1 /* $NetBSD: liolib.c,v 1.5 2016/01/28 14:41:39 lneto Exp $ */ 2 3 /* 4 ** Id: liolib.c,v 2.148 2015/11/23 11:36:11 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 29 30 /* 31 ** Change this macro to accept other modes for 'fopen' besides 32 ** the standard ones. 33 */ 34 #if !defined(l_checkmode) 35 36 /* accepted extensions to 'mode' in 'fopen' */ 37 #if !defined(L_MODEEXT) 38 #define L_MODEEXT "b" 39 #endif 40 41 /* Check whether 'mode' matches '[rwa]%+?[L_MODEEXT]*' */ 42 #define l_checkmode(mode) \ 43 (*mode != '\0' && strchr("rwa", *(mode++)) != NULL && \ 44 (*mode != '+' || (++mode, 1)) && /* skip if char is '+' */ \ 45 (strspn(mode, L_MODEEXT) == strlen(mode))) 46 47 #endif 48 49 /* 50 ** {====================================================== 51 ** l_popen spawns a new process connected to the current 52 ** one through the file streams. 53 ** ======================================================= 54 */ 55 56 #if !defined(l_popen) /* { */ 57 58 #if defined(LUA_USE_POSIX) /* { */ 59 60 #define l_popen(L,c,m) (fflush(NULL), popen(c,m)) 61 #define l_pclose(L,file) (pclose(file)) 62 63 #elif defined(LUA_USE_WINDOWS) /* }{ */ 64 65 #define l_popen(L,c,m) (_popen(c,m)) 66 #define l_pclose(L,file) (_pclose(file)) 67 68 #else /* }{ */ 69 70 /* ISO C definitions */ 71 #define l_popen(L,c,m) \ 72 ((void)((void)c, m), \ 73 luaL_error(L, "'popen' not supported"), \ 74 (FILE*)0) 75 #define l_pclose(L,file) ((void)L, (void)file, -1) 76 77 #endif /* } */ 78 79 #endif /* } */ 80 81 /* }====================================================== */ 82 83 84 #if !defined(l_getc) /* { */ 85 86 #if defined(LUA_USE_POSIX) 87 #define l_getc(f) getc_unlocked(f) 88 #define l_lockfile(f) flockfile(f) 89 #define l_unlockfile(f) funlockfile(f) 90 #else 91 #define l_getc(f) getc(f) 92 #define l_lockfile(f) ((void)0) 93 #define l_unlockfile(f) ((void)0) 94 #endif 95 96 #endif /* } */ 97 98 99 /* 100 ** {====================================================== 101 ** l_fseek: configuration for longer offsets 102 ** ======================================================= 103 */ 104 105 #if !defined(l_fseek) /* { */ 106 107 #if defined(LUA_USE_POSIX) /* { */ 108 109 #include <sys/types.h> 110 111 #define l_fseek(f,o,w) fseeko(f,o,w) 112 #define l_ftell(f) ftello(f) 113 #define l_seeknum off_t 114 115 #elif defined(LUA_USE_WINDOWS) && !defined(_CRTIMP_TYPEINFO) \ 116 && defined(_MSC_VER) && (_MSC_VER >= 1400) /* }{ */ 117 118 /* Windows (but not DDK) and Visual C++ 2005 or higher */ 119 #define l_fseek(f,o,w) _fseeki64(f,o,w) 120 #define l_ftell(f) _ftelli64(f) 121 #define l_seeknum __int64 122 123 #else /* }{ */ 124 125 /* ISO C definitions */ 126 #define l_fseek(f,o,w) fseek(f,o,w) 127 #define l_ftell(f) ftell(f) 128 #define l_seeknum long 129 130 #endif /* } */ 131 132 #endif /* } */ 133 134 /* }====================================================== */ 135 136 137 #define IO_PREFIX "_IO_" 138 #define IOPREF_LEN (sizeof(IO_PREFIX)/sizeof(char) - 1) 139 #define IO_INPUT (IO_PREFIX "input") 140 #define IO_OUTPUT (IO_PREFIX "output") 141 142 143 typedef luaL_Stream LStream; 144 145 146 #define tolstream(L) ((LStream *)luaL_checkudata(L, 1, LUA_FILEHANDLE)) 147 148 #define isclosed(p) ((p)->closef == NULL) 149 150 151 static int io_type (lua_State *L) { 152 LStream *p; 153 luaL_checkany(L, 1); 154 p = (LStream *)luaL_testudata(L, 1, LUA_FILEHANDLE); 155 if (p == NULL) 156 lua_pushnil(L); /* not a file */ 157 else if (isclosed(p)) 158 lua_pushliteral(L, "closed file"); 159 else 160 lua_pushliteral(L, "file"); 