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  1. /*
  2. ** $Id: liolib.c,v 2.108 2011/11/25 12:50:03 roberto Exp $
  3. ** Standard I/O (and system) library
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7.  
  8. /*
  9. ** POSIX idiosyncrasy!
  10. ** This definition must come before the inclusion of 'stdio.h'; it
  11. ** should not affect non-POSIX systems
  12. */
  13. #if !defined(_FILE_OFFSET_BITS)
  14. #define _FILE_OFFSET_BITS 64
  15. #endif
  16.  
  17.  
  18. #include <errno.h>
  19. #include <stdio.h>
  20. #include <stdlib.h>
  21. #include <string.h>
  22.  
  23. #define liolib_c
  24. #define LUA_LIB
  25.  
  26. #include "lua.h"
  27.  
  28. #include "lauxlib.h"
  29. #include "lualib.h"
  30.  
  31.  
  32.  
  33. /*
  34. ** {======================================================
  35. ** lua_popen spawns a new process connected to the current
  36. ** one through the file streams.
  37. ** =======================================================
  38. */
  39.  
  40. #if !defined(lua_popen) /* { */
  41.  
  42. #if defined(LUA_USE_POPEN)      /* { */
  43.  
  44. #define lua_popen(L,c,m)        ((void)L, fflush(NULL), popen(c,m))
  45. #define lua_pclose(L,file)      ((void)L, pclose(file))
  46.  
  47. #elif defined(LUA_WIN)          /* }{ */
  48.  
  49. #define lua_popen(L,c,m)                ((void)L, _popen(c,m))
  50. #define lua_pclose(L,file)              ((void)L, _pclose(file))
  51.  
  52.  
  53. #else                           /* }{ */
  54.  
  55. #define lua_popen(L,c,m)                ((void)((void)c, m),  \
  56.                 luaL_error(L, LUA_QL("popen") " not supported"), (FILE*)0)
  57. #define lua_pclose(L,file)              ((void)((void)L, file), -1)
  58.  
  59.  
  60. #endif                          /* } */
  61.  
  62. #endif                  /* } */
  63.  
  64. /* }====================================================== */
  65.  
  66.  
  67. /*
  68. ** {======================================================
  69. ** lua_fseek/lua_ftell: configuration for longer offsets
  70. ** =======================================================
  71. */
  72.  
  73. #if !defined(lua_fseek) /* { */
  74.  
  75. #if defined(LUA_USE_POSIX)
  76.  
  77. #define l_fseek(f,o,w)          fseeko(f,o,w)
  78. #define l_ftell(f)              ftello(f)
  79. #define l_seeknum               off_t
  80.  
  81. #elif defined(LUA_WIN) && !defined(_CRTIMP_TYPEINFO) \
  82.    && defined(_MSC_VER) && (_MSC_VER >= 1400)
  83. /* Windows (but not DDK) and Visual C++ 2005 or higher */
  84.  
  85. #define l_fseek(f,o,w)          _fseeki64(f,o,w)
  86. #define l_ftell(f)              _ftelli64(f)
  87. #define l_seeknum               __int64
  88.  
  89. #else
  90.  
  91. #define l_fseek(f,o,w)          fseek(f,o,w)
  92. #define l_ftell(f)              ftell(f)
  93. #define l_seeknum               long
  94.  
  95. #endif
  96.  
  97. #endif                  /* } */
  98.  
  99. /* }====================================================== */
  100.  
  101.  
  102. #define IO_PREFIX       "_IO_"
  103. #define IO_INPUT        (IO_PREFIX "input")
  104. #define IO_OUTPUT       (IO_PREFIX "output")
  105.  
  106.  
  107. typedef luaL_Stream LStream;
  108.  
  109.  
  110. #define tolstream(L)    ((LStream *)luaL_checkudata(L, 1, LUA_FILEHANDLE))
  111.  
  112. #define isclosed(p)     ((p)->closef == NULL)
  113.  
  114.  
  115. static int io_type (lua_State *L) {
  116.   LStream *p;
  117.   luaL_checkany(L, 1);
  118.   p = (LStream *)luaL_testudata(L, 1, LUA_FILEHANDLE);
  119.   if (p == NULL)
  120.     lua_pushnil(L);  /* not a file */
  121.   else if (isclosed(p))
  122.     lua_pushliteral(L, "closed file");
  123.   else
  124.     lua_pushliteral(L, "file");
  125.   return 1;
  126. }
  127.  
