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
35static lua_State *globalL = NULL;
36
37static const char *progname = LUA_PROGNAME;
38
39
40#if defined(LUA_USE_POSIX) /* { */
41
42/*
43** Use 'sigaction' when available.
44*/
45static 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*/
63static 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*/
76static 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
83static 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*/
110static 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*/
121static 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*/
134static 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*/
153static 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
167static 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*/
181static void createargtable (lua_State *L, char **argv, int argc, int script) {
182 int i, narg;
183 if (script == argc) script = 0; /* no script name? */
184 narg = argc - (script + 1); /* number of positive indices */
185 lua_createtable(L, narg, script + 1);
186 for (i = 0; i < argc; i++) {
187 lua_pushstring(L, argv[i]);
188 lua_rawseti(L, -2, i - script);
189 }
190 lua_setglobal(L, "arg");
191}
192
193
194static int dochunk (lua_State *L, int status) {
195 if (status == LUA_OK) status = docall(L, 0, 0);
196 return report(L, status);
197}
198
199
200static int dofile (lua_State *L, const char *name) {
201 return dochunk(L, luaL_loadfile(L, name));
202}
203
204
205static int dostring (lua_State *L, const char *s, const char *name) {
206 return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
207}
208
209
210/*
211** Receives 'globname[=modname]' and runs 'globname = require(modname)'.
212*/
213static int dolibrary (lua_State *L, char *globname) {
214 int status;
215 char *modname = strchr(globname, '=');
216 if (modname == NULL) /* no explicit name? */
217 modname = globname; /* module name is equal to global name */
218 else {
219 *modname = '\0'; /* global name ends here */
220 modname++; /* module name starts after the '=' */
221 }
222 lua_getglobal(L, "require");
223 lua_pushstring(L, modname);
224 status = docall(L, 1, 1); /* call 'require(modname)' */
225 if (status == LUA_OK)
226 lua_setglobal(L, globname); /* globname = require(modname) */
227 return report(L, status);
228}
229
230
231/*
232** Push on the stack the contents of table 'arg' from 1 to #arg
233*/
234static int pushargs (lua_State *L) {
235 int i, n;
236 if (lua_getglobal(L, "arg") != LUA_TTABLE)
237 luaL_error(L, "'arg' is not a table");
238 n = (int)luaL_len(L, -1);
239 luaL_checkstack(L, n + 3, "too many arguments to script");
240 for (i = 1; i <= n; i++)
241 lua_rawgeti(L, -i, i);
242 lua_remove(L, -i); /* remove table from the stack */
243 return n;
244}
245
246
247static int handle_script (lua_State *L, char **argv) {
248 int status;
249 const char *fname = argv[0];
250 if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
251 fname = NULL; /* stdin */
252 status = luaL_loadfile(L, fname);
253 if (status == LUA_OK) {
254 int n = pushargs(L); /* push arguments to script */
255 status = docall(L, n, LUA_MULTRET);
256 }
257 return report(L, status);
258}
259
260
261/* bits of various argument indicators in 'args' */
262#define has_error 1 /* bad option */
263#define has_i 2 /* -i */
264#define has_v 4 /* -v */
265#define has_e 8 /* -e */
266#define has_E 16 /* -E */
267
268
269/*
270** Traverses all arguments from 'argv', returning a mask with those
271** needed before running any Lua code (or an error code if it finds
272** any invalid argument). 'first' returns the first not-handled argument
273** (either the script name or a bad argument in case of error).
