compat-5.3.c

// Enable build against Lua older than 5.3
// taken fromhttps://github.com/lunarmodules/lua-compat-5.3
// under the following MIT license:
/* The MIT License (MIT)

  Copyright (C) 1994-2020 Lua.org, PUC-Rio.
  Copyright (C) 2013-2022 The Lua-Compat-5.3 authors.

  Permission is hereby granted, free of charge, to any person obtaining a copy of
  this software and associated documentation files (the "Software"), to deal in
  the Software without restriction, including without limitation the rights to
  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
  the Software, and to permit persons to whom the Software is furnished to do so,
  subject to the following conditions:

  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
  IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include "compat-5.3.h"

/* don't compile it again if it already is included via compat53.h */
#ifndef COMPAT53_C_
#define COMPAT53_C_



/* definitions for Lua 5.1 only */
#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 501

#ifndef COMPAT53_FOPEN_NO_LOCK
#  if defined(_MSC_VER)
#    define COMPAT53_FOPEN_NO_LOCK 1
#  else /* otherwise */
#    define COMPAT53_FOPEN_NO_LOCK 0
#  endif /* VC++ only so far */
#endif /* No-lock fopen_s usage if possible */

#if defined(_MSC_VER) && COMPAT53_FOPEN_NO_LOCK
#  include <share.h>
#endif /* VC++ _fsopen for share-allowed file read */

#ifndef COMPAT53_HAVE_STRERROR_R
#  if (!defined(_WIN32)) && \
      ((defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || \
      (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600) || \
      defined(__APPLE__))
#    define COMPAT53_HAVE_STRERROR_R 1
#  else /* none of the defines matched: define to 0 */
#    define COMPAT53_HAVE_STRERROR_R 0
#  endif /* have strerror_r of some form */
#endif /* strerror_r */

#ifndef COMPAT53_HAVE_STRERROR_S
#  if defined(_MSC_VER) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L && \
      defined(__STDC_LIB_EXT1__) && __STDC_LIB_EXT1__)
#    define COMPAT53_HAVE_STRERROR_S 1
#  else /* not VC++ or C11 */
#    define COMPAT53_HAVE_STRERROR_S 0
#  endif /* strerror_s from VC++ or C11 */
#endif /* strerror_s */

#ifndef COMPAT53_LUA_FILE_BUFFER_SIZE
#  define COMPAT53_LUA_FILE_BUFFER_SIZE 4096
#endif /* Lua File Buffer Size */


static char* compat53_strerror (int en, char* buff, size_t sz) {
#if COMPAT53_HAVE_STRERROR_R
  /* use strerror_r here, because it's available on these specific platforms */
  if (sz > 0) {
    buff[0] = '\0';
    /* we don't care whether the GNU version or the XSI version is used: */
    if (strerror_r(en, buff, sz)) {
      /* Yes, we really DO want to ignore the return value!
       * GCC makes that extra hard, not even a (void) cast will do. */
    }
    if (buff[0] == '\0') {
      /* Buffer is unchanged, so we probably have called GNU strerror_r which
       * returned a static constant string. Chances are that strerror will
       * return the same static constant string and therefore be thread-safe. */
      return strerror(en);
    }
  }
  return buff; /* sz is 0 *or* strerror_r wrote into the buffer */
#elif COMPAT53_HAVE_STRERROR_S
  /* for MSVC and other C11 implementations, use strerror_s since it's
   * provided by default by the libraries */
  strerror_s(buff, sz, en);
  return buff;
#else
  /* fallback, but strerror is not guaranteed to be threadsafe due to modifying
   * errno itself and some impls not locking a static buffer for it ... but most
   * known systems have threadsafe errno: this might only change if the locale
   * is changed out from under someone while this function is being called */
  (void)buff;
  (void)sz;
  return strerror(en);
#endif
}