  128.  
  129. static int f_tostring (lua_State *L) {
  130.   LStream *p = tolstream(L);
  131.   if (isclosed(p))
  132.     lua_pushliteral(L, "file (closed)");
  133.   else
  134.     lua_pushfstring(L, "file (%p)", p->f);
  135.   return 1;
  136. }
  137.  
  138.  
  139. static FILE *tofile (lua_State *L) {
  140.   LStream *p = tolstream(L);
  141.   if (isclosed(p))
  142.     luaL_error(L, "attempt to use a closed file");
  143.   lua_assert(p->f);
  144.   return p->f;
  145. }
  146.  
  147.  
  148. /*
  149. ** When creating file handles, always creates a `closed' file handle
  150. ** before opening the actual file; so, if there is a memory error, the
  151. ** file is not left opened.
  152. */
  153. static LStream *newprefile (lua_State *L) {
  154.   LStream *p = (LStream *)lua_newuserdata(L, sizeof(LStream));
  155.   p->closef = NULL;  /* mark file handle as 'closed' */
  156.   luaL_setmetatable(L, LUA_FILEHANDLE);
  157.   return p;
  158. }
  159.  
  160.  
  161. static int aux_close (lua_State *L) {
  162.   LStream *p = tolstream(L);
  163.   lua_CFunction cf = p->closef;
  164.   p->closef = NULL;  /* mark stream as closed */
  165.   return (*cf)(L);  /* close it */
  166. }
  167.  
  168.  
  169. static int io_close (lua_State *L) {
  170.   if (lua_isnone(L, 1))  /* no argument? */
  171.     lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT);  /* use standard output */
  172.   tofile(L);  /* make sure argument is an open stream */
  173.   return aux_close(L);
  174. }
  175.  
  176.  
  177. static int f_gc (lua_State *L) {
  178.   LStream *p = tolstream(L);
  179.   if (!isclosed(p) && p->f != NULL)
  180.     aux_close(L);  /* ignore closed and incompletely open files */
  181.   return 0;
  182. }
  183.  
  184.  
  185. /*
  186. ** function to close regular files
  187. */
  188. static int io_fclose (lua_State *L) {
  189.   LStream *p = tolstream(L);
  190.   int res = fclose(p->f);
  191.   return luaL_fileresult(L, (res == 0), NULL);
  192. }
  193.  
  194.  
  195. static LStream *newfile (lua_State *L) {
  196.   LStream *p = newprefile(L);
  197.   p->f = NULL;
  198.   p->closef = &io_fclose;
  199.   return p;
  200. }
  201.  
  202.  
  203. static void opencheck (lua_State *L, const char *fname, const char *mode) {
  204.   LStream *p = newfile(L);
  205.   p->f = fopen(fname, mode);
  206.   if (p->f == NULL)
  207.     luaL_error(L, "cannot open file " LUA_QS " (%s)", fname, strerror(errno));
  208. }
  209.  
  210.  
  211. static int io_open (lua_State *L) {
  212.   const char *filename = luaL_checkstring(L, 1);
  213.   const char *mode = luaL_optstring(L, 2, "r");
  214.   LStream *p = newfile(L);
  215.   int i = 0;
  216.   /* check whether 'mode' matches '[rwa]%+?b?' */
  217.   if (!(mode[i] != '\0' && strchr("rwa", mode[i++]) != NULL &&
  218.        (mode[i] != '+' || ++i) &&  /* skip if char is '+' */
  219.        (mode[i] != 'b' || ++i) &&  /* skip if char is 'b' */
  220.        (mode[i] == '\0')))
  221.     return luaL_error(L, "invalid mode " LUA_QS
  222.                          " (should match " LUA_QL("[rwa]%%+?b?") ")", mode);
  223.   p->f = fopen(filename, mode);
  224.   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
  225. }
  226.  
  227.  
  228. /*
  229. ** function to close 'popen' files
  230. */
  231. static int io_pclose (lua_State *L) {
  232.   LStream *p = tolstream(L);
  233.   return luaL_execresult(L, lua_pclose(L, p->f));
  234. }
  235.  
