luabaselite.c

/*
Lua's base library contains a bunch of stuff I'd rather
not have available by default (dofile, setfenv, coroutine)
because they break the sandbox ckv tries to create. The safe
parts of Lua's standard library are reproduced in this file
almost exactly, and are covered under the license below.

All the unsafe libraries can be loaded by passing -a to ckv.
*/

/*
LICENSE FOR CODE BELOW COPIED FROM LUA'S SOURCE

Copyright (c) 1994–2008 Lua.org, PUC-Rio.

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated
documentation files (the "Software"), to deal in the
Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software,
and to permit persons to whom the Software is furnished to
do so, subject to the following conditions:

The above copyright notice and this permission notice shall
be included in all copies or substantial portions of the
Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include <stdlib.h>

#include "ckv.h"


static
int
ckv_tostring(lua_State *L)
{
	luaL_checkany(L, 1);
	if (luaL_callmeta(L, 1, "__tostring"))  /* is there a metafield? */
		return 1;  /* use its value */
	switch (lua_type(L, 1)) {
	case LUA_TNUMBER:
		lua_pushstring(L, lua_tostring(L, 1));
		break;
	case LUA_TSTRING:
		lua_pushvalue(L, 1);
		break;
	case LUA_TBOOLEAN:
		lua_pushstring(L, (lua_toboolean(L, 1) ? "true" : "false"));
		break;
	case LUA_TNIL:
		lua_pushliteral(L, "nil");
		break;
	default:
		lua_pushfstring(L, "%s: %p", luaL_typename(L, 1), lua_topointer(L, 1));
		break;
	}
	return 1;
}

static
int
ckv_print(lua_State *L)
{
	int n = lua_gettop(L);  /* number of arguments */
	int i;
	lua_getglobal(L, "tostring");
	for (i=1; i<=n; i++) {
		const char *s;
		lua_pushvalue(L, -1);  /* function to be called */
		lua_pushvalue(L, i);   /* value to print */
		lua_call(L, 1, 1);
		s = lua_tostring(L, -1);  /* get result */
		if (s == NULL)
			return luaL_error(L, LUA_QL("tostring") " must return a string to "
			                     LUA_QL("print"));
		if (i>1) fputs("\t", stdout);
		fputs(s, stdout);
		lua_pop(L, 1);  /* pop result */
	}
	fputs("\n", stdout);
	fflush(stdout);
	return 0;
}

static
int
ckv_type(lua_State *L)
{
	luaL_checkany(L, 1);
	lua_pushstring(L, luaL_typename(L, 1));
	return 1;
}

static
int
ckv_next(lua_State *L)
{
	luaL_checktype(L, 1, LUA_TTABLE);
	lua_settop(L, 2);  /* create a 2nd argument if there isn't one */
	if (lua_next(L, 1))
		return 2;
	else {
		lua_pushnil(L);
		return 1;
	}
}

static
int
ckv_pairs (lua_State *L)
{
	luaL_checktype(L, 1, LUA_TTABLE);
	lua_pushvalue(L, lua_upvalueindex(1));  /* return generator, */
	lua_pushvalue(L, 1);  /* state, */
	lua_pushnil(L);  /* and initial value */
	return 3;
}

static
int
ipairsaux(lua_State *L)
{
	int i = luaL_checkint(L, 2);
	luaL_checktype(L, 1, LUA_TTABLE);
	i++;  /* next value */
	lua_pushinteger(L, i);
	lua_rawgeti(L, 1, i);
	return (lua_isnil(L, -1)) ? 0 : 2;
}

static
int
ckv_ipairs(lua_State *L)
{
	luaL_checktype(L, 1, LUA_TTABLE);
	lua_pushvalue(L, lua_upvalueindex(1));  /* return generator, */
	lua_pushvalue(L, 1);  /* state, */
	lua_pushinteger(L, 0);  /* and initial value */
	return 3;
}

/* LIBRARY REGISTRATION */

static
const
luaL_Reg
luabaselite[] = {
	{ "tostring", ckv_tostring },
	{ "print", ckv_print },
	{ "type", ckv_type },
	{ "next", ckv_next },
	{ NULL, NULL }
};

static
void
auxopen(lua_State *L, const char *name, lua_CFunction f, lua_CFunction u)
{
	lua_pushcfunction(L, u);
	lua_pushcclosure(L, f, 1);
	lua_setfield(L, -2, name);
}

/* opens library */
int
open_luabaselite(lua_State *L)
{
	lua_pushvalue(L, LUA_GLOBALSINDEX);
	luaL_register(L, NULL, luabaselite);
	
	/* `ipairs' and `pairs' need auxliliary functions as upvalues */
	auxopen(L, "ipairs", ckv_ipairs, ipairsaux);
	auxopen(L, "pairs", ckv_pairs, ckv_next);
	
	return 1;
}