Add checks for whether references to tables and userdata are valid

src/luerl.hrl

@@ -1,4 +1,4 @@
-%% Copyright (c) 2013-2019 Robert Virding
+%% Copyright (c) 2013-2024 Robert Virding
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -111,10 +111,10 @@
 		  body}).			%Code block
 -define(IS_LUAFUNC(F), is_record(F, lua_func)).
 
--record(erl_func,{code}).			%Erlang code (fun)
+-record(erl_func,{code}).                       %Erlang code (fun)
 -define(IS_ERLFUNC(F), is_record(F, erl_func)).
 
--record(erl_mfa,{m,f,a}).           %Erlang code (MFA)
+-record(erl_mfa,{m,f,a}).                       %Erlang code (MFA)
 -define(IS_ERLMFA(F), is_record(F, erl_mfa)).
 
 %% Test if it a function, of either sort.
@@ -145,28 +145,31 @@
 -define(SET_TABLE(N, T, Ts), maps:put(N, T, Ts)).
 -define(UPD_TABLE(N, Upd, Ts), maps:update_with(N, Upd, Ts)).
 -define(DEL_TABLE(N, Ts), maps:remove(N, Ts)).
+-define(CHK_TABLE(N, Ts), maps:is_key(N, Ts)).
 -define(FILTER_TABLES(Pred, Ts), maps:filter(Pred, Ts)).
 -define(FOLD_TABLES(Fun, Acc, Ts), maps:fold(Fun, Acc, Ts)).
 -endif.
 
 -ifdef(TS_USE_ARRAY).
-%% Use arrays to handle tables.
+%% Use arrays to handle tables. We leave the default value as undefined.
 -define(MAKE_TABLE(), array:new()).
 -define(GET_TABLE(N, Ar), array:get(N, Ar)).
 -define(SET_TABLE(N, T, Ar), array:set(N, T, Ar)).
 -define(UPD_TABLE(N, Upd, Ar),
-	array:set(N, (Upd)(array:get(N, Ar)), Ar)).
+        array:set(N, (Upd)(array:get(N, Ar)), Ar)).
 -define(DEL_TABLE(N, Ar), array:reset(N, Ar)).
+-define(CHK_TABLE(N, Ar),
+        ((N >= 0) andalso (array:get(N, Ar) =/= undefined))).
 -define(FILTER_TABLES(Pred, Ar),
-	((fun (___Def) ->
-		  ___Fil = fun (___K, ___V) ->
-				   case Pred(___K, ___V) of
-				       true -> ___V;
-				       false -> ___Def
-				   end
-			   end,
-		  array:sparse_map(___Fil, Ar)
-	  end)(array:default(Ar)))).
+        ((fun (___Def) ->
+                  ___Fil = fun (___K, ___V) ->
+                                   case Pred(___K, ___V) of
+                                       true -> ___V;
+                                       false -> ___Def
+                                   end
+                           end,
+                  array:sparse_map(___Fil, Ar)
+          end)(array:default(Ar)))).
 -define(FOLD_TABLES(Fun, Acc, Ar), array:sparse_foldl(Fun, Acc, Ar)).
 -endif.
 
@@ -177,6 +180,7 @@
 -define(SET_TABLE(N, T, Ts), orddict:store(N, T, Ts)).
 -define(UPD_TABLE(N, Upd, Ts), orddict:update(N, Upd, Ts)).
 -define(DEL_TABLE(N, Ts), orddict:erase(N, Ts)).
+-define(CHK_TABLE(N, Ts), orddict:is_key(N, Ts)).
 -define(FILTER_TABLES(Pred, Ts), orddict:filter(Pred, Ts)).
 -define(FOLD_TABLES(Fun, Acc, Ts), orddict:fold(Fun, Acc, Ts)).
 -endif.
@@ -188,6 +192,7 @@
 -define(SET_TABLE(N, T, Pd), put(N, T)).
 -define(UPD_TABLE(N, Upd, Pd), put(N, (Upd)(get(N)))).
 -define(DEL_TABLE(N, Pd), erase(N)).
+-define(CHK_TABLE(N, Pd), (get(N) =/= undefined)).
 -define(FILTER_TABLES(Pred, Pd), Pd).           %This needs work
 -define(FOLD_TABLES(Fun, Acc, Pd), Pd).         %This needs work
 -endif.

