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** $Id: lua.c $

** Lua stand-alone interpreter

** See Copyright Notice in lua.h

#define lua_c

#include "lprefix.h"

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <signal.h>

#include "lua.h"

#include "lauxlib.h"

#include "lualib.h"

#include "llimits.h"

#if !defined(LUA_PROGNAME)

#define LUA_PROGNAME "lua"

#endif

#if !defined(LUA_INIT_VAR)

#define LUA_INIT_VAR "LUA_INIT"

#endif

/* Name of the environment variable with the name of the readline library */

#if !defined(LUA_RLLIB_VAR)

#define LUA_RLLIB_VAR "LUA_READLINELIB"

#endif

#define LUA_INITVARVERSION LUA_INIT_VAR LUA_VERSUFFIX

static lua_State *globalL = NULL;

static const char *progname = LUA_PROGNAME;

#if defined(LUA_USE_POSIX) /* { */

** Use 'sigaction' when available.

static void setsignal (int sig, void (*handler)(int)) {

struct sigaction sa;

sa.sa_handler = handler;

sa.sa_flags = 0;

sigemptyset(&sa.sa_mask); /* do not mask any signal */

sigaction(sig, &sa, NULL);

}

#else /* }{ */

#define setsignal signal

#endif /* } */

** Hook set by signal function to stop the interpreter.

static void lstop (lua_State *L, lua_Debug *ar) {

(void)ar; /* unused arg. */

lua_sethook(L, NULL, 0, 0); /* reset hook */

luaL_error(L, "interrupted!");

}

** Function to be called at a C signal. Because a C signal cannot

** just change a Lua state (as there is no proper synchronization),

** this function only sets a hook that, when called, will stop the

** interpreter.

static void laction (int i) {

int flag = LUA_MASKCALL | LUA_MASKRET | LUA_MASKLINE | LUA_MASKCOUNT;

setsignal(i, SIG_DFL); /* if another SIGINT happens, terminate process */

lua_sethook(globalL, lstop, flag, 1);

}

static void print_usage (const char *badoption) {

lua_writestringerror("%s: ", progname);

if (badoption[1] == 'e' || badoption[1] == 'l')

lua_writestringerror("'%s' needs argument\n", badoption);

else

lua_writestringerror("unrecognized option '%s'\n", badoption);

lua_writestringerror(

"usage: %s [options] [script [args]]\n"

"Available options are:\n"

" -e stat execute string 'stat'\n"

" -i enter interactive mode after executing 'script'\n"

" -l mod require library 'mod' into global 'mod'\n"

" -l g=mod require library 'mod' into global 'g'\n"

" -v show version information\n"

" -E ignore environment variables\n"

" -W turn warnings on\n"

" -- stop handling options\n"

" - stop handling options and execute stdin\n"

progname);

}

** Prints an error message, adding the program name in front of it

** (if present)

static void l_message (const char *pname, const char *msg) {

if (pname) lua_writestringerror("%s: ", pname);

lua_writestringerror("%s\n", msg);

}

** Check whether 'status' is not OK and, if so, prints the error

** message on the top of the stack.

static int report (lua_State *L, int status) {

if (status != LUA_OK) {

const char *msg = lua_tostring(L, -1);

if (msg == NULL)

msg = "(error message not a string)";

l_message(progname, msg);

lua_pop(L, 1); /* remove message */

}

return status;

}

** Message handler used to run all chunks

static int msghandler (lua_State *L) {

const char *msg = lua_tostring(L, 1);

if (msg == NULL) { /* is error object not a string? */

if (luaL_callmeta(L, 1, "__tostring") && /* does it have a metamethod */

lua_type(L, -1) == LUA_TSTRING) /* that produces a string? */

return 1; /* that is the message */

else

msg = lua_pushfstring(L, "(error object is a %s value)",

luaL_typename(L, 1));

