external/mit/lua/dist/src/liolib.c

   1 /*      $NetBSD: liolib.c,v 1.4 2015/10/08 13:21:00 mbalmer Exp $       */
   2
   3 /*
   4 ** Id: liolib.c,v 2.144 2015/04/03 18:41:57 roberto Exp
   5 ** Standard I/O (and system) library
   6 ** See Copyright Notice in lua.h
   7 */
   8
   9 #define liolib_c
  10 #define LUA_LIB
  11
  12 #include "lprefix.h"
  13
  14
  15 #include <ctype.h>
  16 #include <errno.h>
  17 #include <locale.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21
  22 #include "lua.h"
  23
  24 #include "lauxlib.h"
  25 #include "lualib.h"
  26
  27
  28 #if !defined(l_checkmode)
  29
  30 /*
  31 ** Check whether 'mode' matches '[rwa]%+?b?'.
  32 ** Change this macro to accept other modes for 'fopen' besides
  33 ** the standard ones.
  34 */
  35 #define l_checkmode(mode) \
  36         (*mode != '\0' && strchr("rwa", *(mode++)) != NULL &&   \
  37         (*mode != '+' || ++mode) &&  /* skip if char is '+' */  \
  38         (*mode != 'b' || ++mode) &&  /* skip if char is 'b' */  \
  39         (*mode == '\0'))
  40
  41 #endif
  42
  43 /*
  44 ** {======================================================
  45 ** l_popen spawns a new process connected to the current
  46 ** one through the file streams.
  47 ** =======================================================
  48 */
  49
  50 #if !defined(l_popen)           /* { */
  51
  52 #if defined(LUA_USE_POSIX)      /* { */
  53
  54 #define l_popen(L,c,m)          (fflush(NULL), popen(c,m))
  55 #define l_pclose(L,file)        (pclose(file))
  56
  57 #elif defined(LUA_USE_WINDOWS)  /* }{ */
  58
  59 #define l_popen(L,c,m)          (_popen(c,m))
  60 #define l_pclose(L,file)        (_pclose(file))
  61
  62 #else                           /* }{ */
  63
  64 /* ISO C definitions */
  65 #define l_popen(L,c,m)  \
  66           ((void)((void)c, m), \
  67           luaL_error(L, "'popen' not supported"), \
  68           (FILE*)0)
  69 #define l_pclose(L,file)                ((void)L, (void)file, -1)
  70
  71 #endif                          /* } */
  72
  73 #endif                          /* } */
  74
  75 /* }====================================================== */
  76
  77
  78 #if !defined(l_getc)            /* { */
  79
  80 #if defined(LUA_USE_POSIX)
  81 #define l_getc(f)               getc_unlocked(f)
  82 #define l_lockfile(f)           flockfile(f)
  83 #define l_unlockfile(f)         funlockfile(f)
  84 #else
  85 #define l_getc(f)               getc(f)
  86 #define l_lockfile(f)           ((void)0)
  87 #define l_unlockfile(f)         ((void)0)
  88 #endif
  89
  90 #endif                          /* } */
  91
  92
  93 /*
  94 ** {======================================================
  95 ** l_fseek: configuration for longer offsets
  96 ** =======================================================
  97 */
  98
  99 #if !defined(l_fseek)           /* { */
 100
 101 #if defined(LUA_USE_POSIX)      /* { */
 102
 103 #include <sys/types.h>
 104
 105 #define l_fseek(f,o,w)          fseeko(f,o,w)
 106 #define l_ftell(f)              ftello(f)
 107 #define l_seeknum               off_t
 108
 109 #elif defined(LUA_USE_WINDOWS) && !defined(_CRTIMP_TYPEINFO) \
 110    && defined(_MSC_VER) && (_MSC_VER >= 1400)   /* }{ */
 111
 112 /* Windows (but not DDK) and Visual C++ 2005 or higher */
 113 #define l_fseek(f,o,w)          _fseeki64(f,o,w)
 114 #define l_ftell(f)              _ftelli64(f)