274*/
275static int collectargs (char **argv, int *first) {
276 int args = 0;
277 int i;
278 for (i = 1; argv[i] != NULL; i++) {
279 *first = i;
280 if (argv[i][0] != '-') /* not an option? */
281 return args; /* stop handling options */
282 switch (argv[i][1]) { /* else check option */
283 case '-': /* '--' */
284 if (argv[i][2] != '\0') /* extra characters after '--'? */
285 return has_error; /* invalid option */
286 *first = i + 1;
287 return args;
288 case '\0': /* '-' */
289 return args; /* script "name" is '-' */
290 case 'E':
291 if (argv[i][2] != '\0') /* extra characters? */
292 return has_error; /* invalid option */
293 args |= has_E;
294 break;
295 case 'W':
296 if (argv[i][2] != '\0') /* extra characters? */
297 return has_error; /* invalid option */
298 break;
299 case 'i':
300 args |= has_i; /* (-i implies -v) *//* FALLTHROUGH */
301 case 'v':
302 if (argv[i][2] != '\0') /* extra characters? */
303 return has_error; /* invalid option */
304 args |= has_v;
305 break;
306 case 'e':
307 args |= has_e; /* FALLTHROUGH */
308 case 'l': /* both options need an argument */
309 if (argv[i][2] == '\0') { /* no concatenated argument? */
310 i++; /* try next 'argv' */
311 if (argv[i] == NULL || argv[i][0] == '-')
312 return has_error; /* no next argument or it is another option */
313 }
314 break;
315 default: /* invalid option */
316 return has_error;
317 }
318 }
319 *first = i; /* no script name */
320 return args;
321}
322
323
324/*
325** Processes options 'e' and 'l', which involve running Lua code, and
326** 'W', which also affects the state.
327** Returns 0 if some code raises an error.
328*/
329static int runargs (lua_State *L, char **argv, int n) {
330 int i;
331 for (i = 1; i < n; i++) {
332 int option = argv[i][1];
333 lua_assert(argv[i][0] == '-'); /* already checked */
334 switch (option) {
335 case 'e': case 'l': {
336 int status;
337 char *extra = argv[i] + 2; /* both options need an argument */
338 if (*extra == '\0') extra = argv[++i];
339 lua_assert(extra != NULL);
340 status = (option == 'e')
341 ? dostring(L, extra, "=(command line)")
342 : dolibrary(L, extra);
343 if (status != LUA_OK) return 0;
344 break;
345 }
346 case 'W':
347 lua_warning(L, "@on", 0); /* warnings on */
348 break;
349 }
350 }
351 return 1;
352}
353
354
355static int handle_luainit (lua_State *L) {
356 const char *name = "=" LUA_INITVARVERSION;
357 const char *init = getenv(name + 1);
358 if (init == NULL) {
359 name = "=" LUA_INIT_VAR;
360 init = getenv(name + 1); /* try alternative name */
361 }
362 if (init == NULL) return LUA_OK;
363 else if (init[0] == '@')
364 return dofile(L, init+1);
365 else
366 return dostring(L, init, name);
367}
368
369
370/*
371** {==================================================================
372** Read-Eval-Print Loop (REPL)
373** ===================================================================
374*/
375
376#if !defined(LUA_PROMPT)
377#define LUA_PROMPT "> "
378#define LUA_PROMPT2 ">> "
379#endif
380
381#if !defined(LUA_MAXINPUT)
382#define LUA_MAXINPUT 512
383#endif
384
385
386/*
387** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
388** is, whether we're running lua interactively).
389*/
390#if !defined(lua_stdin_is_tty) /* { */
391
392#if defined(LUA_USE_POSIX) /* { */
393
394#include <unistd.h>
395#define lua_stdin_is_tty() isatty(0)
396
397#elif defined(LUA_USE_WINDOWS) /* }{ */
398
399#include <io.h>
400#include <windows.h>
401
402#define lua_stdin_is_tty() _isatty(_fileno(stdin))
403
404#else /* }{ */
405
406/* ISO C definition */
407#define lua_stdin_is_tty() 1 /* assume stdin is a tty */
408
409#endif /* } */
410
411#endif /* } */
412
413
414/*
415** lua_readline defines how to show a prompt and then read a line from
416** the standard input.
417** lua_saveline defines how to "save" a read line in a "history".
418** lua_freeline defines how to free a line read by lua_readline.
