%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1997-2017. 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%
%%
-module(os).
%% Provides a common operating system interface.
-export([type/0, version/0, cmd/1, cmd/2, find_executable/1, find_executable/2]).
-include("file.hrl").
%%% BIFs
-export([getenv/0, getenv/1, getenv/2, getpid/0,
perf_counter/0, perf_counter/1,
putenv/2, system_time/0, system_time/1,
timestamp/0, unsetenv/1]).
-type os_command() :: atom() | io_lib:chars().
-type os_command_opts() :: #{ max_size => non_neg_integer() | infinity }.
-export_type([os_command/0, os_command_opts/0]).
-spec getenv() -> [string()].
getenv() -> erlang:nif_error(undef).
-spec getenv(VarName) -> Value | false when
VarName :: string(),
Value :: string().
getenv(_) ->
erlang:nif_error(undef).
-spec getenv(VarName, DefaultValue) -> Value when
VarName :: string(),
DefaultValue :: string(),
Value :: string().
getenv(VarName, DefaultValue) ->
case os:getenv(VarName) of
false ->
DefaultValue;
Value ->
Value
end.
-spec getpid() -> Value when
Value :: string().
getpid() ->
erlang:nif_error(undef).
-spec perf_counter() -> Counter when
Counter :: integer().
perf_counter() ->
erlang:nif_error(undef).
-spec perf_counter(Unit) -> integer() when
Unit :: erlang:time_unit().
perf_counter(Unit) ->
erlang:convert_time_unit(os:perf_counter(), perf_counter, Unit).
-spec putenv(VarName, Value) -> true when
VarName :: string(),
Value :: string().
putenv(_, _) ->
erlang:nif_error(undef).
-spec system_time() -> integer().
system_time() ->
erlang:nif_error(undef).
-spec system_time(Unit) -> integer() when
Unit :: erlang:time_unit().
system_time(_Unit) ->
erlang:nif_error(undef).
-spec timestamp() -> Timestamp when
Timestamp :: erlang:timestamp().
timestamp() ->
erlang:nif_error(undef).
-spec unsetenv(VarName) -> true when
VarName :: string().
unsetenv(_) ->
erlang:nif_error(undef).
%%% End of BIFs
-spec type() -> {Osfamily, Osname} when
Osfamily :: unix | win32,
Osname :: atom().
type() ->
erlang:system_info(os_type).
-spec version() -> VersionString | {Major, Minor, Release} when
VersionString :: string(),
Major :: non_neg_integer(),
Minor :: non_neg_integer(),
Release :: non_neg_integer().
version() ->
erlang:system_info(os_version).
-spec find_executable(Name) -> Filename | 'false' when
Name :: string(),
Filename :: string().
find_executable(Name) ->
find_executable(Name, os:getenv("PATH", "")).
-spec find_executable(Name, Path) -> Filename | 'false' when
Name :: string(),
Path :: string(),
Filename :: string().
find_executable(Name, Path) ->
Extensions = extensions(),
case filename:pathtype(Name) of
relative ->
find_executable1(Name, split_path(Path), Extensions);
_ ->
case verify_executable(Name, Extensions, Extensions) of
{ok, Complete} ->
Complete;
error ->
false
end
end.
find_executable1(Name, [Base|Rest], Extensions) ->
Complete0 = filename:join(Base, Name),
case verify_executable(Complete0, Extensions, Extensions) of
{ok, Complete} ->
Complete;
error ->
find_executable1(Name, Rest, Extensions)
end;
find_executable1(_Name, [], _Extensions) ->
false.
verify_executable(Name0, [Ext|Rest], OrigExtensions) ->
Name1 = Name0 ++ Ext,
case file:read_file_info(Name1) of
{ok, #file_info{type=regular,mode=Mode}}
when Mode band 8#111 =/= 0 ->
%% XXX This test for execution permission is not fool-proof
%% on Unix, since we test if any execution bit is set.
{ok, Name1};
_ ->
verify_executable(Name0, Rest, OrigExtensions)
end;
verify_executable(Name, [], OrigExtensions) when OrigExtensions =/= [""] -> %% Windows
%% Will only happen on windows, hence case insensitivity
case can_be_full_name(string:to_lower(Name),OrigExtensions) of
true ->
verify_executable(Name,[""],[""]);
_ ->
error
end;
verify_executable(_, [], _) ->
error.
can_be_full_name(_Name,[]) ->
false;
can_be_full_name(Name,[H|T]) ->
case lists:suffix(H,Name) of %% Name is in lowercase, cause this is a windows thing
true ->
true;
_ ->
can_be_full_name(Name,T)
end.
split_path(Path) ->
case type() of
{win32, _} ->
{ok,Curr} = file:get_cwd(),
split_path(Path, $;, [], [Curr]);
_ ->
split_path(Path, $:, [], [])
end.
split_path([Sep|Rest], Sep, Current, Path) ->
split_path(Rest, Sep, [], [reverse_element(Current)|Path]);
split_path([C|Rest], Sep, Current, Path) ->
split_path(Rest, Sep, [C|Current], Path);
split_path([], _, Current, Path) ->
lists:reverse(Path, [reverse_element(Current)]).
reverse_element([]) -> ".";
reverse_element([$"|T]) -> %"
case lists:reverse(T) of
[$"|List] -> List; %"
List -> List ++ [$"] %"
end;
reverse_element(List) ->
lists:reverse(List).
