1 /* $NetBSD: lua.c,v 1.12 2023/06/08 21:12:08 nikita Exp $ */ 2 3 /* 4 ** Id: lua.c 5 ** Lua stand-alone interpreter 6 ** See Copyright Notice in lua.h 7 */ 8 9 #define lua_c 10 11 #include "lprefix.h" 12 13 14 #include <stdio.h> 15 #include <stdlib.h> 16 #include <string.h> 17 18 #include <signal.h> 19 20 #include "lua.h" 21 22 #include "lauxlib.h" 23 #include "lualib.h" 24 25 26 #if !defined(LUA_PROGNAME) 27 #define LUA_PROGNAME "lua" 28 #endif 29 30 #if !defined(LUA_INIT_VAR) 31 #define LUA_INIT_VAR "LUA_INIT" 32 #endif 33 34 #define LUA_INITVARVERSION LUA_INIT_VAR LUA_VERSUFFIX 35 36 37 static lua_State *globalL = NULL; 38 39 static const char *progname = LUA_PROGNAME; 40 41 42 #if defined(LUA_USE_POSIX) /* { */ 43 44 /* 45 ** Use 'sigaction' when available. 46 */ 47 static void setsignal (int sig, void (*handler)(int)) { 48 struct sigaction sa; 49 sa.sa_handler = handler; 50 sa.sa_flags = 0; 51 sigemptyset(&sa.sa_mask); /* do not mask any signal */ 52 sigaction(sig, &sa, NULL); 53 } 54 55 #else /* }{ */ 56 57 #define setsignal signal 58 59 #endif /* } */ 60 61 62 /* 63 ** Hook set by signal function to stop the interpreter. 64 */ 65 static void lstop (lua_State *L, lua_Debug *ar) { 66 (void)ar; /* unused arg. */ 67 lua_sethook(L, NULL, 0, 0); /* reset hook */ 68 luaL_error(L, "interrupted!"); 69 } 70 71 72 /* 73 ** Function to be called at a C signal. Because a C signal cannot 74 ** just change a Lua state (as there is no proper synchronization), 75 ** this function only sets a hook that, when called, will stop the 76 ** interpreter. 77 */ 78 static void laction (int i) { 79 int flag = LUA_MASKCALL | LUA_MASKRET | LUA_MASKLINE | LUA_MASKCOUNT; 80 setsignal(i, SIG_DFL); /* if another SIGINT happens, terminate process */ 81 lua_sethook(globalL, lstop, flag, 1); 82 } 83 84 85 static void print_usage (const char *badoption) { 86 lua_writestringerror("%s: ", progname); 87 if (badoption[1] == 'e' || badoption[1] == 'l') 88 lua_writestringerror("'%s' needs argument\n", badoption); 89 else 90 lua_writestringerror("unrecognized option '%s'\n", badoption); 91 lua_writestringerror( 92 "usage: %s [options] [script [args]]\n" 93 "Available options are:\n" 94 " -e stat execute string 'stat'\n" 95 " -i enter interactive mode after executing 'script'\n" 96 " -l mod require library 'mod' into global 'mod'\n" 97 " -l g=mod require library 'mod' into global 'g'\n" 98 " -v show version information\n" 99 " -E ignore environment variables\n" 100 " -W turn warnings on\n" 101 " -- stop handling options\n" 102 " - stop handling options and execute stdin\n" 103 , 104 progname); 105 } 106 107 108 /* 109 ** Prints an error message, adding the program name in front of it 110 ** (if present) 111 */ 112 static void l_message (const char *pname, const char *msg) { 113 if (pname) lua_writestringerror("%s: ", pname); 114 lua_writestringerror("%s\n", msg); 115 } 116 117 118 /* 119 ** Check whether 'status' is not OK and, if so, prints the error 120 ** message on the top of the stack. It assumes that the error object 121 ** is a string, as it was either generated by Lua or by 'msghandler'. 