diff options
Diffstat (limited to 'erts/emulator/test/bif_SUITE.erl')
| -rw-r--r-- | erts/emulator/test/bif_SUITE.erl | 533 |
1 files changed, 510 insertions, 23 deletions
diff --git a/erts/emulator/test/bif_SUITE.erl b/erts/emulator/test/bif_SUITE.erl index d31399e4af..9e7bcd5255 100644 --- a/erts/emulator/test/bif_SUITE.erl +++ b/erts/emulator/test/bif_SUITE.erl @@ -1,7 +1,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 2005-2016. All Rights Reserved. +%% Copyright Ericsson AB 2005-2018. All Rights Reserved. %% %% Licensed under the Apache License, Version 2.0 (the "License"); %% you may not use this file except in compliance with the License. @@ -24,14 +24,20 @@ -include_lib("kernel/include/file.hrl"). -export([all/0, suite/0, - display/1, display_huge/0, + display/1, display_huge/0, display_string/1, erl_bif_types/1,guard_bifs_in_erl_bif_types/1, - shadow_comments/1, + shadow_comments/1,list_to_utf8_atom/1, specs/1,improper_bif_stubs/1,auto_imports/1, t_list_to_existing_atom/1,os_env/1,otp_7526/1, binary_to_atom/1,binary_to_existing_atom/1, atom_to_binary/1,min_max/1, erlang_halt/1, - is_builtin/1]). + erl_crash_dump_bytes/1, + is_builtin/1, error_stacktrace/1, + error_stacktrace_during_call_trace/1, + group_leader_prio/1, group_leader_prio_dirty/1, + is_process_alive/1, + process_info_blast/1, + os_env_case_sensitivity/1]). suite() -> [{ct_hooks,[ts_install_cth]}, @@ -41,9 +47,12 @@ all() -> [erl_bif_types, guard_bifs_in_erl_bif_types, shadow_comments, specs, improper_bif_stubs, auto_imports, t_list_to_existing_atom, os_env, otp_7526, - display, + display, display_string, list_to_utf8_atom, atom_to_binary, binary_to_atom, binary_to_existing_atom, - min_max, erlang_halt, is_builtin]. + erl_crash_dump_bytes, min_max, erlang_halt, is_builtin, + error_stacktrace, error_stacktrace_during_call_trace, + group_leader_prio, group_leader_prio_dirty, + is_process_alive, process_info_blast, os_env_case_sensitivity]. %% Uses erlang:display to test that erts_printf does not do deep recursion display(Config) when is_list(Config) -> @@ -65,6 +74,28 @@ deeep(N,Acc) -> deeep(N) -> deeep(N,[hello]). +display_string(Config) when is_list(Config) -> + true = erlang:display_string("hej"), + true = erlang:display_string(""), + true = erlang:display_string("hopp"), + true = erlang:display_string("\n"), + true = erlang:display_string(lists:seq(1100,1200)), + {error,badarg} = try + erlang:display_string(atom), + ok + catch + T0:E0 -> + {T0, E0} + end, + {error,badarg} = try + erlang:display_string(make_ref()), + ok + catch + T1:E1 -> + {T1, E1} + end, + ok. + erl_bif_types(Config) when is_list(Config) -> ensure_erl_bif_types_compiled(), @@ -336,6 +367,38 @@ check_stub({_,F,A}, B) -> ct:fail(invalid_body) end. +list_to_utf8_atom(Config) when is_list(Config) -> + 'hello' = atom_roundtrip("hello"), + 'こんにちは' = atom_roundtrip("こんにちは"), + + %% Test all edge cases. + _ = atom_roundtrip([16#80]), + _ = atom_roundtrip([16#7F]), + _ = atom_roundtrip([16#FF]), + _ = atom_roundtrip([16#100]), + _ = atom_roundtrip([16#7FF]), + _ = atom_roundtrip([16#800]), + _ = atom_roundtrip([16#D7FF]), + atom_badarg([16#D800]), + atom_badarg([16#DFFF]), + _ = atom_roundtrip([16#E000]), + _ = atom_roundtrip([16#FFFF]), + _ = atom_roundtrip([16#1000]), + _ = atom_roundtrip([16#10FFFF]), + atom_badarg([16#110000]), + ok. + +atom_roundtrip(String) -> + Atom = list_to_atom(String), + Atom = list_to_existing_atom(String), + String = atom_to_list(Atom), + Atom. + +atom_badarg(String) -> + {'EXIT',{badarg,_}} = (catch list_to_atom(String)), + {'EXIT',{badarg,_}} = (catch list_to_existing_atom(String)), + ok. + t_list_to_existing_atom(Config) when is_list(Config) -> all = list_to_existing_atom("all"), ?MODULE = list_to_existing_atom(?MODULE_STRING), @@ -381,6 +444,17 @@ os_env_long(Min, Max, Value) -> true = os:unsetenv(EnvVar), os_env_long(Min+1, Max, Value). +os_env_case_sensitivity(Config) when is_list(Config) -> + %% The keys in os:getenv/putenv must be case-insensitive on Windows, and + %% case-sensitive elsewhere. + true = os:putenv("os_env_gurka", "gaffel"), + Expected = case os:type() of + {win32, _} -> "gaffel"; + _ -> false + end, + Expected = os:getenv("OS_ENV_GURKA"), + ok. + %% Test that string:to_integer does not Halloc in wrong order. otp_7526(Config) when is_list(Config) -> ok = test_7526(256). @@ -426,6 +500,8 @@ binary_to_atom(Config) when is_list(Config) -> Long = lists:seq(0, 254), LongAtom = list_to_atom(Long), LongBin = list_to_binary(Long), + UnicodeLongAtom = list_to_atom([$é || _ <- lists:seq(0, 254)]), + UnicodeLongBin = << <<"é"/utf8>> || _ <- lists:seq(0, 254)>>, %% latin1 '' = test_binary_to_atom(<<>>, latin1), @@ -437,12 +513,17 @@ binary_to_atom(Config) when is_list(Config) -> '' = test_binary_to_atom(<<>>, utf8), HalfLongAtom = test_binary_to_atom(HalfLongBin, utf8), HalfLongAtom = test_binary_to_atom(HalfLongBin, unicode), + UnicodeLongAtom = test_binary_to_atom(UnicodeLongBin, utf8), + UnicodeLongAtom = test_binary_to_atom(UnicodeLongBin, unicode), [] = [C || C <- lists:seq(128, 255), begin list_to_atom([C]) =/= test_binary_to_atom(<<C/utf8>>, utf8) end], + <<"こんにちは"/utf8>> = + atom_to_binary(test_binary_to_atom(<<"こんにちは"/utf8>>, utf8), utf8), + %% badarg failures. fail_binary_to_atom(atom), fail_binary_to_atom(42), @@ -461,10 +542,8 @@ binary_to_atom(Config) when is_list(Config) -> ?BADARG(binary_to_atom(id(<<255>>), utf8)), ?BADARG(binary_to_atom(id(<<255,0>>), utf8)), ?BADARG(binary_to_atom(id(<<16#C0,16#80>>), utf8)), %Overlong 0. - [?BADARG(binary_to_atom(<<C/utf8>>, utf8)) || C <- lists:seq(256, 16#D7FF)], - [?BADARG(binary_to_atom(<<C/utf8>>, utf8)) || C <- lists:seq(16#E000, 16#FFFD)], - [?BADARG(binary_to_atom(<<C/utf8>>, utf8)) || C <- lists:seq(16#10000, 16#8FFFF)], - [?BADARG(binary_to_atom(<<C/utf8>>, utf8)) || C <- lists:seq(16#90000, 16#10FFFF)], + <<B:1/binary, _/binary>> = id(<<194, 163>>), %Truncated character ERL-474 + ?BADARG(binary_to_atom(B, utf8)), %% system_limit failures. ?SYS_LIMIT(binary_to_atom(id(<<0:512/unit:8,255>>), utf8)), @@ -653,6 +732,9 @@ erlang_halt(Config) when is_list(Config) -> {badrpc,nodedown} = rpc:call(N3, erlang, halt, [0,[]]), {ok,N4} = slave:start(H, halt_node4), {badrpc,nodedown} = rpc:call(N4, erlang, halt, [lists:duplicate(300,$x)]), + %% Test unicode slogan + {ok,N4} = slave:start(H, halt_node4), + {badrpc,nodedown} = rpc:call(N4, erlang, halt, [[339,338,254,230,198,295,167,223,32,12507,12531,12480]]), % This test triggers a segfault when dumping a crash dump % to make sure that we can handle it properly. @@ -664,12 +746,14 @@ erlang_halt(Config) when is_list(Config) -> [available_internal_state, true]), {badrpc,nodedown} = rpc:call(N4, erts_debug, set_internal_state, [broken_halt, "Validate correct crash dump"]), - ok = wait_until_stable_size(CrashDump,-1), + {ok,_} = wait_until_stable_size(CrashDump,-1), {ok, Bin} = file:read_file(CrashDump), - case {string:str(binary_to_list(Bin),"\n=end\n"), - string:str(binary_to_list(Bin),"\r\n=end\r\n")} of - {0,0} -> ct:fail("Could not find end marker in crash dump"); - _ -> ok + case {string:find(Bin, <<"\n=end\n">>), + string:find(Bin, <<"\r\n=end\r\n">>)} of + {nomatch,nomatch} -> + ct:fail("Could not find end marker in crash dump"); + {_,_} -> + ok end. wait_until_stable_size(_File,-10) -> @@ -681,29 +765,424 @@ wait_until_stable_size(File,PrevSz) -> wait_until_stable_size(File,PrevSz-1); {ok,#file_info{size = PrevSz }} when PrevSz /= -1 -> io:format("Crashdump file size was: ~p (~s)~n",[PrevSz,File]), - ok; + {ok,PrevSz}; {ok,#file_info{size = NewSz }} -> wait_until_stable_size(File,NewSz) end. +% Test erlang:halt with ERL_CRASH_DUMP_BYTES +erl_crash_dump_bytes(Config) when is_list(Config) -> + Bytes = 1000, + CrashDump = do_limited_crash_dump(Config, Bytes), + {ok,ActualBytes} = wait_until_stable_size(CrashDump,-1), + true = ActualBytes < (Bytes + 100), + + NoDump = do_limited_crash_dump(Config,0), + {error,enoent} = wait_until_stable_size(NoDump,-8), + ok. + +do_limited_crash_dump(Config, Bytes) -> + H = hostname(), + {ok,N} = slave:start(H, halt_node), + BytesStr = integer_to_list(Bytes), + CrashDump = filename:join(proplists:get_value(priv_dir,Config), + "erl_crash." ++ BytesStr ++ ".dump"), + true = rpc:call(N, os, putenv, ["ERL_CRASH_DUMP",CrashDump]), + true = rpc:call(N, os, putenv, ["ERL_CRASH_DUMP_BYTES",BytesStr]), + {badrpc,nodedown} = rpc:call(N, erlang, halt, ["Testing ERL_CRASH_DUMP_BYTES"]), + CrashDump. + + is_builtin(_Config) -> Exp0 = [{M,F,A} || {M,_} <- code:all_loaded(), {F,A} <- M:module_info(exports)], Exp = ordsets:from_list(Exp0), - %% erlang:apply/3 is considered to be built-in, but is not - %% implemented as other BIFs. + %% Built-ins implemented as special instructions. + Instructions = [{erlang,apply,2},{erlang,apply,3},{erlang,yield,0}], - Builtins0 = [{erlang,apply,3}|erlang:system_info(snifs)], + Builtins0 = Instructions ++ erlang:system_info(snifs), Builtins = ordsets:from_list(Builtins0), - NotBuiltin = ordsets:subtract(Exp, Builtins), - _ = [true = erlang:is_builtin(M, F, A) || {M,F,A} <- Builtins], - _ = [false = erlang:is_builtin(M, F, A) || {M,F,A} <- NotBuiltin], + + Fakes = [{M,F,42} || {M,F,_} <- Instructions], + All = ordsets:from_list(Fakes ++ Exp), + NotBuiltin = ordsets:subtract(All, Builtins), + + _ = [{true,_} = {erlang:is_builtin(M, F, A),MFA} || + {M,F,A}=MFA <- Builtins], + _ = [{false,_} = {erlang:is_builtin(M, F, A),MFA} || + {M,F,A}=MFA <- NotBuiltin], ok. +error_stacktrace(Config) when is_list(Config) -> + error_stacktrace_test(). + +error_stacktrace_during_call_trace(Config) when is_list(Config) -> + Tracer = spawn_link(fun () -> + receive after infinity -> ok end + end), + Mprog = [{'_',[],[{exception_trace}]}], + erlang:trace_pattern({?MODULE,'_','_'}, Mprog, [local]), + 1 = erlang:trace_pattern({erlang,error,2}, Mprog, [local]), + 1 = erlang:trace_pattern({erlang,error,1}, Mprog, [local]), + erlang:trace(all, true, [call,return_to,timestamp,{tracer, Tracer}]), + try + error_stacktrace_test() + after + erlang:trace(all, false, [call,return_to,timestamp,{tracer, Tracer}]), + erlang:trace_pattern({erlang,error,2}, false, [local]), + erlang:trace_pattern({erlang,error,1}, false, [local]), + erlang:trace_pattern({?MODULE,'_','_'}, false, [local]), + unlink(Tracer), + exit(Tracer, kill), + Mon = erlang:monitor(process, Tracer), + receive + {'DOWN', Mon, process, Tracer, _} -> ok + end + end, + ok. -%% Helpers +error_stacktrace_test() -> + Types = [apply_const_last, apply_const, apply_last, + apply, double_apply_const_last, double_apply_const, + double_apply_last, double_apply, multi_apply_const_last, + multi_apply_const, multi_apply_last, multi_apply, + call_const_last, call_last, call_const, call], + lists:foreach(fun (Type) -> + {Pid, Mon} = spawn_monitor( + fun () -> + stk([a,b,c,d], Type, error_2) + end), + receive + {'DOWN', Mon, process, Pid, Reason} -> + {oops, Stack} = Reason, +%% io:format("Type: ~p Stack: ~p~n", +%% [Type, Stack]), + [{?MODULE, do_error_2, [Type], _}, + {?MODULE, stk, 3, _}, + {?MODULE, stk, 3, _}] = Stack + end + end, + Types), + lists:foreach(fun (Type) -> + {Pid, Mon} = spawn_monitor( + fun () -> + stk([a,b,c,d], Type, error_1) + end), + receive + {'DOWN', Mon, process, Pid, Reason} -> + {oops, Stack} = Reason, +%% io:format("Type: ~p Stack: ~p~n", +%% [Type, Stack]), + [{?MODULE, do_error_1, 1, _}, + {?MODULE, stk, 3, _}, + {?MODULE, stk, 3, _}] = Stack + end + end, + Types), + ok. + +stk([], Type, Func) -> + tail(Type, Func, jump), + ok; +stk([_|L], Type, Func) -> + stk(L, Type, Func), + ok. + +tail(Type, Func, jump) -> + tail(Type, Func, do); +tail(Type, error_1, do) -> + do_error_1(Type); +tail(Type, error_2, do) -> + do_error_2(Type). + +do_error_2(apply_const_last) -> + erlang:apply(erlang, error, [oops, [apply_const_last]]); +do_error_2(apply_const) -> + erlang:apply(erlang, error, [oops, [apply_const]]), + ok; +do_error_2(apply_last) -> + erlang:apply(id(erlang), id(error), id([oops, [apply_last]])); +do_error_2(apply) -> + erlang:apply(id(erlang), id(error), id([oops, [apply]])), + ok; +do_error_2(double_apply_const_last) -> + erlang:apply(erlang, apply, [erlang, error, [oops, [double_apply_const_last]]]); +do_error_2(double_apply_const) -> + erlang:apply(erlang, apply, [erlang, error, [oops, [double_apply_const]]]), + ok; +do_error_2(double_apply_last) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(error), id([oops, [double_apply_last]])]); +do_error_2(double_apply) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(error), id([oops, [double_apply]])]), + ok; +do_error_2(multi_apply_const_last) -> + erlang:apply(erlang, apply, [erlang, apply, [erlang, apply, [erlang, error, [oops, [multi_apply_const_last]]]]]); +do_error_2(multi_apply_const) -> + erlang:apply(erlang, apply, [erlang, apply, [erlang, apply, [erlang, error, [oops, [multi_apply_const]]]]]), + ok; +do_error_2(multi_apply_last) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(error), id([oops, [multi_apply_last]])]]]); +do_error_2(multi_apply) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(error), id([oops, [multi_apply]])]]]), + ok; +do_error_2(call_const_last) -> + erlang:error(oops, [call_const_last]); +do_error_2(call_last) -> + erlang:error(id(oops), id([call_last])); +do_error_2(call_const) -> + erlang:error(oops, [call_const]), + ok; +do_error_2(call) -> + erlang:error(id(oops), id([call])). + + +do_error_1(apply_const_last) -> + erlang:apply(erlang, error, [oops]); +do_error_1(apply_const) -> + erlang:apply(erlang, error, [oops]), + ok; +do_error_1(apply_last) -> + erlang:apply(id(erlang), id(error), id([oops])); +do_error_1(apply) -> + erlang:apply(id(erlang), id(error), id([oops])), + ok; +do_error_1(double_apply_const_last) -> + erlang:apply(erlang, apply, [erlang, error, [oops]]); +do_error_1(double_apply_const) -> + erlang:apply(erlang, apply, [erlang, error, [oops]]), + ok; +do_error_1(double_apply_last) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(error), id([oops])]); +do_error_1(double_apply) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(error), id([oops])]), + ok; +do_error_1(multi_apply_const_last) -> + erlang:apply(erlang, apply, [erlang, apply, [erlang, apply, [erlang, error, [oops]]]]); +do_error_1(multi_apply_const) -> + erlang:apply(erlang, apply, [erlang, apply, [erlang, apply, [erlang, error, [oops]]]]), + ok; +do_error_1(multi_apply_last) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(error), id([oops])]]]); +do_error_1(multi_apply) -> + erlang:apply(id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(apply), [id(erlang), id(error), id([oops])]]]), + ok; +do_error_1(call_const_last) -> + erlang:error(oops); +do_error_1(call_last) -> + erlang:error(id(oops)); +do_error_1(call_const) -> + erlang:error(oops), + ok; +do_error_1(call) -> + erlang:error(id(oops)). + + +group_leader_prio(Config) when is_list(Config) -> + group_leader_prio_test(false). + +group_leader_prio_dirty(Config) when is_list(Config) -> + group_leader_prio_test(true). + +group_leader_prio_test(Dirty) -> + %% + %% Unfortunately back in the days node local group_leader/2 was not + %% implemented as sending an asynchronous signal to the process to change + %% group leader for. Instead it has always been synchronously changed, and + %% nothing in the documentation have hinted otherwise... Therefore I do not + %% dare the change this. + %% + %% In order to prevent priority inversion, the priority of the receiver of + %% the group leader signal is elevated while handling incoming signals if + %% the sender has a higher priority than the receiver. This test tests that + %% the priority elevation actually works... + %% + Tester = self(), + Init = erlang:whereis(init), + GL = erlang:group_leader(), + process_flag(priority, max), + {TestProcFun, NTestProcs} + = case Dirty of + false -> + %% These processes will handle all incoming signals + %% by them selves... + {fun () -> + Tester ! {alive, self()}, + receive after infinity -> ok end + end, + 100}; + true -> + %% These processes wont handle incoming signals by + %% them selves since they are stuck on dirty schedulers + %% when we try to change group leader. A dirty process + %% signal handler process (system process) will be notified + %% of the need to handle incoming signals for these processes, + %% and will instead handle the signal for these processes... + {fun () -> + %% The following sends the message '{alive, self()}' + %% to Tester once on a dirty io scheduler, then wait + %% there until the process terminates... + erts_debug:dirty_io(alive_waitexiting, Tester) + end, + erlang:system_info(dirty_io_schedulers)} + end, + TPs = lists:map(fun (_) -> + spawn_opt(TestProcFun, + [link, {priority, normal}]) + end, lists:seq(1, NTestProcs)), + lists:foreach(fun (TP) -> receive {alive, TP} -> ok end end, TPs), + TLs = lists:map(fun (_) -> + spawn_opt(fun () -> tok_loop() end, + [link, {priority, high}]) + end, + lists:seq(1, 2*erlang:system_info(schedulers))), + %% Wait to ensure distribution of high prio processes over