}

luaL_traceback(L, L, msg, 1); /* append a standard traceback */

return 1; /* return the traceback */

}

** Interface to 'lua_pcall', which sets appropriate message function

** and C-signal handler. Used to run all chunks.

static int docall (lua_State *L, int narg, int nres) {

int status;

int base = lua_gettop(L) - narg; /* function index */

lua_pushcfunction(L, msghandler); /* push message handler */

lua_insert(L, base); /* put it under function and args */

globalL = L; /* to be available to 'laction' */

setsignal(SIGINT, laction); /* set C-signal handler */

status = lua_pcall(L, narg, nres, base);

setsignal(SIGINT, SIG_DFL); /* reset C-signal handler */

lua_remove(L, base); /* remove message handler from the stack */

return status;

}

static void print_version (void) {

lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));

lua_writeline();

}

** Create the 'arg' table, which stores all arguments from the

** command line ('argv'). It should be aligned so that, at index 0,

** it has 'argv[script]', which is the script name. The arguments

** to the script (everything after 'script') go to positive indices;

** other arguments (before the script name) go to negative indices.

** If there is no script name, assume interpreter's name as base.

** (If there is no interpreter's name either, 'script' is -1, so

** table sizes are zero.)

static void createargtable (lua_State *L, char **argv, int argc, int script) {

int i, narg;

narg = argc - (script + 1); /* number of positive indices */

lua_createtable(L, narg, script + 1);

for (i = 0; i < argc; i++) {

lua_pushstring(L, argv[i]);

lua_rawseti(L, -2, i - script);

}

lua_setglobal(L, "arg");

}

static int dochunk (lua_State *L, int status) {

if (status == LUA_OK) status = docall(L, 0, 0);

return report(L, status);

}

static int dofile (lua_State *L, const char *name) {

return dochunk(L, luaL_loadfilex(L, name, "bt"));

}

static int dostring (lua_State *L, const char *s, const char *name) {

return dochunk(L, luaL_loadbufferx(L, s, strlen(s), name, "t"));

}

** Receives 'globname[=modname]' and runs 'globname = require(modname)'.

** If there is no explicit modname and globname contains a '-', cut

** the suffix after '-' (the "version") to make the global name.

static int dolibrary (lua_State *L, char *globname) {

int status;

char *suffix = NULL;

char *modname = strchr(globname, '=');

if (modname == NULL) { /* no explicit name? */

modname = globname; /* module name is equal to global name */

suffix = strchr(modname, *LUA_IGMARK); /* look for a suffix mark */

}

else {

*modname = '\0'; /* global name ends here */

modname++; /* module name starts after the '=' */

}

lua_getglobal(L, "require");

lua_pushstring(L, modname);

status = docall(L, 1, 1); /* call 'require(modname)' */

if (status == LUA_OK) {

if (suffix != NULL) /* is there a suffix mark? */

*suffix = '\0'; /* remove suffix from global name */

lua_setglobal(L, globname); /* globname = require(modname) */

}

return report(L, status);

}

** Push on the stack the contents of table 'arg' from 1 to #arg

static int pushargs (lua_State *L) {

int i, n;

if (lua_getglobal(L, "arg") != LUA_TTABLE)

luaL_error(L, "'arg' is not a table");

n = (int)luaL_len(L, -1);

luaL_checkstack(L, n + 3, "too many arguments to script");

for (i = 1; i <= n; i++)

lua_rawgeti(L, -i, i);

lua_remove(L, -i); /* remove table from the stack */

return n;

}

static int handle_script (lua_State *L, char **argv) {

int status;

const char *fname = argv[0];

if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)

fname = NULL; /* stdin */

status = luaL_loadfilex(L, fname, "bt");

if (status == LUA_OK) {

int n = pushargs(L); /* push arguments to script */

status = docall(L, n, LUA_MULTRET);

}

return report(L, status);

