From fa44f865c3fc6253cf4691cf94839c303a3ee40f Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Tue, 15 Dec 2015 20:32:39 +0100 Subject: erts: Make erlang:purge_module/1 safe Problem: erlang:purge_module/1 is not safe in the sense that very bad things may happen if the code to be purged is still referred to by live processes. Introduce erts_internal:purge_module which is the same as the old erlang:purge_module BIF (except it returns false if no such old module). Implement erlang:purge_module in Erlang and let it invoke erts_code_purger for safe purging where all clogging processes first are killed. --- erts/emulator/beam/beam_bif_load.c | 14 ++++++++++---- erts/emulator/beam/bif.tab | 2 +- erts/preloaded/ebin/erlang.beam | Bin 102216 -> 102556 bytes erts/preloaded/ebin/erts_code_purger.beam | Bin 9020 -> 8992 bytes erts/preloaded/ebin/erts_internal.beam | Bin 6260 -> 6432 bytes erts/preloaded/ebin/init.beam | Bin 44700 -> 44728 bytes erts/preloaded/src/erlang.erl | 12 ++++++++++-- erts/preloaded/src/erts_code_purger.erl | 14 +++----------- erts/preloaded/src/erts_internal.erl | 6 ++++++ erts/preloaded/src/init.erl | 4 ++-- lib/kernel/test/code_SUITE.erl | 21 +++++++++++++++++---- 11 files changed, 49 insertions(+), 24 deletions(-) diff --git a/erts/emulator/beam/beam_bif_load.c b/erts/emulator/beam/beam_bif_load.c index 6bb70cc5a7..014ee35fd0 100644 --- a/erts/emulator/beam/beam_bif_load.c +++ b/erts/emulator/beam/beam_bif_load.c @@ -1094,7 +1094,12 @@ static void copy_literals_commit(void* null) { #endif /* ERTS_SMP */ -BIF_RETTYPE purge_module_1(BIF_ALIST_1) +/* Do the actualy module purging and return: + * true for success + * false if no such old module + * BADARG if not an atom + */ +BIF_RETTYPE erts_internal_purge_module_1(BIF_ALIST_1) { ErtsCodeIndex code_ix; BeamInstr* code; @@ -1108,7 +1113,8 @@ BIF_RETTYPE purge_module_1(BIF_ALIST_1) } if (!erts_try_seize_code_write_permission(BIF_P)) { - ERTS_BIF_YIELD1(bif_export[BIF_purge_module_1], BIF_P, BIF_ARG_1); + ERTS_BIF_YIELD1(bif_export[BIF_erts_internal_purge_module_1], + BIF_P, BIF_ARG_1); } code_ix = erts_active_code_ix(); @@ -1118,7 +1124,7 @@ BIF_RETTYPE purge_module_1(BIF_ALIST_1) */ if ((modp = erts_get_module(BIF_ARG_1, code_ix)) == NULL) { - ERTS_BIF_PREP_ERROR(ret, BIF_P, BADARG); + ERTS_BIF_PREP_RET(ret, am_false); } else { erts_rwlock_old_code(code_ix); @@ -1127,7 +1133,7 @@ BIF_RETTYPE purge_module_1(BIF_ALIST_1) * Any code to purge? */ if (!modp->old.code_hdr) { - ERTS_BIF_PREP_ERROR(ret, BIF_P, BADARG); + ERTS_BIF_PREP_RET(ret, am_false); } else { /* diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab index 0aee8681c6..3b95ec508c 100644 --- a/erts/emulator/beam/bif.tab +++ b/erts/emulator/beam/bif.tab @@ -125,7 +125,6 @@ bif erlang:process_flag/3 bif erlang:process_info/1 bif erlang:process_info/2 bif erlang:processes/0 -bif erlang:purge_module/1 bif erlang:put/2 bif erlang:register/2 bif erlang:registered/0 @@ -643,6 +642,7 @@ bif erts_debug:map_info/1 # bif erlang:copy_literals/2 +bif erts_internal:purge_module/1 bif binary:split/2 bif binary:split/3 bif erts_debug:size_shared/1 diff --git a/erts/preloaded/ebin/erlang.beam b/erts/preloaded/ebin/erlang.beam index 68578c3a49..4353e115ca 100644 Binary files a/erts/preloaded/ebin/erlang.beam and b/erts/preloaded/ebin/erlang.beam differ diff --git a/erts/preloaded/ebin/erts_code_purger.beam b/erts/preloaded/ebin/erts_code_purger.beam index adfe298a44..553b34b105 100644 Binary files a/erts/preloaded/ebin/erts_code_purger.beam and b/erts/preloaded/ebin/erts_code_purger.beam differ diff --git a/erts/preloaded/ebin/erts_internal.beam b/erts/preloaded/ebin/erts_internal.beam index 4e1cb7f8a0..150e76505d 100644 Binary files a/erts/preloaded/ebin/erts_internal.beam and b/erts/preloaded/ebin/erts_internal.beam differ diff --git a/erts/preloaded/ebin/init.beam b/erts/preloaded/ebin/init.beam index a44b022931..b6d1df7bbc 100644 Binary files a/erts/preloaded/ebin/init.beam and b/erts/preloaded/ebin/init.beam differ diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl index