2 ** $Id: lua.c,v 1.226 2015/08/14 19:11:20 roberto Exp $
3 ** Lua stand-alone interpreter
4 ** See Copyright Notice in lua.h
23 #if !defined(LUA_PROMPT)
24 #define LUA_PROMPT "> "
25 #define LUA_PROMPT2 ">> "
28 #if !defined(LUA_PROGNAME)
29 #define LUA_PROGNAME "lua"
32 #if !defined(LUA_MAXINPUT)
33 #define LUA_MAXINPUT 512
36 #if !defined(LUA_INIT_VAR)
37 #define LUA_INIT_VAR "LUA_INIT"
40 #define LUA_INITVARVERSION \
41 LUA_INIT_VAR "_" LUA_VERSION_MAJOR "_" LUA_VERSION_MINOR
45 ** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
46 ** is, whether we're running lua interactively).
48 #if !defined(lua_stdin_is_tty) /* { */
50 #if defined(LUA_USE_POSIX) /* { */
53 #define lua_stdin_is_tty() isatty(0)
55 #elif defined(LUA_USE_WINDOWS) /* }{ */
58 #define lua_stdin_is_tty() _isatty(_fileno(stdin))
62 /* ISO C definition */
63 #define lua_stdin_is_tty() 1 /* assume stdin is a tty */
71 ** lua_readline defines how to show a prompt and then read a line from
72 ** the standard input.
73 ** lua_saveline defines how to "save" a read line in a "history".
74 ** lua_freeline defines how to free a line read by lua_readline.
76 #if !defined(lua_readline) /* { */
78 #if defined(LUA_USE_READLINE) /* { */
80 #include <readline/readline.h>
81 #include <readline/history.h>
82 #define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
83 #define lua_saveline(L,line) ((void)L, add_history(line))
84 #define lua_freeline(L,b) ((void)L, free(b))
88 #define lua_readline(L,b,p) \
89 ((void)L, fputs(p, stdout), fflush(stdout), /* show prompt */ \
90 fgets(b, LUA_MAXINPUT, stdin) != NULL) /* get line */
91 #define lua_saveline(L,line) { (void)L; (void)line; }
92 #define lua_freeline(L,b) { (void)L; (void)b; }
101 static lua_State *globalL = NULL;
103 static const char *progname = LUA_PROGNAME;
107 ** Hook set by signal function to stop the interpreter.
109 static void lstop (lua_State *L, lua_Debug *ar) {
110 (void)ar; /* unused arg. */
111 lua_sethook(L, NULL, 0, 0); /* reset hook */
112 luaL_error(L, "interrupted!");
117 ** Function to be called at a C signal. Because a C signal cannot
118 ** just change a Lua state (as there is no proper synchronization),
119 ** this function only sets a hook that, when called, will stop the
122 static void laction (int i) {
123 signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
124 lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
128 static void print_usage (const char *badoption) {
129 lua_writestringerror("%s: ", progname);
130 if (badoption[1] == 'e' || badoption[1] == 'l')
131 lua_writestringerror("'%s' needs argument\n", badoption);
133 lua_writestringerror("unrecognized option '%s'\n", badoption);
134 lua_writestringerror(
135 "usage: %s [options] [script [args]]\n"
136 "Available options are:\n"
137 " -e stat execute string 'stat'\n"
138 " -i enter interactive mode after executing 'script'\n"
139 " -l name require library 'name'\n"
140 " -v show version information\n"
141 " -E ignore environment variables\n"
142 " -- stop handling options\n"
143 " - stop handling options and execute stdin\n"
150 ** Prints an error message, adding the program name in front of it
153 static void l_message (const char *pname, const char *msg) {
154 if (pname) lua_writestringerror("%s: ", pname);
155 lua_writestringerror("%s\n", msg);
160 ** Check whether 'status' is not OK and, if so, prints the error
161 ** message on the top of the stack. It assumes that the error object
162 ** is a string, as it was either generated by Lua or by 'msghandler'.