 115 #define l_seeknum               __int64
 116
 117 #else                           /* }{ */
 118
 119 /* ISO C definitions */
 120 #define l_fseek(f,o,w)          fseek(f,o,w)
 121 #define l_ftell(f)              ftell(f)
 122 #define l_seeknum               long
 123
 124 #endif                          /* } */
 125
 126 #endif                          /* } */
 127
 128 /* }====================================================== */
 129
 130
 131 #define IO_PREFIX       "_IO_"
 132 #define IOPREF_LEN      (sizeof(IO_PREFIX)/sizeof(char) - 1)
 133 #define IO_INPUT        (IO_PREFIX "input")
 134 #define IO_OUTPUT       (IO_PREFIX "output")
 135
 136
 137 typedef luaL_Stream LStream;
 138
 139
 140 #define tolstream(L)    ((LStream *)luaL_checkudata(L, 1, LUA_FILEHANDLE))
 141
 142 #define isclosed(p)     ((p)->closef == NULL)
 143
 144
 145 static int io_type (lua_State *L) {
 146   LStream *p;
 147   luaL_checkany(L, 1);
 148   p = (LStream *)luaL_testudata(L, 1, LUA_FILEHANDLE);
 149   if (p == NULL)
 150     lua_pushnil(L);  /* not a file */
 151   else if (isclosed(p))
 152     lua_pushliteral(L, "closed file");
 153   else
 154     lua_pushliteral(L, "file");
 155   return 1;
 156 }
 157
 158
 159 static int f_tostring (lua_State *L) {
 160   LStream *p = tolstream(L);
 161   if (isclosed(p))
 162     lua_pushliteral(L, "file (closed)");
 163   else
 164     lua_pushfstring(L, "file (%p)", p->f);
 165   return 1;
 166 }
 167
 168
 169 static FILE *tofile (lua_State *L) {
 170   LStream *p = tolstream(L);
 171   if (isclosed(p))
 172     luaL_error(L, "attempt to use a closed file");
 173   lua_assert(p->f);
 174   return p->f;
 175 }
 176
 177
 178 /*
 179 ** When creating file handles, always creates a 'closed' file handle
 180 ** before opening the actual file; so, if there is a memory error, the
 181 ** file is not left opened.
 182 */
 183 static LStream *newprefile (lua_State *L) {
 184   LStream *p = (LStream *)lua_newuserdata(L, sizeof(LStream));
 185   p->closef = NULL;  /* mark file handle as 'closed' */
 186   luaL_setmetatable(L, LUA_FILEHANDLE);
 187   return p;
 188 }
 189
 190
 191 /*
 192 ** Calls the 'close' function from a file handle. The 'volatile' avoids
 193 ** a bug in some versions of the Clang compiler (e.g., clang 3.0 for
 194 ** 32 bits).
 195 */
 196 static int aux_close (lua_State *L) {
 197   LStream *p = tolstream(L);
 198   volatile lua_CFunction cf = p->closef;
 199   p->closef = NULL;  /* mark stream as closed */
 200   return (*cf)(L);  /* close it */
 201 }
 202
 203
 204 static int io_close (lua_State *L) {
 205   if (lua_isnone(L, 1))  /* no argument? */
 206     lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT);  /* use standard output */
 207   tofile(L);  /* make sure argument is an open stream */
 208   return aux_close(L);
 209 }
 210
 211
 212 static int f_gc (lua_State *L) {
 213   LStream *p = tolstream(L);
 214   if (!isclosed(p) && p->f != NULL)
 215     aux_close(L);  /* ignore closed and incompletely open files */
 216   return 0;
 217 }
 218
 219
 220 /*
 221 ** function to close regular files
 222 */
 223 static int io_fclose (lua_State *L) {
 224   LStream *p = tolstream(L);
 225   int res = fclose(p->f);
 226   return luaL_fileresult(L, (res == 0), NULL);
 227 }
 228
 229
 230 static LStream *newfile (lua_State *L) {
 231   LStream *p = newprefile(L);
 232   p->f = NULL;
