File 5251-Add-application-get_supervisor-1.patch of Package erlang

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File 5251-Add-application-get_supervisor-1.patch of Package erlang (Revision e0e016f64b94e78db3440770f914218d)

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From 26237d26a47416d1143218f98086b622cc9e19f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Valim?= <jose.valim@dashbit.co>
Date: Mon, 30 May 2022 23:50:15 +0200
Subject: [PATCH] Add application:get_supervisor/1

It returns the Pid of the supervisor running at
the root of the given application.

This allows tools for introspection and debugging
to print supervision trees without relying on
private APIs.
---
 lib/kernel/doc/src/application.xml    | 10 ++++++++++
 lib/kernel/src/application.erl        | 16 +++++++++++++++-
 lib/kernel/src/application_master.erl |  2 +-
 lib/kernel/test/application_SUITE.erl | 10 ++++++++--
 4 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/lib/kernel/doc/src/application.xml b/lib/kernel/doc/src/application.xml
index 2a807e62bb..d4d7810531 100644
--- a/lib/kernel/doc/src/application.xml
+++ b/lib/kernel/doc/src/application.xml
@@ -180,6 +180,16 @@
 
       </desc>
     </func>
+    <func>
+      <name name="get_supervisor" arity="1" since="OTP 25.1"/>
+      <fsummary>Get the supervisor of an application.</fsummary>
+      <desc>
+        <p>Returns the <c><anno>Pid</anno></c> of the supervisor running
+          at the root of <c><anno>Application</anno></c>.</p>
+        <p>If the specified application does not exist or does not
+          define a callback module, the function returns <c>undefined</c>.</p>
+      </desc>
+    </func>
     <func>
       <name name="load" arity="1" since=""/>
       <name name="load" arity="2" since=""/>
diff --git a/lib/kernel/src/application.erl b/lib/kernel/src/application.erl
index 3eb87d73c7..3214d85944 100644
--- a/lib/kernel/src/application.erl
+++ b/lib/kernel/src/application.erl
@@ -28,7 +28,7 @@
 -export([set_env/1, set_env/2, set_env/3, set_env/4, unset_env/2, unset_env/3]).
 -export([get_env/1, get_env/2, get_env/3, get_all_env/0, get_all_env/1]).
 -export([get_key/1, get_key/2, get_all_key/0, get_all_key/1]).
--export([get_application/0, get_application/1, info/0]).
+-export([get_application/0, get_application/1, get_supervisor/1, info/0]).
 -export([start_type/0]).
 
 -export_type([start_type/0]).
@@ -466,6 +466,20 @@ get_application(Pid) when is_pid(Pid) ->
 get_application(Module) when is_atom(Module) ->
     application_controller:get_application_module(Module).
 
+-spec get_supervisor(Application) -> 'undefined' | {'ok', Pid} when
+      Pid :: pid(),
+      Application :: atom().
+
+get_supervisor(Application) when is_atom(Application) ->
+    case application_controller:get_master(Application) of
+        undefined -> undefined;
+        Master ->
+            case application_master:get_child(Master) of
+                {Root, _App} -> {ok, Root};
+                error -> undefined
+            end
+    end.
+
 -spec start_type() -> StartType | 'undefined' | 'local' when
       StartType :: start_type().
 
diff --git a/lib/kernel/src/application_master.erl b/lib/kernel/src/application_master.erl
index 35c9db170e..880e36047d 100644
--- a/lib/kernel/src/application_master.erl
+++ b/lib/kernel/src/application_master.erl
@@ -75,7 +75,7 @@ call(AppMaster, Req) ->
     AppMaster ! {Req, Tag, self()},
     receive 
 	{'DOWN', Ref, process, _, _Info} ->
-	    ok;
+	    error;
 	{Tag, Res} ->
 	    erlang:demonitor(Ref, [flush]),
 	    Res
diff --git a/lib/kernel/test/application_SUITE.erl b/lib/kernel/test/application_SUITE.erl
index 6817435576..88784cc1b7 100644
--- a/lib/kernel/test/application_SUITE.erl
+++ b/lib/kernel/test/application_SUITE.erl
@@ -30,7 +30,7 @@
 	 otp_1586/1, otp_2078/1, otp_2012/1, otp_2718/1, otp_2973/1,
 	 otp_3002/1, otp_3184/1, otp_4066/1, otp_4227/1, otp_5363/1,
 	 otp_5606/1,
-	 start_phases/1, get_key/1, get_env/1,
+	 start_phases/1, get_key/1, get_env/1, get_supervisor/1,
 	 set_env/1, set_env_persistent/1, set_env_errors/1, optional_applications/1,
 	 permit_false_start_local/1, permit_false_start_dist/1, script_start/1, 
 	 nodedown_start/1, init2973/0, loop2973/0, loop5606/1, otp_16504/1]).
@@ -58,7 +58,7 @@ all() ->
      load_use_cache, ensure_started, {group, reported_bugs}, start_phases,
      script_start, nodedown_start, permit_false_start_local,
      permit_false_start_dist, get_key, get_env, ensure_all_started,
-     set_env, set_env_persistent, set_env_errors,
+     set_env, set_env_persistent, set_env_errors, get_supervisor,
      {group, distr_changed}, config_change, shutdown_func, shutdown_timeout,
      shutdown_deadlock, config_relative_paths, optional_applications,
      persistent_env, handle_many_config_files, format_log_1, format_log_2,
@@ -1652,6 +1652,12 @@ get_env(Conf) when is_list(Conf) ->
     default   = application:get_env(kernel, error_logger_xyz, default),
     ok.
 
+get_supervisor(Conf) when is_list(Conf) ->
+    undefined = application:get_supervisor(stdlib),
+    {ok, Pid} = application:get_supervisor(kernel),
+    Pid = erlang:whereis(kernel_sup),
+    ok.
+
 %%-----------------------------------------------------------------
 %% Should be started in a CC view with:
 %% erl -sname XXX -rsh ctrsh where XX not in [cp1, cp2, cp3]
-- 
2.35.3

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File 5251-Add-application-get_supervisor-1.patch of Package erlang (Revision e0e016f64b94e78db3440770f914218d)

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