}

/* bits of various argument indicators in 'args' */

#define has_error 1 /* bad option */

#define has_i 2 /* -i */

#define has_v 4 /* -v */

#define has_e 8 /* -e */

#define has_E 16 /* -E */

** Traverses all arguments from 'argv', returning a mask with those

** needed before running any Lua code or an error code if it finds any

** invalid argument. In case of error, 'first' is the index of the bad

** argument. Otherwise, 'first' is -1 if there is no program name,

** 0 if there is no script name, or the index of the script name.

static int collectargs (char **argv, int *first) {

int args = 0;

int i;

if (argv[0] != NULL) { /* is there a program name? */

if (argv[0][0]) /* not empty? */

progname = argv[0]; /* save it */

}

else { /* no program name */

*first = -1;

return 0;

}

for (i = 1; argv[i] != NULL; i++) { /* handle arguments */

*first = i;

if (argv[i][0] != '-') /* not an option? */

return args; /* stop handling options */

switch (argv[i][1]) { /* else check option */

case '-': /* '--' */

if (argv[i][2] != '\0') /* extra characters after '--'? */

return has_error; /* invalid option */

/* if there is a script name, it comes after '--' */

*first = (argv[i + 1] != NULL) ? i + 1 : 0;

return args;

case '\0': /* '-' */

return args; /* script "name" is '-' */

case 'E':

if (argv[i][2] != '\0') /* extra characters? */

return has_error; /* invalid option */

args |= has_E;

break;

case 'W':

if (argv[i][2] != '\0') /* extra characters? */

return has_error; /* invalid option */

break;

case 'i':

args |= has_i; /* (-i implies -v) *//* FALLTHROUGH */

case 'v':

if (argv[i][2] != '\0') /* extra characters? */

return has_error; /* invalid option */

args |= has_v;

break;

case 'e':

args |= has_e; /* FALLTHROUGH */

case 'l': /* both options need an argument */

if (argv[i][2] == '\0') { /* no concatenated argument? */

i++; /* try next 'argv' */

if (argv[i] == NULL || argv[i][0] == '-')

return has_error; /* no next argument or it is another option */

}

break;

default: /* invalid option */

return has_error;

}

*first = 0; /* no script name */

return args;

}

** Processes options 'e' and 'l', which involve running Lua code, and

** 'W', which also affects the state.

** Returns 0 if some code raises an error.

static int runargs (lua_State *L, char **argv, int n) {

int i;

lua_warning(L, "@off", 0); /* by default, Lua stand-alone has warnings off */

for (i = 1; i < n; i++) {

int option = argv[i][1];

lua_assert(argv[i][0] == '-'); /* already checked */

switch (option) {

case 'e': case 'l': {

int status;

char *extra = argv[i] + 2; /* both options need an argument */

if (*extra == '\0') extra = argv[++i];

lua_assert(extra != NULL);

status = (option == 'e')

? dostring(L, extra, "=(command line)")

: dolibrary(L, extra);

if (status != LUA_OK) return 0;

break;

}

case 'W':

lua_warning(L, "@on", 0); /* warnings on */

break;

}

return 1;

}

static char *(*l_getenv)(const char *name);

/* Function to ignore environment variables, used by option -E */

static char *no_getenv (const char *name) {

UNUSED(name);

return NULL;

}

static int handle_luainit (lua_State *L) {

const char *name = "=" LUA_INITVARVERSION;

const char *init = l_getenv(name + 1);

if (init == NULL) {

name = "=" LUA_INIT_VAR;

init = l_getenv(name + 1); /* try alternative name */

}

if (init == NULL) return LUA_OK;

else if (init[0] == '@')

return dofile(L, init+1);

else

return dostring(L, init, name);

}

** {==================================================================

** Read-Eval-Print Loop (REPL)

** ===================================================================

#if !defined(LUA_PROMPT)

#define LUA_PROMPT "> "

#define LUA_PROMPT2 ">> "

#endif

#if !defined(LUA_MAXINPUT)

