text: /*
   ** $Id: liolib.c $
   ** 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]*' */
  static int l_checkmode(const char* mode) {
      return (*mode != '\0' && strchr("rwa", *(mode++)) != NULL &&
          (*mode != '+' || ((void)(++mode), 1)) &&  /* skip if char is '+' */
          (strspn(mode, L_MODEEXT) == strlen(mode)));  /* check extensions */
  }
  
  #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)c, (void)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 = 0;
      luaL_checkany(L, 1);
      p = (LStream*)luaL_testudata(L, 1, LUA_FILEHANDLE);
      if (p == NULL)
          luaL_pushfail(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_newuserdatauv(L, sizeof(LStream), 0);
      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 f_close(lua_State* L) {
      tofile(L);  /* make sure argument is an open stream */
      return aux_close(L);
  }
  
  
  static int io_close(lua_State* L) {
      if (lua_isnone(L, 1))  /* no argument? */
          lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT);  /* use default output */
      return f_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);
      errno = 0;
      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 = 0;
      lua_getfield(L, LUA_REGISTRYINDEX, findex);
      p = (LStream*)lua_touserdata(L, -1);
      if (isclosed(p))
          luaL_error(L, "default %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
  
   /*
    ** Auxiliary function to create the iteration function for 'lines'.
    ** The iteration function is a closure over 'io_readline', with
    ** the following upvalues:
    ** 1) The file being read (first value in the stack)
    ** 2) the number of arguments to read
    ** 3) a boolean, true iff file has to be closed when finished ('toclose')
    ** *) a variable number of format arguments (rest of the stack)
    */
  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_pushvalue(L, 1);  /* file */
      lua_pushinteger(L, n);  /* number of arguments to read */
      lua_pushboolean(L, toclose);  /* close/not close file when finished */
      lua_rotate(L, 2, 3);  /* move the three values 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;
  }
  
  
  /*
   ** Return an iteration function for 'io.lines'. If file has to be
   ** closed, also returns the file itself as a second result (to be
   ** closed as the state at the exit of a generic for).
   */
  static int io_lines(lua_State* L) {
      int toclose = 0;
      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);  /* push iteration function */
      if (toclose) {
          lua_pushnil(L);  /* state */
          lua_pushnil(L);  /* control */
          lua_pushvalue(L, 1);  /* file is the to-be-closed variable (4th result) */
          return 4;
      }
      else
          return 1;
  }
  
  
  /*
   ** {======================================================
   ** READ
   ** =======================================================
   */
  
  
   /* maximum length of a numeral */
  #if !defined (L_MAXLENNUM)
  #define L_MAXLENNUM     200
  #endif
  
  
  /* 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[L_MAXLENNUM + 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 >= L_MAXLENNUM) {  /* 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 2)
   */
  static int test2(RN* rn, const char* set) {
      if (rn->c == set[0] || rn->c == set[1])
          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 = { 0 };
      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] = '.';  /* always accept a dot */
      l_lockfile(rn.f);
      do { rn.c = l_getc(rn.f); } while (isspace(rn.c));  /* skip spaces */
      test2(&rn, "-+");  /* optional sign */
      if (test2(&rn, "00")) {
          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 sign */
          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 = { 0 };
      int c = EOF;
      luaL_buffinit(L, &b);
      do {  /* may need to read several chunks to get whole line */
          char* buff = luaL_prepbuffer(&b);  /* preallocate buffer space */
          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;  /* read up to end of line or buffer limit */
          l_unlockfile(f);
          luaL_addsize(&b, i);
      } while (c != EOF && c != '\n');  /* repeat until end of line */
      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 = 0;
      luaL_Buffer b = { 0 };
      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 = 0;  /* number of chars actually read */
      char* p = 0;
      luaL_Buffer b = { 0 };
      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 n = 0, success = 0;
      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 */
          luaL_pushfail(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);
  }
  
  
  /*
   ** Iteration function for 'lines'.
   */
  static int io_readline(lua_State* L) {
      LStream* p = (LStream*)lua_touserdata(L, lua_upvalueindex(1));
      int i = 0;
      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 false: 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);  /* clear stack */
              lua_pushvalue(L, lua_upvalueindex(1));  /* push file at index 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,
                      (LUAI_UACINT)lua_tointeger(L, arg))
                  : fprintf(f, LUA_NUMBER_FMT,
                      (LUAI_UACNUMBER)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 meth[] = {
      {"read", f_read},
      {"write", f_write},
      {"lines", f_lines},
      {"flush", f_flush},
      {"seek", f_seek},
      {"close", f_close},
      {"setvbuf", f_setvbuf},
      {NULL, NULL}
  };
  
  
  /*
   ** metamethods for file handles
   */
  static const luaL_Reg metameth[] = {
      {"__index", NULL},  /* place holder */
      {"__gc", f_gc},
      {"__close", f_gc},
      {"__tostring", f_tostring},
      {NULL, NULL}
  };
  
  
  static void createmeta(lua_State* L, int fix) {
      luaL_newmetatable(L, LUA_FILEHANDLE, fix);  /* metatable for file handles */
      luaL_setfuncs(L, metameth, 0);  /* add metamethods to new metatable */
      luaL_newlibtable(L, meth, fix);  /* create method table */
      luaL_setfuncs(L, meth, 0);  /* add file methods to method table */
      lua_setfield(L, -2, "__index");  /* metatable.__index = method table */
      lua_pop(L, 1);  /* pop 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 */
      luaL_pushfail(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, 1);  /* new module */
      createmeta(L, 1);
      /* create (and set) default files */
      createstdfile(L, stdin, IO_INPUT, "stdin");
      createstdfile(L, stdout, IO_OUTPUT, "stdout");
      createstdfile(L, stderr, NULL, "stderr");
      return 1;
  }
  
  