Add functions to create and extract escripts

Both reltool and rebar needs to parse escripts. They are currently
using an undocumented function called escript:foldl/3. It folds a
function over all files in the body of an escript. If the body
contains source code the function compiles it and the gives debug
compiled beam code to the fold fun. If the body is an archive the fun
is applied for all files in the archive.

Instead of making the undocumented function public, the new functions
escript:create/2 and escript:extract/2 has been introduced. Together
with the new zip:foldl/3 function they have the same functionality as
escript:foldl/3 in a more flexible and generic way.

escript:foldl/3 should be removed as soon as reltool and rebar has
been adopted to use the new functions. The simplest way for reltool
and rebar to do this is to just copy the code from
escript_SUITE:escript_foldl/3, which happens to provide a future
compatible implementation of an emulated escript:foldl/3 function.

I was quite hesitant when I introduced the compile_source option.  It
feels that it does not belong there but the alternative felt worse.

The rationale for the compile_source option is that it is a bit
cumbersome to compile the source code, as the source in most cases is
partial. In order to do compile the source you need to know about some
internals in escript. Without compile_source I think that these
internals should be documented. Further you need to duplicate parts of
the code.

Without the compile_source option you need to first parse the source
to forms, using an undocumented function in epp with an extended
format of predefined macros which also is undocumented. Then you need
to investigate the forms to see if you need to add an export form for
main. When that is done you can run the rest of the compiler passes as
usual. It is not so much code (60 lines or so) to write, but I do not
want to urge people to write it. I actually wrote the code (see
escript_SUITE:escript_foldl/3) before I decided to introduce the
compile_source option.

1 files changed, 325 insertions, 76 deletions

diff --git a/lib/stdlib/src/escript.erl b/lib/stdlib/src/escript.erl
index 5958a58d7c..bf32e15209 100644
--- a/lib/stdlib/src/escript.erl
+++ b/lib/stdlib/src/escript.erl
@@ -19,11 +19,17 @@
 -module(escript).
 
 %% Useful functions that can be called from scripts.
--export([script_name/0, foldl/3]).
+-export([script_name/0, create/2, extract/2]).
+-export([foldl/3]). % Undocumented function that will be removed
 
 %% Internal API.
 -export([start/0, start/1]).
 
