/*
	** $Id: liolib.c,v 2.148 2015/11/23 11:36:11 roberto Exp $
	** Standard I/O (and system) library
	** See Copyright Notice in lua.h
	*/
	
	#define liolib_c
	#define LUA_LIB
	
	#include "lprefix.h"
	
	
	#include <ctype.h>
	#include <errno.h>
	#include <locale.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	
	#include "lua.h"
	
	#include "lauxlib.h"
	#include "lualib.h"
	
	
	
	
	/*
	** Change this macro to accept other modes for 'fopen' besides
	** the standard ones.
	*/
	#if !defined(l_checkmode)
	
	/* accepted extensions to 'mode' in 'fopen' */
	#if !defined(L_MODEEXT)
	#define L_MODEEXT	"b"
	#endif
	
	/* Check whether 'mode' matches '[rwa]%+?[L_MODEEXT]*' */
	#define l_checkmode(mode) \
		(*mode != '\0' && strchr("rwa", *(mode++)) != NULL &&	\
		(*mode != '+' || (++mode, 1)) &&  /* skip if char is '+' */	\
		(strspn(mode, L_MODEEXT) == strlen(mode)))
	
	#endif
	
	/*
	** {======================================================
	** l_popen spawns a new process connected to the current
	** one through the file streams.
	** =======================================================
	*/
	
	#if !defined(l_popen)		/* { */
	
	#if defined(LUA_USE_POSIX)	/* { */
	
	#define l_popen(L,c,m)		(fflush(NULL), popen(c,m))
	#define l_pclose(L,file)	(pclose(file))
	
	#elif defined(LUA_USE_WINDOWS)	/* }{ */
	
	#define l_popen(L,c,m)		(_popen(c,m))
	#define l_pclose(L,file)	(_pclose(file))
	
	#else				/* }{ */
	
	/* ISO C definitions */
	#define l_popen(L,c,m)  \
		  ((void)((void)c, m), \
		  luaL_error(L, "'popen' not supported"), \
		  (FILE*)0)
	#define l_pclose(L,file)		((void)L, (void)file, -1)
	
	#endif				/* } */
	
	#endif				/* } */
	
	/* }====================================================== */
	
	
	#if !defined(l_getc)		/* { */
	
	#if defined(LUA_USE_POSIX)
	#define l_getc(f)		getc_unlocked(f)
	#define l_lockfile(f)		flockfile(f)
	#define l_unlockfile(f)		funlockfile(f)
	#else
	#define l_getc(f)		getc(f)
	#define l_lockfile(f)		((void)0)
	#define l_unlockfile(f)		((void)0)
	#endif
	
	#endif				/* } */
	
	
	/*
	** {======================================================
	** l_fseek: configuration for longer offsets
	** =======================================================
	*/
	
	#if !defined(l_fseek)		/* { */
	
	#if defined(LUA_USE_POSIX)	/* { */
	
	#include <sys/types.h>
	
	#define l_fseek(f,o,w)		fseeko(f,o,w)
	#define l_ftell(f)		ftello(f)
	#define l_seeknum		off_t
	
	#elif defined(LUA_USE_WINDOWS) && !defined(_CRTIMP_TYPEINFO) \
	   && defined(_MSC_VER) && (_MSC_VER >= 1400)	/* }{ */
	
	/* Windows (but not DDK) and Visual C++ 2005 or higher */
	#define l_fseek(f,o,w)		_fseeki64(f,o,w)
	#define l_ftell(f)		_ftelli64(f)
	#define l_seeknum		__int64
	
	#else				/* }{ */
	
	/* ISO C definitions */
	#define l_fseek(f,o,w)		fseek(f,o,w)
	#define l_ftell(f)		ftell(f)
	#define l_seeknum		long
	
	#endif				/* } */
	
	#endif				/* } */
	
	/* }====================================================== */
	
	
	#define IO_PREFIX	"_IO_"
	#define IOPREF_LEN	(sizeof(IO_PREFIX)/sizeof(char) - 1)
	#define IO_INPUT	(IO_PREFIX "input")
	#define IO_OUTPUT	(IO_PREFIX "output")
	
	
	typedef luaL_Stream LStream;
	
	
	#define tolstream(L)	((LStream *)luaL_checkudata(L, 1, LUA_FILEHANDLE))
	