122 */ 123 static int report (lua_State *L, int status) { 124 if (status != LUA_OK) { 125 const char *msg = lua_tostring(L, -1); 126 l_message(progname, msg); 127 lua_pop(L, 1); /* remove message */ 128 } 129 return status; 130 } 131 132 133 /* 134 ** Message handler used to run all chunks 135 */ 136 static int msghandler (lua_State *L) { 137 const char *msg = lua_tostring(L, 1); 138 if (msg == NULL) { /* is error object not a string? */ 139 if (luaL_callmeta(L, 1, "__tostring") && /* does it have a metamethod */ 140 lua_type(L, -1) == LUA_TSTRING) /* that produces a string? */ 141 return 1; /* that is the message */ 142 else 143 msg = lua_pushfstring(L, "(error object is a %s value)", 144 luaL_typename(L, 1)); 145 } 146 luaL_traceback(L, L, msg, 1); /* append a standard traceback */ 147 return 1; /* return the traceback */ 148 } 149 150 151 /* 152 ** Interface to 'lua_pcall', which sets appropriate message function 153 ** and C-signal handler. Used to run all chunks. 154 */ 155 static int docall (lua_State *L, int narg, int nres) { 156 int status; 157 int base = lua_gettop(L) - narg; /* function index */ 158 lua_pushcfunction(L, msghandler); /* push message handler */ 159 lua_insert(L, base); /* put it under function and args */ 160 globalL = L; /* to be available to 'laction' */ 161 setsignal(SIGINT, laction); /* set C-signal handler */ 162 status = lua_pcall(L, narg, nres, base); 163 setsignal(SIGINT, SIG_DFL); /* reset C-signal handler */ 164 lua_remove(L, base); /* remove message handler from the stack */ 165 return status; 166 } 167 168 169 static void print_version (void) { 170 lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT)); 171 lua_writeline(); 172 } 173 174 175 /* 176 ** Create the 'arg' table, which stores all arguments from the 177 ** command line ('argv'). It should be aligned so that, at index 0, 178 ** it has 'argv[script]', which is the script name. The arguments 179 ** to the script (everything after 'script') go to positive indices; 180 ** other arguments (before the script name) go to negative indices. 181 ** If there is no script name, assume interpreter's name as base. 182 ** (If there is no interpreter's name either, 'script' is -1, so 183 ** table sizes are zero.) 184 */ 185 static void createargtable (lua_State *L, char **argv, int argc, int script) { 186 int i, narg; 187 narg = argc - (script + 1); /* number of positive indices */ 188 lua_createtable(L, narg, script + 1); 189 for (i = 0; i < argc; i++) { 190 lua_pushstring(L, argv[i]); 191 lua_rawseti(L, -2, i - script); 192 } 193 lua_setglobal(L, "arg"); 194 } 195 196 197 static int dochunk (lua_State *L, int status) { 198 if (status == LUA_OK) status = docall(L, 0, 0); 199 return report(L, status); 200 } 201 202 203 static int dofile (lua_State *L, const char *name) { 204 return dochunk(L, luaL_loadfile(L, name)); 205 } 206 207 208 static int dostring (lua_State *L, const char *s, const char *name) { 209 return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name)); 210 } 211 212 213 /* 214 ** Receives 'globname[=modname]' and runs 'globname = require(modname)'. 215 */ 216 static int dolibrary (lua_State *L, char *globname) { 217 int status; 218 char *modname = strchr(globname, '='); 219 if (modname == NULL) /* no explicit name? */ 220 modname = globname; /* module name is equal to global name */ 221 else { 222 *modname = '\0'; /* global name ends here */ 223 modname++; /* module name starts after the '=' */ 224 } 225 lua_getglobal(L, "require"); 226 lua_pushstring(L, modname); 227 status = docall(L, 1, 1); /* call 'require(modname)' */ 228 if (status == LUA_OK) 229 lua_setglobal(L, globname); /* globname = require(modname) */ 230 return report(L, status); 231 } 232 233 234 /* 235 ** Push on the stack the contents of table 'arg' from 1 to #arg 236 */ 237 static int pushargs (lua_State *L) { 238 int i, n; 239 if (lua_getglobal(L, "arg") != LUA_TTABLE) 240 