Modify version_compare so that eg 5.0 is eq 5. On application start, check that we have a sufficient version of ertsbug22637

2 files changed, 28 insertions, 12 deletions

diff --git a/src/rabbit.erl b/src/rabbit.erl
index bbda29c9..47684411 100644
--- a/src/rabbit.erl
+++ b/src/rabbit.erl
@@ -228,14 +228,18 @@ rotate_logs(BinarySuffix) ->
 %%--------------------------------------------------------------------
 
 start(normal, []) ->
-    {ok, SupPid} = rabbit_sup:start_link(),
+    case erts_version_check() of
+        ok ->
+            {ok, SupPid} = rabbit_sup:start_link(),
 
-    print_banner(),
-    [ok = run_boot_step(Step) || Step <- boot_steps()],
-    io:format("~nbroker running~n"),
-
-    {ok, SupPid}.
+            print_banner(),
+            [ok = run_boot_step(Step) || Step <- boot_steps()],
+            io:format("~nbroker running~n"),
 
+            {ok, SupPid};
+        Error ->
+            Error
+    end.
 
 stop(_State) ->
     terminated_ok = error_logger:delete_report_handler(rabbit_error_logger),
@@ -248,6 +252,14 @@ stop(_State) ->
 
 %%---------------------------------------------------------------------------
 
+erts_version_check() ->
+    FoundVer = erlang:system_info(version),
+    case rabbit_misc:version_compare(?ERTS_MINIMUM, FoundVer, lte) of
+        true  -> ok;
+        false -> {error, {erlang_version_too_old,
+                          {found, FoundVer}, {required, ?ERTS_MINIMUM}}}
+    end.
+
 boot_error(Format, Args) ->
     io:format("BOOT ERROR: " ++ Format, Args),
     error_logger:error_msg(Format, Args),
diff --git a/src/rabbit_misc.erl b/src/rabbit_misc.erl
index 2c180846..59ba2776 100644
--- a/src/rabbit_misc.erl
+++ b/src/rabbit_misc.erl
@@ -598,24 +598,28 @@ version_compare(A, B, gte) ->
 version_compare(A, B, Result) ->
     Result =:= version_compare(A, B).
 
-version_compare([], []) ->
+version_compare(A, A) ->
     eq;
-version_compare([], _ ) ->
+version_compare([], [$0 | B]) ->
+    version_compare([], dropdot(B));
+version_compare([], _) ->
     lt; %% 2.3 < 2.3.1
-version_compare(_ , []) ->
+version_compare([$0 | A], []) ->
+    version_compare(dropdot(A), []);
+version_compare(_, []) ->
     gt; %% 2.3.1 > 2.3
 version_compare(A,  B) ->
     {AStr, ATl} = lists:splitwith(fun (X) -> X =/= $. end, A),
     {BStr, BTl} = lists:splitwith(fun (X) -> X =/= $. end, B),
     ANum = list_to_integer(AStr),
     BNum = list_to_integer(BStr),
-    if ANum =:= BNum -> ATl1 = lists:dropwhile(fun (X) -> X =:= $. end, ATl),
-                        BTl1 = lists:dropwhile(fun (X) -> X =:= $. end, BTl),
-                        version_compare(ATl1, BTl1);
+    if ANum =:= BNum -> version_compare(dropdot(ATl), dropdot(BTl));
        ANum < BNum   -> lt;
        ANum > BNum   -> gt
     end.
 
+dropdot(A) -> lists:dropwhile(fun (X) -> X =:= $. end, A).
+
 recursive_delete(Files) ->
     lists:foldl(fun (Path,  ok                   ) -> recursive_delete1(Path);
                     (_Path, {error, _Err} = Error) -> Error