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Support long PATH values in erlexec
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Previously a finite 10240 buffer was used. Long paths can fail
semi-silently, while long paths that already contain the erlang bindir
at the end can cause a crash.

Co-authored-by: Eric Meadows-Jönsson <[email protected]>
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@HoloRin @ericmj
HoloRin and ericmj committed Jan 23, 2025
1 parent 85ab462 commit c4257e7
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Showing 2 changed files with 83 additions and 49 deletions.
46 changes: 31 additions & 15 deletions erts/etc/common/erlexec.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -555,37 +555,53 @@ int main(int argc, char **argv)
if (s == NULL) {
erts_snprintf(tmpStr, sizeof(tmpStr),
"%s" PATHSEP "%s" DIRSEP "bin" PATHSEP, bindir, rootdir);
set_env("PATH", tmpStr);
} else if (strstr(s, rootdir) == NULL) {
erts_snprintf(tmpStr, sizeof(tmpStr),
"%s" PATHSEP "%s" DIRSEP "bin" PATHSEP "%s", bindir, rootdir, s);
set_env("PATH", tmpStr);
} else {
const char *bindir_slug, *bindir_slug_index;
int bindir_slug_length;
char *pathBuf = NULL;
int pathBufLen = 0;

char *sep_index;
int sep_length = strlen(PATHSEP);
int bindir_length = strlen(bindir);
const char *in_index;
char *out_index;

erts_snprintf(tmpStr, sizeof(tmpStr), "%s" PATHSEP, bindir);
pathBufLen = strlen(s) + strlen(bindir) + strlen(PATHSEP);
pathBuf = emalloc(pathBufLen);

bindir_slug = strsave(tmpStr);
bindir_slug_length = strlen(bindir_slug);
strcpy(pathBuf, bindir);

out_index = &tmpStr[bindir_slug_length];
out_index = &pathBuf[bindir_length];
in_index = s;

while ((bindir_slug_index = strstr(in_index, bindir_slug))) {
int block_length = (bindir_slug_index - in_index);
while ((sep_index = strstr(in_index, PATHSEP))) {
int elem_length = (sep_index - in_index);

memcpy(out_index, in_index, block_length);
if (bindir_length != elem_length ||
0 != strncmp(in_index, bindir, elem_length)) {
strcpy(out_index, PATHSEP);
out_index += sep_length;
memcpy(out_index, in_index, elem_length);
out_index += elem_length;
}

in_index = bindir_slug_index + bindir_slug_length;
out_index += block_length;
in_index = sep_index + sep_length;
}
efree((void*)bindir_slug);
strcpy(out_index, in_index);
}

if (0 != strcmp(in_index, bindir)) {
strcpy(out_index, PATHSEP);
out_index += sep_length;
strcpy(out_index, in_index);
}

set_env("PATH", pathBuf);
efree(pathBuf);
}
free_env_val(s);
set_env("PATH", tmpStr);

i = 1;

Expand Down
86 changes: 52 additions & 34 deletions erts/test/erlexec_SUITE.erl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,17 +32,18 @@

-export([args_file/1, evil_args_file/1, missing_args_file/1, env/1, args_file_env/1,
otp_7461/1, otp_7461_remote/1, argument_separation/1, argument_with_option/1,
zdbbl_dist_buf_busy_limit/1]).
zdbbl_dist_buf_busy_limit/1, long_path_env/1]).

-include_lib("common_test/include/ct.hrl").

suite() ->
[{ct_hooks,[ts_install_cth]},
{timetrap, {minutes, 1}}].

all() ->
all() ->
[args_file, evil_args_file, missing_args_file, env, args_file_env,
otp_7461, argument_separation, argument_with_option, zdbbl_dist_buf_busy_limit].
otp_7461, argument_separation, argument_with_option, zdbbl_dist_buf_busy_limit,
long_path_env].

init_per_suite(Config) ->
[{suite_erl_flags, save_env()} | Config].
Expand Down Expand Up @@ -108,9 +109,9 @@ loop_ping(_,0) ->
loop_ping(Node,N) ->
case net_adm:ping(Node) of
pang ->
receive
receive
after 500 ->
ok
ok
end,
loop_ping(Node, N-1);
pong ->
Expand Down Expand Up @@ -147,7 +148,7 @@ argument_with_option(Config) when is_list(Config) ->
ok
end
end,

[begin
MissingCheck(CmdLine,"-",""),

Expand All @@ -172,7 +173,7 @@ argument_with_option(Config) when is_list(Config) ->
end || CmdLine <- EmuSingle],

ErlDouble = ["env"],

[begin
MissingCheck(CmdLine,"-",""),
MissingCheck(CmdLine,"-"," a"),
Expand Down Expand Up @@ -354,16 +355,16 @@ args_file_env(Config) when is_list(Config) ->
ok.