419*/
420#if !defined(lua_readline) /* { */
421
422#if defined(LUA_USE_READLINE) /* { */
423
424#include <readline/readline.h>
425#include <readline/history.h>
426#define lua_initreadline(L) ((void)L, rl_readline_name="lua")
427#define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
428#define lua_saveline(L,line) ((void)L, add_history(line))
429#define lua_freeline(L,b) ((void)L, free(b))
430
431#else /* }{ */
432
433#define lua_initreadline(L) ((void)L)
434#define lua_readline(L,b,p) \
435 ((void)L, fputs(p, stdout), fflush(stdout), /* show prompt */ \
436 fgets(b, LUA_MAXINPUT, stdin) != NULL) /* get line */
437#define lua_saveline(L,line) { (void)L; (void)line; }
438#define lua_freeline(L,b) { (void)L; (void)b; }
439
440#endif /* } */
441
442#endif /* } */
443
444
445/*
446** Return the string to be used as a prompt by the interpreter. Leave
447** the string (or nil, if using the default value) on the stack, to keep
448** it anchored.
449*/
450static const char *get_prompt (lua_State *L, int firstline) {
451 if (lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2") == LUA_TNIL)
452 return (firstline ? LUA_PROMPT : LUA_PROMPT2); /* use the default */
453 else { /* apply 'tostring' over the value */
454 const char *p = luaL_tolstring(L, -1, NULL);
455 lua_remove(L, -2); /* remove original value */
456 return p;
457 }
458}
459
460/* mark in error messages for incomplete statements */
461#define EOFMARK "<eof>"
462#define marklen (sizeof(EOFMARK)/sizeof(char) - 1)
463
464
465/*
466** Check whether 'status' signals a syntax error and the error
467** message at the top of the stack ends with the above mark for
468** incomplete statements.
469*/
470static int incomplete (lua_State *L, int status) {
471 if (status == LUA_ERRSYNTAX) {
472 size_t lmsg;
473 const char *msg = lua_tolstring(L, -1, &lmsg);
474 if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0) {
475 lua_pop(L, 1);
476 return 1;
477 }
478 }
479 return 0; /* else... */
480}
481
482
483/*
484** Prompt the user, read a line, and push it into the Lua stack.
485*/
486static int pushline (lua_State *L, int firstline) {
487 char buffer[LUA_MAXINPUT];
488 char *b = buffer;
489 size_t l;
490 const char *prmt = get_prompt(L, firstline);
491 int readstatus = lua_readline(L, b, prmt);
492 if (readstatus == 0)
493 return 0; /* no input (prompt will be popped by caller) */
494 lua_pop(L, 1); /* remove prompt */
495 l = strlen(b);
496 if (l > 0 && b[l-1] == '\n') /* line ends with newline? */
497 b[--l] = '\0'; /* remove it */
498 if (firstline && b[0] == '=') /* for compatibility with 5.2, ... */
499 lua_pushfstring(L, "return %s", b + 1); /* change '=' to 'return' */
500 else
501 lua_pushlstring(L, b, l);
502 lua_freeline(L, b);
503 return 1;
504}
505
506
507/*
508** Try to compile line on the stack as 'return <line>;'; on return, stack
509** has either compiled chunk or original line (if compilation failed).
510*/
511static int addreturn (lua_State *L) {
512 const char *line = lua_tostring(L, -1); /* original line */
513 const char *retline = lua_pushfstring(L, "return %s;", line);
514 int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
515 if (status == LUA_OK) {
516 lua_remove(L, -2); /* remove modified line */
517 if (line[0] != '\0') /* non empty? */
518 lua_saveline(L, line); /* keep history */
519 }
520 else
521 lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */
522 return status;
523}
524
525
526/*
527** Read multiple lines until a complete Lua statement
528*/
529static int multiline (lua_State *L) {
530 for (;;) { /* repeat until gets a complete statement */
531 size_t len;
532 const char *line = lua_tolstring(L, 1, &len); /* get what it has */
533 int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */
534 if (!incomplete(L, status) || !pushline(L, 0)) {
535 lua_saveline(L, line); /* keep history */
536 return status; /* cannot or should not try to add continuation line */
537 }
538 lua_pushliteral(L, "\n"); /* add newline... */
539 lua_insert(L, -2); /* ...between the two lines */
540 lua_concat(L, 3); /* join them */
541 }
542}
543
544
545/*
546** Read a line and try to load (compile) it first as an expression (by
547** adding "return " in front of it) and second as a statement. Return
548** the final status of load/call with the resulting function (if any)
549** in the top of the stack.
