/*
* Return the registered ID function for 'index' (deep userdata proxy),
* or NULL if 'index' is not a deep userdata proxy.
*/
static inline luaG_IdFunction get_idfunc( lua_State* L, int index, enum eLookupMode mode_)
{
// when looking inside a keeper, we are 100% sure the object is a deep userdata
if( mode_ == eLM_FromKeeper)
{
DEEP_PRELUDE** proxy = (DEEP_PRELUDE**) lua_touserdata( L, index);
// we can (and must) cast and fetch the internally stored idfunc
return (*proxy)->idfunc;
}
else
{
// essentially we are making sure that the metatable of the object we want to copy is stored in our metatable/idfunc database
// it is the only way to ensure that the userdata is indeed a deep userdata!
// of course, we could just trust the caller, but we won't
luaG_IdFunction ret;
STACK_GROW( L, 1);
STACK_CHECK( L);
if( !lua_getmetatable( L, index)) // deep ... metatable?
{
return NULL; // no metatable: can't be a deep userdata object!
}
// replace metatable with the idfunc pointer, if it is actually a deep userdata
get_deep_lookup( L); // deep ... idfunc|nil
ret = (luaG_IdFunction) lua_touserdata( L, -1); // NULL if not a userdata
lua_pop( L, 1);
STACK_END( L, 0);
return ret;
}
}
/*
* Return the registered ID function for 'index' (deep userdata proxy),
* or NULL if 'index' is not a deep userdata proxy.
*/
static
lua_CFunction get_idfunc( lua_State *L, int index ) {
lua_CFunction ret;
index= STACK_ABS(L,index);
STACK_GROW(L,1);
STACK_CHECK(L)
if (!lua_getmetatable( L, index ))
return NULL; // no metatable
// [-1]: metatable of [index]
get_deep_lookup(L);
//
// [-1]: idfunc/nil
ret= lua_tocfunction(L,-1);
lua_pop(L,1);
STACK_END(L,0)
return ret;
}
/*
* Push a proxy userdata on the stack.
*
* Initializes necessary structures if it's the first time 'idfunc' is being
* used in this Lua state (metatable, registring it). Otherwise, increments the
* reference count.
*/
void luaG_push_proxy( lua_State *L, lua_CFunction idfunc, DEEP_PRELUDE *prelude ) {
DEEP_PRELUDE **proxy;
MUTEX_LOCK( &deep_lock );
++(prelude->refcount); // one more proxy pointing to this deep data
MUTEX_UNLOCK( &deep_lock );
STACK_GROW(L,4);
STACK_CHECK(L)
proxy= lua_newuserdata( L, sizeof( DEEP_PRELUDE* ) );
ASSERT_L(proxy);
*proxy= prelude;
// Get/create metatable for 'idfunc' (in this state)
//
lua_pushcfunction( L, idfunc ); // key
get_deep_lookup(L);
//
// [-2]: proxy
// [-1]: metatable / nil
if (lua_isnil(L,-1)) {
// No metatable yet; make one and register it
//
lua_pop(L,1);
// tbl= idfunc( "metatable" )
//
lua_pushcfunction( L, idfunc );
lua_pushliteral( L, "metatable" );
lua_call( L, 1 /*args*/, 1 /*results*/ );
//
// [-2]: proxy
// [-1]: metatable (returned by 'idfunc')
if (!lua_istable(L,-1))
luaL_error( L, "Bad idfunc on \"metatable\": did not return one" );
// Add '__gc' method
//
lua_pushcfunction( L, deep_userdata_gc );
lua_setfield( L, -2, "__gc" );
// Memorize for later rounds
//
lua_pushvalue( L,-1 );
lua_pushcfunction( L, idfunc );
//
// [-4]: proxy
// [-3]: metatable (2nd ref)
// [-2]: metatable
// [-1]: idfunc
set_deep_lookup(L);
}
STACK_MID(L,2)
ASSERT_L( lua_isuserdata(L,-2) );
ASSERT_L( lua_istable(L,-1) );
// [-2]: proxy userdata
// [-1]: metatable to use
lua_setmetatable( L, -2 );
STACK_END(L,1)
// [-1]: proxy userdata
}
/*
* Push a proxy userdata on the stack.
* returns NULL if ok, else some error string related to bad idfunc behavior or module require problem
* (error cannot happen with mode_ == eLM_ToKeeper)
*
* Initializes necessary structures if it's the first time 'idfunc' is being
* used in this Lua state (metatable, registring it). Otherwise, increments the
* reference count.
*/
char const* push_deep_proxy( struct s_Universe* U, lua_State* L, DEEP_PRELUDE* prelude, enum eLookupMode mode_)
{
DEEP_PRELUDE** proxy;
// Check if a proxy already exists
push_registry_subtable_mode( L, DEEP_PROXY_CACHE_KEY, "v"); // DPC
lua_pushlightuserdata( L, prelude->deep); // DPC deep
lua_rawget( L, -2); // DPC proxy
if ( !lua_isnil( L, -1))
{
lua_remove( L, -2); // proxy
return NULL;
}
else
{
lua_pop( L, 1); // DPC
}
MUTEX_LOCK( &U->deep_lock);
++ (prelude->refcount); // one more proxy pointing to this deep data
MUTEX_UNLOCK( &U->deep_lock);
STACK_GROW( L, 7);
STACK_CHECK( L);
proxy = lua_newuserdata( L, sizeof( DEEP_PRELUDE*)); // DPC proxy
ASSERT_L( proxy);
*proxy = prelude;
// Get/create metatable for 'idfunc' (in this state)
lua_pushlightuserdata( L, prelude->idfunc); // DPC proxy idfunc
get_deep_lookup( L); // DPC proxy metatable?
if( lua_isnil( L, -1)) // // No metatable yet.
