erl_tar: Fix handling of date and time

Since aa0c4b0df7cdc, erl_tar would write the local time (instead of
the POSIX time) into the tar header for the archived files. When
extracting the tar file, the extracted file could be set to a future
time (depending on the time zone).

We could do a minimal fix, but this seems to be a good time
to rewrite the time handling to use the new features that
allow file info to be read and written in the POSIX time
format.

First reported here: https://github.com/erlang/rebar3/issues/1554

1 files changed, 39 insertions, 2 deletions

diff --git a/lib/stdlib/test/tar_SUITE.erl b/lib/stdlib/test/tar_SUITE.erl
index e9ab12e061..4061008812 100644
--- a/lib/stdlib/test/tar_SUITE.erl
+++ b/lib/stdlib/test/tar_SUITE.erl
@@ -27,7 +27,8 @@
 	 extract_from_binary_compressed/1, extract_filtered/1,
 	 extract_from_open_file/1, symlinks/1, open_add_close/1, cooked_compressed/1,
 	 memory/1,unicode/1,read_other_implementations/1,
-         sparse/1, init/1, leading_slash/1, dotdot/1]).
+         sparse/1, init/1, leading_slash/1, dotdot/1,
+         roundtrip_metadata/1]).
 
 -include_lib("common_test/include/ct.hrl").
 -include_lib("kernel/include/file.hrl").
@@ -41,7 +42,7 @@ all() ->
      extract_filtered,
      symlinks, open_add_close, cooked_compressed, memory, unicode,
      read_other_implementations,
-     sparse,init,leading_slash,dotdot].
+     sparse,init,leading_slash,dotdot,roundtrip_metadata].
 
 groups() -> 
     [].
@@ -953,6 +954,42 @@ dotdot(Config) ->
 
     ok.
 
+roundtrip_metadata(Config) ->
+    PrivDir = proplists:get_value(priv_dir, Config),
+    Dir = filename:join(PrivDir, ?FUNCTION_NAME),
+    ok = file:make_dir(Dir),
+
+    do_roundtrip_metadata(Dir, "name-does-not-matter"),
+    ok.
+
+do_roundtrip_metadata(Dir, File) ->
+    Tar = filename:join(Dir, atom_to_list(?FUNCTION_NAME)++".tar"),
+    BeamFile = code:which(compile),
+    {ok,Fd} = erl_tar:open(Tar, [write]),
+    ok = erl_tar:add(Fd, BeamFile, File, []),
+    ok = erl_tar:close(Fd),
+
+    ok = erl_tar:extract(Tar, [{cwd,Dir}]),
+
+    %% Make sure that size and modification times are the same
+    %% on all platforms.
+    {ok,OrigInfo} = file:read_file_info(BeamFile),
+    ExtractedFile = filename:join(Dir, File),
+    {ok,ExtractedInfo} = file:read_file_info(ExtractedFile),
+    #file_info{size=Size,mtime=Mtime,type=regular} = OrigInfo,
+    #file_info{size=Size,mtime=Mtime,type=regular} = ExtractedInfo,
+
+    %% On Unix platforms more fields are expected to be the same.
+    case os:type() of
+        {unix,_} ->
+            #file_info{access=Access,mode=Mode} = OrigInfo,
+            #file_info{access=Access,mode=Mode} = ExtractedInfo,
+            ok;
+        _ ->
+            ok
+    end.
+
+
 %% Delete the given list of files.
 delete_files([]) -> ok;
 delete_files([Item|Rest]) ->