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 } 754 755