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/*
41** Hook set by signal function to stop the interpreter.
42*/
43static 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*/
56static 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
63static 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*/
89static 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*/
100static 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*/
113static 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*/
132static 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
146static 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*/
160static 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
173static 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
179static int dofile (lua_State *L, const char *name) {
180 return dochunk(L, luaL_loadfile(L, name));
181}
182
183
184static 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*/
193static 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*/
207static 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
220static 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*/
248static 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*/
302static 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
328static 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** Returns the string to be used as a prompt by the interpreter.
420*/
421static const char *get_prompt (lua_State *L, int firstline) {
422 const char *p;
423 lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
424 p = lua_tostring(L, -1);
425 if (p == NULL) p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
426 return p;
427}
428
429/* mark in error messages for incomplete statements */
430#define EOFMARK "<eof>"
431#define marklen (sizeof(EOFMARK)/sizeof(char) - 1)
432
433
434/*
435** Check whether 'status' signals a syntax error and the error
436** message at the top of the stack ends with the above mark for
437** incomplete statements.
438*/
439static int incomplete (lua_State *L, int status) {
440 if (status == LUA_ERRSYNTAX) {
441 size_t lmsg;
442 const char *msg = lua_tolstring(L, -1, &lmsg);
443 if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0) {
444 lua_pop(L, 1);
445 return 1;
446 }
447 }
448 return 0; /* else... */
449}
450
451
452/*
453** Prompt the user, read a line, and push it into the Lua stack.
454*/
455static int pushline (lua_State *L, int firstline) {
456 char buffer[LUA_MAXINPUT];
457 char *b = buffer;
458 size_t l;
459 const char *prmt = get_prompt(L, firstline);
460 int readstatus = lua_readline(L, b, prmt);
461 if (readstatus == 0)
462 return 0; /* no input (prompt will be popped by caller) */
463 lua_pop(L, 1); /* remove prompt */
464 l = strlen(b);
465 if (l > 0 && b[l-1] == '\n') /* line ends with newline? */
466 b[--l] = '\0'; /* remove it */
467 if (firstline && b[0] == '=') /* for compatibility with 5.2, ... */
468 lua_pushfstring(L, "return %s", b + 1); /* change '=' to 'return' */
469 else
470 lua_pushlstring(L, b, l);
471 lua_freeline(L, b);
472 return 1;
473}
474
475
476/*
477** Try to compile line on the stack as 'return <line>;'; on return, stack
478** has either compiled chunk or original line (if compilation failed).
479*/
480static int addreturn (lua_State *L) {
481 const char *line = lua_tostring(L, -1); /* original line */
482 const char *retline = lua_pushfstring(L, "return %s;", line);
483 int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
484 if (status == LUA_OK) {
485 lua_remove(L, -2); /* remove modified line */
486 if (line[0] != '\0') /* non empty? */
487 lua_saveline(L, line); /* keep history */
488 }
489 else
490 lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */
491 return status;
492}
493
494
495/*
496** Read multiple lines until a complete Lua statement
497*/
498static int multiline (lua_State *L) {
499 for (;;) { /* repeat until gets a complete statement */
500 size_t len;
501 const char *line = lua_tolstring(L, 1, &len); /* get what it has */
502 int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */
503 if (!incomplete(L, status) || !pushline(L, 0)) {
504 lua_saveline(L, line); /* keep history */
505 return status; /* cannot or should not try to add continuation line */
506 }
507 lua_pushliteral(L, "\n"); /* add newline... */
508 lua_insert(L, -2); /* ...between the two lines */
509 lua_concat(L, 3); /* join them */
510 }
511}
512
513
514/*
515** Read a line and try to load (compile) it first as an expression (by
516** adding "return " in front of it) and second as a statement. Return
517** the final status of load/call with the resulting function (if any)
518** in the top of the stack.