+-include_lib("kernel/include/file.hrl").
+
+-define(SHEBANG,  "/usr/bin/env escript").
+-define(COMMENT,  "This is an -*- erlang -*- file").
+
 -record(state, {file,
                 module,
                 forms_or_bin,
@@ -32,46 +38,247 @@
                 mode,
                 exports_main,
                 has_records}).
-    
+-record(sections, {type,
+		   shebang,
+		   comment,
+		   emu_args,
+		   body}).
+-record(extract_options, {compile_source}).
+
+-type shebang() :: string().
+-type comment() :: string().
+-type emu_args() :: string().
+-type escript_filename() :: string().
+-type filename() :: string().
+-type zip_file() ::
+	filename()
+	| {filename(), binary()}
+	| {filename(), binary(), #file_info{}}.
+-type zip_create_option() :: term().
+-type section() ::
+	  shebang
+	| {shebang, shebang()}
+	| comment
+	| {comment, comment()}
+	| {emu_args, emu_args()}
+	| {source, filename() | binary()}
+	| {beam, filename() | binary()}
+	| {archive, filename() | binary()}
+	| {archive, [zip_file()], [zip_create_option()]}.
+
+%% Create a complete escript file with both header and body
+-spec create(escript_filename() | binary, [section()]) ->
+		    ok | {ok, binary()} | {error, term()}.
+
+create(File, Options) when is_list(Options) ->
+    try
+	S = prepare(Options, #sections{}),
+	BinList =
+	    [Section || Section <- [S#sections.shebang,
+				    S#sections.comment,
+				    S#sections.emu_args,
+				    S#sections.body],
+			Section =/= undefined],
+	case File of
+	    binary ->
+		{ok, list_to_binary(BinList)};
+	    _ ->
+		case file:write_file(File, BinList) of
+		    ok ->
+			ok;
+		    {error, Reason} ->
+			{error, {Reason, File}}
+		end
+	end
+    catch
+	throw:PrepareReason ->
+	    {error, PrepareReason}
+    end.
+
+prepare([H | T], S) ->
+    case H of
+	{shebang, undefined} ->
+	    prepare(T, S);
+	shebang ->
+	    prepare(T, S#sections{shebang = "#!" ++ ?SHEBANG ++ "\n"});
+	{shebang, default} ->
+	    prepare(T, S#sections{shebang = "#!" ++ ?SHEBANG ++ "\n"});
+	{shebang, Shebang} when is_list(Shebang) ->
+	    prepare(T, S#sections{shebang = "#!" ++ Shebang ++ "\n"});
+	{comment, undefined} ->
+	    prepare(T, S);
+	comment ->
+	    prepare(T, S#sections{comment = "%% " ++ ?COMMENT ++ "\n"});
+	{comment, default} ->
+	    prepare(T, S#sections{comment = "%% " ++ ?COMMENT ++ "\n"});
+	{comment, Comment} when is_list(Comment) ->
+	    prepare(T, S#sections{comment = "%% " ++ Comment ++ "\n"});
+	{emu_args, undefined} ->
+	    prepare(T, S);
+	{emu_args, Args} when is_list(Args) ->
+	    prepare(T, S#sections{emu_args = "%%!" ++ Args ++ "\n"});
+	{Type, File} when is_list(File) ->
+	    case file:read_file(File) of
+		{ok, Bin} ->
+		    prepare(T, S#sections{type = Type, body = Bin});
+		{error, Reason} ->
+		    throw({Reason, H})
+	    end;
+	{Type, Bin} when is_binary(Bin) ->
+	    prepare(T, S#sections{type = Type, body = Bin});
+	{archive = Type, ZipFiles, ZipOptions}
+	  when is_list(ZipFiles), is_list(ZipOptions) ->
+	    File = "dummy.zip",
+	    case zip:create(File, ZipFiles, ZipOptions ++ [memory]) of
+		{ok, {File, ZipBin}} ->
+		    prepare(T, S#sections{type = Type, body = ZipBin});
+		{error, Reason} ->
+		    throw({Reason, H})
+	    end;
+	_ ->
+	    throw({badarg, H})
+    end;
+prepare([], #sections{body = undefined}) ->
+    throw(missing_body);
+prepare([], #sections{type = Type} = S)
+  when Type =:= source; Type =:= beam; Type =:= archive ->
+    S;
+prepare([], #sections{type = Type}) ->
+    throw({illegal_type, Type});
+prepare(BadOptions, _) ->
+    throw({badarg, BadOptions}).
+
+-type section_name() :: shebang | comment | emu_args | body .
+-type extract_option() :: compile_source | {section, [section_name()]}.
+-spec extract(filename(), [extract_option()]) -> {ok, [section()]} | {error, term()}.
+extract(File, Options) when is_list(File), is_list(Options) ->
+    try
+	EO = parse_extract_options(Options,
+				   #extract_options{compile_source = false}),
+	{HeaderSz, NextLineNo, Fd, Sections} =
+	    parse_header(File, not EO#extract_options.compile_source),
+	Type = Sections#sections.type,
+	case {Type, EO#extract_options.compile_source} of
+	    {source, true} ->
+		Bin = compile_source(Type, File, Fd, NextLineNo, HeaderSz);
+	    {_, _} ->
+		ok = file:close(Fd),
+		case file:read_file(File) of
+		    {ok, <<_Header:HeaderSz/binary, Bin/binary>>} ->
+			ok;
+		    {error, ReadReason} ->
+			Bin = get_rid_of_compiler_warning,
+			throw(ReadReason)
+		end
+	end,
+	return_sections(Sections, Bin)
+    catch
+	throw:Reason ->
+	    {error, Reason}
+    end.
+
+parse_extract_options([H | T], EO) ->
+    case H of
+	compile_source ->
+	    EO2 = EO#extract_options{compile_source = true},
+	    parse_extract_options(T, EO2);
+	_ ->
+	    throw({badarg, H})
+    end;
+parse_extract_options([], EO) ->
+    EO.
+
+compile_source(Type, File, Fd, NextLineNo, HeaderSz) ->
+    {text, _Module, Forms, _HasRecs, _Mode} =
+	do_parse_file(Type, File, Fd, NextLineNo, HeaderSz, false),
+    ok = file:close(Fd),
+    case compile:forms(Forms, [return_errors, debug_info]) of
+	{ok, _, BeamBin} ->
+	    BeamBin;
+	{error, Errors, Warnings} ->
+	    throw({compile, [{errors, format_errors(Errors)},
+			     {warnings, format_errors(Warnings)}]})
+    end.
+
+format_errors(CompileErrors) ->
+    [lists:flatten([File, ":", integer_to_list(LineNo), ": ",
+		    Mod:format_error(Error)]) ||
+	{File, FileErrors} <- CompileErrors,
+	{LineNo, Mod, Error} <- FileErrors].
+
+return_sections(S, Bin) ->
+    {ok, [normalize_section(shebang,  S#sections.shebang),
+	  normalize_section(comment,  S#sections.comment),
+	  normalize_section(emu_args, S#sections.emu_args),
+	  normalize_section(S#sections.type, Bin)]}.
+
+normalize_section(Name, undefined) ->
+    {Name, undefined};
+normalize_section(shebang, "#!" ++ Chars) ->
+    Chopped = string:strip(Chars, right, $\n),
+    Stripped = string:strip(Chopped, both),
+    if
+	Stripped =:= ?SHEBANG ->
+	    {shebang, default};
+	true ->
+	    {shebang, Stripped}
+    end;
+normalize_section(comment, Chars) ->
+    Chopped = string:strip(Chars, right, $\n),
+    Stripped = string:strip(string:strip(Chopped, left, $%), both),
+    if
+	Stripped =:= ?COMMENT ->
+	    {comment, default};
+	true ->
+	    {comment, Stripped}
+    end;
+normalize_section(emu_args, "%%!" ++ Chars) ->
+    Chopped = string:strip(Chars, right, $\n),
+    Stripped = string:strip(Chopped, both),
+    {emu_args, Stripped};
+normalize_section(Name, Chars) ->
+    {Name, Chars}.
+
+-spec script_name() -> string().
 script_name() ->
     [ScriptName|_] = init:get_plain_arguments(),
     ScriptName.
 