src/luerl_heap.erl

@@ -1,4 +1,4 @@
-%% Copyright (c) 2020-2023 Robert Virding
+%% Copyright (c) 2020-2024 Robert Virding
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -30,12 +30,12 @@
 %% External interface.
 -export([gc/1,
          alloc_table/1,alloc_table/2,free_table/2,
-         get_table/2,set_table/3,upd_table/3,
+         get_table/2,set_table/3,upd_table/3,chk_table/2,
          get_global_key/2,set_global_key/3,
          get_table_key/3,set_table_key/4,
          raw_get_table_key/3,raw_set_table_key/4,
-         alloc_userdata/2,alloc_userdata/3,
-         get_userdata/2,set_userdata/3,upd_userdata/3,
+         alloc_userdata/2,alloc_userdata/3,free_userdata/2,
+         get_userdata/2,set_userdata/3,upd_userdata/3,chk_userdata/2,
          set_userdata_data/3,get_userdata_data/2,
          alloc_funcdef/2,get_funcdef/2,set_funcdef/3,
          alloc_environment/2,get_env_var/3,set_env_var/4,
@@ -69,6 +69,7 @@ init_tables(St) ->
 %% set_tstruct(Index, Val, #tstruct{}) -> #tstruct{}.
 %% upd_tstruct(Index, UpdFun, #tstruct{}) -> #tstruct{}.
 %% del_tstruct(Index, #tstruct{}) -> #tstruct{}.
+%% chk_tstruct(Index, #tstruct{}) -> ok | error.
 %%
 %%  Functions for accessing tstructs.
 
@@ -98,6 +99,12 @@ del_tstruct(N, #tstruct{data=D0,free=Ns}=Tstr) ->
 get_tstruct(N, Tstr) ->
     ?GET_TABLE(N, Tstr#tstruct.data).
 
+chk_tstruct(N, Tstr) ->
+    case ?CHK_TABLE(N, Tstr#tstruct.data) of
+        true -> ok;
+        false -> error
+    end.
+
 %% alloc_table(State) -> {Tref,State}
 %%
 %% Allocate an empty table.
@@ -164,6 +171,13 @@ upd_table(#tref{i=N}, Upd, #luerl{tabs=Tst0}=St) ->
     Tst1 = upd_tstruct(N, Upd, Tst0),
     St#luerl{tabs=Tst1}.
 
+%% chk_table(Tref, State) -> ok | error.
+%%
+%% Check the table referenced by Tref actually exists.
+
+chk_table(#tref{i=N}, #luerl{tabs=Tst}) ->
+    chk_tstruct(N, Tst).
+
 %% set_global_key(Key, Value, State) ->
 %%     {value,Value,State} | {meta,Method,Args,State} | {error,Error,State}
 %%
@@ -397,6 +411,14 @@ alloc_userdata(Data, Meta, #luerl{usds=Ust0}=St) ->
     {N,Ust1} = alloc_tstruct(Ud, Ust0),
     {#usdref{i=N},St#luerl{usds=Ust1}}.
 
+%% free_userdata(Usdref, State) -> State
+%%
+%% Delete a table freeing its space.
+
+free_userdata(#usdref{i=N}, #luerl{usds=Ust0}=St) ->
+    Ust1 = del_tstruct(N, Ust0),
+    St#luerl{usds=Ust1}.
+
 %% get_userdata(Usdref, State) -> {UserData,State}
 %%
 %% Get the userdata refered to by Usdref,
@@ -422,6 +444,13 @@ upd_userdata(#usdref{i=N}, Upd, #luerl{usds=Ust0}=St) ->
     Ust1 = upd_tstruct(N, Upd, Ust0),
     St#luerl{usds=Ust1}.
 
+%% chk_userdata(Usdref, State) -> ok | error.
+%%
+%% Check the userdata referenced by Tref actually exists.
+
+chk_userdata(#usdref{i=N}, #luerl{usds=Ust}) ->
+    chk_tstruct(N, Ust).
+
 %% get_userdata_data(Usdref, State) -> {Data,State}
 %%
 %% Get the data form the userdata refered to by Usdref.