luaL_error(L, "'arg' is not a table"); 241 n = (int)luaL_len(L, -1); 242 luaL_checkstack(L, n + 3, "too many arguments to script"); 243 for (i = 1; i <= n; i++) 244 lua_rawgeti(L, -i, i); 245 lua_remove(L, -i); /* remove table from the stack */ 246 return n; 247 } 248 249 250 static int handle_script (lua_State *L, char **argv) { 251 int status; 252 const char *fname = argv[0]; 253 if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0) 254 fname = NULL; /* stdin */ 255 status = luaL_loadfile(L, fname); 256 if (status == LUA_OK) { 257 int n = pushargs(L); /* push arguments to script */ 258 status = docall(L, n, LUA_MULTRET); 259 } 260 return report(L, status); 261 } 262 263 264 /* bits of various argument indicators in 'args' */ 265 #define has_error 1 /* bad option */ 266 #define has_i 2 /* -i */ 267 #define has_v 4 /* -v */ 268 #define has_e 8 /* -e */ 269 #define has_E 16 /* -E */ 270 271 272 /* 273 ** Traverses all arguments from 'argv', returning a mask with those 274 ** needed before running any Lua code or an error code if it finds any 275 ** invalid argument. In case of error, 'first' is the index of the bad 276 ** argument. Otherwise, 'first' is -1 if there is no program name, 277 ** 0 if there is no script name, or the index of the script name. 278 */ 279 static int collectargs (char **argv, int *first) { 280 int args = 0; 281 int i; 282 if (argv[0] != NULL) { /* is there a program name? */ 283 if (argv[0][0]) /* not empty? */ 284 progname = argv[0]; /* save it */ 285 } 286 else { /* no program name */ 287 *first = -1; 288 return 0; 289 } 290 for (i = 1; argv[i] != NULL; i++) { /* handle arguments */ 291 *first = i; 292 if (argv[i][0] != '-') /* not an option? */ 293 return args; /* stop handling options */ 294 switch (argv[i][1]) { /* else check option */ 295 case '-': /* '--' */ 296 if (argv[i][2] != '\0') /* extra characters after '--'? */ 297 return has_error; /* invalid option */ 298 *first = i + 1; 299 return args; 300 case '\0': /* '-' */ 301 return args; /* script "name" is '-' */ 302 case 'E': 303 if (argv[i][2] != '\0') /* extra characters? */ 304 return has_error; /* invalid option */ 305 args |= has_E; 306 break; 307 case 'W': 308 if (argv[i][2] != '\0') /* extra characters? */ 309 return has_error; /* invalid option */ 310 break; 311 case 'i': 312 args |= has_i; /* (-i implies -v) *//* FALLTHROUGH */ 313 case 'v': 314 if (argv[i][2] != '\0') /* extra characters? */ 315 return has_error; /* invalid option */ 316 args |= has_v; 317 break; 318 case 'e': 319 args |= has_e; /* FALLTHROUGH */ 320 case 'l': /* both options need an argument */ 321 if (argv[i][2] == '\0') { /* no concatenated argument? */ 322 i++; /* try next 'argv' */ 323 if (argv[i] == NULL || argv[i][0] == '-') 324 return has_error; /* no next argument or it is another option */ 325 } 326 break; 327 default: /* invalid option */ 328 return has_error; 329 } 330 } 331 *first = 0; /* no script name */ 332 return args; 333 } 334 335 336 /* 337 ** Processes options 'e' and 'l', which involve running Lua code, and 338 ** 'W', which also affects the state. 339 ** Returns 0 if some code raises an error. 