From c2d70945dce9cb09d5d7120d6e9ddf7faac8d230 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?John=20H=C3=B6gberg?= Date: Wed, 22 Nov 2017 13:19:57 +0100 Subject: Replace the libc environment with a thread-safe emulation putenv(3) and friends aren't thread-safe regardless of how you slice it; a global lock around all environment operations (like before) keeps things safe as far as our own operations go, but we have absolutely no control over what libc or a library dragged in by a driver/NIF does -- they're free to call getenv(3) or putenv(3) without honoring our lock. This commit solves this by setting up an "emulated" environment which can't be touched without going through our interfaces. Third-party libraries can still shoot themselves in the foot but benign uses of os:putenv/2 will no longer risk crashing the emulator. --- erts/emulator/test/driver_SUITE.erl | 47 ++++++++++ erts/emulator/test/driver_SUITE_data/Makefile.src | 3 +- erts/emulator/test/driver_SUITE_data/env_drv.c | 108 ++++++++++++++++++++++ 3 files changed, 157 insertions(+), 1 deletion(-) create mode 100644 erts/emulator/test/driver_SUITE_data/env_drv.c (limited to 'erts/emulator/test') diff --git a/erts/emulator/test/driver_SUITE.erl b/erts/emulator/test/driver_SUITE.erl index 475e03087a..884f697384 100644 --- a/erts/emulator/test/driver_SUITE.erl +++ b/erts/emulator/test/driver_SUITE.erl @@ -80,6 +80,7 @@ async_blast/1, thr_msg_blast/1, consume_timeslice/1, + env/1, z_test/1]). -export([bin_prefix/2]). @@ -166,6 +167,7 @@ all() -> %% Keep a_test first and z_test last... async_blast, thr_msg_blast, consume_timeslice, + env, z_test]. groups() -> @@ -2360,6 +2362,51 @@ count_proc_sched(Ps, PNs) -> PNs end. +%% +%% Tests whether erl_drv_putenv reflects in os:getenv and vice versa. +%% +env(Config) when is_list(Config) -> + ok = load_driver(proplists:get_value(data_dir, Config), env_drv), + Port = open_port({spawn_driver, env_drv}, []), + true = is_port(Port), + + Keys = ["env_drv_a_key", "env_drv_b_key", "env_drv_c_key"], + Values = ["a_value", "b_value", "c_value"], + + [env_put_test(Port, Key, Value) || Key <- Keys, Value <- Values], + [env_get_test(Port, Key, Value) || Key <- Keys, Value <- Values], + [env_oversize_test(Port, Key) || Key <- Keys], + [env_notfound_test(Port, Key) || Key <- Keys], + + true = port_close(Port), + erl_ddll:unload_driver(env_drv), + ok. + +env_control(Port, Command, Key, Value) -> + KeyBin = list_to_binary(Key), + ValueBin = list_to_binary(Value), + Header = <<(byte_size(KeyBin)), (byte_size(ValueBin))>>, + Payload = <>, + port_control(Port, Command, <
>). + +env_put_test(Port, Key, Value) -> + os:unsetenv(Key), + [0] = env_control(Port, 0, Key, Value), + Value = os:getenv(Key). + +env_get_test(Port, Key, ExpectedValue) -> + true = os:putenv(Key, ExpectedValue), + [0] = env_control(Port, 1, Key, ExpectedValue). + +env_oversize_test(Port, Key) -> + os:putenv(Key, [$A || _ <- lists:seq(1, 1024)]), + [127] = env_control(Port, 1, Key, ""). + +env_notfound_test(Port, Key) -> + true = os:unsetenv(Key), + [255] = env_control(Port, 1, Key, ""). + + a_test(Config) when