xref: /freebsd/contrib/lua/src/lua.c (revision 3068d706eabe99f930fb01d3cbfd74ff1f0eb5a2)
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.
119 */
report(lua_State * L,int status)120 static int report (lua_State *L, int status) {
121   if (status != LUA_OK) {
122     const char *msg = lua_tostring(L, -1);
123     if (msg == NULL)
124       msg = "(error message not a string)";
125     l_message(progname, msg);
126     lua_pop(L, 1);  /* remove message */
127   }
128   return status;
129 }
130 
131 
132 /*
133 ** Message handler used to run all chunks
134 */
msghandler(lua_State * L)135 static int msghandler (lua_State *L) {
136   const char *msg = lua_tostring(L, 1);
137   if (msg == NULL) {  /* is error object not a string? */
138     if (luaL_callmeta(L, 1, "__tostring") &&  /* does it have a metamethod */
139         lua_type(L, -1) == LUA_TSTRING)  /* that produces a string? */
140       return 1;  /* that is the message */
141     else
142       msg = lua_pushfstring(L, "(error object is a %s value)",
143                                luaL_typename(L, 1));
144   }
145   luaL_traceback(L, L, msg, 1);  /* append a standard traceback */
146   return 1;  /* return the traceback */
147 }
148 
149 
150 /*
151 ** Interface to 'lua_pcall', which sets appropriate message function
152 ** and C-signal handler. Used to run all chunks.
153 */
docall(lua_State * L,int narg,int nres)154 static int docall (lua_State *L, int narg, int nres) {
155   int status;
156   int base = lua_gettop(L) - narg;  /* function index */
157   lua_pushcfunction(L, msghandler);  /* push message handler */
158   lua_insert(L, base);  /* put it under function and args */
159   globalL = L;  /* to be available to 'laction' */
160   setsignal(SIGINT, laction);  /* set C-signal handler */
161   status = lua_pcall(L, narg, nres, base);
162   setsignal(SIGINT, SIG_DFL); /* reset C-signal handler */
163   lua_remove(L, base);  /* remove message handler from the stack */
164   return status;
165 }
166 
167 
print_version(void)168 static void print_version (void) {
169   lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));
170   lua_writeline();
171 }
172 
173 
174 /*
175 ** Create the 'arg' table, which stores all arguments from the
176 ** command line ('argv'). It should be aligned so that, at index 0,
177 ** it has 'argv[script]', which is the script name. The arguments
178 ** to the script (everything after 'script') go to positive indices;
179 ** other arguments (before the script name) go to negative indices.
180 ** If there is no script name, assume interpreter's name as base.
181 ** (If there is no interpreter's name either, 'script' is -1, so
182 ** table sizes are zero.)
183 */
createargtable(lua_State * L,char ** argv,int argc,int script)184 static void createargtable (lua_State *L, char **argv, int argc, int script) {
185   int i, narg;
186   narg = argc - (script + 1);  /* number of positive indices */
187   lua_createtable(L, narg, script + 1);
188   for (i = 0; i < argc; i++) {
189     lua_pushstring(L, argv[i]);
190     lua_rawseti(L, -2, i - script);
191   }
192   lua_setglobal(L, "arg");
193 }
194 
195 
dochunk(lua_State * L,int status)196 static int dochunk (lua_State *L, int status) {
197   if (status == LUA_OK) status = docall(L, 0, 0);
198   return report(L, status);
199 }
200 
201 
dofile(lua_State * L,const char * name)202 static int dofile (lua_State *L, const char *name) {
203   return dochunk(L, luaL_loadfile(L, name));
204 }
205 
206 
dostring(lua_State * L,const char * s,const char * name)207 static int dostring (lua_State *L, const char *s, const char *name) {
208   return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
209 }
210 
211 
212 /*
213 ** Receives 'globname[=modname]' and runs 'globname = require(modname)'.
214 ** If there is no explicit modname and globname contains a '-', cut
215 ** the suffix after '-' (the "version") to make the global name.
