Add comments to make erl_prim_loader primary archive handling more readable

This commit introduces no functional change. It only adds comments and
changes some function/variable names.

1 files changed, 74 insertions, 52 deletions

diff --git a/erts/preloaded/src/erl_prim_loader.erl b/erts/preloaded/src/erl_prim_loader.erl
index f820d6226d..eb59cbe6f6 100644
--- a/erts/preloaded/src/erl_prim_loader.erl
+++ b/erts/preloaded/src/erl_prim_loader.erl
@@ -833,8 +833,8 @@ prim_set_primary_archive(PS, ArchiveFile0, ArchiveBin, #file_info{} = FileInfo)
         case PS#prim_state.primary_archive of
             undefined ->
                 Fun =
-                    fun({Funny, _GI, _GB}, A) ->
-                            case Funny of
+                    fun({Components, _GI, _GB}, A) ->
+                            case Components of
                                 ["", "nibe", RevApp] -> % Reverse ebin
                                     %% Collect ebin directories in archive
                                     Ebin = reverse(RevApp) ++ "/ebin",
@@ -874,11 +874,11 @@ prim_get_file(PS, File) ->
                 {Res, PS};
             {archive, ArchiveFile, FileInArchive} ->
                 debug(PS, {archive_get_file, ArchiveFile, FileInArchive}),
-                FunnyFile = funny_split(FileInArchive, $/),
+                FileComponents = path_split(FileInArchive),
                 Fun =
-                    fun({Funny, _GetInfo, GetBin}, Acc) ->
+                    fun({Components, _GetInfo, GetBin}, Acc) ->
                             if
-                                Funny =:= FunnyFile ->
+                                Components =:= FileComponents ->
                                     {false, {ok, GetBin()}};
                                 true ->
                                     {true, Acc}
@@ -901,11 +901,11 @@ prim_list_dir(PS, Dir) ->
                 {Res, PS};
             {archive, ArchiveFile, FileInArchive} ->
                 debug(PS, {archive_list_dir, ArchiveFile, FileInArchive}),
-                FunnyDir = funny_split(FileInArchive, $/),
+                DirComponents = path_split(FileInArchive),
                 Fun =
-                    fun({Funny, _GetInfo, _GetBin}, {Status, Names} = Acc) ->
-                            case Funny of
-                                [RevName | FD] when FD =:= FunnyDir ->
+                    fun({Components, _GetInfo, _GetBin}, {Status, Names} = Acc) ->
+                            case Components of
+                                [RevName | DC] when DC =:= DirComponents ->
                                     case RevName of
                                         "" ->
                                             %% The listed directory
@@ -915,16 +915,16 @@ prim_list_dir(PS, Dir) ->
                                             Name = reverse(RevName),
                                             {true, {Status, [Name | Names]}}
                                     end;
-                                ["", RevName | FD] when FD =:= FunnyDir ->
+                                ["", RevName | DC] when DC =:= DirComponents ->
                                     %% Directory
                                     Name = reverse(RevName),
                                     {true, {Status, [Name | Names]}};
-                                [RevName] when FunnyDir =:= [""] ->
-                                    %% Top file
+                                [RevName] when DirComponents =:= [""] ->
+                                    %% File in top directory
                                     Name = reverse(RevName),
                                     {true, {ok, [Name | Names]}};
-                                ["", RevName] when FunnyDir =:= [""] ->
-                                    %% Top file
+                                ["", RevName] when DirComponents =:= [""] ->
+                                    %% Directory in top directory
                                     Name = reverse(RevName),
                                     {true, {ok, [Name | Names]}};
                                 _ ->
@@ -963,15 +963,14 @@ prim_read_file_info(PS, File) ->
                 end;
             {archive, ArchiveFile, FileInArchive} ->
                 debug(PS, {archive_read_file_info, File}),
-                FunnyFile = funny_split(FileInArchive, $/),
+                FileComponents = path_split(FileInArchive),
                 Fun =
-                    fun({Funny, GetInfo, _GetBin}, Acc)  ->
-			    case Funny of
-				[H | T] when  H =:= "",
-					      T =:= FunnyFile ->
+                    fun({Components, GetInfo, _GetBin}, Acc)  ->
+			    case Components of
+				["" | F] when F =:= FileComponents ->
                                     %% Directory
                                     {false, {ok, GetInfo()}};
-                                F when F =:= FunnyFile ->
+                                F when F =:= FileComponents ->
                                     %% Plain file
                                     {false, {ok, GetInfo()}};
                                 _ ->
@@ -1064,50 +1063,69 @@ open_archive(Archive, Acc, Fun) ->
 	    {error, Reason}
     end.
 