161 return 1; 162 } 163 164 165 static int f_tostring (lua_State *L) { 166 LStream *p = tolstream(L); 167 if (isclosed(p)) 168 lua_pushliteral(L, "file (closed)"); 169 else 170 lua_pushfstring(L, "file (%p)", p->f); 171 return 1; 172 } 173 174 175 static FILE *tofile (lua_State *L) { 176 LStream *p = tolstream(L); 177 if (isclosed(p)) 178 luaL_error(L, "attempt to use a closed file"); 179 lua_assert(p->f); 180 return p->f; 181 } 182 183 184 /* 185 ** When creating file handles, always creates a 'closed' file handle 186 ** before opening the actual file; so, if there is a memory error, the 187 ** handle is in a consistent state. 188 */ 189 static LStream *newprefile (lua_State *L) { 190 LStream *p = (LStream *)lua_newuserdata(L, sizeof(LStream)); 191 p->closef = NULL; /* mark file handle as 'closed' */ 192 luaL_setmetatable(L, LUA_FILEHANDLE); 193 return p; 194 } 195 196 197 /* 198 ** Calls the 'close' function from a file handle. The 'volatile' avoids 199 ** a bug in some versions of the Clang compiler (e.g., clang 3.0 for 200 ** 32 bits). 201 */ 202 static int aux_close (lua_State *L) { 203 LStream *p = tolstream(L); 204 volatile lua_CFunction cf = p->closef; 205 p->closef = NULL; /* mark stream as closed */ 206 return (*cf)(L); /* close it */ 207 } 208 209 210 static int io_close (lua_State *L) { 211 if (lua_isnone(L, 1)) /* no argument? */ 212 lua_getfield(L, LUA_REGISTRYINDEX, IO_OUTPUT); /* use standard output */ 213 tofile(L); /* make sure argument is an open stream */ 214 return aux_close(L); 215 } 216 217 218 static int f_gc (lua_State *L) { 219 LStream *p = tolstream(L); 220 if (!isclosed(p) && p->f != NULL) 221 aux_close(L); /* ignore closed and incompletely open files */ 222 return 0; 223 } 224 225 226 /* 227 ** function to close regular files 228 */ 229 static int io_fclose (lua_State *L) { 230 LStream *p = tolstream(L); 231 int res = fclose(p->f); 232 return luaL_fileresult(L, (res == 0), NULL); 233 } 234 235 236 static LStream *newfile (lua_State *L) { 237 LStream *p = newprefile(L); 238 p->f = NULL; 239 p->closef = &io_fclose; 240 return p; 241 } 242 243 244 static void opencheck (lua_State *L, const char *fname, const char *mode) { 245 LStream *p = newfile(L); 246 p->f = fopen(fname, mode); 247 if (p->f == NULL) 248 luaL_error(L, "cannot open file '%s' (%s)", fname, strerror(errno)); 249 } 250 251 252 static int io_open (lua_State *L) { 253 const char *filename = luaL_checkstring(L, 1); 254 const char *mode = luaL_optstring(L, 2, "r"); 255 LStream *p = newfile(L); 256 const char *md = mode; /* to traverse/check mode */ 257 luaL_argcheck(L, l_checkmode(md), 2, "invalid mode"); 258 p->f = fopen(filename, mode); 259 return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1; 260 } 261 262 263 /* 264 ** function to close 'popen' files 265 */ 266 static int io_pclose (lua_State *L) { 267 LStream *p = tolstream(L); 268 return luaL_execresult(L, l_pclose(L, p->f)); 269 } 270 271 272 static int io_popen (lua_State *L) { 273 const char *filename = luaL_checkstring(L, 1); 274 const char *mode = luaL_optstring(L, 2, "r"); 275 LStream *p = newprefile(L); 276 p->f = l_popen(L, filename, mode); 277 p->closef = &io_pclose; 278 return (p->f == NULL) ? luaL_fileresult(L, 0, filename) : 1; 279 } 280 281 282 static int io_tmpfile (lua_State *L) { 283 LStream *p = newfile(L); 284 p->f = tmpfile(); 285 return (p->f == NULL) ? luaL_fileresult(L, 0, NULL) : 1; 286 } 287 288 289 static FILE *getiofile (lua_State *L, const char *findex) { 290 LStream *p; 291 