340 */ 341 static int runargs (lua_State *L, char **argv, int n) { 342 int i; 343 for (i = 1; i < n; i++) { 344 int option = argv[i][1]; 345 lua_assert(argv[i][0] == '-'); /* already checked */ 346 switch (option) { 347 case 'e': case 'l': { 348 int status; 349 char *extra = argv[i] + 2; /* both options need an argument */ 350 if (*extra == '\0') extra = argv[++i]; 351 lua_assert(extra != NULL); 352 status = (option == 'e') 353 ? dostring(L, extra, "=(command line)") 354 : dolibrary(L, extra); 355 if (status != LUA_OK) return 0; 356 break; 357 } 358 case 'W': 359 lua_warning(L, "@on", 0); /* warnings on */ 360 break; 361 } 362 } 363 return 1; 364 } 365 366 367 static int handle_luainit (lua_State *L) { 368 const char *name = "=" LUA_INITVARVERSION; 369 const char *init = getenv(name + 1); 370 if (init == NULL) { 371 name = "=" LUA_INIT_VAR; 372 init = getenv(name + 1); /* try alternative name */ 373 } 374 if (init == NULL) return LUA_OK; 375 else if (init[0] == '@') 376 return dofile(L, init+1); 377 else 378 return dostring(L, init, name); 379 } 380 381 382 /* 383 ** {================================================================== 384 ** Read-Eval-Print Loop (REPL) 385 ** =================================================================== 386 */ 387 388 #if !defined(LUA_PROMPT) 389 #define LUA_PROMPT "> " 390 #define LUA_PROMPT2 ">> " 391 #endif 392 393 #if !defined(LUA_MAXINPUT) 394 #define LUA_MAXINPUT 512 395 #endif 396 397 398 /* 399 ** lua_stdin_is_tty detects whether the standard input is a 'tty' (that 400 ** is, whether we're running lua interactively). 401 */ 402 #if !defined(lua_stdin_is_tty) /* { */ 403 404 #if defined(LUA_USE_POSIX) /* { */ 405 406 #include <unistd.h> 407 #define lua_stdin_is_tty() isatty(0) 408 409 #elif defined(LUA_USE_WINDOWS) /* }{ */ 410 411 #include <io.h> 412 #include <windows.h> 413 414 #define lua_stdin_is_tty() _isatty(_fileno(stdin)) 415 416 #else /* }{ */ 417 418 /* ISO C definition */ 419 #define lua_stdin_is_tty() 1 /* assume stdin is a tty */ 420 421 #endif /* } */ 422 423 #endif /* } */ 424 425 426 /* 427 ** lua_readline defines how to show a prompt and then read a line from 428 ** the standard input. 429 ** lua_saveline defines how to "save" a read line in a "history". 430 ** lua_freeline defines how to free a line read by lua_readline. 431 */ 432 #if !defined(lua_readline) /* { */ 433 434 #if defined(LUA_USE_READLINE) /* { */ 435 436 #include <readline/readline.h> 437 #include <readline/history.h> 438 #define lua_initreadline(L) ((void)L, rl_readline_name="lua") 439 #define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL) 440 #define lua_saveline(L,line) ((void)L, add_history(line)) 441 #define lua_freeline(L,b) ((void)L, free(b)) 442 443 #else /* }{ */ 444 445 #define lua_initreadline(L) ((void)L) 446 #define lua_readline(L,b,p) \ 447 ((void)L, fputs(p, stdout), fflush(stdout), /* show prompt */ \ 448 fgets(b, LUA_MAXINPUT, stdin) != NULL) /* get line */ 449 #define lua_saveline(L,line) { (void)L; (void)line; } 450 #define lua_freeline(L,b) { (void)L; (void)b; } 451 452 #endif /* } */ 453 454 #endif /* } */ 455 456 457 /* 458 ** Return the string to be used as a prompt by the interpreter. Leave 459 ** the string (or nil, if using the default value) on the stack, to keep 460 ** it anchored. 461 */ 462 static const char *get_prompt (lua_State *L, int firstline) { 463 if (lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2") == LUA_TNIL) 464 return (firstline ? LUA_PROMPT : LUA_PROMPT2); /* use the default */ 465 else { /* apply 'tostring' over the value */ 466 const char *p = luaL_tolstring(L, -1, NULL); 467 lua_remove(L, -2); /* remove original value */ 468 return p; 469 } 470 } 471 472 /* mark in error messages for incomplete statements */ 473 #define EOFMARK "<eof>" 474 #define marklen (sizeof(EOFMARK)/sizeof(char) - 1) 475 476 477 /* 478 ** Check whether 'status' signals a syntax error and the error 479 ** message at the top of the stack ends with the above mark for 480 ** incomplete statements. 