#define LUA_MAXINPUT 512

#endif

** lua_stdin_is_tty detects whether the standard input is a 'tty' (that

** is, whether we're running lua interactively).

#if !defined(lua_stdin_is_tty) /* { */

#if defined(LUA_USE_POSIX) /* { */

#include <unistd.h>

#define lua_stdin_is_tty() isatty(0)

#elif defined(LUA_USE_WINDOWS) /* }{ */

#include <io.h>

#include <windows.h>

#define lua_stdin_is_tty() _isatty(_fileno(stdin))

#else /* }{ */

/* ISO C definition */

#define lua_stdin_is_tty() 1 /* assume stdin is a tty */

#endif /* } */

** * lua_initreadline initializes the readline system.

** * lua_readline defines how to show a prompt and then read a line from

** the standard input.

** * lua_saveline defines how to "save" a read line in a "history".

** * lua_freeline defines how to free a line read by lua_readline.

#if !defined(lua_readline) /* { */

/* Otherwise, all previously listed functions should be defined. */

#if defined(LUA_USE_READLINE) /* { */

/* Lua will be linked with '-lreadline' */

#include <readline/readline.h>

#include <readline/history.h>

#define lua_initreadline(L) ((void)L, rl_readline_name="lua")

#define lua_readline(buff,prompt) ((void)buff, readline(prompt))

#define lua_saveline(line) add_history(line)

#define lua_freeline(line) free(line)

#else /* }{ */

/* use dynamically loaded readline (or nothing) */

/* pointer to 'readline' function (if any) */

typedef char *(*l_readlineT) (const char *prompt);

static l_readlineT l_readline = NULL;

/* pointer to 'add_history' function (if any) */

typedef void (*l_addhistT) (const char *string);

static l_addhistT l_addhist = NULL;

static char *lua_readline (char *buff, const char *prompt) {

if (l_readline != NULL) /* is there a 'readline'? */

return (*l_readline)(prompt); /* use it */

else { /* emulate 'readline' over 'buff' */

fputs(prompt, stdout);

fflush(stdout); /* show prompt */

return fgets(buff, LUA_MAXINPUT, stdin); /* read line */

}

static void lua_saveline (const char *line) {

if (l_addhist != NULL) /* is there an 'add_history'? */

(*l_addhist)(line); /* use it */

/* else nothing to be done */

}

static void lua_freeline (char *line) {

if (l_readline != NULL) /* is there a 'readline'? */

free(line); /* free line created by it */

/* else 'lua_readline' used an automatic buffer; nothing to free */

}

#if defined(LUA_USE_DLOPEN) && defined(LUA_READLINELIB) /* { */

/* try to load 'readline' dynamically */

#include <dlfcn.h>

static void lua_initreadline (lua_State *L) {

const char *rllib = l_getenv(LUA_RLLIB_VAR); /* name of readline library */

void *lib; /* library handle */

if (rllib == NULL) /* no environment variable? */

rllib = LUA_READLINELIB; /* use default name */

lib = dlopen(rllib, RTLD_NOW | RTLD_LOCAL);

if (lib != NULL) {

const char **name = cast(const char**, dlsym(lib, "rl_readline_name"));

if (name != NULL)

*name = "lua";

l_readline = cast(l_readlineT, cast_func(dlsym(lib, "readline")));

l_addhist = cast(l_addhistT, cast_func(dlsym(lib, "add_history")));

if (l_readline != NULL) /* could load readline function? */

return; /* everything ok */

/* else emit a warning */

}

lua_warning(L, "unable to load readline library '", 1);

lua_warning(L, rllib, 1);

lua_warning(L, "'", 0);

}

#else /* }{ */

/* no dlopen or LUA_READLINELIB undefined */

/* Leave pointers with NULL */

#define lua_initreadline(L) ((void)L)