  236.  
  237. static int io_popen (lua_State *L) {
  238.   const char *filename = luaL_checkstring(L, 1);
  239.   const char *mode = luaL_optstring(L, 2, "r");
  240.   LStream *p = newprefile(L);
  241.   p->f = lua_popen(L, filename, mode);
  242.   p->closef = &io_pclose;
  243.   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
  244. }
  245.  
  246.  
  247. static int io_tmpfile (lua_State *L) {
  248.   LStream *p = newfile(L);
  249.   p->f = tmpfile();
  250.   return (p->f == NULL) ? luaL_fileresult(L, 0, NULL) : 1;
  251. }
  252.  
  253.  
  254. static FILE *getiofile (lua_State *L, const char *findex) {
  255.   LStream *p;
  256.   lua_getfield(L, LUA_REGISTRYINDEX, findex);
  257.   p = (LStream *)lua_touserdata(L, -1);
  258.   if (isclosed(p))
  259.     luaL_error(L, "standard %s file is closed", findex + strlen(IO_PREFIX));
  260.   return p->f;
  261. }
  262.  
  263.  
  264. static int g_iofile (lua_State *L, const char *f, const char *mode) {
  265.   if (!lua_isnoneornil(L, 1)) {
  266.     const char *filename = lua_tostring(L, 1);
  267.     if (filename)
  268.       opencheck(L, filename, mode);
  269.     else {
  270.       tofile(L);  /* check that it's a valid file handle */
  271.       lua_pushvalue(L, 1);
  272.     }
  273.     lua_setfield(L, LUA_REGISTRYINDEX, f);
  274.   }
  275.   /* return current value */
  276.   lua_getfield(L, LUA_REGISTRYINDEX, f);
  277.   return 1;
  278. }
  279.  
  280.  
  281. static int io_input (lua_State *L) {
  282.   return g_iofile(L, IO_INPUT, "r");
  283. }
  284.  
  285.  
  286. static int io_output (lua_State *L) {
  287.   return g_iofile(L, IO_OUTPUT, "w");
  288. }
  289.  
  290.  
  291. static int io_readline (lua_State *L);
  292.  
  293.  
  294. static void aux_lines (lua_State *L, int toclose) {
  295.   int i;
  296.   int n = lua_gettop(L) - 1;  /* number of arguments to read */
  297.   /* ensure that arguments will fit here and into 'io_readline' stack */
  298.   luaL_argcheck(L, n <= LUA_MINSTACK - 3, LUA_MINSTACK - 3, "too many options");
  299.   lua_pushvalue(L, 1);  /* file handle */
  300.   lua_pushinteger(L, n);  /* number of arguments to read */
  301.   lua_pushboolean(L, toclose);  /* close/not close file when finished */
  302.   for (i = 1; i <= n; i++) lua_pushvalue(L, i + 1);  /* copy arguments */
  303.   lua_pushcclosure(L, io_readline, 3 + n);
  304. }
  305.  
  306.  
  307. static int f_lines (lua_State *L) {
  308.   tofile(L);  /* check that it's a valid file handle */
  309.   aux_lines(L, 0);
  310.   return 1;
  311. }
  312.  
  313.  
  314. static int io_lines (lua_State *L) {
  315.   int toclose;
  316.   if (lua_isnone(L, 1)) lua_pushnil(L);  /* at least one argument */
  317.   if (lua_isnil(L, 1)) {  /* no file name? */
  318.     lua_getfield(L, LUA_REGISTRYINDEX, IO_INPUT);  /* get default input */
  319.     lua_replace(L, 1);  /* put it at index 1 */
  320.     tofile(L);  /* check that it's a valid file handle */
  321.     toclose = 0;  /* do not close it after iteration */
  322.   }
  323.   else {  /* open a new file */
  324.     const char *filename = luaL_checkstring(L, 1);
  325.     opencheck(L, filename, "r");
  326.     lua_replace(L, 1);  /* put file at index 1 */
  327.     toclose = 1;  /* close it after iteration */
  328.   }
  329.   aux_lines(L, toclose);
  330.   return 1;
  331. }
  332.  
  333.  
  334. /*
  335. ** {======================================================
  336. ** READ
  337. ** =======================================================
  338. */
  339.  
  340.  
