/*

** $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"

#include "llimits.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))

#if !defined(l_checkmodep)

/* Windows accepts "[rw][bt]?" as valid modes */

#define l_checkmodep(m) ((m[0] == 'r' || m[0] == 'w') && \

  (m[1] == '\0' || ((m[1] == 'b' || m[1] == 't') && m[2] == '\0')))

#endif

#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_checkmodep)

/* By default, Lua accepts only "r" or "w" as valid modes */

#define l_checkmodep(m)        ((m[0] == 'r' || m[0] == 'w') && m[1] == '\0')

#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) || defined(LUA_USE_OFF_T)  /* { */

#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)

    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 (l_unlikely(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);

  errno = 0;

  return luaL_fileresult(L, (fclose(p->f) == 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 (l_unlikely(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");

  errno = 0;

  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);

  luaL_argcheck(L, l_checkmodep(mode), 2, "invalid mode");

  errno = 0;

  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);

  errno = 0;

  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 (l_unlikely(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;

  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 (l_unlikely(rn->n >= L_MAXLENNUM)) {  /* buffer overflow? */

    rn->buff[0] = '\0';  /* invalidate result */

    return 0;  /* fail */

  }

  else {

    rn->buff[rn->n++] = cast_char(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 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 (l_likely(lua_stringtonumber(L, rn.buff)))

    return 1;  /* ok, it is a valid number */

  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;

  luaL_buffinit(L, &b);

  do {  /* may need to read several chunks to get whole line */

    char *buff = luaL_prepbuffer(&b);  /* preallocate buffer space */

    unsigned 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++] = cast_char(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, '\n');  /* 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 n, success;

  clearerr(f);

  errno = 0;

  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;

  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;

  size_t totalbytes = 0;  /* total number of bytes written */

  errno = 0;

  for (; nargs--; arg++) {  /* for each argument */

    char buff[LUA_N2SBUFFSZ];

    const char *s;

    size_t numbytes;  /* bytes written in one call to 'fwrite' */

    size_t len = lua_numbertocstring(L, arg, buff);  /* try as a number */

    if (len > 0) {  /* did conversion work (value was a number)? */

      s = buff;

      len--;

    }

    else  /* must be a string */

      s = luaL_checklstring(L, arg, &len);

    numbytes = fwrite(s, sizeof(char), len, f);

    totalbytes += numbytes;

    if (numbytes < len) {  /* write error? */

      int n = luaL_fileresult(L, 0, NULL);

      lua_pushinteger(L, cast_st2S(totalbytes));

      return n + 1;  /* return fail, error msg., error code, and counter */

    }

  }

  return 1;  /* no errors; file handle already on stack top */

}

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");

  errno = 0;

  op = l_fseek(f, offset, mode[op]);

  if (l_unlikely(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;

  errno = 0;

  res = setvbuf(f, NULL, mode[op], (size_t)sz);

  return luaL_fileresult(L, res == 0, NULL);

}

static int aux_flush (lua_State *L, FILE *f) {

  errno = 0;

  return luaL_fileresult(L, fflush(f) == 0, NULL);

}

static int f_flush (lua_State *L) {

  return aux_flush(L, tofile(L));

}

static int io_flush (lua_State *L) {

  return aux_flush(L, getiofile(L, IO_OUTPUT));

}

/*

** 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},  /* placeholder */

  {"__gc", f_gc},

  {"__close", f_gc},

  {"__tostring", f_tostring},

  {NULL, NULL}

};

static void createmeta (lua_State *L) {

  luaL_newmetatable(L, LUA_FILEHANDLE);  /* metatable for file handles */

  luaL_setfuncs(L, metameth, 0);  /* add metamethods to new metatable */

  luaL_newlibtable(L, meth);  /* 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);  /* 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;

}