%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1998-2013. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
-module(dbg_debugged).
%% External exports
%% Avoid warning for local function demonitor/1 clashing with autoimported BIF.
-compile({no_auto_import,[demonitor/1]}).
-export([eval/3]).
%%====================================================================
%% External exports
%%====================================================================
%%--------------------------------------------------------------------
%% eval(Mod, Func, Args) -> Value
%% Main entry point from external (non-interpreted) code.
%% Called via the error handler.
%%--------------------------------------------------------------------
eval(Mod, Func, Args) ->
SaveStacktrace = erlang:get_stacktrace(),
Meta = dbg_ieval:eval(Mod, Func, Args),
Mref = erlang:monitor(process, Meta),
msg_loop(Meta, Mref, SaveStacktrace).
%%====================================================================
%% Internal functions
%%====================================================================
msg_loop(Meta, Mref, SaveStacktrace) ->
receive
%% Evaluated function has returned a value
{sys, Meta, {ready, Val}} ->
demonitor(Mref),
%% Restore original stacktrace and return the value
try erlang:raise(throw, stack, SaveStacktrace)
catch
throw:stack ->
case Val of
{dbg_apply,M,F,A} ->
apply(M, F, A);
_ ->
Val
end
end;
%% Evaluated function raised an (uncaught) exception
{sys, Meta, {exception,{Class,Reason,Stacktrace}}} ->
demonitor(Mref),
%% ...raise the same exception
erlang:error(erlang:raise(Class, Reason, Stacktrace),
[Class,Reason,Stacktrace]);
%% Meta is evaluating a receive, must be done within context
%% of real (=this) process
{sys, Meta, {'receive',Msg}} ->
receive Msg -> Meta ! {self(), rec_acked} end,
msg_loop(Meta, Mref, SaveStacktrace);
%% Meta needs something evaluated within context of real process
{sys, Meta, {command,Command}} ->
Reply = handle_command(Command),
Meta ! {sys, self(), Reply},
msg_loop(Meta, Mref, SaveStacktrace);
%% Meta has terminated
%% Must be due to int:stop() (or -heaven forbid- a debugger bug)
{'DOWN', Mref, _, _, Reason} ->
%% Restore original stacktrace and return a dummy value
try erlang:raise(throw, stack, SaveStacktrace)
catch
throw:stack ->
{interpreter_terminated, Reason}
end
end.
handle_command(Command) ->
try
reply(Command)
catch Class:Reason ->
Stacktrace = stacktrace_f(erlang:get_stacktrace()),
{exception,{Class,Reason,Stacktrace}}
end.
reply({apply,M,F,As}) ->
{value, erlang:apply(M,F,As)};
reply({eval,Expr,Bs}) ->
%% Bindings is an orddict (sort them)
erl_eval:expr(Expr, lists:sort(Bs)). % {value, Value, Bs2}
%% Demonitor and delete message from inbox
%%
demonitor(Mref) ->
erlang:demonitor(Mref),
receive {'DOWN',Mref,_,_,_} -> ok
after 0 -> ok
end.
%% Fix stacktrace - keep all above call to this module.
%%
stacktrace_f([]) -> [];
stacktrace_f([{?MODULE,_,_,_}|_]) -> [];
stacktrace_f([F|S]) -> [F|stacktrace_f(S)].