481 */ 482 static int incomplete (lua_State *L, int status) { 483 if (status == LUA_ERRSYNTAX) { 484 size_t lmsg; 485 const char *msg = lua_tolstring(L, -1, &lmsg); 486 if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0) { 487 lua_pop(L, 1); 488 return 1; 489 } 490 } 491 return 0; /* else... */ 492 } 493 494 495 /* 496 ** Prompt the user, read a line, and push it into the Lua stack. 497 */ 498 static int pushline (lua_State *L, int firstline) { 499 char buffer[LUA_MAXINPUT]; 500 char *b = buffer; 501 size_t l; 502 const char *prmt = get_prompt(L, firstline); 503 int readstatus = lua_readline(L, b, prmt); 504 if (readstatus == 0) 505 return 0; /* no input (prompt will be popped by caller) */ 506 lua_pop(L, 1); /* remove prompt */ 507 l = strlen(b); 508 if (l > 0 && b[l-1] == '\n') /* line ends with newline? */ 509 b[--l] = '\0'; /* remove it */ 510 if (firstline && b[0] == '=') /* for compatibility with 5.2, ... */ 511 lua_pushfstring(L, "return %s", b + 1); /* change '=' to 'return' */ 512 else 513 lua_pushlstring(L, b, l); 514 lua_freeline(L, b); 515 return 1; 516 } 517 518 519 /* 520 ** Try to compile line on the stack as 'return <line>;'; on return, stack 521 ** has either compiled chunk or original line (if compilation failed). 522 */ 523 static int addreturn (lua_State *L) { 524 const char *line = lua_tostring(L, -1); /* original line */ 525 const char *retline = lua_pushfstring(L, "return %s;", line); 526 int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin"); 527 if (status == LUA_OK) { 528 lua_remove(L, -2); /* remove modified line */ 529 if (line[0] != '\0') /* non empty? */ 530 lua_saveline(L, line); /* keep history */ 531 } 532 else 533 lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */ 534 return status; 535 } 536 537 538 /* 539 ** Read multiple lines until a complete Lua statement 540 */ 541 static int multiline (lua_State *L) { 542 for (;;) { /* repeat until gets a complete statement */ 543 size_t len; 544 const char *line = lua_tolstring(L, 1, &len); /* get what it has */ 545 int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */ 546 if (!incomplete(L, status) || !pushline(L, 0)) { 547 lua_saveline(L, line); /* keep history */ 548 return status; /* cannot or should not try to add continuation line */ 549 } 550 lua_pushliteral(L, "\n"); /* add newline... */ 551 lua_insert(L, -2); /* ...between the two lines */ 552 lua_concat(L, 3); /* join them */ 553 } 554 } 555 556 557 /* 558 ** Read a line and try to load (compile) it first as an expression (by 559 ** adding "return " in front of it) and second as a statement. Return 560 ** the final status of load/call with the resulting function (if any) 561 ** in the top of the stack. 562 */ 563 static int loadline (lua_State *L) { 564 int status; 565 lua_settop(L, 0); 566 if (!pushline(L, 1)) 567 return -1; /* no input */ 568 if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */ 569 status = multiline(L); /* try as command, maybe with continuation lines */ 570 lua_remove(L, 1); /* remove line from the stack */ 571 lua_assert(lua_gettop(L) == 1); 572 return status; 573 } 574 575 576 /* 577 ** Prints (calling the Lua 'print' function) any values on the stack 578 */ 579 static void l_print (lua_State *L) { 580 int n = lua_gettop(L); 581 if (n > 0) { /* any result to be printed? */ 582 luaL_checkstack(L, LUA_MINSTACK, "too many results to print"); 583 lua_getglobal(L, "print"); 584 lua_insert(L, 1); 585 if (lua_pcall(L, n, 0, 0) != LUA_OK) 586 l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)", 587 lua_tostring(L, -1))); 588 } 589 } 590 591 592 /* 593 ** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and 594 ** print any results. 