lua_getfield(L, LUA_REGISTRYINDEX, findex); 292 p = (LStream *)lua_touserdata(L, -1); 293 if (isclosed(p)) 294 luaL_error(L, "standard %s file is closed", findex + IOPREF_LEN); 295 return p->f; 296 } 297 298 299 static int g_iofile (lua_State *L, const char *f, const char *mode) { 300 if (!lua_isnoneornil(L, 1)) { 301 const char *filename = lua_tostring(L, 1); 302 if (filename) 303 opencheck(L, filename, mode); 304 else { 305 tofile(L); /* check that it's a valid file handle */ 306 lua_pushvalue(L, 1); 307 } 308 lua_setfield(L, LUA_REGISTRYINDEX, f); 309 } 310 /* return current value */ 311 lua_getfield(L, LUA_REGISTRYINDEX, f); 312 return 1; 313 } 314 315 316 static int io_input (lua_State *L) { 317 return g_iofile(L, IO_INPUT, "r"); 318 } 319 320 321 static int io_output (lua_State *L) { 322 return g_iofile(L, IO_OUTPUT, "w"); 323 } 324 325 326 static int io_readline (lua_State *L); 327 328 329 /* 330 ** maximum number of arguments to 'f:lines'/'io.lines' (it + 3 must fit 331 ** in the limit for upvalues of a closure) 332 */ 333 #define MAXARGLINE 250 334 335 static void aux_lines (lua_State *L, int toclose) { 336 int n = lua_gettop(L) - 1; /* number of arguments to read */ 337 luaL_argcheck(L, n <= MAXARGLINE, MAXARGLINE + 2, "too many arguments"); 338 lua_pushinteger(L, n); /* number of arguments to read */ 339 lua_pushboolean(L, toclose); /* close/not close file when finished */ 340 lua_rotate(L, 2, 2); /* move 'n' and 'toclose' to their positions */ 341 lua_pushcclosure(L, io_readline, 3 + n); 342 } 343 344 345 static int f_lines (lua_State *L) { 346 tofile(L); /* check that it's a valid file handle */ 347 aux_lines(L, 0); 348 return 1; 349 } 350 351 352 static int io_lines (lua_State *L) { 353 int toclose; 354 if (lua_isnone(L, 1)) lua_pushnil(L); /* at least one argument */ 355 if (lua_isnil(L, 1)) { /* no file name? */ 356 lua_getfield(L, LUA_REGISTRYINDEX, IO_INPUT); /* get default input */ 357 lua_replace(L, 1); /* put it at index 1 */ 358 tofile(L); /* check that it's a valid file handle */ 359 toclose = 0; /* do not close it after iteration */ 360 } 361 else { /* open a new file */ 362 const char *filename = luaL_checkstring(L, 1); 363 opencheck(L, filename, "r"); 364 lua_replace(L, 1); /* put file at index 1 */ 365 toclose = 1; /* close it after iteration */ 366 } 367 aux_lines(L, toclose); 368 return 1; 369 } 370 371 372 /* 373 ** {====================================================== 374 ** READ 375 ** ======================================================= 376 */ 377 378 379 /* maximum length of a numeral */ 380 #define MAXRN 200 381 382 /* auxiliary structure used by 'read_number' */ 383 typedef struct { 384 FILE *f; /* file being read */ 385 int c; /* current character (look ahead) */ 386 int n; /* number of elements in buffer 'buff' */ 387 char buff[MAXRN + 1]; /* +1 for ending '\0' */ 388 } RN; 389 390 391 /* 392 ** Add current char to buffer (if not out of space) and read next one 393 */ 394 static int nextc (RN *rn) { 395 if (rn->n >= MAXRN) { /* buffer overflow? */ 396 rn->buff[0] = '\0'; /* invalidate result */ 397 return 0; /* fail */ 398 } 399 else { 400 rn->buff[rn->n++] = rn->c; /* save current char */ 401 rn->c = l_getc(rn->f); /* read next one */ 402 return 1; 403 } 404 } 405 406 407 /* 408 ** Accept current char if it is in 'set' (of size 1 or 2) 409 */ 410 static int test2 (RN *rn, const char *set) { 411 if (rn->c == set[0] || (rn->c == set[1] && rn->c != '\0')) 412 return nextc(rn); 413 else return 0; 414 } 415 416 417 /* 418 ** Read a sequence of (hex)digits 419 */ 420 static int readdigits (RN *rn, int hex) { 421 int count = 0; 422 while ((hex ? isxdigit(rn->c) : isdigit(rn->c)) && nextc(rn)) 423 count++; 424 return count; 425 } 426 427 428 /* 429 ** Read a number: first reads a valid prefix of a numeral into a buffer. 