 %% Apply Fun(Name, GetInfo, GetBin, Acc) for each file in the escript.
-%% 
+%%
 %% Fun/2 must return a new accumulator which is passed to the next call.
 %% The function returns the final value of the accumulator. Acc0 is
 %% returned if the escript contain an empty archive.
-%% 
+%%
 %% GetInfo/0 is a fun that returns a #file_info{} record for the file.
 %% GetBin/0 is a fun that returns a the contents of the file as a binary.
 %%
 %% An escript may contain erlang code, beam code or an archive:
 %%
-%% archive - the Fun/2 will be applied for each file in the archive
-%% beam - the Fun/2 will be applied once and GetInfo/0 returns the file
+%% archive - the Fun/4 will be applied for each file in the archive
+%% beam - the Fun/4 will be applied once and GetInfo/0 returns the file
 %%        info for the (entire) escript file
-%% erl - the Fun/2 will be applied once, GetInfo/0 returns the file
+%% erl - the Fun/4 will be applied once, GetInfo/0 returns the file
 %%       info for the (entire) escript file and the GetBin returns
 %%       the compiled beam code
 
-%%-spec foldl(fun((string(),
-%%                 fun(() -> #file_info()), 
-%%                 fun(() -> binary() -> term()),
-%%                 term()) -> term()),
-%%            term(),
-%%            string()).
+-spec foldl(fun((string(),
+                 fun(() -> #file_info{}),
+                 fun(() -> binary()),
+                 term()) -> term()),
+            term(),
+            string()) -> {ok, term()} | {error, term()}.
 foldl(Fun, Acc0, File) when is_function(Fun, 4) ->
     case parse_file(File, false) of
         {text, _, Forms, _HasRecs, _Mode} when is_list(Forms) ->
-            GetInfo = fun() -> file:read_file_info(File) end,
+            GetInfo = fun() -> {ok, FI} = file:read_file_info(File), FI end,
             GetBin =
                 fun() ->
                         case compile:forms(Forms, [return_errors, debug_info]) of
                             {ok, _, BeamBin} ->
                                 BeamBin;
                             {error, _Errors, _Warnings} ->
-				fatal("There were compilation errors.")
+				throw("There were compilation errors.")
                         end
                 end,
             try
@@ -81,7 +288,7 @@ foldl(Fun, Acc0, File) when is_function(Fun, 4) ->
                     {error, Reason}
             end;
         {beam, _, BeamBin, _HasRecs, _Mode} when is_binary(BeamBin) ->
-            GetInfo = fun() -> file:read_file_info(File) end,
+            GetInfo = fun() -> {ok, FI} = file:read_file_info(File), FI end,
             GetBin = fun() -> BeamBin end,
             try
                 {ok, Fun(".", GetInfo, GetBin, Acc0)}
@@ -110,11 +317,13 @@ foldl(Fun, Acc0, File) when is_function(Fun, 4) ->
 %% Internal API.
 %%
 