COMPAT53_API int lua_absindex (lua_State *L, int i) {
  if (i < 0 && i > LUA_REGISTRYINDEX)
    i += lua_gettop(L) + 1;
  return i;
}


static void compat53_call_lua (lua_State *L, char const code[], size_t len,
                               int nargs, int nret) {
  lua_rawgetp(L, LUA_REGISTRYINDEX, (void*)code);
  if (lua_type(L, -1) != LUA_TFUNCTION) {
    lua_pop(L, 1);
    if (luaL_loadbuffer(L, code, len, "=none"))
      lua_error(L);
    lua_pushvalue(L, -1);
    lua_rawsetp(L, LUA_REGISTRYINDEX, (void*)code);
  }
  lua_insert(L, -nargs-1);
  lua_call(L, nargs, nret);
}


static const char compat53_arith_code[] =
  "local op,a,b=...\n"
  "if op==0 then return a+b\n"
  "elseif op==1 then return a-b\n"
  "elseif op==2 then return a*b\n"
  "elseif op==3 then return a/b\n"
  "elseif op==4 then return a%b\n"
  "elseif op==5 then return a^b\n"
  "elseif op==6 then return -a\n"
  "end\n";

COMPAT53_API void lua_arith (lua_State *L, int op) {
  if (op < LUA_OPADD || op > LUA_OPUNM)
    luaL_error(L, "invalid 'op' argument for lua_arith");
  luaL_checkstack(L, 5, "not enough stack slots");
  if (op == LUA_OPUNM)
    lua_pushvalue(L, -1);
  lua_pushnumber(L, op);
  lua_insert(L, -3);
  compat53_call_lua(L, compat53_arith_code,
                    sizeof(compat53_arith_code)-1, 3, 1);
}


static const char compat53_compare_code[] =
  "local a,b=...\n"
  "return a<=b\n";

COMPAT53_API int lua_compare (lua_State *L, int idx1, int idx2, int op) {
  int result = 0;
  switch (op) {
    case LUA_OPEQ:
      return lua_equal(L, idx1, idx2);
    case LUA_OPLT:
      return lua_lessthan(L, idx1, idx2);
    case LUA_OPLE:
      luaL_checkstack(L, 5, "not enough stack slots");
      idx1 = lua_absindex(L, idx1);
      idx2 = lua_absindex(L, idx2);
      lua_pushvalue(L, idx1);
      lua_pushvalue(L, idx2);
      compat53_call_lua(L, compat53_compare_code,
                        sizeof(compat53_compare_code)-1, 2, 1);
      result = lua_toboolean(L, -1);
      lua_pop(L, 1);
      return result;
    default:
      luaL_error(L, "invalid 'op' argument for lua_compare");
  }
  return 0;
}


COMPAT53_API void lua_copy (lua_State *L, int from, int to) {
  int abs_to = lua_absindex(L, to);
  luaL_checkstack(L, 1, "not enough stack slots");
  lua_pushvalue(L, from);
  lua_replace(L, abs_to);
}


COMPAT53_API void lua_len (lua_State *L, int i) {
  switch (lua_type(L, i)) {
    case LUA_TSTRING:
      lua_pushnumber(L, (lua_Number)lua_objlen(L, i));
      break;
    case LUA_TTABLE:
      if (!luaL_callmeta(L, i, "__len"))
        lua_pushnumber(L, (lua_Number)lua_objlen(L, i));
      break;
    case LUA_TUSERDATA:
      if (luaL_callmeta(L, i, "__len"))
        break;
      /* FALLTHROUGH */
    default:
      luaL_error(L, "attempt to get length of a %s value",
                 lua_typename(L, lua_type(L, i)));
  }
}


COMPAT53_API int lua_rawgetp (lua_State *L, int i, const void *p) {
  int abs_i = lua_absindex(L, i);
  lua_pushlightuserdata(L, (void*)p);
  lua_rawget(L, abs_i);
  return lua_type(L, -1);
}

COMPAT53_API void lua_rawsetp (lua_State *L, int i, const void *p) {
  int abs_i = lua_absindex(L, i);
  luaL_checkstack(L, 1, "not enough stack slots");
  lua_pushlightuserdata(L, (void*)p);
  lua_insert(L, -2);
  lua_rawset(L, abs_i);
}


COMPAT53_API lua_Number lua_tonumberx (lua_State *L, int i, int *isnum) {
  lua_Number n = lua_tonumber(L, i);
  if (isnum != NULL) {
    *isnum = (n != 0 || lua_isnumber(L, i));
  }
  return n;
}