216 */
dolibrary(lua_State * L,char * globname)217 static int dolibrary (lua_State *L, char *globname) {
218   int status;
219   char *suffix = NULL;
220   char *modname = strchr(globname, '=');
221   if (modname == NULL) {  /* no explicit name? */
222     modname = globname;  /* module name is equal to global name */
223     suffix = strchr(modname, *LUA_IGMARK);  /* look for a suffix mark */
224   }
225   else {
226     *modname = '\0';  /* global name ends here */
227     modname++;  /* module name starts after the '=' */
228   }
229   lua_getglobal(L, "require");
230   lua_pushstring(L, modname);
231   status = docall(L, 1, 1);  /* call 'require(modname)' */
232   if (status == LUA_OK) {
233     if (suffix != NULL)  /* is there a suffix mark? */
234       *suffix = '\0';  /* remove suffix from global name */
235     lua_setglobal(L, globname);  /* globname = require(modname) */
236   }
237   return report(L, status);
238 }
239 
240 
241 /*
242 ** Push on the stack the contents of table 'arg' from 1 to #arg
243 */
pushargs(lua_State * L)244 static int pushargs (lua_State *L) {
245   int i, n;
246   if (lua_getglobal(L, "arg") != LUA_TTABLE)
247     luaL_error(L, "'arg' is not a table");
248   n = (int)luaL_len(L, -1);
249   luaL_checkstack(L, n + 3, "too many arguments to script");
250   for (i = 1; i <= n; i++)
251     lua_rawgeti(L, -i, i);
252   lua_remove(L, -i);  /* remove table from the stack */
253   return n;
254 }
255 
256 
handle_script(lua_State * L,char ** argv)257 static int handle_script (lua_State *L, char **argv) {
258   int status;
259   const char *fname = argv[0];
260   if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
261     fname = NULL;  /* stdin */
262   status = luaL_loadfile(L, fname);
263   if (status == LUA_OK) {
264     int n = pushargs(L);  /* push arguments to script */
265     status = docall(L, n, LUA_MULTRET);
266   }
267   return report(L, status);
268 }
269 
270 
271 /* bits of various argument indicators in 'args' */
272 #define has_error	1	/* bad option */
273 #define has_i		2	/* -i */
274 #define has_v		4	/* -v */
275 #define has_e		8	/* -e */
276 #define has_E		16	/* -E */
277 
278 
279 /*
280 ** Traverses all arguments from 'argv', returning a mask with those
281 ** needed before running any Lua code or an error code if it finds any
282 ** invalid argument. In case of error, 'first' is the index of the bad
283 ** argument.  Otherwise, 'first' is -1 if there is no program name,
284 ** 0 if there is no script name, or the index of the script name.
285 */
collectargs(char ** argv,int * first)286 static int collectargs (char **argv, int *first) {
287   int args = 0;
288   int i;
289   if (argv[0] != NULL) {  /* is there a program name? */
290     if (argv[0][0])  /* not empty? */
291       progname = argv[0];  /* save it */
292   }
293   else {  /* no program name */
294     *first = -1;
295     return 0;
296   }
297   for (i = 1; argv[i] != NULL; i++) {  /* handle arguments */
298     *first = i;
299     if (argv[i][0] != '-')  /* not an option? */
300         return args;  /* stop handling options */
301     switch (argv[i][1]) {  /* else check option */
302       case '-':  /* '--' */
303         if (argv[i][2] != '\0')  /* extra characters after '--'? */
304           return has_error;  /* invalid option */
305         *first = i + 1;
306         return args;
307       case '\0':  /* '-' */
308         return args;  /* script "name" is '-' */
309       case 'E':
310         if (argv[i][2] != '\0')  /* extra characters? */
311           return has_error;  /* invalid option */
312         args |= has_E;
313         break;
314       case 'W':
315         if (argv[i][2] != '\0')  /* extra characters? */
316           return has_error;  /* invalid option */
317         break;
318       case 'i':
319         args |= has_i;  /* (-i implies -v) *//* FALLTHROUGH */
320       case 'v':
321         if (argv[i][2] != '\0')  /* extra characters? */
322           return has_error;  /* invalid option */
323         args |= has_v;
324         break;
325       case 'e':
326         args |= has_e;  /* FALLTHROUGH */
327       case 'l':  /* both options need an argument */
328         if (argv[i][2] == '\0') {  /* no concatenated argument? */
329           i++;  /* try next 'argv' */
330           if (argv[i] == NULL || argv[i][0] == '-')
331             return has_error;  /* no next argument or it is another option */
332         }
333         break;
334       default:  /* invalid option */
335         return has_error;
336     }
337   }
338   *first = 0;  /* no script name */
339   return args;
340 }
341 
342 
343 /*
344 ** Processes options 'e' and 'l', which involve running Lua code, and
345 ** 'W', which also affects the state.