+-spec start() -> no_return().
 start() ->
     start([]).
 
+-spec start([string()]) -> no_return().
 start(EscriptOptions) ->
-    try 
+    try
         %% Commands run using -run or -s are run in a process
         %% trap_exit set to false. Because this behaviour is
         %% surprising for users of escript, make sure to reset
@@ -143,11 +352,11 @@ parse_and_run(File, Args, Options) ->
 	parse_file(File, CheckOnly),
     Mode2 =
         case lists:member("d", Options) of
-            true  -> 
+            true  ->
 		debug;
             false ->
 		case lists:member("c", Options) of
-		    true  -> 
+		    true  ->
 			compile;
 		    false ->
 			case lists:member("i", Options) of
@@ -177,7 +386,7 @@ parse_and_run(File, Args, Options) ->
                         _Other ->
                             fatal("There were compilation errors.")
                     end
-            end;                    
+            end;
         is_binary(FormsOrBin) ->
             case Source of
                 archive ->
@@ -190,11 +399,13 @@ parse_and_run(File, Args, Options) ->
 					true ->
 					    my_halt(0);
 					false ->
-					    Text = lists:concat(["Function ", Module, ":main/1 is not exported"]),
+					    Text = lists:concat(["Function ", Module,
+								 ":main/1 is not exported"]),
 					    fatal(Text)
 				    end;
 				_ ->
-				    Text = lists:concat(["Cannot load module ", Module, " from archive"]),
+				    Text = lists:concat(["Cannot load module ", Module,
+							 " from archive"]),
 				    fatal(Text)
 			    end;
 			ok ->
@@ -212,7 +423,7 @@ parse_and_run(File, Args, Options) ->
                         run ->
                             {module, Module} = code:load_binary(Module, File, FormsOrBin),
                             run(Module, Args);
-                        debug -> 
+                        debug ->
 			    [Base | Rest] = lists:reverse(filename:split(File)),
 			    Base2 = filename:basename(Base, code:objfile_extension()),
 			    Rest2 =
@@ -222,8 +433,8 @@ parse_and_run(File, Args, Options) ->
 				end,
 			    SrcFile = filename:join(lists:reverse([Base2 ++ ".erl" | Rest2])),
 			    debug(Module, {Module, SrcFile, File, FormsOrBin}, Args)
-                    end             
-            end             
+                    end
+            end
     end.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -231,25 +442,19 @@ parse_and_run(File, Args, Options) ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 parse_file(File, CheckOnly) ->
-    S = #state{file = File,
-               n_errors = 0,
-               mode = interpret,
-               exports_main = false,
-               has_records = false},
-    {ok, Fd} = 
-        case file:open(File, [read]) of
-            {ok, Fd0} ->
-                {ok, Fd0};
-            {error, R} ->
-                fatal(lists:concat([file:format_error(R), ": '", File, "'"]))
-        end,
-    {HeaderSz, StartLine, ScriptType} = skip_header(Fd, 1),
+    {HeaderSz, NextLineNo, Fd, Sections} =
+	parse_header(File, false),
+    do_parse_file(Sections#sections.type,
+		  File, Fd, NextLineNo, HeaderSz, CheckOnly).
+
+do_parse_file(Type, File, Fd, NextLineNo, HeaderSz, CheckOnly) ->
+    S = initial_state(File),
     #state{mode = Mode,
 	   source = Source,
 	   module = Module,
 	   forms_or_bin = FormsOrBin,
 	   has_records = HasRecs} =
-	case ScriptType of
+	case Type of
 	    archive ->
 		%% Archive file
 		ok = file:close(Fd),
@@ -260,51 +465,93 @@ parse_file(File, CheckOnly) ->
 		parse_beam(S, File, HeaderSz, CheckOnly);
 	    source ->
 		%% Source code
-		parse_source(S, File, Fd, StartLine, HeaderSz, CheckOnly)
+		parse_source(S, File, Fd, NextLineNo, HeaderSz, CheckOnly)
         end,
     {Source, Module, FormsOrBin, HasRecs, Mode}.
 