COMPAT53_API void luaL_checkversion (lua_State *L) {
  (void)L;
}


COMPAT53_API void luaL_checkstack (lua_State *L, int sp, const char *msg) {
  if (!lua_checkstack(L, sp+LUA_MINSTACK)) {
    if (msg != NULL)
      luaL_error(L, "stack overflow (%s)", msg);
    else {
      lua_pushliteral(L, "stack overflow");
      lua_error(L);
    }
  }
}


COMPAT53_API int luaL_getsubtable (lua_State *L, int i, const char *name) {
  int abs_i = lua_absindex(L, i);
  luaL_checkstack(L, 3, "not enough stack slots");
  lua_pushstring(L, name);
  lua_gettable(L, abs_i);
  if (lua_istable(L, -1))
    return 1;
  lua_pop(L, 1);
  lua_newtable(L);
  lua_pushstring(L, name);
  lua_pushvalue(L, -2);
  lua_settable(L, abs_i);
  return 0;
}


COMPAT53_API lua_Integer luaL_len (lua_State *L, int i) {
  lua_Integer res = 0;
  int isnum = 0;
  luaL_checkstack(L, 1, "not enough stack slots");
  lua_len(L, i);
  res = lua_tointegerx(L, -1, &isnum);
  lua_pop(L, 1);
  if (!isnum)
    luaL_error(L, "object length is not an integer");
  return res;
}


COMPAT53_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
  luaL_checkstack(L, nup+1, "too many upvalues");
  for (; l->name != NULL; l++) {  /* fill the table with given functions */
    int i;
    lua_pushstring(L, l->name);
    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
      lua_pushvalue(L, -(nup + 1));
    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
    lua_settable(L, -(nup + 3)); /* table must be below the upvalues, the name and the closure */
  }
  lua_pop(L, nup);  /* remove upvalues */
}


COMPAT53_API void luaL_setmetatable (lua_State *L, const char *tname) {
  luaL_checkstack(L, 1, "not enough stack slots");
  luaL_getmetatable(L, tname);
  lua_setmetatable(L, -2);
}


COMPAT53_API void *luaL_testudata (lua_State *L, int i, const char *tname) {
  void *p = lua_touserdata(L, i);
  luaL_checkstack(L, 2, "not enough stack slots");
  if (p == NULL || !lua_getmetatable(L, i))
    return NULL;
  else {
    int res = 0;
    luaL_getmetatable(L, tname);
    res = lua_rawequal(L, -1, -2);
    lua_pop(L, 2);
    if (!res)
      p = NULL;
  }
  return p;
}


static int compat53_countlevels (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;
}

static int compat53_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 (compat53_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 */
}

static int compat53_pushglobalfuncname (lua_State *L, lua_Debug *ar) {
  int top = lua_gettop(L);
  lua_getinfo(L, "f", ar);  /* push function */
  lua_pushvalue(L, LUA_GLOBALSINDEX);
  if (compat53_findfield(L, top + 1, 2)) {
    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 compat53_pushfuncname (lua_State *L, lua_Debug *ar) {
  if (*ar->namewhat != '\0')  /* is there a name? */
    lua_pushfstring(L, "function " LUA_QS, ar->name);
  else if (*ar->what == 'm')  /* main? */
      lua_pushliteral(L, "main chunk");
  else if (*ar->what == 'C') {
    if (compat53_pushglobalfuncname(L, ar)) {
      lua_pushfstring(L, "function " LUA_QS, lua_tostring(L, -1));
      lua_remove(L, -2);  /* remove name */
    }
    else
      lua_pushliteral(L, "?");
  }
  else
    lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);
}

#define COMPAT53_LEVELS1 12  /* size of the first part of the stack */
#define COMPAT53_LEVELS2 10  /* size of the second part of the stack */

COMPAT53_API void luaL_traceback (lua_State *L, lua_State *L1,
                                  const char *msg, int level) {
  lua_Debug ar;
  int top = lua_gettop(L);
  int numlevels = compat53_countlevels(L1);
  int mark = (numlevels > COMPAT53_LEVELS1 + COMPAT53_LEVELS2) ? COMPAT53_LEVELS1 : 0;
  if (msg) lua_pushfstring(L, "%s\n", msg);
  lua_pushliteral(L, "stack traceback:");
  while (lua_getstack(L1, level++, &ar)) {
    if (level == mark) {  /* too many levels? */
      lua_pushliteral(L, "\n\t...");  /* add a '...' */
      level = numlevels - COMPAT53_LEVELS2;  /* 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 ");
      compat53_pushfuncname(L, &ar);
      lua_concat(L, lua_gettop(L) - top);
    }
  }
  lua_concat(L, lua_gettop(L) - top);
}