	#define isclosed(p)	((p)->closef == NULL)
	
	
	static int io_type (lua_State *L) {
	  LStream *p;
	  luaL_checkany(L, 1);
	  p = (LStream *)luaL_testudata(L, 1, LUA_FILEHANDLE);
	  if (p == NULL)
	    lua_pushnil(L);  /* not a file */
	  else if (isclosed(p))
	    lua_pushliteral(L, "closed file");
	  else
	    lua_pushliteral(L, "file");
	  return 1;
	}
	
	
	static int f_tostring (lua_State *L) {
	  LStream *p = tolstream(L);
	  if (isclosed(p))
	    lua_pushliteral(L, "file (closed)");
	  else
	    lua_pushfstring(L, "file (%p)", p->f);
	  return 1;
	}
	
	
	static FILE *tofile (lua_State *L) {
	  LStream *p = tolstream(L);
	  if (isclosed(p))
	    luaL_error(L, "attempt to use a closed file");
	  lua_assert(p->f);
	  return p->f;
	}
	
	
	/*
	** When creating file handles, always creates a 'closed' file handle
	** before opening the actual file; so, if there is a memory error, the
	** handle is in a consistent state.
	*/
	static LStream *newprefile (lua_State *L) {
	  LStream *p = (LStream *)lua_newuserdata(L, sizeof(LStream));
	  p->closef = NULL;  /* mark file handle as 'closed' */
	  luaL_setmetatable(L, LUA_FILEHANDLE);
	  return p;
	}
	
	
	/*
	** Calls the 'close' function from a file handle. The 'volatile' avoids
	** a bug in some versions of the Clang compiler (e.g., clang 3.0 for
	** 32 bits).
	*/
	static int aux_close (lua_State *L) {
	  LStream *p = tolstream(L);
	  volatile lua_CFunction cf = p->closef;
	  p->closef = NULL;  /* mark stream as closed */
	  return (*cf)(L);  /* close it */
	}
	
	
	static int io_close (lua_State *L) {
	  if (lua_isnone(L, 1))  /* no argument? */
	    lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT);  /* use standard output */
	  tofile(L);  /* make sure argument is an open stream */
	  return aux_close(L);
	}
	
	
	static int f_gc (lua_State *L) {
	  LStream *p = tolstream(L);
	  if (!isclosed(p) && p->f != NULL)
	    aux_close(L);  /* ignore closed and incompletely open files */
	  return 0;
	}
	
	
	/*
	** function to close regular files
	*/
	static int io_fclose (lua_State *L) {
	  LStream *p = tolstream(L);
	  int res = fclose(p->f);
	  return luaL_fileresult(L, (res == 0), NULL);
	}
	
	
	static LStream *newfile (lua_State *L) {
	  LStream *p = newprefile(L);
	  p->f = NULL;
	  p->closef = &io_fclose;
	  return p;
	}
	
	
	static void opencheck (lua_State *L, const char *fname, const char *mode) {
	  LStream *p = newfile(L);
	  p->f = fopen(fname, mode);
	  if (p->f == NULL)
	    luaL_error(L, "cannot open file '%s' (%s)", fname, strerror(errno));
	}
	
	
	static int io_open (lua_State *L) {
	  const char *filename = luaL_checkstring(L, 1);
	  const char *mode = luaL_optstring(L, 2, "r");
	  LStream *p = newfile(L);
	  const char *md = mode;  /* to traverse/check mode */
	  luaL_argcheck(L, l_checkmode(md), 2, "invalid mode");
	  p->f = fopen(filename, mode);
	  return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
	}
	
	
	/*
	** function to close 'popen' files
	*/
	static int io_pclose (lua_State *L) {
	  LStream *p = tolstream(L);
	  return luaL_execresult(L, l_pclose(L, p->f));
	}
	
	
	static int io_popen (lua_State *L) {
	  const char *filename = luaL_checkstring(L, 1);
	  const char *mode = luaL_optstring(L, 2, "r");
	  LStream *p = newprefile(L);
	  p->f = l_popen(L, filename, mode);
	  p->closef = &io_pclose;
	  return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
	}
	
	
	static int io_tmpfile (lua_State *L) {
	  LStream *p = newfile(L);
	  p->f = tmpfile();
	  return (p->f == NULL) ? luaL_fileresult(L, 0, NULL) : 1;
	}
	
