luaa: change looping detection algo (FS#488)

Signed-off-by: Julien Danjou <julien@danjou.info>
This commit is contained in:
Julien Danjou 2009-04-03 11:07:18 +02:00
parent 3bf7d2ba2b
commit 4605bf5d55
1 changed files with 51 additions and 23 deletions

74
luaa.c
View File

@ -552,7 +552,42 @@ luaA_hasitem(lua_State *L, const void *item)
return false; return false;
} }
/** Check if a table is a loop. When using table as direct acyclic digram, /** Browse a table pushed on top of the index, and put all its table and
* sub-table into an array.
* \param L The Lua VM state.
* \param elems The elements array.
* \return False if we encounter an elements already in list.
*/
static bool
luaA_isloop_check(lua_State *L, void_array_t *elems)
{
const void *object = lua_topointer(L, -1);
/* Check that the object table is not already in the list */
for(int i = 0; i < elems->len; i++)
if(elems->tab[i] == object)
return false;
/* push the table in the elements list */
void_array_append(elems, object);
/* look every object in the "table" */
lua_pushnil(L);
while(luaA_next(L, -2))
{
if(!luaA_isloop_check(L, elems))
{
/* remove key and value */
lua_pop(L, 2);
return false;
}
/* remove value, keep key for next iteration */
lua_pop(L, 1);
}
return true;
}
/** Check if a table is a loop. When using tables as direct acyclic digram,
* this is useful. * this is useful.
* \param L The Lua VM state. * \param L The Lua VM state.
* \param idx The index of the table in the stack * \param idx The index of the table in the stack
@ -561,28 +596,21 @@ luaA_hasitem(lua_State *L, const void *item)
bool bool
luaA_isloop(lua_State *L, int idx) luaA_isloop(lua_State *L, int idx)
{ {
if(lua_istable(L, idx)) /* elems is an elements array that we will fill with all array we
{ * encounter while browsing the tables */
lua_pushvalue(L, idx); /* push table on top */ void_array_t elems;
if(luaA_hasitem(L, lua_topointer(L, -1))) bool ret = false;
{
lua_pop(L, 1); /* remove pushed table */ void_array_init(&elems);
return true;
} /* push table on top */
lua_pushnil(L); lua_pushvalue(L, idx);
while(luaA_next(L, -2))
{ ret = luaA_isloop_check(L, &elems);
/* check for recursivity */
if(luaA_isloop(L, -1)) void_array_wipe(&elems);
{
lua_pop(L, 2); /* remove key and value */ return !ret;
return true;
}
lua_pop(L, 1); /* remove value */
}
lua_pop(L, 1); /* remove pushed table */
}
return false;
} }
/** Spawn a program. /** Spawn a program.