COMPAT53_API int luaL_fileresult (lua_State *L, int stat, const char *fname) {
  const char *serr = NULL;
  int en = errno;  /* calls to Lua API may change this value */
  char buf[512] = { 0 };
  if (stat) {
    lua_pushboolean(L, 1);
    return 1;
  }
  else {
    lua_pushnil(L);
    serr = compat53_strerror(en, buf, sizeof(buf));
    if (fname)
      lua_pushfstring(L, "%s: %s", fname, serr);
    else
      lua_pushstring(L, serr);
    lua_pushnumber(L, (lua_Number)en);
    return 3;
  }
}


static int compat53_checkmode (lua_State *L, const char *mode, const char *modename, int err) {
  if (mode && strchr(mode, modename[0]) == NULL) {
    lua_pushfstring(L, "attempt to load a %s chunk (mode is '%s')", modename, mode);
    return err;
  }
  return LUA_OK;
}


typedef struct {
  lua_Reader reader;
  void *ud;
  int has_peeked_data;
  const char *peeked_data;
  size_t peeked_data_size;
} compat53_reader_data;


static const char *compat53_reader (lua_State *L, void *ud, size_t *size) {
  compat53_reader_data *data = (compat53_reader_data *)ud;
  if (data->has_peeked_data) {
    data->has_peeked_data = 0;
    *size = data->peeked_data_size;
    return data->peeked_data;
  } else
    return data->reader(L, data->ud, size);
}


COMPAT53_API int lua_load (lua_State *L, lua_Reader reader, void *data, const char *source, const char *mode) {
  int status = LUA_OK;
  compat53_reader_data compat53_data = { 0, NULL, 1, 0, 0 };
  compat53_data.reader = reader;
  compat53_data.ud = data;
  compat53_data.peeked_data = reader(L, data, &(compat53_data.peeked_data_size));
  if (compat53_data.peeked_data && compat53_data.peeked_data_size &&
      compat53_data.peeked_data[0] == LUA_SIGNATURE[0]) /* binary file? */
      status = compat53_checkmode(L, mode, "binary", LUA_ERRSYNTAX);
  else
      status = compat53_checkmode(L, mode, "text", LUA_ERRSYNTAX);
  if (status != LUA_OK)
    return status;
  /* we need to call the original 5.1 version of lua_load! */
#undef lua_load
  return lua_load(L, compat53_reader, &compat53_data, source);
#define lua_load COMPAT53_CONCAT(COMPAT53_PREFIX, _load_53)
}


typedef struct {
  int n;  /* number of pre-read characters */
  FILE *f;  /* file being read */
  char buff[COMPAT53_LUA_FILE_BUFFER_SIZE];  /* area for reading file */
} compat53_LoadF;


static const char *compat53_getF (lua_State *L, void *ud, size_t *size) {
  compat53_LoadF *lf = (compat53_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
       'compat53_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 compat53_errfile (lua_State *L, const char *what, int fnameindex) {
  char buf[512] = {0};
  const char *serr = compat53_strerror(errno, buf, sizeof(buf));
  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 compat53_skipBOM (compat53_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++] = (char)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 compat53_skipcomment (compat53_LoadF *lf, int *cp) {
  int c = *cp = compat53_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 */
}


COMPAT53_API int luaL_loadfilex (lua_State *L, const char *filename, const char *mode) {
  compat53_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);
#if defined(_MSC_VER)
    /* This code is here to stop a deprecation error that stops builds
     * if a certain macro is defined. While normally not caring would
     * be best, some header-only libraries and builds can't afford to
     * dictate this to the user. A quick check shows that fopen_s this
     * goes back to VS 2005, and _fsopen goes back to VS 2003 .NET,
     * possibly even before that so we don't need to do any version
     * number checks, since this has been there since forever.  */

