Merge branch 'john/erts/fix-heart-command-overflow/OTP-15034/ERIERL-166' into maint-20

* john/erts/fix-heart-command-overflow/OTP-15034/ERIERL-166:
  heart: Use ntohs instead of manual conversion

# Conflicts:
#	lib/kernel/test/heart_SUITE.erl

2 files changed, 11 insertions, 7 deletions

diff --git a/erts/etc/common/heart.c b/erts/etc/common/heart.c
index bc353e384e..8f1e89b638 100644
--- a/erts/etc/common/heart.c
+++ b/erts/etc/common/heart.c
@@ -825,11 +825,8 @@ write_message(fd, mp)
   int   fd;
   struct msg *mp;
 {
-  int   len;
-  char* tmp;
+  int len = ntohs(mp->len);
 
-  tmp = (char*) &(mp->len);
-  len = (*tmp * 256) + *(tmp+1); 
   if ((len == 0) || (len > MSG_BODY_SIZE)) {
     return MSG_HDR_SIZE;
   }				/* cc68k wants (char *) */
diff --git a/lib/kernel/test/heart_SUITE.erl b/lib/kernel/test/heart_SUITE.erl
index 45032faf6d..22db24de5f 100644
--- a/lib/kernel/test/heart_SUITE.erl
+++ b/lib/kernel/test/heart_SUITE.erl
@@ -346,9 +346,16 @@ clear_cmd(Config) when is_list(Config) ->
 
 get_cmd(Config) when is_list(Config) ->
     {ok, Node} = start_check(slave, ?UNIQ_NODE_NAME),
-    Cmd = "test",
-    ok  = rpc:call(Node, heart, set_cmd, [Cmd]),
-    {ok, Cmd} = rpc:call(Node, heart, get_cmd, []),
+
+    ShortCmd = "test",
+    ok  = rpc:call(Node, heart, set_cmd, [ShortCmd]),
+    {ok, ShortCmd} = rpc:call(Node, heart, get_cmd, []),
+
+    %% This would hang prior to OTP-15024 being fixed.
+    LongCmd = [$a || _ <- lists:seq(1, 160)],
+    ok  = rpc:call(Node, heart, set_cmd, [LongCmd]),
+    {ok, LongCmd} = rpc:call(Node, heart, get_cmd, []),
+
     stop_node(Node),
     ok.