%% Make sure "erl -detached" survives when parent process group gets killed
otp_7461(Config) when is_list(Config) ->
otp_7461(Config) when is_list(Config) ->
case os:type() of
{unix,_} ->
{NetStarted, _} = net_kernel:start([test_server, shortnames]),
try
net_kernel:monitor_nodes(true),
register(otp_7461, self()),
register(otp_7461, self()),

otp_7461_do(Config)
after
otp_7461_do(Config)
after
catch unregister(otp_7461),
catch net_kernel:monitor_nodes(false),
case NetStarted of
Expand All @@ -374,7 +375,7 @@ otp_7461(Config) when is_list(Config) ->
_ ->
{skip,"Only on Unix."}
end.

otp_7461_do(Config) ->
io:format("alive=~p node=~p\n",[is_alive(), node()]),
TestProg = filename:join([proplists:get_value(data_dir, Config), "erlexec_tests"]),
Expand All @@ -384,40 +385,40 @@ otp_7461_do(Config) ->
" -setcookie " ++ atom_to_list(erlang:get_cookie()) ++
" -pa " ++ filename:dirname(code:which(?MODULE)) ++
" -s erlexec_SUITE otp_7461_remote init " ++ atom_to_list(node()),

%% otp_7461 --------> erlexec_tests.c --------> cerl -detached
%% open_port fork+exec

io:format("spawn port prog ~p\n",[Cmd]),
Port = open_port({spawn, Cmd}, [eof]),
io:format("Wait for node to connect...\n",[]),

io:format("Wait for node to connect...\n",[]),
{nodeup, Slave} = receive Msg -> Msg
after 20*1000 -> timeout end,
io:format("Node alive: ~p\n", [Slave]),

pong = net_adm:ping(Slave),
io:format("Ping ok towards ~p\n", [Slave]),

Port ! { self(), {command, "K"}}, % Kill child process group
{Port, {data, "K"}} = receive Msg2 -> Msg2 end,
port_close(Port),

%% Now the actual test. Detached node should still be alive.
pong = net_adm:ping(Slave),
io:format("Ping still ok towards ~p\n", [Slave]),

%% Halt node
rpc:cast(Slave, ?MODULE, otp_7461_remote, [[halt, self()]]),

{nodedown, Slave} = receive
Msg3 -> Msg3
after 20*1000 -> timeout
end,
io:format("Node dead: ~p\n", [Slave]),
ok.


%% Executed on slave node
otp_7461_remote([init, Master]) ->
io:format("otp_7461_remote(init,~p) at ~p\n",[Master, node()]),
Expand All @@ -442,7 +443,22 @@ zdbbl_dist_buf_busy_limit(Config) when is_list(Config) ->
LimB = rpc:call(SName,erlang,system_info,[dist_buf_busy_limit]),
ok = cleanup_node(SNameS, 10),
ok.


long_path_env(Config) when is_list(Config) ->
OriginalPath = os:getenv("PATH"),
[BinPath, _RestPath] = string:split(OriginalPath, ":"),
LongPath = lists:duplicate(10240, "x"),
TestPath = OriginalPath ++ ":" ++ LongPath ++ ":" ++ BinPath,
AssertPath = OriginalPath ++ ":" ++ LongPath,
os:putenv("PATH", TestPath),

{ok, [[PName]]} = init:get_argument(progname),
Cmd = PName ++ " -noshell -eval 'io:format(\"~ts\", [os:getenv(\"PATH\")]),erlang:halt()'",
Output = os:cmd(Cmd),

true = string:equal(AssertPath, Output),
ok.


%%
%% Utils
Expand All @@ -452,29 +468,31 @@ save_env() ->
{erl_flags,
os:getenv("ERL_AFLAGS"),
os:getenv("ERL_FLAGS"),
os:getenv("ERL_"++erlang:system_info(otp_release)++"_FLAGS"),
os:getenv("ERL_ZFLAGS")}.
os:getenv("ERL_" ++ erlang:system_info(otp_release) ++ "_FLAGS"),
os:getenv("ERL_ZFLAGS"),
os:getenv("PATH")}.

restore_env(EVar, false) when is_list(EVar) ->
restore_env(EVar, "");
restore_env(EVar, "") when is_list(EVar) ->
case os:getenv(EVar) of
false -> ok;
"" -> ok;
" " -> ok;
_ -> os:putenv(EVar, " ")
false -> ok;
"" -> ok;
" " -> ok;
_ -> os:putenv(EVar, " ")
end;
restore_env(EVar, Value) when is_list(EVar), is_list(Value) ->
case os:getenv(EVar) of
Value -> ok;
_ -> os:putenv(EVar, Value)
Value -> ok;
_ -> os:putenv(EVar, Value)
end.

restore_env({erl_flags, AFlgs, Flgs, RFlgs, ZFlgs}) ->
restore_env({erl_flags, AFlgs, Flgs, RFlgs, ZFlgs, Path}) ->
restore_env("ERL_AFLAGS", AFlgs),
restore_env("ERL_FLAGS", Flgs),
restore_env("ERL_"++erlang:system_info(otp_release)++"_FLAGS", RFlgs),
restore_env("ERL_"++erlang:system_info(otp_release) ++ "_FLAGS", RFlgs),
restore_env("ERL_ZFLAGS", ZFlgs),
restore_env("PATH", Path),
ok.

privfile(Name, Config) ->
Expand Down Expand Up @@ -544,7 +562,7 @@ split_emu_clt([A|As], Emu, Misc, Extra, misc = Type) ->

split_emu_clt([A|As], Emu, Misc, Extra, extra = Type) ->
split_emu_clt(As, Emu, Misc, [A|Extra], Type).


get_nodename(T) ->
atom_to_list(T)
Expand Down

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