 233   p->closef = &io_fclose;
 234   return p;
 235 }
 236
 237
 238 static void opencheck (lua_State *L, const char *fname, const char *mode) {
 239   LStream *p = newfile(L);
 240   p->f = fopen(fname, mode);
 241   if (p->f == NULL)
 242     luaL_error(L, "cannot open file '%s' (%s)", fname, strerror(errno));
 243 }
 244
 245
 246 static int io_open (lua_State *L) {
 247   const char *filename = luaL_checkstring(L, 1);
 248   const char *mode = luaL_optstring(L, 2, "r");
 249   LStream *p = newfile(L);
 250   const char *md = mode;  /* to traverse/check mode */
 251   luaL_argcheck(L, l_checkmode(md), 2, "invalid mode");
 252   p->f = fopen(filename, mode);
 253   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
 254 }
 255
 256
 257 /*
 258 ** function to close 'popen' files
 259 */
 260 static int io_pclose (lua_State *L) {
 261   LStream *p = tolstream(L);
 262   return luaL_execresult(L, l_pclose(L, p->f));
 263 }
 264
 265
 266 static int io_popen (lua_State *L) {
 267   const char *filename = luaL_checkstring(L, 1);
 268   const char *mode = luaL_optstring(L, 2, "r");
 269   LStream *p = newprefile(L);
 270   p->f = l_popen(L, filename, mode);
 271   p->closef = &io_pclose;
 272   return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1;
 273 }
 274
 275
 276 static int io_tmpfile (lua_State *L) {
 277   LStream *p = newfile(L);
 278   p->f = tmpfile();
 279   return (p->f == NULL) ? luaL_fileresult(L, 0, NULL) : 1;
 280 }
 281
 282
 283 static FILE *getiofile (lua_State *L, const char *findex) {
 284   LStream *p;
 285   lua_getfield(L, LUA_REGISTRYINDEX, findex);
 286   p = (LStream *)lua_touserdata(L, -1);
 287   if (isclosed(p))
 288     luaL_error(L, "standard %s file is closed", findex + IOPREF_LEN);
 289   return p->f;
 290 }
 291
 292
 293 static int g_iofile (lua_State *L, const char *f, const char *mode) {
 294   if (!lua_isnoneornil(L, 1)) {
 295     const char *filename = lua_tostring(L, 1);
 296     if (filename)
 297       opencheck(L, filename, mode);
 298     else {
 299       tofile(L);  /* check that it's a valid file handle */
 300       lua_pushvalue(L, 1);
 301     }
 302     lua_setfield(L, LUA_REGISTRYINDEX, f);
 303   }
 304   /* return current value */
 305   lua_getfield(L, LUA_REGISTRYINDEX, f);
 306   return 1;
 307 }
 308
 309
 310 static int io_input (lua_State *L) {
 311   return g_iofile(L, IO_INPUT, "r");
 312 }
 313
 314
 315 static int io_output (lua_State *L) {
 316   return g_iofile(L, IO_OUTPUT, "w");
 317 }
 318
 319
 320 static int io_readline (lua_State *L);
 321
 322
 323 static void aux_lines (lua_State *L, int toclose) {
 324   int n = lua_gettop(L) - 1;  /* number of arguments to read */
 325   lua_pushinteger(L, n);  /* number of arguments to read */
 326   lua_pushboolean(L, toclose);  /* close/not close file when finished */
 327   lua_rotate(L, 2, 2);  /* move 'n' and 'toclose' to their positions */
 328   lua_pushcclosure(L, io_readline, 3 + n);
 329 }
 330
 331
 332 static int f_lines (lua_State *L) {
 333   tofile(L);  /* check that it's a valid file handle */
 334   aux_lines(L, 0);
 335   return 1;
 336 }
 337
 338
 339 static int io_lines (lua_State *L) {
 340   int toclose;
 341   if (lua_isnone(L, 1)) lua_pushnil(L);  /* at least one argument */
 342   if (lua_isnil(L, 1)) {  /* no file name? */
 343     lua_getfield(L, LUA_REGISTRYINDEX, IO_INPUT);  /* get default input */
