Allow appup instruction delete_module module which is not loaded

The appup instruction 'delete_module' would cause a crash during
upgrade if the module to be deleted was not loaded. The reason was
that the release_handler tried to read the version number of the old
module after the code path had changed to point to the new version of
the application. Thus, if the module had not been loaded before the
upgrade, there would no longer be any such module in the path
(delete_module indicates that the module is deleted from the new
version of the application).

This is corrected by letting the release_handler read the old version
of the module only if the module is updated - not if it is
removed. And it is always read before the code path is changed.

1 files changed, 22 insertions, 37 deletions

diff --git a/lib/sasl/src/release_handler_1.erl b/lib/sasl/src/release_handler_1.erl
index 3d6bc9fbc3..ff62f847ac 100644
--- a/lib/sasl/src/release_handler_1.erl
+++ b/lib/sasl/src/release_handler_1.erl
@@ -33,7 +33,7 @@
 %% libdirs   = [{Lib, LibVsn, LibDir}] - Maps Lib to Vsn and Directory
 %% unpurged  = [{Mod, soft_purge | brutal_purge}]
 %% vsns      = [{Mod, OldVsn, NewVsn}] - remember the old vsn of a mod
-%%                  before it is removed/a new vsn is loaded; the new vsn
+%%                  before a new vsn is loaded; the new vsn
 %%                  is kept in case of a downgrade, where the code_change
 %%                  function receives the vsn of the module to downgrade
 %%                  *to*.
@@ -224,7 +224,7 @@ eval({load_object_code, {Lib, LibVsn, Modules}}, EvalState) ->
 				    FName = filename:join([LibDir, "ebin", File]),
 				    case erl_prim_loader:get_file(FName) of
 					{ok, Bin, FName2} ->
-					    NVsns = add_new_vsn(Mod, Bin, Vsns),
+					    NVsns = add_vsns(Mod, Bin, Vsns),
 					    {[{Mod, Bin, FName2} | Bins],NVsns};
 					error ->
 					    throw({error, {no_such_file,FName}})
@@ -258,32 +258,21 @@ eval({load, {Mod, _PrePurgeMethod, PostPurgeMethod}}, EvalState) ->
     {value, {_Mod, Bin, File}} = lists:keysearch(Mod, 1, Bins),
     % load_binary kills all procs running old code
     % if soft_purge, we know that there are no such procs now
-    Vsns = EvalState#eval_state.vsns,
-    NewVsns = add_old_vsn(Mod, Vsns),
     code:load_binary(Mod, File, Bin),
     % Now, the prev current is old.  There might be procs
     % running it.  Find them.
     Unpurged = do_soft_purge(Mod,PostPurgeMethod,EvalState#eval_state.unpurged),
     EvalState#eval_state{bins = lists:keydelete(Mod, 1, Bins),
-			 unpurged = Unpurged,
-			 vsns = NewVsns};
+			 unpurged = Unpurged};
 eval({remove, {Mod, _PrePurgeMethod, PostPurgeMethod}}, EvalState) ->
-    % purge kills all procs running old code
-    % if soft_purge, we know that there are no such procs now
-    Vsns = EvalState#eval_state.vsns,
-    NewVsns = add_old_vsn(Mod, Vsns),
+    %% purge kills all procs running old code
+    %% if soft_purge, we know that there are no such procs now
     code:purge(Mod),
     code:delete(Mod),
-    % Now, the prev current is old.  There might be procs
-    % running it.  Find them.
-    Unpurged =
-	case code:soft_purge(Mod) of
-	    true -> EvalState#eval_state.unpurged;
-	    false -> [{Mod, PostPurgeMethod} | EvalState#eval_state.unpurged]
-	end,
-%%    Bins = EvalState#eval_state.bins,
-%%    EvalState#eval_state{bins = lists:keydelete(Mod, 1, Bins),
-    EvalState#eval_state{unpurged = Unpurged, vsns = NewVsns};
+    %% Now, the prev current is old.  There might be procs
+    %% running it.  Find them.
+    Unpurged = do_soft_purge(Mod,PostPurgeMethod,EvalState#eval_state.unpurged),
+    EvalState#eval_state{unpurged = Unpurged};
 eval({purge, Modules}, EvalState) ->
     % Now, if there are any processes still executing old code, OR
     % if some new processes started after suspend but before load,
@@ -606,26 +595,20 @@ sync_nodes(Id, Nodes) ->
 		  end,
 		  NNodes).
 
-add_old_vsn(Mod, Vsns) ->
+add_vsns(Mod, NewBin, Vsns) ->
+    OldVsn = get_current_vsn(Mod),
+    NewVsn = get_vsn(NewBin),
     case lists:keysearch(Mod, 1, Vsns) of
-	{value, {Mod, undefined, NewVsn}} ->
-	    OldVsn = get_current_vsn(Mod),
-	    lists:keyreplace(Mod, 1, Vsns, {Mod, OldVsn, NewVsn});
-	{value, {Mod, _OldVsn, _NewVsn}} ->
-	    Vsns;
+	{value, {Mod, OldVsn0, NewVsn0}} ->
+	    lists:keyreplace(Mod, 1, Vsns, {Mod,
+					    replace_undefined(OldVsn0,OldVsn),
+					    replace_undefined(NewVsn0,NewVsn)});
 	false ->
-	    OldVsn = get_current_vsn(Mod),
-	    [{Mod, OldVsn, undefined} | Vsns]
+	    [{Mod, OldVsn, NewVsn} | Vsns]
     end.
 
-add_new_vsn(Mod, Bin, Vsns) ->
-    NewVsn = get_vsn(Bin),
-    case lists:keysearch(Mod, 1, Vsns) of
-	{value, {Mod, OldVsn, undefined}} ->
-	    lists:keyreplace(Mod, 1, Vsns, {Mod, OldVsn, NewVsn});
-	false ->
-	    [{Mod, undefined, NewVsn} | Vsns]
-    end.
+replace_undefined(undefined,Vsn) -> Vsn;
+replace_undefined(Vsn,_) -> Vsn.
 
 %%-----------------------------------------------------------------
 %% Func: get_current_vsn/1
@@ -645,7 +628,9 @@ get_current_vsn(Mod) ->
 	{ok, Bin, _File2} ->
 	    get_vsn(Bin);
 	error ->
-	    throw({error, {no_such_file, File}})
+	    %% This is the case when a new module is added, there will
+	    %% be no current version of it at the time of this call.
+	    undefined
     end.
 
 %%-----------------------------------------------------------------