1 files changed, 438 insertions, 0 deletions
diff --git a/src/sysbin/lx/main.c b/src/sysbin/lx/main.c
new file mode 100644
index 0000000..ecfecd8
--- /dev/null
+++ b/src/sysbin/lx/main.c
@@ -0,0 +1,438 @@
+/*
+** 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>
+
+
+#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));
+}
+
+
+/*
+** Calls 'require(name)' and stores the result in a global variable
+** with the given name.
+*/
+int dolibrary (lua_State *L, const char *name) {
+  int status;
+  lua_getglobal(L, "require");
+  lua_pushstring(L, name);
+  status = docall(L, 1, 1);  /* call 'require(name)' */
+  if (status == LUA_OK)
+    lua_setglobal(L, name);  /* global[name] = require return */
+  return report(L, status);
+}
+
+
+/*
+** 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;
+}
+
+
+/*
+** Push on the stack the contents of table 'arg' from 1 to #arg
+*/
+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;
+}
+
+
+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);
+}
+
+
+
+int handle_luainit (lua_State *L) {
+  const char *name = "=" LUA_INITVARVERSION;
+  const char *init = LUA_INITSTR;
+
+  return dostring(L, init, name);
+}
+
+
+/*
+** Main body of stand-alone interpreter (to be called in protected mode).
+** Reads the options and handles them all.
+*/
+int pmain (lua_State *L) {
+  int status;
+  luaL_checkversion(L);  /* check that interpreter has correct version */
+
+  print_version();
+
+  luaL_openlibs(L);  /* open standard libraries */
+
+  if (handle_luainit(L) != LUA_OK)  /* run LUA_INIT */
+    return 0;  /* error running LUA_INIT */
+
+  lua_getglobal(L, "require");
+  lua_pushstring(L, "main");
+  status = docall(L, 1, 1);  /* call 'require("main")' */
+  if (status != LUA_OK) {
+    // no main, launch a REPL
+    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_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 :*/