-spec extensions() -> [string(),...].
%% Extensions in lower case
extensions() ->
case type() of
{win32, _} -> [".exe",".com",".cmd",".bat"];
{unix, _} -> [""]
end.
%% Executes the given command in the default shell for the operating system.
-spec cmd(Command) -> string() when
Command :: os_command().
cmd(Cmd) ->
cmd(Cmd, #{ }).
-spec cmd(Command, Options) -> string() when
Command :: os_command(),
Options :: os_command_opts().
cmd(Cmd, Opts) ->
validate(Cmd),
{SpawnCmd, SpawnOpts, SpawnInput, Eot} = mk_cmd(os:type(), Cmd),
Port = open_port({spawn, SpawnCmd}, [binary, stderr_to_stdout,
stream, in, hide | SpawnOpts]),
MonRef = erlang:monitor(port, Port),
true = port_command(Port, SpawnInput),
Bytes = get_data(Port, MonRef, Eot, [], 0, maps:get(max_size, Opts, infinity)),
demonitor(MonRef, [flush]),
String = unicode:characters_to_list(Bytes),
if %% Convert to unicode list if possible otherwise return bytes
is_list(String) -> String;
true -> binary_to_list(Bytes)
end.
mk_cmd({win32,Wtype}, Cmd) ->
Command = case {os:getenv("COMSPEC"),Wtype} of
{false,windows} -> lists:concat(["command.com /c", Cmd]);
{false,_} -> lists:concat(["cmd /c", Cmd]);
{Cspec,_} -> lists:concat([Cspec," /c",Cmd])
end,
{Command, [], [], <<>>};
mk_cmd(OsType,Cmd) when is_atom(Cmd) ->
mk_cmd(OsType, atom_to_list(Cmd));
mk_cmd(_,Cmd) ->
%% Have to send command in like this in order to make sh commands like
%% cd and ulimit available
{"/bin/sh -s unix:cmd", [out],
%% We insert a new line after the command, in case the command
%% contains a comment character.
%%
%% The </dev/null closes stdin, which means that programs
%% that use a closed stdin as an termination indicator works.
%% An example of such a program is 'more'.
%%
%% The "echo ^D" is used to indicate that the program has executed
%% and we should return any output we have gotten. We cannot use
%% termination of the child or closing of stdin/stdout as then
%% starting background jobs from os:cmd will block os:cmd.
%%
%% I tried changing this to be "better", but got bombarded with
%% backwards incompatibility bug reports, so leave this as it is.
["(", unicode:characters_to_binary(Cmd), "\n) </dev/null; echo \"\^D\"\n"],
<<$\^D>>}.
validate(Atom) when is_atom(Atom) ->
ok;
validate(List) when is_list(List) ->
validate1(List).
validate1([C|Rest]) when is_integer(C) ->
validate1(Rest);
validate1([List|Rest]) when is_list(List) ->
validate1(List),
validate1(Rest);
validate1([]) ->
ok.
get_data(Port, MonRef, Eot, Sofar, Size, Max) ->
receive
{Port, {data, Bytes}} ->
case eot(Bytes, Eot, Size, Max) of
more ->
get_data(Port, MonRef, Eot, [Sofar, Bytes],
Size + byte_size(Bytes), Max);
Last ->
catch port_close(Port),
flush_until_down(Port, MonRef),
iolist_to_binary([Sofar, Last])
end;
{'DOWN', MonRef, _, _, _} ->
flush_exit(Port),
iolist_to_binary(Sofar)
end.
eot(_Bs, <<>>, _Size, _Max) ->
more;
eot(Bs, Eot, Size, Max) ->
case binary:match(Bs, Eot) of
nomatch when Size + byte_size(Bs) < Max ->
more;
{Pos, _} when Size + Pos < Max ->
binary:part(Bs,{0, Pos});
_ ->
binary:part(Bs,{0, Max - Size})
end.
%% When port_close returns we know that all the
%% messages sent have been sent and that the
%% DOWN message is after them all.
flush_until_down(Port, MonRef) ->
receive
{Port, {data, _Bytes}} ->
flush_until_down(Port, MonRef);
{'DOWN', MonRef, _, _, _} ->
flush_exit(Port)
end.
%% The exit signal is always delivered before
%% the down signal, so we can be sure that if there
%% was an exit message sent, it will be in the
%% mailbox now.
flush_exit(Port) ->
receive
{'EXIT', Port, _} ->
ok
after 0 ->
ok
end.