 344     lua_replace(L, 1);  /* put it at index 1 */
 345     tofile(L);  /* check that it's a valid file handle */
 346     toclose = 0;  /* do not close it after iteration */
 347   }
 348   else {  /* open a new file */
 349     const char *filename = luaL_checkstring(L, 1);
 350     opencheck(L, filename, "r");
 351     lua_replace(L, 1);  /* put file at index 1 */
 352     toclose = 1;  /* close it after iteration */
 353   }
 354   aux_lines(L, toclose);
 355   return 1;
 356 }
 357
 358
 359 /*
 360 ** {======================================================
 361 ** READ
 362 ** =======================================================
 363 */
 364
 365
 366 /* maximum length of a numeral */
 367 #define MAXRN           200
 368
 369 /* auxiliary structure used by 'read_number' */
 370 typedef struct {
 371   FILE *f;  /* file being read */
 372   int c;  /* current character (look ahead) */
 373   int n;  /* number of elements in buffer 'buff' */
 374   char buff[MAXRN + 1];  /* +1 for ending '\0' */
 375 } RN;
 376
 377
 378 /*
 379 ** Add current char to buffer (if not out of space) and read next one
 380 */
 381 static int nextc (RN *rn) {
 382   if (rn->n >= MAXRN) {  /* buffer overflow? */
 383     rn->buff[0] = '\0';  /* invalidate result */
 384     return 0;  /* fail */
 385   }
 386   else {
 387     rn->buff[rn->n++] = rn->c;  /* save current char */
 388     rn->c = l_getc(rn->f);  /* read next one */
 389     return 1;
 390   }
 391 }
 392
 393
 394 /*
 395 ** Accept current char if it is in 'set' (of size 1 or 2)
 396 */
 397 static int test2 (RN *rn, const char *set) {
 398   if (rn->c == set[0] || (rn->c == set[1] && rn->c != '\0'))
 399     return nextc(rn);
 400   else return 0;
 401 }
 402
 403
 404 /*
 405 ** Read a sequence of (hex)digits
 406 */
 407 static int readdigits (RN *rn, int hex) {
 408   int count = 0;
 409   while ((hex ? isxdigit(rn->c) : isdigit(rn->c)) && nextc(rn))
 410     count++;
 411   return count;
 412 }
 413
 414
 415 /*
 416 ** Read a number: first reads a valid prefix of a numeral into a buffer.
 417 ** Then it calls 'lua_stringtonumber' to check whether the format is
 418 ** correct and to convert it to a Lua number
 419 */
 420 static int read_number (lua_State *L, FILE *f) {
 421   RN rn;
 422   int count = 0;
 423   int hex = 0;
 424   char decp[2];
 425   rn.f = f; rn.n = 0;
 426   decp[0] = lua_getlocaledecpoint();  /* get decimal point from locale */
 427   decp[1] = '\0';
 428   l_lockfile(rn.f);
 429   do { rn.c = l_getc(rn.f); } while (isspace(rn.c));  /* skip spaces */
 430   test2(&rn, "-+");  /* optional signal */
 431   if (test2(&rn, "0")) {
 432     if (test2(&rn, "xX")) hex = 1;  /* numeral is hexadecimal */
 433     else count = 1;  /* count initial '0' as a valid digit */
 434   }
 435   count += readdigits(&rn, hex);  /* integral part */
 436   if (test2(&rn, decp))  /* decimal point? */
 437     count += readdigits(&rn, hex);  /* fractional part */
 438   if (count > 0 && test2(&rn, (hex ? "pP" : "eE"))) {  /* exponent mark? */
 439     test2(&rn, "-+");  /* exponent signal */
 440     readdigits(&rn, 0);  /* exponent digits */
 441   }
 442   ungetc(rn.c, rn.f);  /* unread look-ahead char */
 443   l_unlockfile(rn.f);
 444   rn.buff[rn.n] = '\0';  /* finish string */
 445   if (lua_stringtonumber(L, rn.buff))  /* is this a valid number? */
 446     return 1;  /* ok */
 447   else {  /* invalid format */