430 ** Then it calls 'lua_stringtonumber' to check whether the format is 431 ** correct and to convert it to a Lua number 432 */ 433 static int read_number (lua_State *L, FILE *f) { 434 RN rn; 435 int count = 0; 436 int hex = 0; 437 char decp[2]; 438 rn.f = f; rn.n = 0; 439 decp[0] = lua_getlocaledecpoint(); /* get decimal point from locale */ 440 decp[1] = '\0'; 441 l_lockfile(rn.f); 442 do { rn.c = l_getc(rn.f); } while (isspace(rn.c)); /* skip spaces */ 443 test2(&rn, "-+"); /* optional signal */ 444 if (test2(&rn, "0")) { 445 if (test2(&rn, "xX")) hex = 1; /* numeral is hexadecimal */ 446 else count = 1; /* count initial '0' as a valid digit */ 447 } 448 count += readdigits(&rn, hex); /* integral part */ 449 if (test2(&rn, decp)) /* decimal point? */ 450 count += readdigits(&rn, hex); /* fractional part */ 451 if (count > 0 && test2(&rn, (hex ? "pP" : "eE"))) { /* exponent mark? */ 452 test2(&rn, "-+"); /* exponent signal */ 453 readdigits(&rn, 0); /* exponent digits */ 454 } 455 ungetc(rn.c, rn.f); /* unread look-ahead char */ 456 l_unlockfile(rn.f); 457 rn.buff[rn.n] = '\0'; /* finish string */ 458 if (lua_stringtonumber(L, rn.buff)) /* is this a valid number? */ 459 return 1; /* ok */ 460 else { /* invalid format */ 461 lua_pushnil(L); /* "result" to be removed */ 462 return 0; /* read fails */ 463 } 464 } 465 466 467 static int test_eof (lua_State *L, FILE *f) { 468 int c = getc(f); 469 ungetc(c, f); /* no-op when c == EOF */ 470 lua_pushliteral(L, ""); 471 return (c != EOF); 472 } 473 474 475 static int read_line (lua_State *L, FILE *f, int chop) { 476 luaL_Buffer b; 477 int c = '\0'; 478 luaL_buffinit(L, &b); 479 while (c != EOF && c != '\n') { /* repeat until end of line */ 480 char *buff = luaL_prepbuffer(&b); /* preallocate buffer */ 481 int i = 0; 482 l_lockfile(f); /* no memory errors can happen inside the lock */ 483 while (i < LUAL_BUFFERSIZE && (c = l_getc(f)) != EOF && c != '\n') 484 buff[i++] = c; 485 l_unlockfile(f); 486 luaL_addsize(&b, i); 487 } 488 if (!chop && c == '\n') /* want a newline and have one? */ 489 luaL_addchar(&b, c); /* add ending newline to result */ 490 luaL_pushresult(&b); /* close buffer */ 491 /* return ok if read something (either a newline or something else) */ 492 return (c == '\n' || lua_rawlen(L, -1) > 0); 493 } 494 495 496 static void read_all (lua_State *L, FILE *f) { 497 size_t nr; 498 luaL_Buffer b; 499 luaL_buffinit(L, &b); 500 do { /* read file in chunks of LUAL_BUFFERSIZE bytes */ 501 char *p = luaL_prepbuffer(&b); 502 nr = fread(p, sizeof(char), LUAL_BUFFERSIZE, f); 503 luaL_addsize(&b, nr); 504 } while (nr == LUAL_BUFFERSIZE); 505 luaL_pushresult(&b); /* close buffer */ 506 } 507 508 509 static int read_chars (lua_State *L, FILE *f, size_t n) { 510 size_t nr; /* number of chars actually read */ 511 char *p; 512 luaL_Buffer b; 513 luaL_buffinit(L, &b); 514 p = luaL_prepbuffsize(&b, n); /* prepare buffer to read whole block */ 515 nr = fread(p, sizeof(char), n, f); /* try to read 'n' chars */ 516 luaL_addsize(&b, nr); 517 luaL_pushresult(&b); /* close buffer */ 518 return (nr > 0); /* true iff read something */ 519 } 520 521 522 static int g_read (lua_State *L, FILE *f, int first) { 523 int nargs = lua_gettop(L) - 1; 524 int success; 525 int n; 