	
	static FILE *getiofile (lua_State *L, const char *findex) {
	  LStream *p;
	  lua_getfield(L, LUA_REGISTRYINDEX, findex);
	  p = (LStream *)lua_touserdata(L, -1);
	  if (isclosed(p))
	    luaL_error(L, "standard %s file is closed", findex + IOPREF_LEN);
	  return p->f;
	}
	
	
	static int g_iofile (lua_State *L, const char *f, const char *mode) {
	  if (!lua_isnoneornil(L, 1)) {
	    const char *filename = lua_tostring(L, 1);
	    if (filename)
	      opencheck(L, filename, mode);
	    else {
	      tofile(L);  /* check that it's a valid file handle */
	      lua_pushvalue(L, 1);
	    }
	    lua_setfield(L, LUA_REGISTRYINDEX, f);
	  }
	  /* return current value */
	  lua_getfield(L, LUA_REGISTRYINDEX, f);
	  return 1;
	}
	
	
	static int io_input (lua_State *L) {
	  return g_iofile(L, IO_INPUT, "r");
	}
	
	
	static int io_output (lua_State *L) {
	  return g_iofile(L, IO_OUTPUT, "w");
	}
	
	
	static int io_readline (lua_State *L);
	
	
	/*
	** maximum number of arguments to 'f:lines'/'io.lines' (it + 3 must fit
	** in the limit for upvalues of a closure)
	*/
	#define MAXARGLINE	250
	
	static void aux_lines (lua_State *L, int toclose) {
	  int n = lua_gettop(L) - 1;  /* number of arguments to read */
	  luaL_argcheck(L, n <= MAXARGLINE, MAXARGLINE + 2, "too many arguments");
	  lua_pushinteger(L, n);  /* number of arguments to read */
	  lua_pushboolean(L, toclose);  /* close/not close file when finished */
	  lua_rotate(L, 2, 2);  /* move 'n' and 'toclose' to their positions */
	  lua_pushcclosure(L, io_readline, 3 + n);
	}
	
	
	static int f_lines (lua_State *L) {
	  tofile(L);  /* check that it's a valid file handle */
	  aux_lines(L, 0);
	  return 1;
	}
	
	
	static int io_lines (lua_State *L) {
	  int toclose;
	  if (lua_isnone(L, 1)) lua_pushnil(L);  /* at least one argument */
	  if (lua_isnil(L, 1)) {  /* no file name? */
	    lua_getfield(L, LUA_REGISTRYINDEX, IO_INPUT);  /* get default input */
	    lua_replace(L, 1);  /* put it at index 1 */
	    tofile(L);  /* check that it's a valid file handle */
	    toclose = 0;  /* do not close it after iteration */
	  }
	  else {  /* open a new file */
	    const char *filename = luaL_checkstring(L, 1);
	    opencheck(L, filename, "r");
	    lua_replace(L, 1);  /* put file at index 1 */
	    toclose = 1;  /* close it after iteration */
	  }
	  aux_lines(L, toclose);
	  return 1;
	}
	
	
	/*
	** {======================================================
	** READ
	** =======================================================
	*/
	
	
	/* maximum length of a numeral */
	#define MAXRN		200
	
	/* auxiliary structure used by 'read_number' */
	typedef struct {
	  FILE *f;  /* file being read */
	  int c;  /* current character (look ahead) */
	  int n;  /* number of elements in buffer 'buff' */
	  char buff[MAXRN + 1];  /* +1 for ending '\0' */
	} RN;
	
	
	/*
	** Add current char to buffer (if not out of space) and read next one
	*/
	static int nextc (RN *rn) {
	  if (rn->n >= MAXRN) {  /* buffer overflow? */
	    rn->buff[0] = '\0';  /* invalidate result */
	    return 0;  /* fail */
	  }
	  else {
	    rn->buff[rn->n++] = rn->c;  /* save current char */
	    rn->c = l_getc(rn->f);  /* read next one */
	    return 1;
	  }
	}
	
	
	/*
	** Accept current char if it is in 'set' (of size 1 or 2)
	*/
	static int test2 (RN *rn, const char *set) {
	  if (rn->c == set[0] || (rn->c == set[1] && rn->c != '\0'))
	    return nextc(rn);
	  else return 0;
	}
	