 448    lua_pushnil(L);  /* "result" to be removed */
 449    return 0;  /* read fails */
 450   }
 451 }
 452
 453
 454 static int test_eof (lua_State *L, FILE *f) {
 455   int c = getc(f);
 456   ungetc(c, f);  /* no-op when c == EOF */
 457   lua_pushliteral(L, "");
 458   return (c != EOF);
 459 }
 460
 461
 462 static int read_line (lua_State *L, FILE *f, int chop) {
 463   luaL_Buffer b;
 464   int c = '\0';
 465   luaL_buffinit(L, &b);
 466   while (c != EOF && c != '\n') {  /* repeat until end of line */
 467     char *buff = luaL_prepbuffer(&b);  /* pre-allocate buffer */
 468     int i = 0;
 469     l_lockfile(f);  /* no memory errors can happen inside the lock */
 470     while (i < LUAL_BUFFERSIZE && (c = l_getc(f)) != EOF && c != '\n')
 471       buff[i++] = c;
 472     l_unlockfile(f);
 473     luaL_addsize(&b, i);
 474   }
 475   if (!chop && c == '\n')  /* want a newline and have one? */
 476     luaL_addchar(&b, c);  /* add ending newline to result */
 477   luaL_pushresult(&b);  /* close buffer */
 478   /* return ok if read something (either a newline or something else) */
 479   return (c == '\n' || lua_rawlen(L, -1) > 0);
 480 }
 481
 482
 483 static void read_all (lua_State *L, FILE *f) {
 484   size_t nr;
 485   luaL_Buffer b;
 486   luaL_buffinit(L, &b);
 487   do {  /* read file in chunks of LUAL_BUFFERSIZE bytes */
 488     char *p = luaL_prepbuffsize(&b, LUAL_BUFFERSIZE);
 489     nr = fread(p, sizeof(char), LUAL_BUFFERSIZE, f);
 490     luaL_addsize(&b, nr);
 491   } while (nr == LUAL_BUFFERSIZE);
 492   luaL_pushresult(&b);  /* close buffer */
 493 }
 494
 495
 496 static int read_chars (lua_State *L, FILE *f, size_t n) {
 497   size_t nr;  /* number of chars actually read */
 498   char *p;
 499   luaL_Buffer b;
 500   luaL_buffinit(L, &b);
 501   p = luaL_prepbuffsize(&b, n);  /* prepare buffer to read whole block */
 502   nr = fread(p, sizeof(char), n, f);  /* try to read 'n' chars */
 503   luaL_addsize(&b, nr);
 504   luaL_pushresult(&b);  /* close buffer */
 505   return (nr > 0);  /* true iff read something */
 506 }
 507
 508
 509 static int g_read (lua_State *L, FILE *f, int first) {
 510   int nargs = lua_gettop(L) - 1;
 511   int success;
 512   int n;
 513   clearerr(f);
 514   if (nargs == 0) {  /* no arguments? */
 515     success = read_line(L, f, 1);
 516     n = first+1;  /* to return 1 result */
 517   }
 518   else {  /* ensure stack space for all results and for auxlib's buffer */
 519     luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments");
 520     success = 1;
 521     for (n = first; nargs-- && success; n++) {
 522       if (lua_type(L, n) == LUA_TNUMBER) {
 523         size_t l = (size_t)luaL_checkinteger(L, n);
 524         success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
 525       }
 526       else {
 527         const char *p = luaL_checkstring(L, n);
 528         if (*p == '*') p++;  /* skip optional '*' (for compatibility) */
 529         switch (*p) {
 530           case 'n':  /* number */
 531             success = read_number(L, f);
 532             break;
 533           case 'l':  /* line */
 534             success = read_line(L, f, 1);
 535             break;
 536           case 'L':  /* line with end-of-line */
 537             success = read_line(L, f, 0);
 538             break;
 539           case 'a':  /* file */
 540             read_all(L, f);  /* read entire file */