346 ** Returns 0 if some code raises an error.
347 */
runargs(lua_State * L,char ** argv,int n)348 static int runargs (lua_State *L, char **argv, int n) {
349   int i;
350   for (i = 1; i < n; i++) {
351     int option = argv[i][1];
352     lua_assert(argv[i][0] == '-');  /* already checked */
353     switch (option) {
354       case 'e':  case 'l': {
355         int status;
356         char *extra = argv[i] + 2;  /* both options need an argument */
357         if (*extra == '\0') extra = argv[++i];
358         lua_assert(extra != NULL);
359         status = (option == 'e')
360                  ? dostring(L, extra, "=(command line)")
361                  : dolibrary(L, extra);
362         if (status != LUA_OK) return 0;
363         break;
364       }
365       case 'W':
366         lua_warning(L, "@on", 0);  /* warnings on */
367         break;
368     }
369   }
370   return 1;
371 }
372 
373 
handle_luainit(lua_State * L)374 static int handle_luainit (lua_State *L) {
375   const char *name = "=" LUA_INITVARVERSION;
376   const char *init = getenv(name + 1);
377   if (init == NULL) {
378     name = "=" LUA_INIT_VAR;
379     init = getenv(name + 1);  /* try alternative name */
380   }
381   if (init == NULL) return LUA_OK;
382   else if (init[0] == '@')
383     return dofile(L, init+1);
384   else
385     return dostring(L, init, name);
386 }
387 
388 
389 /*
390 ** {==================================================================
391 ** Read-Eval-Print Loop (REPL)
392 ** ===================================================================
393 */
394 
395 #if !defined(LUA_PROMPT)
396 #define LUA_PROMPT		"> "
397 #define LUA_PROMPT2		">> "
398 #endif
399 
400 #if !defined(LUA_MAXINPUT)
401 #define LUA_MAXINPUT		512
402 #endif
403 
404 
405 /*
406 ** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
407 ** is, whether we're running lua interactively).
408 */
409 #if !defined(lua_stdin_is_tty)	/* { */
410 
411 #if defined(LUA_USE_POSIX)	/* { */
412 
413 #include <unistd.h>
414 #define lua_stdin_is_tty()	isatty(0)
415 
416 #elif defined(LUA_USE_WINDOWS)	/* }{ */
417 
418 #include <io.h>
419 #include <windows.h>
420 
421 #define lua_stdin_is_tty()	_isatty(_fileno(stdin))
422 
423 #else				/* }{ */
424 
425 /* ISO C definition */
426 #define lua_stdin_is_tty()	1  /* assume stdin is a tty */
427 
428 #endif				/* } */
429 
430 #endif				/* } */
431 
432 
433 /*
434 ** lua_readline defines how to show a prompt and then read a line from
435 ** the standard input.
436 ** lua_saveline defines how to "save" a read line in a "history".
437 ** lua_freeline defines how to free a line read by lua_readline.
438 */
439 #if !defined(lua_readline)	/* { */
440 
441 #if defined(LUA_USE_READLINE)	/* { */
442 
443 #include <readline/readline.h>
444 #include <readline/history.h>
445 #define lua_initreadline(L)	((void)L, rl_readline_name="lua")
446 #define lua_readline(L,b,p)	((void)L, ((b)=readline(p)) != NULL)
447 #define lua_saveline(L,line)	((void)L, add_history(line))
448 #define lua_freeline(L,b)	((void)L, free(b))
449 
450 #else				/* }{ */
451 
452 #define lua_initreadline(L)  ((void)L)
453 #define lua_readline(L,b,p) \
454         ((void)L, fputs(p, stdout), fflush(stdout),  /* show prompt */ \
455         fgets(b, LUA_MAXINPUT, stdin) != NULL)  /* get line */
456 #define lua_saveline(L,line)	{ (void)L; (void)line; }
457 #define lua_freeline(L,b)	{ (void)L; (void)b; }
458 
459 #endif				/* } */
460 
461 #endif				/* } */
462 
463 
464 /*
465 ** Return the string to be used as a prompt by the interpreter. Leave
466 ** the string (or nil, if using the default value) on the stack, to keep
467 ** it anchored.
