Add filelib:find_file/2/3 and filelib:find_source/1/2/3

This moves, extends and exports functionality that previously existed only
internally in filename:find_src/1/2, adding the ability to automatically
substitute file suffixes and use different rules for different suffixes.

2 files changed, 138 insertions, 58 deletions

diff --git a/lib/stdlib/src/filelib.erl b/lib/stdlib/src/filelib.erl
index 7029389e2f..daa18da9aa 100644
--- a/lib/stdlib/src/filelib.erl
+++ b/lib/stdlib/src/filelib.erl
@@ -24,6 +24,7 @@
 -export([fold_files/5, last_modified/1, file_size/1, ensure_dir/1]).
 -export([wildcard/3, is_dir/2, is_file/2, is_regular/2]).
 -export([fold_files/6, last_modified/2, file_size/2]).
+-export([find_file/2, find_file/3, find_source/1, find_source/2, find_source/3]).
 
 %% For debugging/testing.
 -export([compile_wildcard/1]).
@@ -517,3 +518,124 @@ eval_list_dir(Dir, erl_prim_loader) ->
     end;
 eval_list_dir(Dir, Mod) ->
     Mod:list_dir(Dir).
+
+%% Getting the rules to use for file search
+
+keep_dir_search_rules(Rules) ->
+    [T || {_,_}=T <- Rules].
+
+keep_suffix_search_rules(Rules) ->
+    [T || {_,_,_}=T <- Rules].
+
+get_search_rules() ->
+    case application:get_env(kernel, source_search_rules) of
+        undefined -> default_search_rules();
+        {ok, []}  -> default_search_rules();
+        {ok, R} when is_list(R) -> R
+    end.
+
+default_search_rules() ->
+    [%% suffix-speficic rules for source search
+     {".beam", ".erl", erl_source_search_rules()},
+     {".erl", ".yrl", []},
+     {"", ".src", erl_source_search_rules()},
+     {".so", ".c", c_source_search_rules()},
+     {".o", ".c", c_source_search_rules()},
+     {"", ".c", c_source_search_rules()},
+     {"", ".in", basic_source_search_rules()},
+     %% plain old directory rules, backwards compatible
+     {"", ""},
+     {"ebin","src"},
+     {"ebin","esrc"}
+    ].
+
+basic_source_search_rules() ->
+    (erl_source_search_rules()
+     ++ c_source_search_rules()).
+
+erl_source_search_rules() ->
+    [{"ebin","src"}, {"ebin","esrc"}].
+
+c_source_search_rules() ->
+    [{"priv","c_src"}, {"priv","src"}, {"bin","c_src"}, {"bin","src"}, {"", "src"}].
+
+%% Looks for a file relative to a given directory
+
+-type find_file_rule() :: {ObjDirSuffix::string(), SrcDirSuffix::string()}.
+
+-spec find_file(filename(), filename()) ->
+        {ok, filename()} | {error, not_found}.
+find_file(Filename, Dir) ->
+    find_file(Filename, Dir, []).
+
+-spec find_file(filename(), filename(), [find_file_rule()]) ->
+        {ok, filename()} | {error, not_found}.
+find_file(Filename, Dir, []) ->
+    find_file(Filename, Dir, get_search_rules());
+find_file(Filename, Dir, Rules) ->
+    try_dir_rules(keep_dir_search_rules(Rules), Filename, Dir).
+
+%% Looks for a source file relative to the object file name and directory
+
+-type find_source_rule() :: {ObjExtension::string(), SrcExtension::string(),
+                             [find_file_rule()]}.
+
+-spec find_source(filename()) ->
+        {ok, filename()} | {error, not_found}.
+find_source(FilePath) ->
+    find_source(filename:basename(FilePath), filename:dirname(FilePath)).
+
+-spec find_source(filename(), filename()) ->
+        {ok, filename()} | {error, not_found}.
+find_source(Filename, Dir) ->
+    find_source(Filename, Dir, []).
+
+-spec find_source(filename(), filename(), [find_source_rule()]) ->
+        {ok, filename()} | {error, not_found}.
+find_source(Filename, Dir, []) ->
+    find_source(Filename, Dir, get_search_rules());
+find_source(Filename, Dir, Rules) ->
+    try_suffix_rules(keep_suffix_search_rules(Rules), Filename, Dir).
+
+try_suffix_rules(Rules, Filename, Dir) ->
+    Ext = filename:extension(Filename),
+    try_suffix_rules(Rules, filename:rootname(Filename, Ext), Dir, Ext).
+
+try_suffix_rules([{Ext,Src,Rules}|Rest], Root, Dir, Ext)
+  when is_list(Src), is_list(Rules) ->
+    case try_dir_rules(add_local_search(Rules), Root ++ Src, Dir) of
+        {ok, File} -> {ok, File};
+        _Other ->
+            try_suffix_rules(Rest, Root, Dir, Ext)
+    end;
+try_suffix_rules([_|Rest], Root, Dir, Ext) ->
+    try_suffix_rules(Rest, Root, Dir, Ext);
+try_suffix_rules([], _Root, _Dir, _Ext) ->
+    {error, not_found}.
+
+%% ensuring we check the directory of the object file before any other directory
+add_local_search(Rules) ->
+    Local = {"",""},
+    [Local] ++ lists:filter(fun (X) -> X =/= Local end, Rules).
+
+try_dir_rules([{From, To}|Rest], Filename, Dir)
+  when is_list(From), is_list(To) ->
+    case try_dir_rule(Dir, Filename, From, To) of
+	{ok, File} -> {ok, File};
+	error      -> try_dir_rules(Rest, Filename, Dir)
+    end;
+try_dir_rules([], _Filename, _Dir) ->
+    {error, not_found}.
+
+try_dir_rule(Dir, Filename, From, To) ->
+    case lists:suffix(From, Dir) of
+	true ->
+	    NewDir = lists:sublist(Dir, 1, length(Dir)-length(From))++To,
+	    Src = filename:join(NewDir, Filename),
+	    case is_regular(Src) of
+		true -> {ok, Src};
+		false -> error
+	    end;
+	false ->
+	    error
+    end.
diff --git a/lib/stdlib/src/filename.erl b/lib/stdlib/src/filename.erl
index 51d5ca711d..0ff22f876a 100644
--- a/lib/stdlib/src/filename.erl
+++ b/lib/stdlib/src/filename.erl
@@ -34,8 +34,8 @@
 -export([absname/1, absname/2, absname_join/2, 
 	 basename/1, basename/2, dirname/1,
 	 extension/1, join/1, join/2, pathtype/1,
-	 rootname/1, rootname/2, split/1, nativename/1]).
--export([find_src/1, find_src/2, flatten/1]).
+	 rootname/1, rootname/2, split/1, flatten/1, nativename/1]).
+-export([find_src/1, find_src/2]). % deprecated
 -export([basedir/2, basedir/3]).
 
