From f1ca806498bc7f7dad96f2c7e188fdc55e0124cb Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang.org>
Date: Thu, 14 Jul 2016 12:24:49 +0200
Subject: kernel: Use ^D as eot for os:cmd on unix platforms
This is needed as doing only an 'exit' will only exit the
program, but any children started in the program that have
stdout/stderr still open will keep the port open until they
terminate. i.e.
os:cmd("while true; do echo sleep 1; sleep 1; done&").
would block os:cmd forever because the while loop keeps its copies
of stdout/stderr open forever.
It could be argued that this is correct behaviour, and it is
the way it works on windows, but changing this breaks backwards
compatability for os:cmd which is not acceptable.
---
lib/kernel/src/os.erl | 48 +++++++++++++++++++++++++++++++++++-------------
1 file changed, 35 insertions(+), 13 deletions(-)
(limited to 'lib/kernel/src')
diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl
index f0ad26b1f2..81b70a7fee 100644
--- a/lib/kernel/src/os.erl
+++ b/lib/kernel/src/os.erl
@@ -226,11 +226,13 @@ extensions() ->
Command :: atom() | io_lib:chars().
cmd(Cmd) ->
validate(Cmd),
- {SpawnCmd, SpawnOpts, SpawnInput} = mk_cmd(os:type(), Cmd),
+ {SpawnCmd, SpawnOpts, SpawnInput, Eot} = mk_cmd(os:type(), Cmd),
Port = open_port({spawn, SpawnCmd}, [binary, stderr_to_stdout,
- stream, in, eof, hide | SpawnOpts]),
+ stream, in, hide | SpawnOpts]),
+ MonRef = erlang:monitor(port, Port),
true = port_command(Port, SpawnInput),
- Bytes = get_data(Port, []),
+ Bytes = get_data(Port, MonRef, Eot, []),
+ demonitor(MonRef, [flush]),
String = unicode:characters_to_list(Bytes),
if %% Convert to unicode list if possible otherwise return bytes
is_list(String) -> String;
@@ -243,7 +245,7 @@ mk_cmd({win32,Wtype}, Cmd) ->
{false,_} -> lists:concat(["cmd /c", Cmd]);
{Cspec,_} -> lists:concat([Cspec," /c",Cmd])
end,
- {Command, [], []};
+ {Command, [], [], <<>>};
mk_cmd(OsType,Cmd) when is_atom(Cmd) ->
mk_cmd(OsType, atom_to_list(Cmd));
mk_cmd(_,Cmd) ->
@@ -252,7 +254,8 @@ mk_cmd(_,Cmd) ->
{"/bin/sh -s unix:cmd", [out],
%% We insert a new line after the command, in case the command
%% contains a comment character.
- ["(", unicode:characters_to_binary(Cmd), "\n); exit\n"]}.
+ ["(", unicode:characters_to_binary(Cmd), "\n); echo \"\^D\"\n"],
+ <<$\^D>>}.
validate(Atom) when is_atom(Atom) ->
ok;
@@ -267,16 +270,18 @@ validate1([List|Rest]) when is_list(List) ->
validate1([]) ->
ok.
-get_data(Port, Sofar) ->
+get_data(Port, MonRef, Eot, Sofar) ->
receive
{Port, {data, Bytes}} ->
- get_data(Port, [Sofar,Bytes]);
- {Port, eof} ->
- Port ! {self(), close},
- receive
- {Port, closed} ->
- true
- end,
+ case eot(Bytes, Eot) of
+ more ->
+ get_data(Port, MonRef, Eot, [Sofar,Bytes]);
+ Last ->
+ Port ! {self(), close},
+ flush_until_closed(Port),
+ iolist_to_binary([Sofar, Last])
+ end;
+ {'DOWN', MonRef, _, _ , _} ->
receive
{'EXIT', Port, _} ->
ok
@@ -285,3 +290,20 @@ get_data(Port, Sofar) ->
end,
iolist_to_binary(Sofar)
end.
+
+eot(_Bs, <<>>) ->
+ more;
+eot(Bs, Eot) ->
+ case binary:match(Bs, Eot) of
+ nomatch -> more;
+ {Pos, _} ->
+ binary:part(Bs,{0, Pos})
+ end.
+
+flush_until_closed(Port) ->
+ receive
+ {Port, {data, _Bytes}} ->
+ flush_until_closed(Port);
+ {Port, closed} ->
+ true
+ end.
--
cgit v1.2.3