550*/
551static int loadline (lua_State *L) {
552 int status;
553 lua_settop(L, 0);
554 if (!pushline(L, 1))
555 return -1; /* no input */
556 if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */
557 status = multiline(L); /* try as command, maybe with continuation lines */
558 lua_remove(L, 1); /* remove line from the stack */
559 lua_assert(lua_gettop(L) == 1);
560 return status;
561}
562
563
564/*
565** Prints (calling the Lua 'print' function) any values on the stack
566*/
567static void l_print (lua_State *L) {
568 int n = lua_gettop(L);
569 if (n > 0) { /* any result to be printed? */
570 luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
571 lua_getglobal(L, "print");
572 lua_insert(L, 1);
573 if (lua_pcall(L, n, 0, 0) != LUA_OK)
574 l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)",
575 lua_tostring(L, -1)));
576 }
577}
578
579
580/*
581** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
582** print any results.
583*/
584static void doREPL (lua_State *L) {
585 int status;
586 const char *oldprogname = progname;
587 progname = NULL; /* no 'progname' on errors in interactive mode */
588 lua_initreadline(L);
589 while ((status = loadline(L)) != -1) {
590 if (status == LUA_OK)
591 status = docall(L, 0, LUA_MULTRET);
592 if (status == LUA_OK) l_print(L);
593 else report(L, status);
594 }
595 lua_settop(L, 0); /* clear stack */
596 lua_writeline();
597 progname = oldprogname;
598}
599
600/* }================================================================== */
601
602
603/*
604** Main body of stand-alone interpreter (to be called in protected mode).
605** Reads the options and handles them all.
606*/
607static int pmain (lua_State *L) {
608 int argc = (int)lua_tointeger(L, 1);
609 char **argv = (char **)lua_touserdata(L, 2);
610 int script;
611 int args = collectargs(argv, &script);
612 luaL_checkversion(L); /* check that interpreter has correct version */
613 if (argv[0] && argv[0][0]) progname = argv[0];
614 if (args == has_error) { /* bad arg? */
615 print_usage(argv[script]); /* 'script' has index of bad arg. */
616 return 0;
617 }
618 if (args & has_v) /* option '-v'? */
619 print_version();
620 if (args & has_E) { /* option '-E'? */
621 lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */
622 lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
623 }
624 luaL_openlibs(L); /* open standard libraries */
625 createargtable(L, argv, argc, script); /* create table 'arg' */
626 lua_gc(L, LUA_GCGEN, 0, 0); /* GC in generational mode */
627 if (!(args & has_E)) { /* no option '-E'? */
628 if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
629 return 0; /* error running LUA_INIT */
630 }
631 if (!runargs(L, argv, script)) /* execute arguments -e and -l */
632 return 0; /* something failed */
633 if (script < argc && /* execute main script (if there is one) */
634 handle_script(L, argv + script) != LUA_OK)
635 return 0;
636 if (args & has_i) /* -i option? */
637 doREPL(L); /* do read-eval-print loop */
638 else if (script == argc && !(args & (has_e | has_v))) { /* no arguments? */
639 if (lua_stdin_is_tty()) { /* running in interactive mode? */
640 print_version();
641 doREPL(L); /* do read-eval-print loop */
642 }
643 else dofile(L, NULL); /* executes stdin as a file */
644 }
645 lua_pushboolean(L, 1); /* signal no errors */
646 return 1;
647}
648
649
650int main (int argc, char **argv) {
651 int status, result;
652 lua_State *L = luaL_newstate(); /* create state */
653 if (L == NULL) {
654 l_message(argv[0], "cannot create state: not enough memory");
655 return EXIT_FAILURE;
656 }
657 lua_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */
658 lua_pushinteger(L, argc); /* 1st argument */
659 lua_pushlightuserdata(L, argv); /* 2nd argument */
660 status = lua_pcall(L, 2, 1, 0); /* do the call */
661 result = lua_toboolean(L, -1); /* get result */
662 report(L, status);
663 lua_close(L);
664 return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
665}
666
667