{
char const* modname;
int oldtop = lua_gettop( L); // DPC proxy nil
lua_pop( L, 1); // DPC proxy
// 1 - make one and register it
if( mode_ != eLM_ToKeeper)
{
prelude->idfunc( L, eDO_metatable); // DPC proxy metatable deepversion
if( lua_gettop( L) - oldtop != 1 || !lua_istable( L, -2) || !lua_isstring( L, -1))
{
lua_settop( L, oldtop); // DPC proxy X
lua_pop( L, 3); //
return "Bad idfunc(eOP_metatable): unexpected pushed value";
}
luaG_pushdeepversion( L); // DPC proxy metatable deepversion deepversion
if( !lua501_equal( L, -1, -2))
{
lua_pop( L, 5); //
return "Bad idfunc(eOP_metatable): mismatched deep version";
}
lua_pop( L, 2); // DPC proxy metatable
// make sure the idfunc didn't export __gc, as we will store our own
lua_getfield( L, -1, "__gc"); // DPC proxy metatable __gc
if( !lua_isnil( L, -1))
{
lua_pop( L, 4); //
return "idfunc-created metatable shouldn't contain __gc";
}
lua_pop( L, 1); // DPC proxy metatable
}
else
{
// keepers need a minimal metatable that only contains __gc
lua_newtable( L); // DPC proxy metatable
}
// Add our own '__gc' method
lua_pushcfunction( L, deep_userdata_gc); // DPC proxy metatable __gc
lua_setfield( L, -2, "__gc"); // DPC proxy metatable
// Memorize for later rounds
lua_pushvalue( L, -1); // DPC proxy metatable metatable
lua_pushlightuserdata( L, prelude->idfunc); // DPC proxy metatable metatable idfunc
set_deep_lookup( L); // DPC proxy metatable
// 2 - cause the target state to require the module that exported the idfunc
// this is needed because we must make sure the shared library is still loaded as long as we hold a pointer on the idfunc
{
int oldtop = lua_gettop( L);
modname = (char const*) prelude->idfunc( L, eDO_module); // DPC proxy metatable
// make sure the function pushed nothing on the stack!
if( lua_gettop( L) - oldtop != 0)
{
lua_pop( L, 3); //
return "Bad idfunc(eOP_module): should not push anything";
}
}
if( modname) // we actually got a module name
{
// somehow, L.registry._LOADED can exist without having registered the 'package' library.
lua_getglobal( L, "require"); // DPC proxy metatable require()
// check that the module is already loaded (or being loaded, we are happy either way)
if( lua_isfunction( L, -1))
{
lua_pushstring( L, modname); // DPC proxy metatable require() "module"
lua_getfield( L, LUA_REGISTRYINDEX, "_LOADED"); // DPC proxy metatable require() "module" _R._LOADED
if( lua_istable( L, -1))
{
bool_t alreadyloaded;
lua_pushvalue( L, -2); // DPC proxy metatable require() "module" _R._LOADED "module"
lua_rawget( L, -2); // DPC proxy metatable require() "module" _R._LOADED module
alreadyloaded = lua_toboolean( L, -1);
if( !alreadyloaded) // not loaded
{
int require_result;
lua_pop( L, 2); // DPC proxy metatable require() "module"
// require "modname"
require_result = lua_pcall( L, 1, 0, 0); // DPC proxy metatable error?
if( require_result != LUA_OK)
{
// failed, return the error message
lua_pushfstring( L, "error while requiring '%s' identified by idfunc(eOP_module): ", modname);
lua_insert( L, -2); // DPC proxy metatable prefix error
lua_concat( L, 2); // DPC proxy metatable error
return lua_tostring( L, -1);
}
}
else // already loaded, we are happy
{
lua_pop( L, 4); // DPC proxy metatable
}
}
else // no L.registry._LOADED; can this ever happen?
{
lua_pop( L, 6); //
return "unexpected error while requiring a module identified by idfunc(eOP_module)";
}
}
else // a module name, but no require() function :-(
{
lua_pop( L, 4); //
return "lanes receiving deep userdata should register the 'package' library";
}
}
}
STACK_MID( L, 2); // DPC proxy metatable
ASSERT_L( lua_isuserdata( L, -2));
ASSERT_L( lua_istable( L, -1));
lua_setmetatable( L, -2); // DPC proxy
// If we're here, we obviously had to create a new proxy, so cache it.
lua_pushlightuserdata( L, (*proxy)->deep); // DPC proxy deep
lua_pushvalue( L, -2); // DPC proxy deep proxy
lua_rawset( L, -4); // DPC proxy
lua_remove( L, -2); // proxy
ASSERT_L( lua_isuserdata( L, -1));
STACK_END( L, 0);
return NULL;
}
