Move stuff around

1 files changed, 768 insertions, 0 deletions

diff --git a/src/lib/lua/liolib.c b/src/lib/lua/liolib.c
new file mode 100644
index 0000000..aa78e59
--- /dev/null
+++ b/src/lib/lua/liolib.c
@@ -0,0 +1,768 @@
+/*
+** $Id: liolib.c,v 2.149 2016/05/02 14:03:19 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 */
+#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;
+  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 signal */
+  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 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;
+}
+