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