schedulers... + receive after 1000 -> ok end, + %% + %% Test that we can get group-leader signals through to normal prio + %% processes from a max prio process even though all schedulers are filled + %% with executing high prio processes. + %% + lists:foreach(fun (_) -> + lists:foreach(fun (TP) -> + erlang:yield(), + %% whitebox -- Enqueue some signals on it + %% preventing us from hogging its main lock + %% and set group-leader directly.... + erlang:demonitor(erlang:monitor(process, TP)), + true = erlang:group_leader(Init, TP), + {group_leader, Init} = process_info(TP, group_leader), + erlang:demonitor(erlang:monitor(process, TP)), + true = erlang:group_leader(GL, TP), + {group_leader, GL} = process_info(TP, group_leader) + end, + TPs) + end, + lists:seq(1,100)), + %% + %% Also test when it is exiting... + %% + lists:foreach(fun (TP) -> + erlang:yield(), + M = erlang:monitor(process, TP), + unlink(TP), + exit(TP, bang), + badarg = try + true = erlang:group_leader(Init, TP) + catch + error : What -> What + end, + receive + {'DOWN', M, process, TP, Reason} -> + bang = Reason + end + end, + TPs), + lists:foreach(fun (TL) -> + M = erlang:monitor(process, TL), + unlink(TL), + exit(TL, bang), + receive + {'DOWN', M, process, TL, Reason} -> + bang = Reason + end + end, + TLs), + ok. + +is_process_alive(Config) when is_list(Config) -> + process_flag(priority, max), + Ps = lists:map(fun (_) -> + spawn_opt(fun () -> tok_loop() end, + [{priority, high}, link]) + end, + lists:seq(1, 2*erlang:system_info(schedulers))), + receive after 1000 -> ok end, %% Wait for load to spread + lists:foreach(fun (P) -> + %% Ensure that signal order is preserved + %% and that we are not starved due to + %% priority inversion + true = erlang:is_process_alive(P), + unlink(P), + true = erlang:is_process_alive(P), + exit(P, kill), + false = erlang:is_process_alive(P) + end, + Ps), + ok. + +process_info_blast(Config) when is_list(Config) -> + Tester = self(), + NoAttackers = 1000, + NoAL = lists:seq(1, NoAttackers), + Consume = make_ref(), + Victim = spawn_link(fun () -> + receive + Consume -> + ok + end, + consume_msgs() + end), + AFun = fun () -> + Victim ! hej, + Res = process_info(Victim, message_queue_len), + Tester ! {self(), Res} + end, + Attackers0 = lists:map(fun (_) -> + spawn_link(AFun) + end, + NoAL), + lists:foreach(fun (A) -> + receive + {A, Res} -> + case Res of + {message_queue_len, Len} when Len > 0, Len =< NoAttackers -> + Len; + Error -> + exit({unexpected, Error}) + end + end + end, + Attackers0), + Attackers1 = lists:map(fun (_) -> + spawn_link(AFun) + end, + NoAL), + Victim ! Consume, + lists:foreach(fun (A) -> + receive + {A, Res} -> + case Res of + {message_queue_len, Len} when Len >= 0, Len =< 2*NoAttackers+1 -> + ok; + undefined -> + ok; + Error -> + exit({unexpected, Error}) + end + end + end, + Attackers1), + KillFun = fun (P) -> + unlink(P), + exit(P, kill), + false = erlang:is_process_alive(P) + end, + lists:foreach(fun (A) -> KillFun(A) end, Attackers0), + lists:foreach(fun (A) -> KillFun(A) end, Attackers1), + KillFun(Victim), + ok. + +consume_msgs() -> + receive + _ -> + consume_msgs() + after 0 -> + ok + end. + +%% helpers id(I) -> I. @@ -743,3 +1222,11 @@ hostname([$@ | Hostname]) -> list_to_atom(Hostname); hostname([_C | Cs]) -> hostname(Cs). + +tok_loop() -> + tok_loop(hej). + +tok_loop(hej) -> + tok_loop(hopp); +tok_loop(hopp) -> + tok_loop(hej). |