    /* TO USER: if you want the behavior of typical fopen_s/fopen,
     * which does lock the file on VC++, define the macro used below to 0 */
#if COMPAT53_FOPEN_NO_LOCK
    lf.f = _fsopen(filename, "r", _SH_DENYNO); /* do not lock the file in any way */
    if (lf.f == NULL)
      return compat53_errfile(L, "open", fnameindex);
#else /* use default locking version */
    if (fopen_s(&lf.f, filename, "r") != 0)
      return compat53_errfile(L, "open", fnameindex);
#endif /* Locking vs. No-locking fopen variants */
#else
    lf.f = fopen(filename, "r"); /* default stdlib doesn't forcefully lock files here */
    if (lf.f == NULL) return compat53_errfile(L, "open", fnameindex);
#endif
  }
  if (compat53_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? */
#if defined(_MSC_VER)
    if (freopen_s(&lf.f, filename, "rb", lf.f) != 0)
      return compat53_errfile(L, "reopen", fnameindex);
#else
    lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */
    if (lf.f == NULL) return compat53_errfile(L, "reopen", fnameindex);
#endif
    compat53_skipcomment(&lf, &c);  /* re-read initial portion */
  }
  if (c != EOF)
    lf.buff[lf.n++] = (char)c;  /* 'c' is the first character of the stream */
  status = lua_load(L, &compat53_getF, &lf, lua_tostring(L, -1), mode);
  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 compat53_errfile(L, "read", fnameindex);
  }
  lua_remove(L, fnameindex);
  return status;
}


COMPAT53_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t sz, const char *name, const char *mode) {
  int status = LUA_OK;
  if (sz > 0 && buff[0] == LUA_SIGNATURE[0]) {
    status = compat53_checkmode(L, mode, "binary", LUA_ERRSYNTAX);
  }
  else {
    status = compat53_checkmode(L, mode, "text", LUA_ERRSYNTAX);
  }
  if (status != LUA_OK)
    return status;
  return luaL_loadbuffer(L, buff, sz, name);
}


#if !defined(l_inspectstat) && \
    (defined(unix) || defined(__unix) || defined(__unix__) || \
     defined(__TOS_AIX__) || defined(_SYSTYPE_BSD) || \
     (defined(__APPLE__) && defined(__MACH__)))
/* some form of unix; check feature macros in unistd.h for details */
#  include <unistd.h>
/* check posix version; the relevant include files and macros probably
 * were available before 2001, but I'm not sure */
#  if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
#    include <sys/wait.h>
#    define l_inspectstat(stat,what) \
  if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \
  else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }
#  endif
#endif

/* provide default (no-op) version */
#if !defined(l_inspectstat)
#  define l_inspectstat(stat,what) ((void)0)
#endif


COMPAT53_API int luaL_execresult (lua_State *L, int stat) {
  const char *what = "exit";
  if (stat == -1)
    return luaL_fileresult(L, 0, NULL);
  else {
    l_inspectstat(stat, what);
    if (*what == 'e' && stat == 0)
      lua_pushboolean(L, 1);
    else
      lua_pushnil(L);
    lua_pushstring(L, what);
    lua_pushinteger(L, stat);
    return 3;
  }
}


COMPAT53_API void luaL_buffinit (lua_State *L, luaL_Buffer_53 *B) {
  /* make it crash if used via pointer to a 5.1-style luaL_Buffer */
  B->b.p = NULL;
  B->b.L = NULL;
  B->b.lvl = 0;
  /* reuse the buffer from the 5.1-style luaL_Buffer though! */
  B->ptr = B->b.buffer;
  B->capacity = LUAL_BUFFERSIZE;
  B->nelems = 0;
  B->L2 = L;
}


COMPAT53_API char *luaL_prepbuffsize (luaL_Buffer_53 *B, size_t s) {
  if (B->capacity - B->nelems < s) { /* needs to grow */
    char* newptr = NULL;
    size_t newcap = B->capacity * 2;
    if (newcap - B->nelems < s)
      newcap = B->nelems + s;
    if (newcap < B->capacity) /* overflow */
      luaL_error(B->L2, "buffer too large");
    newptr = (char*)lua_newuserdata(B->L2, newcap);
    memcpy(newptr, B->ptr, B->nelems);
    if (B->ptr != B->b.buffer)
      lua_replace(B->L2, -2); /* remove old buffer */
    B->ptr = newptr;
    B->capacity = newcap;
  }
  return B->ptr+B->nelems;
}