d9dc9a1976..ab54d716cc 100644 --- a/erts/preloaded/src/erlang.erl +++ b/erts/preloaded/src/erlang.erl @@ -1471,8 +1471,16 @@ processes() -> %% purge_module/1 -spec purge_module(Module) -> true when Module :: atom(). -purge_module(_Module) -> - erlang:nif_error(undefined). +purge_module(Module) when erlang:is_atom(Module) -> + case erts_code_purger:purge(Module) of + {false, _} -> + erlang:error(badarg, [Module]); + {true, _} -> + true + end; +purge_module(Arg) -> + erlang:error(badarg, [Arg]). + %% put/2 -spec put(Key, Val) -> term() when diff --git a/erts/preloaded/src/erts_code_purger.erl b/erts/preloaded/src/erts_code_purger.erl index 6bb6e4fcdc..880c86aad1 100644 --- a/erts/preloaded/src/erts_code_purger.erl +++ b/erts/preloaded/src/erts_code_purger.erl @@ -70,12 +70,8 @@ do_purge(Mod) -> true = erlang:copy_literals(Mod, true), DidKill = check_proc_code(erlang:processes(), Mod, true), true = erlang:copy_literals(Mod, false), - try - erlang:purge_module(Mod) - catch - _:_ -> ignore - end, - {true, DidKill} + WasPurged = erts_internal:purge_module(Mod), + {WasPurged, DidKill} end. %% soft_purge(Module) @@ -104,11 +100,7 @@ do_soft_purge(Mod) -> false; true -> true = erlang:copy_literals(Mod, false), - try - erlang:purge_module(Mod) - catch - _:_ -> ignore - end, + erts_internal:purge_module(Mod), true end end. diff --git a/erts/preloaded/src/erts_internal.erl b/erts/preloaded/src/erts_internal.erl index 426749264f..6e649e8395 100644 --- a/erts/preloaded/src/erts_internal.erl +++ b/erts/preloaded/src/erts_internal.erl @@ -38,6 +38,7 @@ -export([request_system_task/3]). -export([check_process_code/2]). +-export([purge_module/1]). -export([flush_monitor_messages/3]). @@ -204,6 +205,11 @@ request_system_task(_Pid, _Prio, _Request) -> check_process_code(_Module, _OptionList) -> erlang:nif_error(undefined). +-spec purge_module(Module) -> boolean() when + Module :: module(). +purge_module(_Module) -> + erlang:nif_error(undefined). + %% term compare where integer() < float() = true -spec cmp_term(A,B) -> Result when diff --git a/erts/preloaded/src/init.erl b/erts/preloaded/src/init.erl index 383c4a1ec6..ed65c57c0d 100644 --- a/erts/preloaded/src/init.erl +++ b/erts/preloaded/src/init.erl @@ -636,9 +636,9 @@ unload(_) -> do_unload(sub([heart|erlang:pre_loaded()],erlang:loaded())). do_unload([M|Mods]) -> - catch erlang:purge_module(M), + catch erts_internal:purge_module(M), catch erlang:delete_module(M), - catch erlang:purge_module(M), + catch erts_internal:purge_module(M), do_unload(Mods); do_unload([]) -> purge_all_hipe_refs(), diff --git a/lib/kernel/test/code_SUITE.erl b/lib/kernel/test/code_SUITE.erl index 071f8d1d3b..772a1e6b14 100644 --- a/lib/kernel/test/code_SUITE.erl +++ b/lib/kernel/test/code_SUITE.erl @@ -380,8 +380,23 @@ purge(Config) when is_list(Config) -> purge_many_exits(Config) when is_list(Config) -> OldFlag = process_flag(trap_exit, true), + code:purge(code_b_test), {'EXIT',_} = (catch code:purge({})), + + CodePurgeF = fun(M, Exp) -> Exp = code:purge(M) end, + purge_many_exits_do(CodePurgeF), + + %% Let's repeat test for erlang:purge_module as it does the same thing + %% now in erts-8.0 (except for return value). + ErlangPurgeF = fun(M, _Exp) -> erlang:purge_module(M) end, + purge_many_exits_do(ErlangPurgeF), + + process_flag(trap_exit, OldFlag), + ok. + + +purge_many_exits_do(PurgeF) -> false = code:purge(code_b_test), TPids = lists:map(fun (_) -> {code_b_test:do_spawn(), @@ -400,7 +415,7 @@ purge_many_exits(Config) when is_list(Config) -> false = code_b_test:check_exit(Pid1), true = erlang:is_process_alive(Pid2) end, TPids), - true = code:purge(code_b_test), + PurgeF(code_b_test, true), lists:foreach(fun ({Pid1, Pid2}) -> false = erlang:is_process_alive(Pid1), true = code_b_test:check_exit(Pid1), @@ -409,9 +424,7 @@ purge_many_exits(Config) when is_list(Config) -> end, TPids), lists:foreach(fun ({_Pid1, Pid2}) -> receive {'EXIT', Pid2, _} -> ok end - end, TPids), - process_flag(trap_exit, OldFlag), - ok. + end, TPids). soft_purge(suite) -> []; 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