#endif /* } */

** Return the string to be used as a prompt by the interpreter. Leave

** the string (or nil, if using the default value) on the stack, to keep

** it anchored.

static const char *get_prompt (lua_State *L, int firstline) {

if (lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2") == LUA_TNIL)

return (firstline ? LUA_PROMPT : LUA_PROMPT2); /* use the default */

else { /* apply 'tostring' over the value */

const char *p = luaL_tolstring(L, -1, NULL);

lua_remove(L, -2); /* remove original value */

return p;

}

/* mark in error messages for incomplete statements */

#define EOFMARK "<eof>"

#define marklen (sizeof(EOFMARK)/sizeof(char) - 1)

** Check whether 'status' signals a syntax error and the error

** message at the top of the stack ends with the above mark for

** incomplete statements.

static int incomplete (lua_State *L, int status) {

if (status == LUA_ERRSYNTAX) {

size_t lmsg;

const char *msg = lua_tolstring(L, -1, &lmsg);

if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0)

return 1;

}

return 0; /* else... */

}

** Prompt the user, read a line, and push it into the Lua stack.

static int pushline (lua_State *L, int firstline) {

char buffer[LUA_MAXINPUT];

size_t l;

const char *prmt = get_prompt(L, firstline);

char *b = lua_readline(buffer, prmt);

lua_pop(L, 1); /* remove prompt */

if (b == NULL)

return 0; /* no input */

l = strlen(b);

if (l > 0 && b[l-1] == '\n') /* line ends with newline? */

b[--l] = '\0'; /* remove it */

lua_pushlstring(L, b, l);

lua_freeline(b);

return 1;

}

** Try to compile line on the stack as 'return <line>;'; on return, stack

** has either compiled chunk or original line (if compilation failed).

static int addreturn (lua_State *L) {

const char *line = lua_tostring(L, -1); /* original line */

const char *retline = lua_pushfstring(L, "return %s;", line);

int status = luaL_loadbufferx(L, retline, strlen(retline), "=stdin", "t");

if (status == LUA_OK)

lua_remove(L, -2); /* remove modified line */

else

lua_pop(L, 2); /* pop result from 'luaL_loadbufferx' and modified line */

return status;

}

static void checklocal (const char *line) {

static const size_t szloc = sizeof("local") - 1;

static const char space[] = " \t";

line += strspn(line, space); /* skip spaces */

if (strncmp(line, "local", szloc) == 0 && /* "local"? */

strchr(space, *(line + szloc)) != NULL) { /* followed by a space? */

lua_writestringerror("%s\n",

"warning: locals do not survive across lines in interactive mode");

}

** Read multiple lines until a complete Lua statement or an error not

** for an incomplete statement. Start with first line already read in

** the stack.

static int multiline (lua_State *L) {

size_t len;

const char *line = lua_tolstring(L, 1, &len); /* get first line */

checklocal(line);

for (;;) { /* repeat until gets a complete statement */

int status = luaL_loadbufferx(L, line, len, "=stdin", "t"); /* try it */

if (!incomplete(L, status) || !pushline(L, 0))

return status; /* should not or cannot try to add continuation line */

lua_remove(L, -2); /* remove error message (from incomplete line) */

lua_pushliteral(L, "\n"); /* add newline... */

lua_insert(L, -2); /* ...between the two lines */

lua_concat(L, 3); /* join them */

line = lua_tolstring(L, 1, &len); /* get what is has */

}

** Read a line and try to load (compile) it first as an expression (by

** adding "return " in front of it) and second as a statement. Return

** the final status of load/call with the resulting function (if any)

** in the top of the stack.

static int loadline (lua_State *L) {

const char *line;

int status;

lua_settop(L, 0);

if (!pushline(L, 1))

return -1; /* no input */

if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */

status = multiline(L); /* try as command, maybe with continuation lines */

line = lua_tostring(L, 1);

if (line[0] != '\0') /* non empty? */

lua_saveline(line); /* keep history */

lua_remove(L, 1); /* remove line from the stack */

lua_assert(lua_gettop(L) == 1);

return status;