COMPAT53_API void luaL_addlstring (luaL_Buffer_53 *B, const char *s, size_t l) {
  memcpy(luaL_prepbuffsize(B, l), s, l);
  luaL_addsize(B, l);
}


COMPAT53_API void luaL_addvalue (luaL_Buffer_53 *B) {
  size_t len = 0;
  const char *s = lua_tolstring(B->L2, -1, &len);
  if (!s)
    luaL_error(B->L2, "cannot convert value to string");
  if (B->ptr != B->b.buffer)
    lua_insert(B->L2, -2); /* userdata buffer must be at stack top */
  luaL_addlstring(B, s, len);
  lua_remove(B->L2, B->ptr != B->b.buffer ? -2 : -1);
}


void luaL_pushresult (luaL_Buffer_53 *B) {
  lua_pushlstring(B->L2, B->ptr, B->nelems);
  if (B->ptr != B->b.buffer)
    lua_replace(B->L2, -2); /* remove userdata buffer */
}


#endif /* Lua 5.1 */



/* definitions for Lua 5.1 and Lua 5.2 */
#if defined( LUA_VERSION_NUM ) && LUA_VERSION_NUM <= 502


COMPAT53_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) {
#undef lua_pushlstring
  lua_pushlstring(L, len > 0 ? s : "", len);
#define lua_pushlstring COMPAT53_CONCAT(COMPAT53_PREFIX, _pushlstring_53)
  return lua_tostring(L, -1);
}


COMPAT53_API int lua_geti (lua_State *L, int index, lua_Integer i) {
  index = lua_absindex(L, index);
  lua_pushinteger(L, i);
  lua_gettable(L, index);
  return lua_type(L, -1);
}


#ifndef LUA_EXTRASPACE
#define LUA_EXTRASPACE (sizeof(void*))
#endif

COMPAT53_API void *lua_getextraspace (lua_State *L) {
  int is_main = 0;
  void *ptr = NULL;
  luaL_checkstack(L, 4, "not enough stack slots available");
  lua_pushliteral(L, "__compat53_extraspace");
  lua_pushvalue(L, -1);
  lua_rawget(L, LUA_REGISTRYINDEX);
  if (!lua_istable(L, -1)) {
    lua_pop(L, 1);
    lua_createtable(L, 0, 2);
    lua_createtable(L, 0, 1);
    lua_pushliteral(L, "k");
    lua_setfield(L, -2, "__mode");
    lua_setmetatable(L, -2);
    lua_pushvalue(L, -2);
    lua_pushvalue(L, -2);
    lua_rawset(L, LUA_REGISTRYINDEX);
  }
  lua_replace(L, -2);
  is_main = lua_pushthread(L);
  lua_rawget(L, -2);
  ptr = lua_touserdata(L, -1);
  if (!ptr) {
    lua_pop(L, 1);
    ptr = lua_newuserdata(L, LUA_EXTRASPACE);
    if (is_main) {
      memset(ptr, '\0', LUA_EXTRASPACE);
      lua_pushthread(L);
      lua_pushvalue(L, -2);
      lua_rawset(L, -4);
      lua_pushboolean(L, 1);
      lua_pushvalue(L, -2);
      lua_rawset(L, -4);
    } else {
      void* mptr = NULL;
      lua_pushboolean(L, 1);
      lua_rawget(L, -3);
      mptr = lua_touserdata(L, -1);
      if (mptr)
        memcpy(ptr, mptr, LUA_EXTRASPACE);
      else
        memset(ptr, '\0', LUA_EXTRASPACE);
      lua_pop(L, 1);
      lua_pushthread(L);
      lua_pushvalue(L, -2);
      lua_rawset(L, -4);
    }
  }
  lua_pop(L, 2);
  return ptr;
}


COMPAT53_API int lua_isinteger (lua_State *L, int index) {
  if (lua_type(L, index) == LUA_TNUMBER) {
    lua_Number n = lua_tonumber(L, index);
    lua_Integer i = lua_tointeger(L, index);
    if (i == n)
      return 1;
  }
  return 0;
}


