Validate the offset values as well, provide a spec.

src/inet_time.erl

@@ -13,15 +13,20 @@
 %%====================================================================
 %% API
 %%====================================================================
+-type date() :: {integer(), integer(), integer()}.
+-type time() :: {integer(), integer(), integer(), integer()}.
+-type offset() :: {'+' | '-', integer(), integer()}.
+
+-spec parse(string()) -> {date(), time(), offset()}.
 parse(String) ->
     {ok, Tokens, _} = inet_time_scanner:string(String),
     {ok, {Date, {Time, Offset}}} = inet_time_parser_simple:parse(Tokens),
     case calendar:valid_date(Date) of
 	true ->
-	    case valid_time(Time) of
-		true -> {ok, {Date, Time, Offset}};
-		false -> {error, {invalid_time, {Date, Time, Offset}}};
-		leap_second -> {error, no_leap_second_handling}
+	    case valid_time_offset(Time, Offset) of
+		ok -> {ok, {Date, Time, Offset}};
+		{error, Reason} ->
+		    {error, {Reason, {Date, Time, Offset}}}
 	    end;
 	false ->
 	    {error, {invalid_date, {Date, Time, Offset}}}
@@ -30,6 +35,19 @@ parse(String) ->
 %%====================================================================
 %% Internal functions
 %%====================================================================
+valid_time_offset(Time, Offset) ->
+    case valid_time(Time) of
+	ok -> valid_offset(Offset);
+	{error, Reason} -> {error, Reason}
+    end.
+
+valid_offset({_, H, M}) when
+      0 =< H,
+      H =< 23,
+      0 =< M,
+      M =< 59 -> ok;
+valid_offset(_) -> {error, invalid_offset}.
+
 valid_time({Hour, Minute, Second, _Frac})
   when 0 =< Hour,
        Hour =< 23,
@@ -38,10 +56,10 @@ valid_time({Hour, Minute, Second, _Frac})
        0 =< Second,
        Second =< 60 ->
     case Second of
-	60 -> leap_second;
-	_  -> true
+	60 -> {error, no_leap_second_handling};
+	_  -> ok
     end;
-valid_time(_Otherwise) -> false.
+valid_time(_Otherwise) -> {error, invalid}.