%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2011. 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_istk).
-export([init/0,to_external/0,from_external/1,
push/3,pop/0,pop/1,stack_level/0,
exception_stacktrace/2,
bindings/1,stack_frame/2,backtrace/1,
in_use_p/2]).
-include("dbg_ieval.hrl").
-define(STACK, ?MODULE).
init() ->
init([]).
to_external() ->
{stack,term_to_binary(get(?STACK))}.
from_external({stack,Stk}) ->
put(?STACK, binary_to_term(Stk)).
init(Stack) ->
put(?STACK, Stack).
%% We keep track of a call stack that is used for
%% 1) saving stack frames that can be inspected from an Attached
%% Process GUI (using dbg_icmd:get(Meta, stack_frame, {Dir, SP})
%% 2) generate an approximation of regular stacktrace -- sent to
%% Debugged when it should raise an exception or evaluate a
%% function (since it might possible raise an exception)
%%
%% Stack = [Entry]
%% Entry = {Le, {MFA, Where, Bs}}
%% Le = int() % current call level
%% MFA = {M,F,Args} % called function (or fun)
%% | {Fun,Args} %
%% Where = {M,Li} % from where (module+line) function is called
%% Bs = bindings() % current variable bindings
%%
%% How to push depends on the "Stack Trace" option (value saved in
%% process dictionary item 'trace_stack').
%% all - everything is pushed
%% no_tail - tail recursive push
%% false - nothing is pushed
%% Whenever a function returns, the corresponding call frame is popped.
push(MFA, Bs, #ieval{level=Le,module=Cm,line=Li,last_call=Lc}) ->
Entry = {Le, {MFA, {Cm,Li}, Bs}},
case get(trace_stack) of
false -> ignore;
no_tail when Lc ->
case get(?STACK) of
[] -> put(?STACK, [Entry]);
[_Entry|Entries] -> put(?STACK, [Entry|Entries])
end;
_ -> % all | no_tail when Lc =:= false
put(?STACK, [Entry|get(?STACK)])
end.
pop() ->
case get(trace_stack) of
false -> ignore;
_ -> % all ¦ no_tail
case get(?STACK) of
[_Entry|Entries] ->
put(?STACK, Entries);
[] ->
ignore
end
end.
pop(Le) ->
case get(trace_stack) of
false -> ignore;
_ -> % all | no_tail
put(?STACK, pop(Le, get(?STACK)))
end.
pop(Level, [{Le, _}|Stack]) when Level=<Le ->
pop(Level, Stack);
pop(_Level, Stack) ->
Stack.
%% stack_level() -> Le
%% stack_level(Stack) -> Le
%% Top call level
stack_level() ->
stack_level(get(?STACK)).
stack_level([]) -> 1;
stack_level([{Le,_}|_]) -> Le.
%% exception_stacktrace(HowMuch, #ieval{}) -> Stacktrace
%% HowMuch = complete | no_current
%% Stacktrace = [{M,F,Args|Arity} | {Fun,Args}]
%% Convert internal stack format to an imitation of the
%% regular stacktrace.
%%
%% Max three elements, no repeated (recursive) calls to the same
%% function and convert argument lists to arity for all but the topmost
%% entry (and funs).
exception_stacktrace(complete, #ieval{}) ->
fix_stacktrace(1);
exception_stacktrace(no_current, #ieval{}) ->
fix_stacktrace(2).
fix_stacktrace(Start) ->
case fix_stacktrace2(sublist(get(?STACK), Start, 3)) of
[] ->
[];
[H|T] ->
[H|args2arity(T)]
end.
sublist([], _Start, _Length) ->
[]; % workaround, lists:sublist([],2,3) fails
sublist(L, Start, Length) ->
lists:sublist(L, Start, Length).
fix_stacktrace2([{_,{{M,F,As1},_,_}}, {_,{{M,F,As2},_,_}}|_])
when length(As1) =:= length(As2) ->
[{M,F,As1}];
fix_stacktrace2([{_,{{Fun,As1},_,_}}, {_,{{Fun,As2},_,_}}|_])
when length(As1) =:= length(As2) ->
[{Fun,As1}];
fix_stacktrace2([{_,{MFA,_,_}}|Entries]) ->
[MFA|fix_stacktrace2(Entries)];
fix_stacktrace2([]) ->
[].
args2arity([{M,F,As}|Entries]) when is_list(As) ->
[{M,F,length(As)}|args2arity(Entries)];
args2arity([Entry|Entries]) ->
[Entry|args2arity(Entries)];
args2arity([]) ->
[].
%% bindings(SP) -> Bs
%% SP = Le % stack pointer
%% Return the bindings for the specified call level
bindings(SP) ->
bindings(SP, get(?STACK)).
bindings(SP, [{SP,{_MFA,_Wh,Bs}}|_]) ->
Bs;
bindings(SP, [_Entry|Entries]) ->
bindings(SP, Entries);
bindings(_SP, []) ->
erl_eval:new_bindings().
%% stack_frame(Dir, SP) -> {Le, Where, Bs} | top | bottom
%% Dir = up | down
%% Where = {Cm, Li}
%% Cm = Module | undefined % module
%% Li = int() | -1 % line number
%% Bs = bindings()
%% Return stack frame info one step up/down from given stack pointer
%% up = to lower call levels
%% down = to higher call levels
stack_frame(up, SP) ->
stack_frame(SP, up, get(?STACK));
stack_frame(down, SP) ->
stack_frame(SP, down, lists:reverse(get(?STACK))).
stack_frame(SP, up, [{Le, {_MFA,Where,Bs}}|_]) when Le<SP ->
{Le, Where, Bs};
stack_frame(SP, down, [{Le, {_MFA,Where,Bs}}|_]) when Le>SP ->
{Le, Where, Bs};
stack_frame(SP, Dir, [{SP, _}|Stack]) ->
case Stack of
[{Le, {_MFA,Where,Bs}}|_] ->
{Le, Where, Bs};
[] when Dir =:= up ->
top;
[] when Dir =:= down ->
bottom
end;
stack_frame(SP, Dir, [_Entry|Stack]) ->
stack_frame(SP, Dir, Stack).
%% backtrace(HowMany) -> Backtrace
%% HowMany = all | int()
%% Backtrace = {Le, MFA}
%% Return all/the last N called functions, in reversed call order
backtrace(HowMany) ->
Stack = case HowMany of
all -> get(?STACK);
N -> lists:sublist(get(?STACK), N)
end,
[{Le, MFA} || {Le,{MFA,_Wh,_Bs}} <- Stack].
%%--------------------------------------------------------------------
%% in_use_p(Mod, Cm) -> boolean()
%% Mod = Cm = atom()
%% Returns true if Mod is found on the stack, otherwise false.
%%--------------------------------------------------------------------
in_use_p(Mod, Mod) -> true;
in_use_p(Mod, _Cm) ->
case get(trace_stack) of
false -> true;
_ -> % all | no_tail
lists:any(fun({_,{M,_,_,_}}) when M =:= Mod -> true;
(_) -> false
end,
get(?STACK))
end.