  341. static int read_number (lua_State *L, FILE *f) {
  342.   lua_Number d;
  343.   if (fscanf(f, LUA_NUMBER_SCAN, &d) == 1) {
  344.     lua_pushnumber(L, d);
  345.     return 1;
  346.   }
  347.   else {
  348.    lua_pushnil(L);  /* "result" to be removed */
  349.    return 0;  /* read fails */
  350.   }
  351. }
  352.  
  353.  
  354. static int test_eof (lua_State *L, FILE *f) {
  355.   int c = getc(f);
  356.   ungetc(c, f);
  357.   lua_pushlstring(L, NULL, 0);
  358.   return (c != EOF);
  359. }
  360.  
  361.  
  362. static int read_line (lua_State *L, FILE *f, int chop) {
  363.   luaL_Buffer b;
  364.   luaL_buffinit(L, &b);
  365.   for (;;) {
  366.     size_t l;
  367.     char *p = luaL_prepbuffer(&b);
  368.     if (fgets(p, LUAL_BUFFERSIZE, f) == NULL) {  /* eof? */
  369.       luaL_pushresult(&b);  /* close buffer */
  370.       return (lua_rawlen(L, -1) > 0);  /* check whether read something */
  371.     }
  372.     l = strlen(p);
  373.     if (l == 0 || p[l-1] != '\n')
  374.       luaL_addsize(&b, l);
  375.     else {
  376.       luaL_addsize(&b, l - chop);  /* chop 'eol' if needed */
  377.       luaL_pushresult(&b);  /* close buffer */
  378.       return 1;  /* read at least an `eol' */
  379.     }
  380.   }
  381. }
  382.  
  383.  
  384. #define MAX_SIZE_T      (~(size_t)0)
  385.  
  386. static void read_all (lua_State *L, FILE *f) {
  387.   size_t rlen = LUAL_BUFFERSIZE;  /* how much to read in each cycle */
  388.   luaL_Buffer b;
  389.   luaL_buffinit(L, &b);
  390.   for (;;) {
  391.     char *p = luaL_prepbuffsize(&b, rlen);
  392.     size_t nr = fread(p, sizeof(char), rlen, f);
  393.     luaL_addsize(&b, nr);
  394.     if (nr < rlen) break;  /* eof? */
  395.     else if (rlen <= (MAX_SIZE_T / 4))  /* avoid buffers too large */
  396.       rlen *= 2;  /* double buffer size at each iteration */
  397.   }
  398.   luaL_pushresult(&b);  /* close buffer */
  399. }
  400.  
  401.  
  402. static int read_chars (lua_State *L, FILE *f, size_t n) {
  403.   size_t nr;  /* number of chars actually read */
  404.   char *p;
  405.   luaL_Buffer b;
  406.   luaL_buffinit(L, &b);
  407.   p = luaL_prepbuffsize(&b, n);  /* prepare buffer to read whole block */
  408.   nr = fread(p, sizeof(char), n, f);  /* try to read 'n' chars */
  409.   luaL_addsize(&b, nr);
  410.   luaL_pushresult(&b);  /* close buffer */
  411.   return (nr > 0);  /* true iff read something */
  412. }
  413.  
  414.  
  415. static int g_read (lua_State *L, FILE *f, int first) {
  416.   int nargs = lua_gettop(L) - 1;
  417.   int success;
  418.   int n;
  419.   clearerr(f);
  420.   if (nargs == 0) {  /* no arguments? */
  421.     success = read_line(L, f, 1);
  422.     n = first+1;  /* to return 1 result */
  423.   }
  424.   else {  /* ensure stack space for all results and for auxlib's buffer */
  425.     luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments");
  426.     success = 1;
  427.     for (n = first; nargs-- && success; n++) {
  428.       if (lua_type(L, n) == LUA_TNUMBER) {
  429.         size_t l = (size_t)lua_tointeger(L, n);
  430.         success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
  431.       }
  432.       else {
  433.         const char *p = lua_tostring(L, n);
  434.         luaL_argcheck(L, p && p[0] == '*', n, "invalid option");
  435.         switch (p[1]) {
  436.           case 'n':  /* number */
  437.             success = read_number(L, f);
  438.             break;
  439.           case 'l':  /* line */
  440.             success = read_line(L, f, 1);
  441.             break;
  442.           case 'L':  /* line with end-of-line */
  443.             success = read_line(L, f, 0);
  444.             break;
  445.           case 'a':  /* file */
  446.             read_all(L, f);  /* read entire file */
  447.             success = 1; /* always success */
  448.             break;
  449.           default:
  450.             return luaL_argerror(L, n, "invalid format");
  451.         }
  452.       }
  453.     }
  454.   }
  455.   if (ferror(f))
  456.     return luaL_fileresult(L, 0, NULL);
  457.   if (!success) {
  458.     lua_pop(L, 1);  /* remove last result */
  459.     lua_pushnil(L);  /* push nil instead */
  460.   }
  461.   return n - first;
  462. }
  463.  