 541             success = 1; /* always success */
 542             break;
 543           default:
 544             return luaL_argerror(L, n, "invalid format");
 545         }
 546       }
 547     }
 548   }
 549   if (ferror(f))
 550     return luaL_fileresult(L, 0, NULL);
 551   if (!success) {
 552     lua_pop(L, 1);  /* remove last result */
 553     lua_pushnil(L);  /* push nil instead */
 554   }
 555   return n - first;
 556 }
 557
 558
 559 static int io_read (lua_State *L) {
 560   return g_read(L, getiofile(L, IO_INPUT), 1);
 561 }
 562
 563
 564 static int f_read (lua_State *L) {
 565   return g_read(L, tofile(L), 2);
 566 }
 567
 568
 569 static int io_readline (lua_State *L) {
 570   LStream *p = (LStream *)lua_touserdata(L, lua_upvalueindex(1));
 571   int i;
 572   int n = (int)lua_tointeger(L, lua_upvalueindex(2));
 573   if (isclosed(p))  /* file is already closed? */
 574     return luaL_error(L, "file is already closed");
 575   lua_settop(L , 1);
 576   luaL_checkstack(L, n, "too many arguments");
 577   for (i = 1; i <= n; i++)  /* push arguments to 'g_read' */
 578     lua_pushvalue(L, lua_upvalueindex(3 + i));
 579   n = g_read(L, p->f, 2);  /* 'n' is number of results */
 580   lua_assert(n > 0);  /* should return at least a nil */
 581   if (lua_toboolean(L, -n))  /* read at least one value? */
 582     return n;  /* return them */
 583   else {  /* first result is nil: EOF or error */
 584     if (n > 1) {  /* is there error information? */
 585       /* 2nd result is error message */
 586       return luaL_error(L, "%s", lua_tostring(L, -n + 1));
 587     }
 588     if (lua_toboolean(L, lua_upvalueindex(3))) {  /* generator created file? */
 589       lua_settop(L, 0);
 590       lua_pushvalue(L, lua_upvalueindex(1));
 591       aux_close(L);  /* close it */
 592     }
 593     return 0;
 594   }
 595 }
 596
 597 /* }====================================================== */
 598
 599
 600 static int g_write (lua_State *L, FILE *f, int arg) {
 601   int nargs = lua_gettop(L) - arg;
 602   int status = 1;
 603   for (; nargs--; arg++) {
 604     if (lua_type(L, arg) == LUA_TNUMBER) {
 605       /* optimization: could be done exactly as for strings */
 606       int len = lua_isinteger(L, arg)
 607                 ? fprintf(f, LUA_INTEGER_FMT, lua_tointeger(L, arg))
 608                 : fprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg));
 609       status = status && (len > 0);
 610     }
 611     else {
 612       size_t l;
 613       const char *s = luaL_checklstring(L, arg, &l);
 614       status = status && (fwrite(s, sizeof(char), l, f) == l);
 615     }
 616   }
 617   if (status) return 1;  /* file handle already on stack top */
 618   else return luaL_fileresult(L, status, NULL);
 619 }
 620
 621
 622 static int io_write (lua_State *L) {
 623   return g_write(L, getiofile(L, IO_OUTPUT), 1);
 624 }
 625
 626
 627 static int f_write (lua_State *L) {
 628   FILE *f = tofile(L);
 629   lua_pushvalue(L, 1);  /* push file at the stack top (to be returned) */
 630   return g_write(L, f, 2);
 631 }
 632
 633
 634 static int f_seek (lua_State *L) {
 635   static const int mode[] = {SEEK_SET, SEEK_CUR, SEEK_END};
 636   static const char *const modenames[] = {"set", "cur", "end", NULL};
 637   FILE *f = tofile(L);
 638   int op = luaL_checkoption(L, 2, "cur", modenames);
 639   lua_Integer p3 = luaL_optinteger(L, 3, 0);