468 */
get_prompt(lua_State * L,int firstline)469 static const char *get_prompt (lua_State *L, int firstline) {
470   if (lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2") == LUA_TNIL)
471     return (firstline ? LUA_PROMPT : LUA_PROMPT2);  /* use the default */
472   else {  /* apply 'tostring' over the value */
473     const char *p = luaL_tolstring(L, -1, NULL);
474     lua_remove(L, -2);  /* remove original value */
475     return p;
476   }
477 }
478 
479 /* mark in error messages for incomplete statements */
480 #define EOFMARK		"<eof>"
481 #define marklen		(sizeof(EOFMARK)/sizeof(char) - 1)
482 
483 
484 /*
485 ** Check whether 'status' signals a syntax error and the error
486 ** message at the top of the stack ends with the above mark for
487 ** incomplete statements.
488 */
incomplete(lua_State * L,int status)489 static int incomplete (lua_State *L, int status) {
490   if (status == LUA_ERRSYNTAX) {
491     size_t lmsg;
492     const char *msg = lua_tolstring(L, -1, &lmsg);
493     if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0)
494       return 1;
495   }
496   return 0;  /* else... */
497 }
498 
499 
500 /*
501 ** Prompt the user, read a line, and push it into the Lua stack.
502 */
pushline(lua_State * L,int firstline)503 static int pushline (lua_State *L, int firstline) {
504   char buffer[LUA_MAXINPUT];
505   char *b = buffer;
506   size_t l;
507   const char *prmt = get_prompt(L, firstline);
508   int readstatus = lua_readline(L, b, prmt);
509   lua_pop(L, 1);  /* remove prompt */
510   if (readstatus == 0)
511     return 0;  /* no input */
512   l = strlen(b);
513   if (l > 0 && b[l-1] == '\n')  /* line ends with newline? */
514     b[--l] = '\0';  /* remove it */
515   if (firstline && b[0] == '=')  /* for compatibility with 5.2, ... */
516     lua_pushfstring(L, "return %s", b + 1);  /* change '=' to 'return' */
517   else
518     lua_pushlstring(L, b, l);
519   lua_freeline(L, b);
520   return 1;
521 }
522 
523 
524 /*
525 ** Try to compile line on the stack as 'return <line>;'; on return, stack
526 ** has either compiled chunk or original line (if compilation failed).
527 */
addreturn(lua_State * L)528 static int addreturn (lua_State *L) {
529   const char *line = lua_tostring(L, -1);  /* original line */
530   const char *retline = lua_pushfstring(L, "return %s;", line);
531   int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
532   if (status == LUA_OK) {
533     lua_remove(L, -2);  /* remove modified line */
534     if (line[0] != '\0')  /* non empty? */
535       lua_saveline(L, line);  /* keep history */
536   }
537   else
538     lua_pop(L, 2);  /* pop result from 'luaL_loadbuffer' and modified line */
539   return status;
540 }
541 
542 
543 /*
544 ** Read multiple lines until a complete Lua statement
545 */
multiline(lua_State * L)546 static int multiline (lua_State *L) {
547   for (;;) {  /* repeat until gets a complete statement */
548     size_t len;
549     const char *line = lua_tolstring(L, 1, &len);  /* get what it has */
550     int status = luaL_loadbuffer(L, line, len, "=stdin");  /* try it */
551     if (!incomplete(L, status) || !pushline(L, 0)) {
552       lua_saveline(L, line);  /* keep history */
553       return status;  /* should not or cannot try to add continuation line */
554     }
555     lua_remove(L, -2);  /* remove error message (from incomplete line) */
556     lua_pushliteral(L, "\n");  /* add newline... */
557     lua_insert(L, -2);  /* ...between the two lines */
558     lua_concat(L, 3);  /* join them */
559   }
560 }
561 
562 
563 /*
564 ** Read a line and try to load (compile) it first as an expression (by
565 ** adding "return " in front of it) and second as a statement. Return
566 ** the final status of load/call with the resulting function (if any)
567 ** in the top of the stack.
