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. --- lib/kernel/src/os.erl | 76 +++++++++++++++++++++++++++++++-------------------- 1 file changed, 47 insertions(+), 29 deletions(-) (limited to 'lib') 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(). -- cgit v1.2.3 From d469368b9e14b9834017a7cf318f02950a4aadcb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?John=20H=C3=B6gberg?= Date: Fri, 1 Dec 2017 12:22:53 +0100 Subject: Disallow NULs in filename-encoded strings Previously we accepted trailing NULs, which was backwards compatible as such usage never resulted in misbehavior in the first place. The downside is that it prevented erts_native_filename_need from returning an accurate number of *actual characters*, needlessly complicating encoding-agnostic code like erts_osenv. --- lib/kernel/doc/src/file.xml | 7 ------- lib/kernel/doc/src/os.xml | 19 ++----------------- 2 files changed, 2 insertions(+), 24 deletions(-) (limited to 'lib') diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml index 58abb35428..8477b0e148 100644 --- a/lib/kernel/doc/src/file.xml +++ b/lib/kernel/doc/src/file.xml @@ -93,13 +93,6 @@ are now rejected and will cause primitive file operations fail.

-

- Currently null characters at the end of the filename - will be accepted by primitive file operations. Such - filenames are however still documented as invalid. The - implementation will also change in the future and - reject such filenames. -

diff --git a/lib/kernel/doc/src/os.xml b/lib/kernel/doc/src/os.xml index 0a08e2c78a..c27182ff0b 100644 --- a/lib/kernel/doc/src/os.xml +++ b/lib/kernel/doc/src/os.xml @@ -58,17 +58,6 @@ operations to fail.

- -

- Currently null characters at the end of filenames, - environment variable names and values will be accepted - by the primitive operations. Such filenames, environment - variable names and values are however still documented as - invalid. The implementation will also change in the - future and reject such filenames, environment variable - names and values. -

- @@ -143,12 +132,8 @@

Previous implementation used to allow all characters as long as they were integer values greater than or equal to zero. This sometimes lead to unwanted results since null characters - (integer value zero) often are interpreted as string termination. - Current implementation still accepts null characters at the end - of Command even though the documentation - states that no null characters are allowed. This will however - be changed in the future so that no null characters at all will - be accepted.

 + (integer value zero) often are interpreted as string termination. The + current implementation rejects these.

Examples:

LsOut = os:cmd("ls"), % on unix platform -- cgit v1.2.3