526 clearerr(f); 527 if (nargs == 0) { /* no arguments? */ 528 success = read_line(L, f, 1); 529 n = first+1; /* to return 1 result */ 530 } 531 else { /* ensure stack space for all results and for auxlib's buffer */ 532 luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments"); 533 success = 1; 534 for (n = first; nargs-- && success; n++) { 535 if (lua_type(L, n) == LUA_TNUMBER) { 536 size_t l = (size_t)luaL_checkinteger(L, n); 537 success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l); 538 } 539 else { 540 const char *p = luaL_checkstring(L, n); 541 if (*p == '*') p++; /* skip optional '*' (for compatibility) */ 542 switch (*p) { 543 case 'n': /* number */ 544 success = read_number(L, f); 545 break; 546 case 'l': /* line */ 547 success = read_line(L, f, 1); 548 break; 549 case 'L': /* line with end-of-line */ 550 success = read_line(L, f, 0); 551 break; 552 case 'a': /* file */ 553 read_all(L, f); /* read entire file */ 554 success = 1; /* always success */ 555 break; 556 default: 557 return luaL_argerror(L, n, "invalid format"); 558 } 559 } 560 } 561 } 562 if (ferror(f)) 563 return luaL_fileresult(L, 0, NULL); 564 if (!success) { 565 lua_pop(L, 1); /* remove last result */ 566 lua_pushnil(L); /* push nil instead */ 567 } 568 return n - first; 569 } 570 571 572 static int io_read (lua_State *L) { 573 return g_read(L, getiofile(L, IO_INPUT), 1); 574 } 575 576 577 static int f_read (lua_State *L) { 578 return g_read(L, tofile(L), 2); 579 } 580 581 582 static int io_readline (lua_State *L) { 583 LStream *p = (LStream *)lua_touserdata(L, lua_upvalueindex(1)); 584 int i; 585 int n = (int)lua_tointeger(L, lua_upvalueindex(2)); 586 if (isclosed(p)) /* file is already closed? */ 587 return luaL_error(L, "file is already closed"); 588 lua_settop(L , 1); 589 luaL_checkstack(L, n, "too many arguments"); 590 for (i = 1; i <= n; i++) /* push arguments to 'g_read' */ 591 lua_pushvalue(L, lua_upvalueindex(3 + i)); 592 n = g_read(L, p->f, 2); /* 'n' is number of results */ 593 lua_assert(n > 0); /* should return at least a nil */ 594 if (lua_toboolean(L, -n)) /* read at least one value? */ 595 return n; /* return them */ 596 else { /* first result is nil: EOF or error */ 597 if (n > 1) { /* is there error information? */ 598 /* 2nd result is error message */ 599 return luaL_error(L, "%s", lua_tostring(L, -n + 1)); 600 } 601 if (lua_toboolean(L, lua_upvalueindex(3))) { /* generator created file? */ 602 lua_settop(L, 0); 603 lua_pushvalue(L, lua_upvalueindex(1)); 604 aux_close(L); /* close it */ 605 } 606 return 0; 607 } 608 } 609 610 /* }====================================================== */ 611 612 613 static int g_write (lua_State *L, FILE *f, int arg) { 614 int nargs = lua_gettop(L) - arg; 615 int status = 1; 616 for (; nargs--; arg++) { 617 if (lua_type(L, arg) == LUA_TNUMBER) { 618 /* optimization: could be done exactly as for strings */ 619 int len = lua_isinteger(L, arg) 620 ? fprintf(f, LUA_INTEGER_FMT, lua_tointeger(L, arg)) 621 : fprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg)); 622 status = status && (len > 0); 623 } 624 else { 625 size_t l; 626 const char *s = luaL_checklstring(L, arg, &l); 627 status = status && (fwrite(s, sizeof(char), l, f) == l); 628 } 629 } 630 if (status) return 1; /* file handle already on stack top */ 631 else return luaL_fileresult(L, status, NULL); 632 } 633 634 635 static int io_write (lua_State *L) { 636 return g_write(L, getiofile(L, IO_OUTPUT), 1); 637 } 638 639 640 static int f_write (lua_State *L) { 641 FILE *f = tofile(L); 642 lua_pushvalue(L, 1); /* push file at the stack top (to be returned) */ 643 return g_write(L, f, 2); 644 } 645 646 647 static int f_seek (lua_State *L) { 648 static const int mode[] = {SEEK_SET, SEEK_CUR, SEEK_END}; 649 static const char *const modenames[] = {"set", "cur", "end", NULL}; 650 FILE *f = tofile(L); 651 int op = luaL_checkoption(L, 2, "cur", modenames); 652 lua_Integer p3 = luaL_optinteger(L, 3, 0); 653 l_seeknum offset = (l_seeknum)p3; 654 luaL_argcheck(L, (lua_Integer)offset == p3, 3, 655 "not an integer in proper range"); 656 op = l_fseek(f, offset, mode[op]); 657 if (op) 658 return luaL_fileresult(L, 0, NULL); /* error */ 659 else { 660 lua_pushinteger(L, (lua_Integer)l_ftell(f)); 661 return 1; 662 } 663 } 664 665 666 static int f_setvbuf (lua_State *L) { 667 static const int mode[] = {_IONBF, _IOFBF, _IOLBF}; 668 static const char *const modenames[] = {"no", "full", "line", NULL}; 669 FILE *f = tofile(L); 670 int op = luaL_checkoption(L, 2, NULL, modenames); 671 lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE); 672 int res = setvbuf(f, NULL, mode[op], (size_t)sz); 673 return luaL_fileresult(L, res == 0, NULL); 674 } 675 676 677 678 static int io_flush (lua_State *L) { 679 return luaL_fileresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL); 680 } 681 682 683 static int f_flush (lua_State *L) { 684 return luaL_fileresult(L, fflush(tofile(L)) == 0, NULL); 685 } 686 687 688 /* 689 ** functions for 'io' library 690 */ 691 static const luaL_Reg iolib[] = { 692 {"close", io_close}, 693 {"flush", io_flush}, 694 {"input", io_input}, 695 {"lines", io_lines}, 696 {"open", io_open}, 697 {"output", io_output}, 698 {"popen", io_popen}, 699 {"read", io_read}, 700 {"tmpfile", io_tmpfile}, 701 {"type", io_type}, 702 {"write", io_write}, 703 {NULL, NULL} 704 }; 705 706 707 /* 708 ** methods for file handles 709 */ 710 static const luaL_Reg flib[] = { 711 {"close", io_close}, 712 {"flush", f_flush}, 713 {"lines", f_lines}, 714 {"read", f_read}, 715 {"seek", f_seek}, 716 {"setvbuf", f_setvbuf}, 717 {"write", f_write}, 718 {"__gc", f_gc}, 719 {"__tostring", f_tostring}, 720 {NULL, NULL} 721 }; 722 723 724 static void createmeta (lua_State *L) { 725 luaL_newmetatable(L, LUA_FILEHANDLE); /* create metatable for file handles */ 726 lua_pushvalue(L, -1); /* push metatable */ 727 lua_setfield(L, -2, "__index"); /* metatable.__index = metatable */ 728 luaL_setfuncs(L, flib, 0); /* add file methods to new metatable */ 729 lua_pop(L, 1); /* pop new metatable */ 730 } 731 732 733 /* 734 ** function to (not) close the standard files stdin, stdout, and stderr 735 */ 736 static int io_noclose (lua_State *L) { 737 LStream *p = tolstream(L); 738 p->closef = &io_noclose; /* keep file opened */ 739 lua_pushnil(L); 740 lua_pushliteral(L, "cannot close standard file"); 741 return 2; 742 } 743 744 745 static void createstdfile (lua_State *L, FILE *f, const char *k, 746 const char *fname) { 747 LStream *p = newprefile(L); 748 p->f = f; 749 p->closef = &io_noclose; 750 if (k != NULL) { 751 lua_pushvalue(L, -1); 752 lua_setfield(L, LUA_REGISTRYINDEX, k); /* add file to registry */ 753 } 754 lua_setfield(L, -2, fname); /* add file to module */ 755 } 756 757 758 LUAMOD_API int luaopen_io (lua_State *L) { 759 luaL_newlib(L, iolib); /* new module */ 760 createmeta(L); 761 /* create (and set) default files */ 762 createstdfile(L, stdin, IO_INPUT, "stdin"); 763 createstdfile(L, stdout, IO_OUTPUT, "stdout"); 764 createstdfile(L, stderr, NULL, "stderr"); 765 return 1; 766 } 767 768