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authorJohn Högberg <[email protected]>2017-11-22 13:19:57 +0100
committerJohn Högberg <[email protected]>2018-01-03 08:14:28 +0100
commitc2d70945dce9cb09d5d7120d6e9ddf7faac8d230 (patch)
tree3cfbaca9af7b6a32871e669a39027ce987c846da /lib/kernel
parentbe9f93b14e0fb9ff09db36abde62ae8099bf5bd0 (diff)
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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.
Diffstat (limited to 'lib/kernel')
-rw-r--r--lib/kernel/src/os.erl76
1 files changed, 47 insertions, 29 deletions
diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl
index b5f19d4b99..fbc046c8f9 100644
--- a/lib/kernel/src/os.erl
+++ b/lib/kernel/src/os.erl
@@ -27,12 +27,13 @@
-export_type([env_var_name/0, env_var_value/0, env_var_name_value/0, command_input/0]).
+-export([getenv/0, getenv/1, getenv/2, putenv/2, unsetenv/1]).
+
%%% BIFs
--export([getenv/0, getenv/1, getenv/2, getpid/0,
- perf_counter/0, perf_counter/1,
- putenv/2, set_signal/2, system_time/0, system_time/1,
- timestamp/0, unsetenv/1]).
+-export([get_env_var/1, getpid/0, list_env_vars/0, perf_counter/0,
+ perf_counter/1, set_env_var/2, set_signal/2, system_time/0,
+ system_time/1, timestamp/0, unset_env_var/1]).
-type env_var_name() :: nonempty_string().
@@ -42,29 +43,15 @@
-type command_input() :: atom() | io_lib:chars().
--spec getenv() -> [env_var_name_value()].
-
-getenv() -> erlang:nif_error(undef).
-
--spec getenv(VarName) -> Value | false when
- VarName :: env_var_name(),
- Value :: env_var_value().
-
-getenv(_) ->
+-spec list_env_vars() -> [{env_var_name(), env_var_value()}].
+list_env_vars() ->
erlang:nif_error(undef).
--spec getenv(VarName, DefaultValue) -> Value when
+-spec get_env_var(VarName) -> Value | false when
VarName :: env_var_name(),
- DefaultValue :: env_var_value(),
Value :: env_var_value().
-
-getenv(VarName, DefaultValue) ->
- case os:getenv(VarName) of
- false ->
- DefaultValue;
- Value ->
- Value
- end.
+get_env_var(_VarName) ->
+ erlang:nif_error(undef).
-spec getpid() -> Value when
Value :: string().
@@ -84,11 +71,10 @@ perf_counter() ->
perf_counter(Unit) ->
erlang:convert_time_unit(os:perf_counter(), perf_counter, Unit).
--spec putenv(VarName, Value) -> true when
+-spec set_env_var(VarName, Value) -> true when
VarName :: env_var_name(),
Value :: env_var_value().
-
-putenv(_, _) ->
+set_env_var(_, _) ->
erlang:nif_error(undef).
-spec system_time() -> integer().
@@ -108,10 +94,9 @@ system_time(_Unit) ->
timestamp() ->
erlang:nif_error(undef).
--spec unsetenv(VarName) -> true when
+-spec unset_env_var(VarName) -> true when
VarName :: env_var_name().
-
-unsetenv(_) ->
+unset_env_var(_) ->
erlang:nif_error(undef).
-spec set_signal(Signal, Option) -> 'ok' when
@@ -125,6 +110,39 @@ set_signal(_Signal, _Option) ->
%%% End of BIFs
+-spec getenv() -> [env_var_name_value()].
+getenv() ->
+ [lists:flatten([Key, $=, Value]) || {Key, Value} <- os:list_env_vars() ].
+
+-spec getenv(VarName) -> Value | false when
+ VarName :: env_var_name(),
+ Value :: env_var_value().
+getenv(VarName) ->
+ os:get_env_var(VarName).
+
+-spec getenv(VarName, DefaultValue) -> Value when
+ VarName :: env_var_name(),
+ DefaultValue :: env_var_value(),
+ Value :: env_var_value().
+getenv(VarName, DefaultValue) ->
+ case os:getenv(VarName) of
+ false ->
+ DefaultValue;
+ Value ->
+ Value
+ end.
+
+-spec putenv(VarName, Value) -> true when
+ VarName :: env_var_name(),
+ Value :: env_var_value().
+putenv(VarName, Value) ->
+ os:set_env_var(VarName, Value).
+
+-spec unsetenv(VarName) -> true when
+ VarName :: env_var_name().
+unsetenv(VarName) ->
+ os:unset_env_var(VarName).
+
-spec type() -> {Osfamily, Osname} when
Osfamily :: unix | win32,
Osname :: atom().