	
	/*
	** Read a sequence of (hex)digits
	*/
	static int readdigits (RN *rn, int hex) {
	  int count = 0;

	  while ((hex ? isxdigit(rn->c) : isdigit(rn->c)) && nextc(rn))
	    count++;
	  return count;
	}
	
	
	/*
	** Read a number: first reads a valid prefix of a numeral into a buffer.
	** Then it calls 'lua_stringtonumber' to check whether the format is
	** correct and to convert it to a Lua number
	*/
	static int read_number (lua_State *L, FILE *f) {
	  RN rn;
	  int count = 0;
	  int hex = 0;
	  char decp[2];
	  rn.f = f; rn.n = 0;
	  decp[0] = lua_getlocaledecpoint();  /* get decimal point from locale */
	  decp[1] = '\0';
	  l_lockfile(rn.f);

	  do { rn.c = l_getc(rn.f); } while (isspace(rn.c));  /* skip spaces */
	  test2(&rn, "-+");  /* optional signal */

	  if (test2(&rn, "0")) {
	    if (test2(&rn, "xX")) hex = 1;  /* numeral is hexadecimal */
	    else count = 1;  /* count initial '0' as a valid digit */

	  }

	  count += readdigits(&rn, hex);  /* integral part */
	  if (test2(&rn, decp))  /* decimal point? */
	    count += readdigits(&rn, hex);  /* fractional part */
	  if (count > 0 && test2(&rn, (hex ? "pP" : "eE"))) {  /* exponent mark? */
	    test2(&rn, "-+");  /* exponent signal */
	    readdigits(&rn, 0);  /* exponent digits */
	  }
	  ungetc(rn.c, rn.f);  /* unread look-ahead char */
	  l_unlockfile(rn.f);
	  rn.buff[rn.n] = '\0';  /* finish string */
	  if (lua_stringtonumber(L, rn.buff))  /* is this a valid number? */
	    return 1;  /* ok */
	  else {  /* invalid format */
	   lua_pushnil(L);  /* "result" to be removed */
	   return 0;  /* read fails */
	  }
	}
	
	
	static int test_eof (lua_State *L, FILE *f) {
	  int c = getc(f);
	  ungetc(c, f);  /* no-op when c == EOF */
	  lua_pushliteral(L, "");
	  return (c != EOF);
	}
	
	
	static int read_line (lua_State *L, FILE *f, int chop) {
	  luaL_Buffer b;
	  int c = '\0';
	  luaL_buffinit(L, &b);
	  while (c != EOF && c != '\n') {  /* repeat until end of line */
	    char *buff = luaL_prepbuffer(&b);  /* preallocate buffer */
	    int i = 0;
	    l_lockfile(f);  /* no memory errors can happen inside the lock */
	    while (i < LUAL_BUFFERSIZE && (c = l_getc(f)) != EOF && c != '\n')
	      buff[i++] = c;
	    l_unlockfile(f);
	    luaL_addsize(&b, i);
	  }
	  if (!chop && c == '\n')  /* want a newline and have one? */
	    luaL_addchar(&b, c);  /* add ending newline to result */
	  luaL_pushresult(&b);  /* close buffer */
	  /* return ok if read something (either a newline or something else) */
	  return (c == '\n' || lua_rawlen(L, -1) > 0);
	}
	
	
	static void read_all (lua_State *L, FILE *f) {
	  size_t nr;
	  luaL_Buffer b;
	  luaL_buffinit(L, &b);
	  do {  /* read file in chunks of LUAL_BUFFERSIZE bytes */
	    char *p = luaL_prepbuffer(&b);
	    nr = fread(p, sizeof(char), LUAL_BUFFERSIZE, f);
	    luaL_addsize(&b, nr);
	  } while (nr == LUAL_BUFFERSIZE);
	  luaL_pushresult(&b);  /* close buffer */
	}
	
	
	static int read_chars (lua_State *L, FILE *f, size_t n) {
	  size_t nr;  /* number of chars actually read */
	  char *p;
	  luaL_Buffer b;
	  luaL_buffinit(L, &b);
	  p = luaL_prepbuffsize(&b, n);  /* prepare buffer to read whole block */
	  nr = fread(p, sizeof(char), n, f);  /* try to read 'n' chars */
	  luaL_addsize(&b, nr);
	  luaL_pushresult(&b);  /* close buffer */
	  return (nr > 0);  /* true iff read something */
	}
	