 640   l_seeknum offset = (l_seeknum)p3;
 641   luaL_argcheck(L, (lua_Integer)offset == p3, 3,
 642                   "not an integer in proper range");
 643   op = l_fseek(f, offset, mode[op]);
 644   if (op)
 645     return luaL_fileresult(L, 0, NULL);  /* error */
 646   else {
 647     lua_pushinteger(L, (lua_Integer)l_ftell(f));
 648     return 1;
 649   }
 650 }
 651
 652
 653 static int f_setvbuf (lua_State *L) {
 654   static const int mode[] = {_IONBF, _IOFBF, _IOLBF};
 655   static const char *const modenames[] = {"no", "full", "line", NULL};
 656   FILE *f = tofile(L);
 657   int op = luaL_checkoption(L, 2, NULL, modenames);
 658   lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE);
 659   int res = setvbuf(f, NULL, mode[op], (size_t)sz);
 660   return luaL_fileresult(L, res == 0, NULL);
 661 }
 662
 663
 664
 665 static int io_flush (lua_State *L) {
 666   return luaL_fileresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL);
 667 }
 668
 669
 670 static int f_flush (lua_State *L) {
 671   return luaL_fileresult(L, fflush(tofile(L)) == 0, NULL);
 672 }
 673
 674
 675 /*
 676 ** functions for 'io' library
 677 */
 678 static const luaL_Reg iolib[] = {
 679   {"close", io_close},
 680   {"flush", io_flush},
 681   {"input", io_input},
 682   {"lines", io_lines},
 683   {"open", io_open},
 684   {"output", io_output},
 685   {"popen", io_popen},
 686   {"read", io_read},
 687   {"tmpfile", io_tmpfile},
 688   {"type", io_type},
 689   {"write", io_write},
 690   {NULL, NULL}
 691 };
 692
 693
 694 /*
 695 ** methods for file handles
 696 */
 697 static const luaL_Reg flib[] = {
 698   {"close", io_close},
 699   {"flush", f_flush},
 700   {"lines", f_lines},
 701   {"read", f_read},
 702   {"seek", f_seek},
 703   {"setvbuf", f_setvbuf},
 704   {"write", f_write},
 705   {"__gc", f_gc},
 706   {"__tostring", f_tostring},
 707   {NULL, NULL}
 708 };
 709
 710
 711 static void createmeta (lua_State *L) {
 712   luaL_newmetatable(L, LUA_FILEHANDLE);  /* create metatable for file handles */
 713   lua_pushvalue(L, -1);  /* push metatable */
 714   lua_setfield(L, -2, "__index");  /* metatable.__index = metatable */
 715   luaL_setfuncs(L, flib, 0);  /* add file methods to new metatable */
 716   lua_pop(L, 1);  /* pop new metatable */
 717 }
 718
 719
 720 /*
 721 ** function to (not) close the standard files stdin, stdout, and stderr
 722 */
 723 static int io_noclose (lua_State *L) {
 724   LStream *p = tolstream(L);
 725   p->closef = &io_noclose;  /* keep file opened */
 726   lua_pushnil(L);
 727   lua_pushliteral(L, "cannot close standard file");
 728   return 2;
 729 }
 730
 731
 732 static void createstdfile (lua_State *L, FILE *f, const char *k,
 733                            const char *fname) {
 734   LStream *p = newprefile(L);
 735   p->f = f;
 736   p->closef = &io_noclose;
 737   if (k != NULL) {
 738     lua_pushvalue(L, -1);
 739     lua_setfield(L, LUA_REGISTRYINDEX, k);  /* add file to registry */
 740   }
 741   lua_setfield(L, -2, fname);  /* add file to module */
 742 }
 743
 744
 745 LUAMOD_API int luaopen_io (lua_State *L) {
 746   luaL_newlib(L, iolib);  /* new module */
 747   createmeta(L);
 748   /* create (and set) default files */
 749   createstdfile(L, stdin, IO_INPUT, "stdin");
 750   createstdfile(L, stdout, IO_OUTPUT, "stdout");
 751   createstdfile(L, stderr, NULL, "stderr");
 752   return 1;
 753 }
 754