164 static int report (lua_State *L, int status) {
165 if (status != LUA_OK) {
166 const char *msg = lua_tostring(L, -1);
167 l_message(progname, msg);
168 lua_pop(L, 1); /* remove message */
175 ** Message handler used to run all chunks
177 static int msghandler (lua_State *L) {
178 const char *msg = lua_tostring(L, 1);
179 if (msg == NULL) { /* is error object not a string? */
180 if (luaL_callmeta(L, 1, "__tostring") && /* does it have a metamethod */
181 lua_type(L, -1) == LUA_TSTRING) /* that produces a string? */
182 return 1; /* that is the message */
184 msg = lua_pushfstring(L, "(error object is a %s value)",
185 luaL_typename(L, 1));
187 luaL_traceback(L, L, msg, 1); /* append a standard traceback */
188 return 1; /* return the traceback */
193 ** Interface to 'lua_pcall', which sets appropriate message function
194 ** and C-signal handler. Used to run all chunks.
196 static int docall (lua_State *L, int narg, int nres) {
198 int base = lua_gettop(L) - narg; /* function index */
199 lua_pushcfunction(L, msghandler); /* push message handler */
200 lua_insert(L, base); /* put it under function and args */
201 globalL = L; /* to be available to 'laction' */
202 signal(SIGINT, laction); /* set C-signal handler */
203 status = lua_pcall(L, narg, nres, base);
204 signal(SIGINT, SIG_DFL); /* reset C-signal handler */
205 lua_remove(L, base); /* remove message handler from the stack */
210 static void print_version (void) {
211 lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));
217 ** Create the 'arg' table, which stores all arguments from the
218 ** command line ('argv'). It should be aligned so that, at index 0,
219 ** it has 'argv[script]', which is the script name. The arguments
220 ** to the script (everything after 'script') go to positive indices;
221 ** other arguments (before the script name) go to negative indices.
222 ** If there is no script name, assume interpreter's name as base.
224 static void createargtable (lua_State *L, char **argv, int argc, int script) {
226 if (script == argc) script = 0; /* no script name? */
227 narg = argc - (script + 1); /* number of positive indices */
228 lua_createtable(L, narg, script + 1);
229 for (i = 0; i < argc; i++) {
230 lua_pushstring(L, argv[i]);
231 lua_rawseti(L, -2, i - script);
233 lua_setglobal(L, "arg");
237 static int dochunk (lua_State *L, int status) {
238 if (status == LUA_OK) status = docall(L, 0, 0);
239 return report(L, status);
243 static int dofile (lua_State *L, const char *name) {
244 return dochunk(L, luaL_loadfile(L, name));
248 static int dostring (lua_State *L, const char *s, const char *name) {
249 return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
254 ** Calls 'require(name)' and stores the result in a global variable
255 ** with the given name.
257 static int dolibrary (lua_State *L, const char *name) {
259 lua_getglobal(L, "require");
260 lua_pushstring(L, name);
261 status = docall(L, 1, 1); /* call 'require(name)' */
262 if (status == LUA_OK)
263 lua_setglobal(L, name); /* global[name] = require return */
264 return report(L, status);
269 ** Returns the string to be used as a prompt by the interpreter.
271 static const char *get_prompt (lua_State *L, int firstline) {
273 lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
274 p = lua_tostring(L, -1);
275 if (p == NULL) p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
279 /* mark in error messages for incomplete statements */
280 #define EOFMARK "<eof>"
281 #define marklen (sizeof(EOFMARK)/sizeof(char) - 1)
285 ** Check whether 'status' signals a syntax error and the error
286 ** message at the top of the stack ends with the above mark for
287 ** incomplete statements.
289 static int incomplete (lua_State *L, int status) {
290 if (status == LUA_ERRSYNTAX) {
292 const char *msg = lua_tolstring(L, -1, &lmsg);
293 if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0) {
298 return 0; /* else... */
303 ** Prompt the user, read a line, and push it into the Lua stack.
305 static int pushline (lua_State *L, int firstline) {
306 char buffer[LUA_MAXINPUT];
309 const char *prmt = get_prompt(L, firstline);
310 int readstatus = lua_readline(L, b, prmt);
312 return 0; /* no input (prompt will be popped by caller) */
313 lua_pop(L, 1); /* remove prompt */
315 if (l > 0 && b[l-1] == '\n') /* line ends with newline? */
316 b[--l] = '\0'; /* remove it */
317 if (firstline && b[0] == '=') /* for compatibility with 5.2, ... */
318 lua_pushfstring(L, "return %s", b + 1); /* change '=' to 'return' */
320 lua_pushlstring(L, b, l);
327 ** Try to compile line on the stack as 'return <line>;'; on return, stack
328 ** has either compiled chunk or original line (if compilation failed).
