stdlib: Fix a Dets bug where files were deleted

Instead of deleting the small file when opening it with
dets:open_file/2 an error message is returned, mimicking the behaviour
when the file is bigger.

open_file/1 has been modified to return the same error message when
the file is small as when the file is bigger.

Thanks to Hakan Mattson for reporting this bug.

1 files changed, 4 insertions, 5 deletions

diff --git a/lib/stdlib/src/dets.erl b/lib/stdlib/src/dets.erl
index 8c5c86f3b9..c32da1624f 100644
--- a/lib/stdlib/src/dets.erl
+++ b/lib/stdlib/src/dets.erl
@@ -2114,6 +2114,8 @@ test_bchunk_format(Head, Term) ->
 
 do_open_file([Fname, Verbose], Parent, Server, Ref) ->
     case catch fopen2(Fname, Ref) of
+	{error, {tooshort, _}} ->
+            err({error, {not_a_dets_file, Fname}});
 	{error, _Reason} = Error ->
 	    err(Error);
 	{ok, Head} ->
@@ -2127,11 +2129,10 @@ do_open_file([Fname, Verbose], Parent, Server, Ref) ->
 	       [Bad]),
 	    {error, {dets_bug, Fname, Bad}}
     end;
-do_open_file([Tab, OpenArgs, Verb], Parent, Server, Ref) ->
+do_open_file([Tab, OpenArgs, Verb], Parent, Server, _Ref) ->
     case catch fopen3(Tab, OpenArgs) of
 	{error, {tooshort, _}} ->
-	    _ = file:delete(OpenArgs#open_args.file),
-	    do_open_file([Tab, OpenArgs, Verb], Parent, Server, Ref);
+            err({error, {not_a_dets_file, OpenArgs#open_args.file}});
 	{error, _Reason} = Error ->
 	    err(Error);
 	{ok, Head} ->
@@ -2487,7 +2488,6 @@ fopen2(Fname, Tab) ->
 	{ok, _} ->
 	    Acc = read_write,
 	    Ram = false, 
-	    %% Fd is not always closed upon error, but exit is soon called.
 	    {ok, Fd, FH} = read_file_header(Fname, Acc, Ram),
             Mod = FH#fileheader.mod,
             Do = case Mod:check_file_header(FH, Fd) of
@@ -2543,7 +2543,6 @@ fopen_existing_file(Tab, OpenArgs) ->
                ram_file = Ram, delayed_write = CacheSz, auto_save =
                Auto, access = Acc, version = Version, debug = Debug} =
         OpenArgs,
-    %% Fd is not always closed upon error, but exit is soon called.
     {ok, Fd, FH} = read_file_header(Fname, Acc, Ram),
     V9 = (Version =:= 9) or (Version =:= default),
     MinF = (MinSlots =:= default) or (MinSlots =:= FH#fileheader.min_no_slots),