  464.  
  465. static int io_read (lua_State *L) {
  466.   return g_read(L, getiofile(L, IO_INPUT), 1);
  467. }
  468.  
  469.  
  470. static int f_read (lua_State *L) {
  471.   return g_read(L, tofile(L), 2);
  472. }
  473.  
  474.  
  475. static int io_readline (lua_State *L) {
  476.   LStream *p = (LStream *)lua_touserdata(L, lua_upvalueindex(1));
  477.   int i;
  478.   int n = (int)lua_tointeger(L, lua_upvalueindex(2));
  479.   if (isclosed(p))  /* file is already closed? */
  480.     return luaL_error(L, "file is already closed");
  481.   lua_settop(L , 1);
  482.   for (i = 1; i <= n; i++)  /* push arguments to 'g_read' */
  483.     lua_pushvalue(L, lua_upvalueindex(3 + i));
  484.   n = g_read(L, p->f, 2);  /* 'n' is number of results */
  485.   lua_assert(n > 0);  /* should return at least a nil */
  486.   if (!lua_isnil(L, -n))  /* read at least one value? */
  487.     return n;  /* return them */
  488.   else {  /* first result is nil: EOF or error */
  489.     if (n > 1) {  /* is there error information? */
  490.       /* 2nd result is error message */
  491.       return luaL_error(L, "%s", lua_tostring(L, -n + 1));
  492.     }
  493.     if (lua_toboolean(L, lua_upvalueindex(3))) {  /* generator created file? */
  494.       lua_settop(L, 0);
  495.       lua_pushvalue(L, lua_upvalueindex(1));
  496.       aux_close(L);  /* close it */
  497.     }
  498.     return 0;
  499.   }
  500. }
  501.  
  502. /* }====================================================== */
  503.  
  504.  
  505. static int g_write (lua_State *L, FILE *f, int arg) {
  506.   int nargs = lua_gettop(L) - arg;
  507.   int status = 1;
  508.   for (; nargs--; arg++) {
  509.     if (lua_type(L, arg) == LUA_TNUMBER) {
  510.       /* optimization: could be done exactly as for strings */
  511.       status = status &&
  512.           fprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg)) > 0;
  513.     }
  514.     else {
  515.       size_t l;
  516.       const char *s = luaL_checklstring(L, arg, &l);
  517.       status = status && (fwrite(s, sizeof(char), l, f) == l);
  518.     }
  519.   }
  520.   if (status) return 1;  /* file handle already on stack top */
  521.   else return luaL_fileresult(L, status, NULL);
  522. }
  523.  
  524.  
  525. static int io_write (lua_State *L) {
  526.   return g_write(L, getiofile(L, IO_OUTPUT), 1);
  527. }
  528.  
  529.  
  530. static int f_write (lua_State *L) {
  531.   FILE *f = tofile(L);
  532.   lua_pushvalue(L, 1);  /* push file at the stack top (to be returned) */
  533.   return g_write(L, f, 2);
  534. }
  535.  
  536.  
  537. static int f_seek (lua_State *L) {
  538.   static const int mode[] = {SEEK_SET, SEEK_CUR, SEEK_END};
  539.   static const char *const modenames[] = {"set", "cur", "end", NULL};
  540.   FILE *f = tofile(L);
  541.   int op = luaL_checkoption(L, 2, "cur", modenames);
  542.   lua_Number p3 = luaL_optnumber(L, 3, 0);
  543.   l_seeknum offset = (l_seeknum)p3;
  544.   luaL_argcheck(L, (lua_Number)offset == p3, 3,
  545.                   "not an integer in proper range");
  546.   op = l_fseek(f, offset, mode[op]);
  547.   if (op)
  548.     return luaL_fileresult(L, 0, NULL);  /* error */
  549.   else {
  550.     lua_pushnumber(L, (lua_Number)l_ftell(f));
  551.     return 1;
  552.   }
  553. }
  554.  