is_list(Config) -> rpc(Config, fun check_io_debug/0). diff --git a/erts/emulator/test/driver_SUITE_data/Makefile.src b/erts/emulator/test/driver_SUITE_data/Makefile.src index 1fedd72200..bcabaa689d 100644 --- a/erts/emulator/test/driver_SUITE_data/Makefile.src +++ b/erts/emulator/test/driver_SUITE_data/Makefile.src @@ -16,7 +16,8 @@ MISC_DRVS = outputv_drv@dll@ \ thr_free_drv@dll@ \ async_blast_drv@dll@ \ thr_msg_blast_drv@dll@ \ - consume_timeslice_drv@dll@ + consume_timeslice_drv@dll@ \ + env_drv@dll@ SYS_INFO_DRVS = sys_info_base_drv@dll@ \ sys_info_prev_drv@dll@ \ diff --git a/erts/emulator/test/driver_SUITE_data/env_drv.c b/erts/emulator/test/driver_SUITE_data/env_drv.c new file mode 100644 index 0000000000..0e910eeb84 --- /dev/null +++ b/erts/emulator/test/driver_SUITE_data/env_drv.c @@ -0,0 +1,108 @@ +/* + * %CopyrightBegin% + * + * Copyright Ericsson AB 2017. 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. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * %CopyrightEnd% + */ + +/* Tests whether erl_drv_putenv/erl_drv_getenv work correctly and reflect + * changes to os:putenv/getenv. */ + +#include +#include + +#include "erl_driver.h" + +static ErlDrvSSizeT env_drv_ctl(ErlDrvData drv_data, unsigned int cmd, + char* buf, ErlDrvSizeT len, char** rbuf, ErlDrvSizeT rsize); + +static ErlDrvEntry env_drv_entry = { + NULL /* init */, + NULL /* start */, + NULL /* stop */, + NULL /* output */, + NULL /* ready_input */, + NULL /* ready_output */, + "env_drv", + NULL /* finish */, + NULL /* handle */, + env_drv_ctl, + NULL /* timeout */, + NULL /* outputv*/, + NULL /* ready_async */, + NULL /* flush */, + NULL /* call*/, + NULL /* event */, + ERL_DRV_EXTENDED_MARKER, + ERL_DRV_EXTENDED_MAJOR_VERSION, + ERL_DRV_EXTENDED_MINOR_VERSION, + ERL_DRV_FLAG_USE_PORT_LOCKING, + NULL /* handle2 */, + NULL /* handle_monitor */ +}; + +DRIVER_INIT(env_drv) { + return &env_drv_entry; +} + +static int test_putenv(ErlDrvData drv_data, char *buf, ErlDrvSizeT len) { + char key[256], value[256]; + int key_len, value_len; + + key_len = buf[0]; + value_len = buf[1]; + + sprintf(key, "%.*s", key_len, &buf[2]); + sprintf(value, "%.*s", value_len, &buf[2 + key_len]); + + return erl_drv_putenv(key, value); +} + +static int test_getenv(ErlDrvData drv_data, char *buf, ErlDrvSizeT len) { + char expected_value[256], stored_value[256], key[256]; + int expected_value_len, key_len; + size_t stored_value_len; + int res; + + key_len = buf[0]; + sprintf(key, "%.*s", key_len, &buf[2]); + + expected_value_len = buf[1]; + sprintf(expected_value, "%.*s", expected_value_len, &buf[2 + key_len]); + + stored_value_len = sizeof(stored_value); + res = erl_drv_getenv(key, stored_value, &stored_value_len); + + if(res == 0) { + return strcmp(stored_value, expected_value) != 0; + } else if(res == 1) { + return 127; + } + + return 255; +} + +static ErlDrvSSizeT env_drv_ctl(ErlDrvData drv_data, unsigned int cmd, + char* buf, ErlDrvSizeT len, char** rbuf, ErlDrvSizeT rsize) { + + if(cmd == 0) { + (**rbuf) = (char)test_putenv(drv_data, buf, len); + } else { + (**rbuf) = (char)test_getenv(drv_data, buf, len); + } + + return 1; +} -- cgit v1.2.3