	
	static int g_read (lua_State *L, FILE *f, int first) {
	  int nargs = lua_gettop(L) - 1;
	  int success;
	  int n;
	  clearerr(f);
	  if (nargs == 0) {  /* no arguments? */
	    success = read_line(L, f, 1);
	    n = first+1;  /* to return 1 result */
	  }
	  else {  /* ensure stack space for all results and for auxlib's buffer */
	    luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments");
	    success = 1;
	    for (n = first; nargs-- && success; n++) {
	      if (lua_type(L, n) == LUA_TNUMBER) {
	        size_t l = (size_t)luaL_checkinteger(L, n);
	        success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
	      }
	      else {
	        const char *p = luaL_checkstring(L, n);
	        if (*p == '*') p++;  /* skip optional '*' (for compatibility) */
	        switch (*p) {
	          case 'n':  /* number */
	            success = read_number(L, f);
	            break;
	          case 'l':  /* line */
	            success = read_line(L, f, 1);
	            break;
	          case 'L':  /* line with end-of-line */
	            success = read_line(L, f, 0);
	            break;
	          case 'a':  /* file */
	            read_all(L, f);  /* read entire file */
	            success = 1; /* always success */
	            break;
	          default:
	            return luaL_argerror(L, n, "invalid format");
	        }
	      }
	    }
	  }
	  if (ferror(f))
	    return luaL_fileresult(L, 0, NULL);
	  if (!success) {
	    lua_pop(L, 1);  /* remove last result */
	    lua_pushnil(L);  /* push nil instead */
	  }
	  return n - first;
	}
	
	
	static int io_read (lua_State *L) {
	  return g_read(L, getiofile(L, IO_INPUT), 1);
	}
	
	
	static int f_read (lua_State *L) {
	  return g_read(L, tofile(L), 2);
	}
	
	
	static int io_readline (lua_State *L) {
	  LStream *p = (LStream *)lua_touserdata(L, lua_upvalueindex(1));
	  int i;
	  int n = (int)lua_tointeger(L, lua_upvalueindex(2));
	  if (isclosed(p))  /* file is already closed? */
	    return luaL_error(L, "file is already closed");
	  lua_settop(L , 1);
	  luaL_checkstack(L, n, "too many arguments");
	  for (i = 1; i <= n; i++)  /* push arguments to 'g_read' */
	    lua_pushvalue(L, lua_upvalueindex(3 + i));
	  n = g_read(L, p->f, 2);  /* 'n' is number of results */
	  lua_assert(n > 0);  /* should return at least a nil */
	  if (lua_toboolean(L, -n))  /* read at least one value? */
	    return n;  /* return them */
	  else {  /* first result is nil: EOF or error */
	    if (n > 1) {  /* is there error information? */
	      /* 2nd result is error message */
	      return luaL_error(L, "%s", lua_tostring(L, -n + 1));
	    }
	    if (lua_toboolean(L, lua_upvalueindex(3))) {  /* generator created file? */
	      lua_settop(L, 0);
	      lua_pushvalue(L, lua_upvalueindex(1));
	      aux_close(L);  /* close it */
	    }
	    return 0;
	  }
	}
	
	/* }====================================================== */
	
	
	static int g_write (lua_State *L, FILE *f, int arg) {
	  int nargs = lua_gettop(L) - arg;
	  int status = 1;
	  for (; nargs--; arg++) {
	    if (lua_type(L, arg) == LUA_TNUMBER) {
	      /* optimization: could be done exactly as for strings */
	      int len = lua_isinteger(L, arg)
	                ? fprintf(f, LUA_INTEGER_FMT, lua_tointeger(L, arg))
	                : fprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg));
	      status = status && (len > 0);
	    }
	    else {
	      size_t l;
	      const char *s = luaL_checklstring(L, arg, &l);
	      status = status && (fwrite(s, sizeof(char), l, f) == l);
	    }
	  }
	  if (status) return 1;  /* file handle already on stack top */
	  else return luaL_fileresult(L, status, NULL);
	}
	
	
	static int io_write (lua_State *L) {
	  return g_write(L, getiofile(L, IO_OUTPUT), 1);
	}
	