}

** Prints (calling the Lua 'print' function) any values on the stack

static void l_print (lua_State *L) {

int n = lua_gettop(L);

if (n > 0) { /* any result to be printed? */

luaL_checkstack(L, LUA_MINSTACK, "too many results to print");

lua_getglobal(L, "print");

lua_insert(L, 1);

if (lua_pcall(L, n, 0, 0) != LUA_OK)

l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)",

lua_tostring(L, -1)));

}

** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and

** print any results.

static void doREPL (lua_State *L) {

int status;

const char *oldprogname = progname;

progname = NULL; /* no 'progname' on errors in interactive mode */

lua_initreadline(L);

while ((status = loadline(L)) != -1) {

if (status == LUA_OK)

status = docall(L, 0, LUA_MULTRET);

if (status == LUA_OK) l_print(L);

else report(L, status);

}

lua_settop(L, 0); /* clear stack */

lua_writeline();

progname = oldprogname;

}

/* }================================================================== */

#if !defined(luai_openlibs)

#if defined(LUA_NODEBUGLIB)

/* With this option, code must require the debug library before using it */

#define luai_openlibs(L) luaL_openselectedlibs(L, ~LUA_DBLIBK, LUA_DBLIBK)

#else

/* The default is to open all standard libraries */

#define luai_openlibs(L) luaL_openselectedlibs(L, ~0, 0)

#endif

** Main body of stand-alone interpreter (to be called in protected mode).

** Reads the options and handles them all.

static int pmain (lua_State *L) {

int argc = (int)lua_tointeger(L, 1);

char **argv = (char **)lua_touserdata(L, 2);

int script;

int args = collectargs(argv, &script);

int optlim = (script > 0) ? script : argc; /* first argv not an option */

luaL_checkversion(L); /* check that interpreter has correct version */

if (args == has_error) { /* bad arg? */

print_usage(argv[script]); /* 'script' has index of bad arg. */

return 0;

}

if (args & has_v) /* option '-v'? */

print_version();

if (args & has_E) { /* option '-E'? */

l_getenv = &no_getenv; /* program will ignore environment variables */

lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */

lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");

}

else

l_getenv = &getenv;

luai_openlibs(L); /* open standard libraries */

createargtable(L, argv, argc, script); /* create table 'arg' */

lua_gc(L, LUA_GCRESTART); /* start GC... */

lua_gc(L, LUA_GCGEN); /* ...in generational mode */

if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */

return 0; /* error running LUA_INIT */

if (!runargs(L, argv, optlim)) /* execute arguments -e, -l, and -W */

return 0; /* something failed */

if (script > 0) { /* execute main script (if there is one) */

if (handle_script(L, argv + script) != LUA_OK)

return 0; /* interrupt in case of error */

}

if (args & has_i) /* -i option? */

doREPL(L); /* do read-eval-print loop */

else if (script < 1 && !(args & (has_e | has_v))) { /* no active option? */

if (lua_stdin_is_tty()) { /* running in interactive mode? */

print_version();

doREPL(L); /* do read-eval-print loop */

}

else dofile(L, NULL); /* executes stdin as a file */

}

lua_pushboolean(L, 1); /* signal no errors */

return 1;

}

int main (int argc, char **argv) {

int status, result;

lua_State *L = luaL_newstate(); /* create state */

if (L == NULL) {

l_message(argv[0], "cannot create state: not enough memory");

return EXIT_FAILURE;

}

lua_gc(L, LUA_GCSTOP); /* stop GC while building state */

lua_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */

lua_pushinteger(L, argc); /* 1st argument */

lua_pushlightuserdata(L, argv); /* 2nd argument */

status = lua_pcall(L, 2, 1, 0); /* do the call */

result = lua_toboolean(L, -1); /* get result */

report(L, status);

lua_close(L);

return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;

}

lua/lua.c at master · lua/lua · GitHub

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