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%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
%% ex: ts=4 sw=4 et
%% -------------------------------------------------------------------
%%
%% rebar: Erlang Build Tools
%%
%% Copyright (c) 2009 Dave Smith (dizzyd@dizzyd.com)
%%
%% Permission is hereby granted, free of charge, to any person obtaining a copy
%% of this software and associated documentation files (the "Software"), to deal
%% in the Software without restriction, including without limitation the rights
%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%% copies of the Software, and to permit persons to whom the Software is
%% furnished to do so, subject to the following conditions:
%%
%% The above copyright notice and this permission notice shall be included in
%% all copies or substantial portions of the Software.
%%
%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
%% THE SOFTWARE.
%%
%% -------------------------------------------------------------------
%% -------------------------------------------------------------------
%% This module borrows heavily from http://github.com/etnt/exrefcheck project as
%% written by Torbjorn Tornkvist <tobbe@kreditor.se>, Daniel Luna
%% <daniel@lunas.se> and others.
%% -------------------------------------------------------------------
-module(rebar_xref).
-include("rebar.hrl").
-export([xref/2]).
%% ===================================================================
%% Public API
%% ===================================================================
xref(Config, _) ->
%% Spin up xref
{ok, _} = xref:start(xref),
ok = xref:set_library_path(xref, code_path(Config)),
xref:set_default(xref, [{warnings,
rebar_config:get(Config, xref_warnings, false)},
{verbose, rebar_config:is_verbose(Config)}]),
{ok, _} = xref:add_directory(xref, "ebin"),
%% Save the code path prior to doing anything
OrigPath = code:get_path(),
true = code:add_path(rebar_utils:ebin_dir()),
%% Get list of xref checks we want to run
XrefChecks = rebar_config:get(Config, xref_checks,
[exports_not_used,
undefined_function_calls]),
%% Look for exports that are unused by anything
ExportsNoWarn =
case lists:member(exports_not_used, XrefChecks) of
true ->
check_exports_not_used();
false ->
true
end,
%% Look for calls to undefined functions
UndefNoWarn =
case lists:member(undefined_function_calls, XrefChecks) of
true ->
check_undefined_function_calls();
false ->
true
end,
%% Run custom queries
QueryChecks = rebar_config:get(Config, xref_queries, []),
QueryNoWarn = lists:all(fun check_query/1, QueryChecks),
%% Restore the original code path
true = code:set_path(OrigPath),
%% Stop xref
stopped = xref:stop(xref),
case lists:member(false, [ExportsNoWarn, UndefNoWarn, QueryNoWarn]) of
true ->
?FAIL;
false ->
ok
end.
%% ===================================================================
%% Internal functions
%% ===================================================================
check_exports_not_used() ->
{ok, UnusedExports0} = xref:analyze(xref, exports_not_used),
UnusedExports = filter_away_ignored(UnusedExports0),
%% Report all the unused functions
display_mfas(UnusedExports, "is unused export (Xref)"),
UnusedExports =:= [].
check_undefined_function_calls() ->
{ok, UndefinedCalls0} = xref:analyze(xref, undefined_function_calls),
UndefinedCalls =
[{find_mfa_source(Caller), format_fa(Caller), format_mfa(Target)}
|| {Caller, Target} <- UndefinedCalls0],
lists:foreach(
fun({{Source, Line}, FunStr, Target}) ->
?CONSOLE("~s:~w: Warning ~s calls undefined function ~s\n",
[Source, Line, FunStr, Target])
end, UndefinedCalls),
UndefinedCalls =:= [].
check_query({Query, Value}) ->
{ok, Answer} = xref:q(xref, Query),
case Answer =:= Value of
false ->
?CONSOLE("Query ~s~n answer ~p~n did not match ~p~n",
[Query, Answer, Value]),
false;
_ ->
true
end.
code_path(Config) ->
BaseDir = rebar_config:get_xconf(Config, base_dir),
[P || P <- code:get_path() ++
[filename:join(BaseDir, filename:join(SubDir, "ebin"))
|| SubDir <- rebar_config:get(Config, sub_dirs, [])],
filelib:is_dir(P)].
%%
%% Ignore behaviour functions, and explicitly marked functions
%%
filter_away_ignored(UnusedExports) ->
%% Functions can be ignored by using
%% -ignore_xref([{F, A}, ...]).
%% Setup a filter function that builds a list of behaviour callbacks and/or
%% any functions marked to ignore. We then use this list to mask any
%% functions marked as unused exports by xref
F = fun(Mod) ->
Attrs = Mod:module_info(attributes),
Ignore = keyall(ignore_xref, Attrs),
Callbacks = [B:behaviour_info(callbacks)
|| B <- keyall(behaviour, Attrs)],
[{Mod, F, A} || {F, A} <- Ignore ++ lists:flatten(Callbacks)]
end,
AttrIgnore =
lists:flatten(
lists:map(F, lists:usort([M || {M, _, _} <- UnusedExports]))),
[X || X <- UnusedExports, not lists:member(X, AttrIgnore)].
keyall(Key, List) ->
lists:flatmap(fun({K, L}) when Key =:= K -> L; (_) -> [] end, List).
display_mfas([], _Message) ->
ok;
display_mfas([{_Mod, Fun, Args} = MFA | Rest], Message) ->
{Source, Line} = find_mfa_source(MFA),
?CONSOLE("~s:~w: Warning: function ~s/~w ~s\n",
[Source, Line, Fun, Args, Message]),
display_mfas(Rest, Message).
format_mfa({M, F, A}) ->
?FMT("~s:~s/~w", [M, F, A]).
format_fa({_M, F, A}) ->
?FMT("~s/~w", [F, A]).
%%
%% Extract an element from a tuple, or undefined if N > tuple size
%%
safe_element(N, Tuple) ->
case catch(element(N, Tuple)) of
{'EXIT', {badarg, _}} ->
undefined;
Value ->
Value
end.
%%
%% Given a MFA, find the file and LOC where it's defined. Note that
%% xref doesn't work if there is no abstract_code, so we can avoid
%% being too paranoid here.
%%
find_mfa_source({M, F, A}) ->
{M, Bin, _} = code:get_object_code(M),
AbstractCode = beam_lib:chunks(Bin, [abstract_code]),
{ok, {M, [{abstract_code, {raw_abstract_v1, Code}}]}} = AbstractCode,
%% Extract the original source filename from the abstract code
[{attribute, 1, file, {Source, _}} | _] = Code,
%% Extract the line number for a given function def
Fn = [E || E <- Code,
safe_element(1, E) == function,
safe_element(3, E) == F,
safe_element(4, E) == A],
case Fn of
[{function, Line, F, _, _}] -> {Source, Line};
%% do not crash if functions are exported, even though they
%% are not in the source.
%% parameterized modules add new/1 and instance/1 for example.
[] -> {Source, function_not_found}
end.
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