595 */ 596 static void doREPL (lua_State *L) { 597 int status; 598 const char *oldprogname = progname; 599 progname = NULL; /* no 'progname' on errors in interactive mode */ 600 lua_initreadline(L); 601 while ((status = loadline(L)) != -1) { 602 if (status == LUA_OK) 603 status = docall(L, 0, LUA_MULTRET); 604 if (status == LUA_OK) l_print(L); 605 else report(L, status); 606 } 607 lua_settop(L, 0); /* clear stack */ 608 lua_writeline(); 609 progname = oldprogname; 610 } 611 612 /* }================================================================== */ 613 614 615 /* 616 ** Main body of stand-alone interpreter (to be called in protected mode). 617 ** Reads the options and handles them all. 618 */ 619 static int pmain (lua_State *L) { 620 int argc = (int)lua_tointeger(L, 1); 621 char **argv = (char **)lua_touserdata(L, 2); 622 int script; 623 int args = collectargs(argv, &script); 624 int optlim = (script > 0) ? script : argc; /* first argv not an option */ 625 luaL_checkversion(L); /* check that interpreter has correct version */ 626 if (args == has_error) { /* bad arg? */ 627 print_usage(argv[script]); /* 'script' has index of bad arg. */ 628 return 0; 629 } 630 if (args & has_v) /* option '-v'? */ 631 print_version(); 632 if (args & has_E) { /* option '-E'? */ 633 lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */ 634 lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV"); 635 } 636 luaL_openlibs(L); /* open standard libraries */ 637 createargtable(L, argv, argc, script); /* create table 'arg' */ 638 lua_gc(L, LUA_GCRESTART); /* start GC... */ 639 lua_gc(L, LUA_GCGEN, 0, 0); /* ...in generational mode */ 640 if (!(args & has_E)) { /* no option '-E'? */ 641 if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */ 642 return 0; /* error running LUA_INIT */ 643 } 644 if (!runargs(L, argv, optlim)) /* execute arguments -e and -l */ 645 return 0; /* something failed */ 646 if (script > 0) { /* execute main script (if there is one) */ 647 if (handle_script(L, argv + script) != LUA_OK) 648 return 0; /* interrupt in case of error */ 649 } 650 if (args & has_i) /* -i option? */ 651 doREPL(L); /* do read-eval-print loop */ 652 else if (script < 1 && !(args & (has_e | has_v))) { /* no active option? */ 653 if (lua_stdin_is_tty()) { /* running in interactive mode? */ 654 print_version(); 655 doREPL(L); /* do read-eval-print loop */ 656 } 657 else dofile(L, NULL); /* executes stdin as a file */ 658 } 659 lua_pushboolean(L, 1); /* signal no errors */ 660 return 1; 661 } 662 663 664 int main (int argc, char **argv) { 665 int status, result; 666 lua_State *L = luaL_newstate(); /* create state */ 667 if (L == NULL) { 668 l_message(argv[0], "cannot create state: not enough memory"); 669 return EXIT_FAILURE; 670 } 671 lua_gc(L, LUA_GCSTOP); /* stop GC while building state */ 672 lua_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */ 673 lua_pushinteger(L, argc); /* 1st argument */ 674 lua_pushlightuserdata(L, argv); /* 2nd argument */ 675 status = lua_pcall(L, 2, 1, 0); /* do the call */ 676 result = lua_toboolean(L, -1); /* get result */ 677 report(L, status); 678 lua_close(L); 679 return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE; 680 } 681 682