330 static int addreturn (lua_State *L) {
331 const char *line = lua_tostring(L, -1); /* original line */
332 const char *retline = lua_pushfstring(L, "return %s;", line);
333 int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
334 if (status == LUA_OK) {
335 lua_remove(L, -2); /* remove modified line */
336 if (line[0] != '\0') /* non empty? */
337 lua_saveline(L, line); /* keep history */
340 lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */
346 ** Read multiple lines until a complete Lua statement
348 static int multiline (lua_State *L) {
349 for (;;) { /* repeat until gets a complete statement */
351 const char *line = lua_tolstring(L, 1, &len); /* get what it has */
352 int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */
353 if (!incomplete(L, status) || !pushline(L, 0)) {
354 lua_saveline(L, line); /* keep history */
355 return status; /* cannot or should not try to add continuation line */
357 lua_pushliteral(L, "\n"); /* add newline... */
358 lua_insert(L, -2); /* ...between the two lines */
359 lua_concat(L, 3); /* join them */
365 ** Read a line and try to load (compile) it first as an expression (by
366 ** adding "return " in front of it) and second as a statement. Return
367 ** the final status of load/call with the resulting function (if any)
368 ** in the top of the stack.
370 static int loadline (lua_State *L) {
374 return -1; /* no input */
375 if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */
376 status = multiline(L); /* try as command, maybe with continuation lines */
377 lua_remove(L, 1); /* remove line from the stack */
378 lua_assert(lua_gettop(L) == 1);
384 ** Prints (calling the Lua 'print' function) any values on the stack
386 static void l_print (lua_State *L) {
387 int n = lua_gettop(L);
388 if (n > 0) { /* any result to be printed? */
389 luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
390 lua_getglobal(L, "print");
392 if (lua_pcall(L, n, 0, 0) != LUA_OK)
393 l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)",
394 lua_tostring(L, -1)));
400 ** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
401 ** print any results.
403 static void doREPL (lua_State *L) {
405 const char *oldprogname = progname;
406 progname = NULL; /* no 'progname' on errors in interactive mode */
407 while ((status = loadline(L)) != -1) {
408 if (status == LUA_OK)
409 status = docall(L, 0, LUA_MULTRET);
410 if (status == LUA_OK) l_print(L);
411 else report(L, status);
413 lua_settop(L, 0); /* clear stack */
415 progname = oldprogname;
420 ** Push on the stack the contents of table 'arg' from 1 to #arg
422 static int pushargs (lua_State *L) {
424 if (lua_getglobal(L, "arg") != LUA_TTABLE)
425 luaL_error(L, "'arg' is not a table");
426 n = (int)luaL_len(L, -1);
427 luaL_checkstack(L, n + 3, "too many arguments to script");
428 for (i = 1; i <= n; i++)
429 lua_rawgeti(L, -i, i);
430 lua_remove(L, -i); /* remove table from the stack */
435 static int handle_script (lua_State *L, char **argv) {
437 const char *fname = argv[0];
438 if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
439 fname = NULL; /* stdin */
440 status = luaL_loadfile(L, fname);
441 if (status == LUA_OK) {
442 int n = pushargs(L); /* push arguments to script */
443 status = docall(L, n, LUA_MULTRET);
445 return report(L, status);
450 /* bits of various argument indicators in 'args' */
451 #define has_error 1 /* bad option */
452 #define has_i 2 /* -i */
453 #define has_v 4 /* -v */
454 #define has_e 8 /* -e */
455 #define has_E 16 /* -E */
458 ** Traverses all arguments from 'argv', returning a mask with those
459 ** needed before running any Lua code (or an error code if it finds
460 ** any invalid argument). 'first' returns the first not-handled argument
461 ** (either the script name or a bad argument in case of error).
