/* $NetBSD: lua.c,v 1.12 2023/06/08 21:12:08 nikita Exp $ */
/*
** 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"
#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME "lua"
#endif
#if !defined(LUA_INIT_VAR)
#define LUA_INIT_VAR "LUA_INIT"
#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. It assumes that the error object
** is a string, as it was either generated by Lua or by 'msghandler'.
*/
static int report (lua_State *L, int status) {
if (status != LUA_OK) {
const char *msg = lua_tostring(L, -1);
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_loadfile(L, name));
}
static int dostring (lua_State *L, const char *s, const char *name) {
return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
}
/*
** Receives 'globname[=modname]' and runs 'globname = require(modname)'.
*/
static int dolibrary (lua_State *L, char *globname) {
int status;
char *modname = strchr(globname, '=');
if (modname == NULL) /* no explicit name? */
modname = globname; /* module name is equal to global name */
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)
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_loadfile(L, fname);
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 */
*first = i + 1;
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;
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 int handle_luainit (lua_State *L) {
const char *name = "=" LUA_INITVARVERSION;
const char *init = getenv(name + 1);
if (init == NULL) {
name = "=" LUA_INIT_VAR;
init = 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 /* } */
#endif /* } */
/*
** 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) /* { */
#if defined(LUA_USE_READLINE) /* { */
#include <readline/readline.h>
#include <readline/history.h>
#define lua_initreadline(L) ((void)L, rl_readline_name="lua")
#define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
#define lua_saveline(L,line) ((void)L, add_history(line))
#define lua_freeline(L,b) ((void)L, free(b))
#else /* }{ */
#define lua_initreadline(L) ((void)L)
#define lua_readline(L,b,p) \
((void)L, fputs(p, stdout), fflush(stdout), /* show prompt */ \
fgets(b, LUA_MAXINPUT, stdin) != NULL) /* get line */
#define lua_saveline(L,line) { (void)L; (void)line; }
#define lua_freeline(L,b) { (void)L; (void)b; }
#endif /* } */
#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) {
lua_pop(L, 1);
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];
char *b = buffer;
size_t l;
const char *prmt = get_prompt(L, firstline);
int readstatus = lua_readline(L, b, prmt);
if (readstatus == 0)
return 0; /* no input (prompt will be popped by caller) */
lua_pop(L, 1); /* remove prompt */
l = strlen(b);
if (l > 0 && b[l-1] == '\n') /* line ends with newline? */
b[--l] = '\0'; /* remove it */
if (firstline && b[0] == '=') /* for compatibility with 5.2, ... */
lua_pushfstring(L, "return %s", b + 1); /* change '=' to 'return' */
else
lua_pushlstring(L, b, l);
lua_freeline(L, 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_loadbuffer(L, retline, strlen(retline), "=stdin");
if (status == LUA_OK) {
lua_remove(L, -2); /* remove modified line */
if (line[0] != '\0') /* non empty? */
lua_saveline(L, line); /* keep history */
}
else
lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */
return status;
}
/*
** Read multiple lines until a complete Lua statement
*/
static int multiline (lua_State *L) {
for (;;) { /* repeat until gets a complete statement */
size_t len;
const char *line = lua_tolstring(L, 1, &len); /* get what it has */
int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */
if (!incomplete(L, status) || !pushline(L, 0)) {
lua_saveline(L, line); /* keep history */
return status; /* cannot or should not try to add continuation line */
}
lua_pushliteral(L, "\n"); /* add newline... */
lua_insert(L, -2); /* ...between the two lines */
lua_concat(L, 3); /* join them */
}
}
/*
** 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) {
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 */
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;
}
/* }================================================================== */
/*
** 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'? */
lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */
lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
}
luaL_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, 0, 0); /* ...in generational mode */
if (!(args & has_E)) { /* no option '-E'? */
if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
return 0; /* error running LUA_INIT */
}
if (!runargs(L, argv, optlim)) /* execute arguments -e and -l */
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;
}