  555.  
  556. static int f_setvbuf (lua_State *L) {
  557.   static const int mode[] = {_IONBF, _IOFBF, _IOLBF};
  558.   static const char *const modenames[] = {"no", "full", "line", NULL};
  559.   FILE *f = tofile(L);
  560.   int op = luaL_checkoption(L, 2, NULL, modenames);
  561.   lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE);
  562.   int res = setvbuf(f, NULL, mode[op], sz);
  563.   return luaL_fileresult(L, res == 0, NULL);
  564. }
  565.  
  566.  
  567.  
  568. static int io_flush (lua_State *L) {
  569.   return luaL_fileresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL);
  570. }
  571.  
  572.  
  573. static int f_flush (lua_State *L) {
  574.   return luaL_fileresult(L, fflush(tofile(L)) == 0, NULL);
  575. }
  576.  
  577.  
  578. /*
  579. ** functions for 'io' library
  580. */
  581. static const luaL_Reg iolib[] = {
  582.   {"close", io_close},
  583.   {"flush", io_flush},
  584.   {"input", io_input},
  585.   {"lines", io_lines},
  586.   {"open", io_open},
  587.   {"output", io_output},
  588.   {"popen", io_popen},
  589.   {"read", io_read},
  590.   {"tmpfile", io_tmpfile},
  591.   {"type", io_type},
  592.   {"write", io_write},
  593.   {NULL, NULL}
  594. };
  595.  
  596.  
  597. /*
  598. ** methods for file handles
  599. */
  600. static const luaL_Reg flib[] = {
  601.   {"close", io_close},
  602.   {"flush", f_flush},
  603.   {"lines", f_lines},
  604.   {"read", f_read},
  605.   {"seek", f_seek},
  606.   {"setvbuf", f_setvbuf},
  607.   {"write", f_write},
  608.   {"__gc", f_gc},
  609.   {"__tostring", f_tostring},
  610.   {NULL, NULL}
  611. };
  612.  
  613.  
  614. static void createmeta (lua_State *L) {
  615.   luaL_newmetatable(L, LUA_FILEHANDLE);  /* create metatable for file handles */
  616.   lua_pushvalue(L, -1);  /* push metatable */
  617.   lua_setfield(L, -2, "__index");  /* metatable.__index = metatable */
  618.   luaL_setfuncs(L, flib, 0);  /* add file methods to new metatable */
  619.   lua_pop(L, 1);  /* pop new metatable */
  620. }
  621.  
  622.  
  623. /*
  624. ** function to (not) close the standard files stdin, stdout, and stderr
  625. */
  626. static int io_noclose (lua_State *L) {
  627.   LStream *p = tolstream(L);
  628.   p->closef = &io_noclose;  /* keep file opened */
  629.   lua_pushnil(L);
  630.   lua_pushliteral(L, "cannot close standard file");
  631.   return 2;
  632. }
  633.  
  634.  
  635. static void createstdfile (lua_State *L, FILE *f, const char *k,
  636.                            const char *fname) {
  637.   LStream *p = newprefile(L);
  638.   p->f = f;
  639.   p->closef = &io_noclose;
  640.   if (k != NULL) {
  641.     lua_pushvalue(L, -1);
  642.     lua_setfield(L, LUA_REGISTRYINDEX, k);  /* add file to registry */
  643.   }
  644.   lua_setfield(L, -2, fname);  /* add file to module */
  645. }
  646.  
  647.  
  648. LUAMOD_API int luaopen_io (lua_State *L) {
  649.   luaL_newlib(L, iolib);  /* new module */
  650.   createmeta(L);
  651.   /* create (and set) default files */
  652.   createstdfile(L, stdin, IO_INPUT, "stdin");
  653.   createstdfile(L, stdout, IO_OUTPUT, "stdout");
  654.   createstdfile(L, stderr, NULL, "stderr");
  655.   return 1;
  656. }
  657.  
  658.