COMPAT53_API lua_Integer lua_tointegerx (lua_State *L, int i, int *isnum) {
  int ok = 0;
  lua_Number n = lua_tonumberx(L, i, &ok);
  if (ok) {
    if (n == (lua_Integer)n) {
      if (isnum)
        *isnum = 1;
      return (lua_Integer)n;
    }
  }
  if (isnum)
    *isnum = 0;
  return 0;
}


static void compat53_reverse (lua_State *L, int a, int b) {
  for (; a < b; ++a, --b) {
    lua_pushvalue(L, a);
    lua_pushvalue(L, b);
    lua_replace(L, a);
    lua_replace(L, b);
  }
}


COMPAT53_API void lua_rotate (lua_State *L, int idx, int n) {
  int n_elems = 0;
  idx = lua_absindex(L, idx);
  n_elems = lua_gettop(L)-idx+1;
  if (n < 0)
    n += n_elems;
  if ( n > 0 && n < n_elems) {
    luaL_checkstack(L, 2, "not enough stack slots available");
    n = n_elems - n;
    compat53_reverse(L, idx, idx+n-1);
    compat53_reverse(L, idx+n, idx+n_elems-1);
    compat53_reverse(L, idx, idx+n_elems-1);
  }
}


COMPAT53_API void lua_seti (lua_State *L, int index, lua_Integer i) {
  luaL_checkstack(L, 1, "not enough stack slots available");
  index = lua_absindex(L, index);
  lua_pushinteger(L, i);
  lua_insert(L, -2);
  lua_settable(L, index);
}


#if !defined(lua_str2number)
#  define lua_str2number(s, p)  strtod((s), (p))
#endif

COMPAT53_API size_t lua_stringtonumber (lua_State *L, const char *s) {
  char* endptr;
  lua_Number n = lua_str2number(s, &endptr);
  if (endptr != s) {
    while (*endptr != '\0' && isspace((unsigned char)*endptr))
      ++endptr;
    if (*endptr == '\0') {
      lua_pushnumber(L, n);
      return endptr - s + 1;
    }
  }
  return 0;
}


COMPAT53_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {
  if (!luaL_callmeta(L, idx, "__tostring")) {
    int t = lua_type(L, idx), tt = 0;
    char const* name = NULL;
    switch (t) {
      case LUA_TNIL:
        lua_pushliteral(L, "nil");
        break;
      case LUA_TSTRING:
      case LUA_TNUMBER:
        lua_pushvalue(L, idx);
        break;
      case LUA_TBOOLEAN:
        if (lua_toboolean(L, idx))
          lua_pushliteral(L, "true");
        else
          lua_pushliteral(L, "false");
        break;
      default:
        tt = luaL_getmetafield(L, idx, "__name");
        name = (tt == LUA_TSTRING) ? lua_tostring(L, -1) : lua_typename(L, t);
        lua_pushfstring(L, "%s: %p", name, lua_topointer(L, idx));
        if (tt != LUA_TNIL)
          lua_replace(L, -2);
        break;
    }
  } else {
    if (!lua_isstring(L, -1))
      luaL_error(L, "'__tostring' must return a string");
  }
  return lua_tolstring(L, -1, len);
}


COMPAT53_API void luaL_requiref (lua_State *L, const char *modname,
                                 lua_CFunction openf, int glb) {
  luaL_checkstack(L, 3, "not enough stack slots available");
  luaL_getsubtable(L, LUA_REGISTRYINDEX, "_LOADED");
  if (lua_getfield(L, -1, modname) == LUA_TNIL) {
    lua_pop(L, 1);
    lua_pushcfunction(L, openf);
    lua_pushstring(L, modname);
    lua_call(L, 1, 1);
    lua_pushvalue(L, -1);
    lua_setfield(L, -3, modname);
  }
  if (glb) {
    lua_pushvalue(L, -1);
    lua_setglobal(L, modname);
  }
  lua_replace(L, -2);
}


#endif /* Lua 5.1 and 5.2 */


#endif /* COMPAT53_C_ */


/*********************************************************************
* This file contains parts of Lua 5.2's and Lua 5.3's source code:
*
* Copyright (C) 1994-2014 Lua.org, PUC-Rio.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*********************************************************************/