File 2616-pg-ensure-argument-is-expected-local-pid-s.patch of Package erlang

From 096fa63c0a1295e8382726e95db886b3b453cea9 Mon Sep 17 00:00:00 2001
From: "Robert A. Nowak" <r.nowak@sciencia.se>
Date: Thu, 13 Feb 2020 15:13:30 +0100
Subject: [PATCH] pg: ensure argument is expected local pid(s)

Changes join/3 and leave/3 to ensure that the expected pid or list of
pids argument is actually a local pid or list of such.
---
 lib/kernel/src/pg.erl | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/lib/kernel/src/pg.erl b/lib/kernel/src/pg.erl
index 0668dd1f79..9b236d3187 100644
--- a/lib/kernel/src/pg.erl
+++ b/lib/kernel/src/pg.erl
@@ -117,31 +117,29 @@ start_link(Scope) when is_atom(Scope) ->
 
 %%--------------------------------------------------------------------
 %% @doc
-%% Joins a single process
+%% Joins a single or a list of processes.
 %% Group is created automatically.
-%% Process must be local to this node.
+%% Processes must be local to this node.
 -spec join(Group :: group(), PidOrPids :: pid() | [pid()]) -> ok.
 join(Group, PidOrPids) ->
     join(?DEFAULT_SCOPE, Group, PidOrPids).
 
 -spec join(Scope :: atom(), Group :: group(), PidOrPids :: pid() | [pid()]) -> ok.
-join(Scope, Group, PidOrPids) ->
-    Node = node(),
-    is_list(PidOrPids) andalso [error({nolocal, Pid}) || Pid <- PidOrPids, node(Pid) =/= Node orelse not is_pid(Pid)],
+join(Scope, Group, PidOrPids) when is_pid(PidOrPids); is_list(PidOrPids) ->
+    ok = ensure_local(PidOrPids),
     gen_server:call(Scope, {join_local, Group, PidOrPids}, infinity).
 
 %%--------------------------------------------------------------------
 %% @doc
-%% Single process leaving the group.
-%% Process must be local to this node.
+%% Single or list of processes leaving the group.
+%% Processes must be local to this node.
 -spec leave(Group :: group(), PidOrPids :: pid() | [pid()]) -> ok.
 leave(Group, PidOrPids) ->
     leave(?DEFAULT_SCOPE, Group, PidOrPids).
 
--spec leave(Scope :: atom(), Group :: group(), Pid :: pid() | [pid()]) -> ok | not_joined.
-leave(Scope, Group, PidOrPids) ->
-    Node = node(),
-    is_list(PidOrPids) andalso [error({nolocal, Pid}) || Pid <- PidOrPids, node(Pid) =/= Node orelse not is_pid(Pid)],
+-spec leave(Scope :: atom(), Group :: group(), PidOrPids :: pid() | [pid()]) -> ok | not_joined.
+leave(Scope, Group, PidOrPids) when is_pid(PidOrPids); is_list(PidOrPids) ->
+    ok = ensure_local(PidOrPids),
     gen_server:call(Scope, {leave_local, Group, PidOrPids}, infinity).
 
 %%--------------------------------------------------------------------
@@ -340,6 +338,20 @@ terminate(_Reason, #state{scope = Scope}) ->
 %%--------------------------------------------------------------------
 %% Internal implementation
 
+%% Ensures argument is either a node-local pid or a list of such, or it throws an error
+ensure_local(Pid) when is_pid(Pid), node(Pid) =:= node() ->
+    ok;
+ensure_local(Pids) when is_list(Pids) ->
+    lists:foreach(
+        fun
+            (Pid) when is_pid(Pid), node(Pid) =:= node() ->
+                ok;
+            (Bad) ->
+                error({nolocal, Bad})
+        end, Pids);
+ensure_local(Bad) ->
+    error({nolocal, Bad}).
+
 %% Override all knowledge of the remote node with information it sends
 %%  to local node. Current implementation must do the full table scan
 %%  to remove stale pids (just as for 'nodedown').
-- 
2.16.4