lua_rawget(L, LUA_REGISTRYINDEX);
      result = lua_touserdata(L, -1); /* stack: key oldvalue */
      if (result == NULL) {
        lua_pop(L,1);
        lua_pushlightuserdata(L, (void *)proto);
        lua_rawset(L, LUA_REGISTRYINDEX);
      } else {
        lua_pop(L,2);
      }
      
    SPIN_UNLOCK(&CC)
    return result;
  }
  
  #define CACHE_OFF 0
  #define CACHE_EXIST 1
  #define CACHE_ON 2
  
  static int cache_key = 0;
  
  static int cache_level(lua_State *L) {
  	int t = lua_rawgetp(L, LUA_REGISTRYINDEX, &cache_key);
  	int r = lua_tointeger(L, -1);
  	lua_pop(L,1);
  	if (t == LUA_TNUMBER) {
  		return r;
  	}
  	return CACHE_ON;
  }
  
  static int cache_mode(lua_State *L) {
  	static const char * lst[] = {
  		"OFF",
  		"EXIST",
  		"ON",
  		NULL,
  	};
  	if (lua_isnoneornil(L,1)) {
  		int t = lua_rawgetp(L, LUA_REGISTRYINDEX, &cache_key);
  		int r = lua_tointeger(L, -1);
  		if (t == LUA_TNUMBER) {
  			if (r < 0  || r >= CACHE_ON) {
  				r = CACHE_ON;
  			}
  		} else {
  			r = CACHE_ON;
  		}
  		lua_pushstring(L, lst[r]);
  		return 1;
  	}
  	int t = luaL_checkoption(L, 1, "OFF" , lst);
  	lua_pushinteger(L, t);
  	lua_rawsetp(L, LUA_REGISTRYINDEX, &cache_key);
  	return 0;
  }
  
  LUALIB_API int luaL_loadfilex (lua_State *L, const char *filename,
                                               const char *mode) {
    int level = cache_level(L);
    if (level == CACHE_OFF) {
      return luaL_loadfilex_(L, filename, mode);
    }
    const void * proto = load(filename);
    if (proto) {
      lua_clonefunction(L, proto);
      return LUA_OK;
    }
    if (level == CACHE_EXIST) {
      return luaL_loadfilex_(L, filename, mode);
    }
    lua_State * eL = luaL_newstate();
    if (eL == NULL) {
      lua_pushliteral(L, "New state failed");
      return LUA_ERRMEM;
    }
    int err = luaL_loadfilex_(eL, filename, mode);
    if (err != LUA_OK) {
      size_t sz = 0;
      const char * msg = lua_tolstring(eL, -1, &sz);
      lua_pushlstring(L, msg, sz);
      lua_close(eL);
      return err;
    }
    proto = lua_topointer(eL, -1);
    const void * oldv = save(filename, proto);
    if (oldv) {
      lua_close(eL);
      lua_clonefunction(L, oldv);
    } else {
      lua_clonefunction(L, proto);
      /* Never close it. notice: memory leak */
    }
  
    return LUA_OK;
  }
  
  static int
  cache_clear(lua_State *L) {
  	(void)(L);
  	clearcache();
  	return 0;
  }
  
  LUAMOD_API int luaopen_cache(lua_State *L) {
  	luaL_Reg l[] = {
  		{ "clear", cache_clear },
  		{ "mode", cache_mode },
  		{ NULL, NULL },
  	};
  	luaL_newlib(L,l);
  	lua_getglobal(L, "loadfile");
  	lua_setfield(L, -2, "loadfile");
  	return 1;
  }
  