519*/
520static int loadline (lua_State *L) {
521 int status;
522 lua_settop(L, 0);
523 if (!pushline(L, 1))
524 return -1; /* no input */
525 if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */
526 status = multiline(L); /* try as command, maybe with continuation lines */
527 lua_remove(L, 1); /* remove line from the stack */
528 lua_assert(lua_gettop(L) == 1);
529 return status;
530}
531
532
533/*
534** Prints (calling the Lua 'print' function) any values on the stack
535*/
536static void l_print (lua_State *L) {
537 int n = lua_gettop(L);
538 if (n > 0) { /* any result to be printed? */
539 luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
540 lua_getglobal(L, "print");
541 lua_insert(L, 1);
542 if (lua_pcall(L, n, 0, 0) != LUA_OK)
543 l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)",
544 lua_tostring(L, -1)));
545 }
546}
547
548
549/*
550** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
551** print any results.
552*/
553static void doREPL (lua_State *L) {
554 int status;
555 const char *oldprogname = progname;
556 progname = NULL; /* no 'progname' on errors in interactive mode */
557 lua_initreadline(L);
558 while ((status = loadline(L)) != -1) {
559 if (status == LUA_OK)
560 status = docall(L, 0, LUA_MULTRET);
561 if (status == LUA_OK) l_print(L);
562 else report(L, status);
563 }
564 lua_settop(L, 0); /* clear stack */
565 lua_writeline();
566 progname = oldprogname;
567}
568
569/* }================================================================== */
570
571
572/*
573** Main body of stand-alone interpreter (to be called in protected mode).
574** Reads the options and handles them all.
575*/
576static int pmain (lua_State *L) {
577 int argc = (int)lua_tointeger(L, 1);
578 char **argv = (char **)lua_touserdata(L, 2);
579 int script;
580 int args = collectargs(argv, &script);
581 luaL_checkversion(L); /* check that interpreter has correct version */
582 if (argv[0] && argv[0][0]) progname = argv[0];
583 if (args == has_error) { /* bad arg? */
584 print_usage(argv[script]); /* 'script' has index of bad arg. */
585 return 0;
586 }
587 if (args & has_v) /* option '-v'? */
588 print_version();
589 if (args & has_E) { /* option '-E'? */
590 lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */
591 lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
592 }
593 luaL_openlibs(L); /* open standard libraries */
594 createargtable(L, argv, argc, script); /* create table 'arg' */
595 lua_gc(L, LUA_GCGEN, 0, 0); /* GC in generational mode */
596 if (!(args & has_E)) { /* no option '-E'? */
597 if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
598 return 0; /* error running LUA_INIT */
599 }
600 if (!runargs(L, argv, script)) /* execute arguments -e and -l */
601 return 0; /* something failed */
602 if (script < argc && /* execute main script (if there is one) */
603 handle_script(L, argv + script) != LUA_OK)
604 return 0;
605 if (args & has_i) /* -i option? */
606 doREPL(L); /* do read-eval-print loop */
607 else if (script == argc && !(args & (has_e | has_v))) { /* no arguments? */
608 if (lua_stdin_is_tty()) { /* running in interactive mode? */
609 print_version();
610 doREPL(L); /* do read-eval-print loop */
611 }
612 else dofile(L, NULL); /* executes stdin as a file */
613 }
614 lua_pushboolean(L, 1); /* signal no errors */
615 return 1;
616}
617
618
619int main (int argc, char **argv) {
620 int status, result;
621 lua_State *L = luaL_newstate(); /* create state */
622 if (L == NULL) {
623 l_message(argv[0], "cannot create state: not enough memory");
624 return EXIT_FAILURE;
625 }
626 lua_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */
627 lua_pushinteger(L, argc); /* 1st argument */
628 lua_pushlightuserdata(L, argv); /* 2nd argument */
629 status = lua_pcall(L, 2, 1, 0); /* do the call */
630 result = lua_toboolean(L, -1); /* get result */
631 report(L, status);
632 lua_close(L);
633 return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
634}
635
636