+%% Open the given archive and iterate through all files with an own
+%% wrapper fun in order to identify each file as a component list as
+%% returned from path_split/1.
+%%
+%% In the archive (zip) file, directory elements might or might not be
+%% present. To ensure consistency, a directory element is added if it
+%% does not already exist (ensure_virual_dir/6). NOTE that there will
+%% be no such directory element for the top directory of the archive.
 open_archive(Archive, FileInfo, Acc, Fun) ->
     FakeFI = FileInfo#file_info{type = directory},
     Wrapper =
-	fun({N, GI, GB}, {A, I, FunnyDirs}) -> % Full iteration at open
-		Funny = funny_split(N, $/),
-		FunnyDirs2 =
-		    case Funny of
-			["" | FunnyDir] ->
-			    [FunnyDir | FunnyDirs];
+	fun({N, GI, GB}, {A, I, Dirs}) ->
+		Components = path_split(N),
+		Dirs2 =
+		    case Components of
+			["" | Dir] ->
+			    %% This is a directory
+			    [Dir | Dirs];
 			_ ->
-			    FunnyDirs
+			    %% This is a regular file
+			    Dirs
 		    end,
-		{Includes, FunnyDirs3, A2} = 
-		    ensure_virtual_dirs(Funny, Fun, FakeFI, [{true, Funny}], FunnyDirs2, A),
-		{_Continue, A3} = Fun({Funny, GI, GB}, A2),
-		{true, Includes, {A3, I, FunnyDirs3}}
+		{Includes, Dirs3, A2} =
+		    ensure_virtual_dirs(Components, Fun, FakeFI,
+					[{true, Components}], Dirs2, A),
+		{_Continue, A3} = Fun({Components, GI, GB}, A2),
+		{true, Includes, {A3, I, Dirs3}}
 	end,
     prim_zip:open(Wrapper, {Acc, FakeFI, []}, Archive).
 
-ensure_virtual_dirs(Funny, Fun, FakeFI, Includes, FunnyDirs, Acc) ->
-    case Funny of
+ensure_virtual_dirs(Components, Fun, FakeFI, Includes, Dirs, Acc) ->
+    case Components of
 	[_] ->
-	    {Includes, FunnyDirs, Acc};
-	[_ | FunnyDir] ->
-	    case lists:member(FunnyDir, FunnyDirs) of % BIF
+	    %% Don't add virtual dir for top directory
+	    {Includes, Dirs, Acc};
+	[_ | Dir] ->
+	    case lists:member(Dir, Dirs) of % BIF
 		false ->
+		    %% The directory does not yet exist - add it
 		    GetInfo = fun() -> FakeFI end,
 		    GetBin = fun() -> <<>> end,
-		    VirtualDir = ["" | FunnyDir],
+		    VirtualDir = ["" | Dir],
 		    Includes2 = [{true, VirtualDir, GetInfo, GetBin} | Includes],
-		    FunnyDirs2 = [FunnyDir | FunnyDirs],
-		    {I, F, Acc2} = ensure_virtual_dirs(FunnyDir, Fun, FakeFI, Includes2, FunnyDirs2, Acc),
+		    Dirs2 = [Dir | Dirs],
+
+		    %% Recursively ensure dir elements on all levels
+		    {I, F, Acc2} = ensure_virtual_dirs(Dir, Fun, FakeFI,
+						       Includes2, Dirs2, Acc),
+
 		    {_Continue, Acc3} = Fun({VirtualDir, GetInfo, GetBin}, Acc2),
 		    {I, F, Acc3};
 		true ->
-		    ensure_virtual_dirs(FunnyDir,Fun,FakeFI,Includes,FunnyDirs,Acc)
+		    %% The directory element does already exist
+		    %% Recursivly ensure dir elements on all levels
+		    ensure_virtual_dirs(Dir,Fun,FakeFI,Includes,Dirs,Acc)
 	    end
-   end.
+    end.
 
 foldl_archive(PrimZip, Acc, Fun) ->
     Wrapper =
-        fun({Funny, GI, GB}, A) ->
+        fun({Components, GI, GB}, A) ->
                 %% Allow partial iteration at foldl
-                {Continue, A2} = Fun({Funny, GI, GB}, A),
+                {Continue, A2} = Fun({Components, GI, GB}, A),
                 {Continue, true, A2}
         end,                        
     prim_zip:foldl(Wrapper, Acc, PrimZip).
@@ -1203,15 +1221,19 @@ reverse([A, B]) ->
 reverse([A, B | L]) ->
     lists:reverse(L, [B, A]). % BIF
                         
-%% Returns all lists in reverse order
-funny_split(List, Sep) ->
-   funny_split(List, Sep, [], []).
-
-funny_split([Sep | Tail], Sep, Path, Paths) ->
-    funny_split(Tail, Sep, [], [Path | Paths]);
-funny_split([Head | Tail], Sep, Path, Paths) ->
-    funny_split(Tail, Sep, [Head | Path], Paths);
-funny_split([], _Sep, Path, Paths) ->
+%% Returns a reversed list of path components, each component itself a
+%% reversed list (string), e.g.
+%% /path/to/file -> ["elif","ot","htap",""]
+%% /path/to/dir/ -> ["","rid","ot","htap",""]
+%% Note the "" marking leading and trailing / (slash).
+path_split(List) ->
+   path_split(List, [], []).
+
+path_split([$/ | Tail], Path, Paths) ->
+    path_split(Tail, [], [Path | Paths]);
+path_split([Head | Tail], Path, Paths) ->
+    path_split(Tail, [Head | Path], Paths);
+path_split([], Path, Paths) ->
     [Path | Paths].
 
 name_split(ArchiveFile, File0) ->