	
	static int f_write (lua_State *L) {
	  FILE *f = tofile(L);
	  lua_pushvalue(L, 1);  /* push file at the stack top (to be returned) */
	  return g_write(L, f, 2);
	}
	
	
	static int f_seek (lua_State *L) {
	  static const int mode[] = {SEEK_SET, SEEK_CUR, SEEK_END};
	  static const char *const modenames[] = {"set", "cur", "end", NULL};
	  FILE *f = tofile(L);
	  int op = luaL_checkoption(L, 2, "cur", modenames);
	  lua_Integer p3 = luaL_optinteger(L, 3, 0);
	  l_seeknum offset = (l_seeknum)p3;
	  luaL_argcheck(L, (lua_Integer)offset == p3, 3,
	                  "not an integer in proper range");
	  op = l_fseek(f, offset, mode[op]);
	  if (op)
	    return luaL_fileresult(L, 0, NULL);  /* error */
	  else {
	    lua_pushinteger(L, (lua_Integer)l_ftell(f));
	    return 1;
	  }
	}
	
	
	static int f_setvbuf (lua_State *L) {
	  static const int mode[] = {_IONBF, _IOFBF, _IOLBF};
	  static const char *const modenames[] = {"no", "full", "line", NULL};
	  FILE *f = tofile(L);
	  int op = luaL_checkoption(L, 2, NULL, modenames);
	  lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE);
	  int res = setvbuf(f, NULL, mode[op], (size_t)sz);
	  return luaL_fileresult(L, res == 0, NULL);
	}
	
	
	
	static int io_flush (lua_State *L) {
	  return luaL_fileresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL);
	}
	
	
	static int f_flush (lua_State *L) {
	  return luaL_fileresult(L, fflush(tofile(L)) == 0, NULL);
	}
	
	
	/*
	** functions for 'io' library
	*/
	static const luaL_Reg iolib[] = {
	  {"close", io_close},
	  {"flush", io_flush},
	  {"input", io_input},
	  {"lines", io_lines},
	  {"open", io_open},
	  {"output", io_output},
	  {"popen", io_popen},
	  {"read", io_read},
	  {"tmpfile", io_tmpfile},
	  {"type", io_type},
	  {"write", io_write},
	  {NULL, NULL}
	};
	
	
	/*
	** methods for file handles
	*/
	static const luaL_Reg flib[] = {
	  {"close", io_close},
	  {"flush", f_flush},
	  {"lines", f_lines},
	  {"read", f_read},
	  {"seek", f_seek},
	  {"setvbuf", f_setvbuf},
	  {"write", f_write},
	  {"__gc", f_gc},
	  {"__tostring", f_tostring},
	  {NULL, NULL}
	};
	
	
	static void createmeta (lua_State *L) {
	  luaL_newmetatable(L, LUA_FILEHANDLE);  /* create metatable for file handles */
	  lua_pushvalue(L, -1);  /* push metatable */
	  lua_setfield(L, -2, "__index");  /* metatable.__index = metatable */
	  luaL_setfuncs(L, flib, 0);  /* add file methods to new metatable */
	  lua_pop(L, 1);  /* pop new metatable */
	}
	
	
	/*
	** function to (not) close the standard files stdin, stdout, and stderr
	*/
	static int io_noclose (lua_State *L) {
	  LStream *p = tolstream(L);
	  p->closef = &io_noclose;  /* keep file opened */
	  lua_pushnil(L);
	  lua_pushliteral(L, "cannot close standard file");
	  return 2;
	}
	
	
	static void createstdfile (lua_State *L, FILE *f, const char *k,
	                           const char *fname) {
	  LStream *p = newprefile(L);
	  p->f = f;
	  p->closef = &io_noclose;
	  if (k != NULL) {
	    lua_pushvalue(L, -1);
	    lua_setfield(L, LUA_REGISTRYINDEX, k);  /* add file to registry */
	  }
	  lua_setfield(L, -2, fname);  /* add file to module */
	}
	
	
	LUAMOD_API int luaopen_io (lua_State *L) {
	  luaL_newlib(L, iolib);  /* new module */
	  createmeta(L);
	  /* create (and set) default files */
	  createstdfile(L, stdin, IO_INPUT, "stdin");
	  createstdfile(L, stdout, IO_OUTPUT, "stdout");
	  createstdfile(L, stderr, NULL, "stderr");
	  return 1;
	}