 %% Undocumented and unsupported exports.
@@ -750,8 +750,12 @@ separators() ->
 	_ -> {false, false}
     end.
 
-
-
+%% NOTE: The find_src/1/2 functions are deprecated; they try to do too much
+%% at once and are not a good fit for this module. Parts of the code have
+%% been moved to filelib:find_file/2 instead. Only this part of this
+%% module is allowed to call the filelib module; such mutual dependency
+%% should otherwise be avoided! This code should eventually be removed.
+%%
 %% find_src(Module) --
 %% find_src(Module, Rules) --
 %%
@@ -815,26 +819,27 @@ find_src(ModOrFile, Rules) when is_list(ModOrFile) ->
     case code:which(Mod) of
 	Possibly_Rel_Path when is_list(Possibly_Rel_Path) ->
             {ok, Cwd} = file:get_cwd(),
-            Dir = dirname(make_abs_path(Cwd, Possibly_Rel_Path)),
-            find_src_1(ModOrFile, Dir, Mod, Extension, Rules);
+            ObjPath = make_abs_path(Cwd, Possibly_Rel_Path),
+            find_src_1(ModOrFile, ObjPath, Mod, Extension, Rules);
 	Ecode when is_atom(Ecode) -> % Ecode :: ecode()
 	    {error, {Ecode, Mod}}
     end.
 
 %% At this point, the Mod is known to be valid.
 %% If the source name is not known, find it.
-find_src_1(ModOrFile, Dir, Mod, Extension, Rules) ->
+find_src_1(ModOrFile, ObjPath, Mod, Extension, Rules) ->
     %% The documentation says this function must return the found path
     %% without extension in all cases. Also, ModOrFile could be given with
     %% or without extension. Hence the calls to rootname below.
     ModOrFileRoot = rootname(ModOrFile, Extension),
-    case readable_file(ModOrFileRoot++Extension) of
+    case filelib:is_regular(ModOrFileRoot++Extension) of
         true  ->
             find_src_2(ModOrFileRoot, Mod);
         false ->
-            case get_source_file(Dir, atom_to_list(Mod)++Extension, Rules) of
-                {ok, Src} ->
-                    find_src_2(rootname(Src, Extension), Mod);
+            SrcName = basename(ObjPath, code:objfile_extension()) ++ Extension,
+            case filelib:find_file(SrcName, dirname(ObjPath), Rules) of
+                {ok, SrcFile} ->
+                    find_src_2(rootname(SrcFile, Extension), Mod);
                 Error ->
                     Error
             end
@@ -879,53 +884,6 @@ filter_options(Base, [_|Rest], Result) ->
 filter_options(_Base, [], Result) ->
     Result.
 
-%% Gets the source file given the object directory.
-
-get_source_file(Dir, Filename, []) ->
-    Rules =
-	case application:get_env(kernel, source_search_rules) of
-	    undefined -> default_source_search_rules();
-	    {ok, []} -> default_source_search_rules();
-	    {ok, R} when is_list(R) -> R
-	end,
-    get_source_file(Dir, Filename, Rules);
-get_source_file(Dir, Filename, Rules) ->
-    source_by_rules(Dir, Filename, Rules).
-
-default_source_search_rules() ->
-    [{"", ""}, {"ebin", "src"}, {"ebin", "esrc"}].
-
-source_by_rules(Dir, Filename, [{From, To}|Rest]) ->
-    case try_rule(Dir, Filename, From, To) of
-	{ok, File} -> {ok, File};
-	error      -> source_by_rules(Dir, Filename, Rest)
-    end;
-source_by_rules(_Dir, _Filename, []) ->
-    {error, source_file_not_found}.
-
-try_rule(Dir, Filename, From, To) ->
-    case lists:suffix(From, Dir) of
-	true -> 
-	    NewDir = lists:sublist(Dir, 1, length(Dir)-length(From))++To,
-	    Src = join(NewDir, Filename),
-	    case readable_file(Src) of
-		true -> {ok, Src};
-		false -> error
-	    end;
-	false ->
-	    error
-    end.
-
-readable_file(File) ->
-    case file:read_file_info(File) of
-	{ok, #file_info{type=regular, access=read}} ->
-	    true;
-	{ok, #file_info{type=regular, access=read_write}} ->
-	    true;
-	_Other ->
-	    false
-    end.
-
 make_abs_path(BasePath, Path) ->
     join(BasePath, Path).