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