568 */
loadline(lua_State * L)569 static int loadline (lua_State *L) {
570   int status;
571   lua_settop(L, 0);
572   if (!pushline(L, 1))
573     return -1;  /* no input */
574   if ((status = addreturn(L)) != LUA_OK)  /* 'return ...' did not work? */
575     status = multiline(L);  /* try as command, maybe with continuation lines */
576   lua_remove(L, 1);  /* remove line from the stack */
577   lua_assert(lua_gettop(L) == 1);
578   return status;
579 }
580 
581 
582 /*
583 ** Prints (calling the Lua 'print' function) any values on the stack
584 */
l_print(lua_State * L)585 static void l_print (lua_State *L) {
586   int n = lua_gettop(L);
587   if (n > 0) {  /* any result to be printed? */
588     luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
589     lua_getglobal(L, "print");
590     lua_insert(L, 1);
591     if (lua_pcall(L, n, 0, 0) != LUA_OK)
592       l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)",
593                                              lua_tostring(L, -1)));
594   }
595 }
596 
597 
598 /*
599 ** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
600 ** print any results.
601 */
doREPL(lua_State * L)602 static void doREPL (lua_State *L) {
603   int status;
604   const char *oldprogname = progname;
605   progname = NULL;  /* no 'progname' on errors in interactive mode */
606   lua_initreadline(L);
607   while ((status = loadline(L)) != -1) {
608     if (status == LUA_OK)
609       status = docall(L, 0, LUA_MULTRET);
610     if (status == LUA_OK) l_print(L);
611     else report(L, status);
612   }
613   lua_settop(L, 0);  /* clear stack */
614   lua_writeline();
615   progname = oldprogname;
616 }
617 
618 /* }================================================================== */
619 
620 
621 /*
622 ** Main body of stand-alone interpreter (to be called in protected mode).
623 ** Reads the options and handles them all.
624 */
pmain(lua_State * L)625 static int pmain (lua_State *L) {
626   int argc = (int)lua_tointeger(L, 1);
627   char **argv = (char **)lua_touserdata(L, 2);
628   int script;
629   int args = collectargs(argv, &script);
630   int optlim = (script > 0) ? script : argc; /* first argv not an option */
631   luaL_checkversion(L);  /* check that interpreter has correct version */
632   if (args == has_error) {  /* bad arg? */
633     print_usage(argv[script]);  /* 'script' has index of bad arg. */
634     return 0;
635   }
636   if (args & has_v)  /* option '-v'? */
637     print_version();
638   if (args & has_E) {  /* option '-E'? */
639     lua_pushboolean(L, 1);  /* signal for libraries to ignore env. vars. */
640     lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
641   }
642   luaL_openlibs(L);  /* open standard libraries */
643   createargtable(L, argv, argc, script);  /* create table 'arg' */
644   lua_gc(L, LUA_GCRESTART);  /* start GC... */
645   lua_gc(L, LUA_GCGEN, 0, 0);  /* ...in generational mode */
646   if (!(args & has_E)) {  /* no option '-E'? */
647     if (handle_luainit(L) != LUA_OK)  /* run LUA_INIT */
648       return 0;  /* error running LUA_INIT */
649   }
650   if (!runargs(L, argv, optlim))  /* execute arguments -e and -l */
651     return 0;  /* something failed */
652   if (script > 0) {  /* execute main script (if there is one) */
653     if (handle_script(L, argv + script) != LUA_OK)
654       return 0;  /* interrupt in case of error */
655   }
656   if (args & has_i)  /* -i option? */
657     doREPL(L);  /* do read-eval-print loop */
658   else if (script < 1 && !(args & (has_e | has_v))) { /* no active option? */
659     if (lua_stdin_is_tty()) {  /* running in interactive mode? */
660       print_version();
661       doREPL(L);  /* do read-eval-print loop */
662     }
663     else dofile(L, NULL);  /* executes stdin as a file */
664   }
665   lua_pushboolean(L, 1);  /* signal no errors */
666   return 1;
667 }
668 
669 
main(int argc,char ** argv)670 int main (int argc, char **argv) {
671   int status, result;
672   lua_State *L = luaL_newstate();  /* create state */
673   if (L == NULL) {
674     l_message(argv[0], "cannot create state: not enough memory");
675     return EXIT_FAILURE;
676   }
677   lua_gc(L, LUA_GCSTOP);  /* stop GC while building state */
678   lua_pushcfunction(L, &pmain);  /* to call 'pmain' in protected mode */
679   lua_pushinteger(L, argc);  /* 1st argument */
680   lua_pushlightuserdata(L, argv); /* 2nd argument */
681   status = lua_pcall(L, 2, 1, 0);  /* do the call */
682   result = lua_toboolean(L, -1);  /* get result */
683   report(L, status);
684   lua_close(L);
685   return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
686 }
687 
688