/*
** lx: Lua Extended, based on the Lua stand-alone interpreter
*/
#define lua_c
#include <lua/lprefix.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <lua/lua.h>
#include <lua/lauxlib.h>
#include <lua/lualib.h>
#include "lxlib.h"
#define LUA_PROMPT "> "
#define LUA_PROMPT2 ">> "
#define LUA_PROGNAME "lx"
#define LUA_MAXINPUT 512
#define LUA_INIT_VAR "LUA_INIT"
#define LUA_INITVARVERSION \
LUA_INIT_VAR "_" LUA_VERSION_MAJOR "_" LUA_VERSION_MINOR
#define LUA_INITSTR "require 'lx.lxinit'"
/*
** 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>
#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.
*/
#include <readline/readline.h>
#include <readline/history.h>
#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))
lua_State *globalL = NULL;
const char *progname = LUA_PROGNAME;
/*
** Hook set by signal function to stop the interpreter.
*/
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.
*/
void laction (int i) {
signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
}
/*
** Prints an error message, adding the program name in front of it
** (if present)
*/
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'.
*/
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
*/
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.
*/
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' */
signal(SIGINT, laction); /* set C-signal handler */
status = lua_pcall(L, narg, nres, base);
signal(SIGINT, SIG_DFL); /* reset C-signal handler */
lua_remove(L, base); /* remove message handler from the stack */
return status;
}
void print_version (void) {
lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));
lua_writeline();
}
int dochunk (lua_State *L, int status) {
if (status == LUA_OK) status = docall(L, 0, 0);
return report(L, status);
}
int dofile (lua_State *L, const char *name) {
return dochunk(L, luaL_loadfile(L, name));
}
int dostring (lua_State *L, const char *s, const char *name) {
return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
}
/*
** Returns the string to be used as a prompt by the interpreter.
*/
const char *get_prompt (lua_State *L, int firstline) {
const char *p;
lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
p = lua_tostring(L, -1);
if (p == NULL) p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
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.
*/
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.
*/
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).
*/
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
*/
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.
*/
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
*/
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.
*/
void doREPL (lua_State *L) {
int status;
const char *oldprogname = progname;
progname = NULL; /* no 'progname' on errors in interactive mode */
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;
}
int handle_luainit (lua_State *L) {
const char *name = "=" LUA_INITVARVERSION;
const char *init = LUA_INITSTR;
return dostring(L, init, name);
}
bool find_lua_main(lua_State *L) {
lua_getglobal(L, "package");
if (lua_getfield(L, -1, "searchers") != LUA_TTABLE)
luaL_error(L, "'package.searchers' must be a table");
lua_remove(L, -2);
for (int i = 1; ; i++) {
if (lua_rawgeti(L, -1, i) == LUA_TNIL) { /* no more searchers? */
lua_pop(L, 2); // pop nil & searchers table
return false;
}
lua_pushstring(L, "main");
lua_call(L, 1, 2); /* call it */
if (lua_isfunction(L, -2)) /* did it find a loader? */
return true; /* module loader found */
else
lua_pop(L, 2); /* remove both returns */
}
}
int pmain (lua_State *L) {
luaL_checkversion(L); /* check that interpreter has correct version */
print_version();
luaL_openlibs(L); /* open standard libraries */
lx_openlibs(L);
if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
return 0; /* error running LUA_INIT */
if (find_lua_main(L)) {
// call loader
lua_pushstring(L, "main");
lua_insert(L, -2);
lua_call(L, 2, 1);
} else {
// no main, launch a REPL
if (lua_stdin_is_tty()) { /* running in interactive mode? */
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_pushcfunction(L, &pmain); /* to call 'pmain' in protected mode */
status = lua_pcall(L, 0, 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;
}
/* vim: set sts=2 ts=2 sw=2 tw=0 et :*/