463 static int collectargs (char **argv, int *first) {
466 for (i = 1; argv[i] != NULL; i++) {
468 if (argv[i][0] != '-') /* not an option? */
469 return args; /* stop handling options */
470 switch (argv[i][1]) { /* else check option */
472 if (argv[i][2] != '\0') /* extra characters after '--'? */
473 return has_error; /* invalid option */
477 return args; /* script "name" is '-' */
479 if (argv[i][2] != '\0') /* extra characters after 1st? */
480 return has_error; /* invalid option */
484 args |= has_i; /* (-i implies -v) *//* FALLTHROUGH */
486 if (argv[i][2] != '\0') /* extra characters after 1st? */
487 return has_error; /* invalid option */
491 args |= has_e; /* FALLTHROUGH */
492 case 'l': /* both options need an argument */
493 if (argv[i][2] == '\0') { /* no concatenated argument? */
494 i++; /* try next 'argv' */
495 if (argv[i] == NULL || argv[i][0] == '-')
496 return has_error; /* no next argument or it is another option */
499 default: /* invalid option */
503 *first = i; /* no script name */
509 ** Processes options 'e' and 'l', which involve running Lua code.
510 ** Returns 0 if some code raises an error.
512 static int runargs (lua_State *L, char **argv, int n) {
514 for (i = 1; i < n; i++) {
515 int option = argv[i][1];
516 lua_assert(argv[i][0] == '-'); /* already checked */
517 if (option == 'e' || option == 'l') {
519 const char *extra = argv[i] + 2; /* both options need an argument */
520 if (*extra == '\0') extra = argv[++i];
521 lua_assert(extra != NULL);
522 status = (option == 'e')
523 ? dostring(L, extra, "=(command line)")
524 : dolibrary(L, extra);
525 if (status != LUA_OK) return 0;
532 static int handle_luainit (lua_State *L) {
533 const char *name = "=" LUA_INITVARVERSION;
534 const char *init = getenv(name + 1);
536 name = "=" LUA_INIT_VAR;
537 init = getenv(name + 1); /* try alternative name */
539 if (init == NULL) return LUA_OK;
540 else if (init[0] == '@')
541 return dofile(L, init+1);
543 return dostring(L, init, name);
548 ** Main body of stand-alone interpreter (to be called in protected mode).
549 ** Reads the options and handles them all.
551 static int pmain (lua_State *L) {
552 int argc = (int)lua_tointeger(L, 1);
553 char **argv = (char **)lua_touserdata(L, 2);
555 int args = collectargs(argv, &script);
556 luaL_checkversion(L); /* check that interpreter has correct version */
557 if (argv[0] && argv[0][0]) progname = argv[0];
558 if (args == has_error) { /* bad arg? */
559 print_usage(argv[script]); /* 'script' has index of bad arg. */
562 if (args & has_v) /* option '-v'? */
564 if (args & has_E) { /* option '-E'? */
565 lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */
566 lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
568 luaL_openlibs(L); /* open standard libraries */
569 createargtable(L, argv, argc, script); /* create table 'arg' */
570 if (!(args & has_E)) { /* no option '-E'? */
571 if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
572 return 0; /* error running LUA_INIT */
574 if (!runargs(L, argv, script)) /* execute arguments -e and -l */
575 return 0; /* something failed */
576 if (script < argc && /* execute main script (if there is one) */
577 handle_script(L, argv + script) != LUA_OK)
579 if (args & has_i) /* -i option? */
580 doREPL(L); /* do read-eval-print loop */
581 else if (script == argc && !(args & (has_e | has_v))) { /* no arguments? */
582 if (lua_stdin_is_tty()) { /* running in interactive mode? */
584 doREPL(L); /* do read-eval-print loop */
586 else dofile(L, NULL); /* executes stdin as a file */
588 lua_pushboolean(L, 1); /* signal no errors */
593 int main (int argc, char **argv) {
595 lua_State *L = luaL_newstate(); /* create state */
597 l_message(argv[0], "cannot create state: not enough memory");
600 lua_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */
601 lua_pushinteger(L, argc); /* 1st argument */
602 lua_pushlightuserdata(L, argv); /* 2nd argument */
603 status = lua_pcall(L, 2, 1, 0); /* do the call */
604 result = lua_toboolean(L, -1); /* get result */
607 return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;