+initial_state(File) ->
+    #state{file = File,
+	   n_errors = 0,
+	   mode = interpret,
+	   exports_main = false,
+	   has_records = false}.
+
 %% Skip header and make a heuristic guess about the script type
-skip_header(P, LineNo) ->
+parse_header(File, KeepFirst) ->
+    LineNo = 1,
+    {ok, Fd} =
+        case file:open(File, [read]) of
+            {ok, Fd0} ->
+                {ok, Fd0};
+            {error, R} ->
+                fatal(lists:concat([file:format_error(R), ": '", File, "'"]))
+        end,
+
     %% Skip shebang on first line
-    {ok, HeaderSz0} = file:position(P, cur),
-    Line1 = get_line(P),
+    {ok, HeaderSz0} = file:position(Fd, cur),
+    Line1 = get_line(Fd),
     case classify_line(Line1) of
         shebang ->
-            find_first_body_line(P, LineNo);
+            find_first_body_line(Fd, HeaderSz0, LineNo, KeepFirst,
+				 #sections{shebang = Line1});
 	archive ->
-	    {HeaderSz0, LineNo, archive};
+	    {HeaderSz0, LineNo, Fd,
+	     #sections{type = archive}};
 	beam ->
-            {HeaderSz0, LineNo, beam};
+            {HeaderSz0, LineNo, Fd,
+	     #sections{type = beam}};
 	_ ->
-            find_first_body_line(P, LineNo)
+            find_first_body_line(Fd, HeaderSz0, LineNo, KeepFirst,
+				 #sections{})
     end.
 
-find_first_body_line(P, LineNo) ->
-    {ok, HeaderSz1} = file:position(P, cur),
+find_first_body_line(Fd, HeaderSz0, LineNo, KeepFirst, Sections) ->
+    {ok, HeaderSz1} = file:position(Fd, cur),
     %% Look for special comment on second line
-    Line2 = get_line(P),
-    {ok, HeaderSz2} = file:position(P, cur),
+    Line2 = get_line(Fd),
+    {ok, HeaderSz2} = file:position(Fd, cur),
     case classify_line(Line2) of
 	emu_args ->
 	    %% Skip special comment on second line
-	    Line3 = get_line(P),
-	    {HeaderSz2, LineNo + 2, guess_type(Line3)};
-	_ ->
+	    Line3 = get_line(Fd),
+	    {HeaderSz2, LineNo + 2, Fd,
+	     Sections#sections{type = guess_type(Line3),
+			       comment = undefined,
+			       emu_args = Line2}};
+	Line2Type ->
 	    %% Look for special comment on third line
-	    Line3 = get_line(P),
-	    {ok, HeaderSz3} = file:position(P, cur),
-	    case classify_line(Line3) of
-		emu_args -> 
+	    Line3 = get_line(Fd),
+	    {ok, HeaderSz3} = file:position(Fd, cur),
+	    Line3Type = classify_line(Line3),
+	    if
+		Line3Type =:= emu_args ->
 		    %% Skip special comment on third line
-		    Line4 = get_line(P),
-		    {HeaderSz3, LineNo + 3, guess_type(Line4)};
-		_ ->
+		    Line4 = get_line(Fd),
+		    {HeaderSz3, LineNo + 3, Fd,
+		     Sections#sections{type = guess_type(Line4),
+				       comment = Line2,
+				       emu_args = Line3}};
+		Sections#sections.shebang =:= undefined,
+		KeepFirst =:= true ->
+		    %% No shebang. Use the entire file
+		    {HeaderSz0, LineNo, Fd,
+		     Sections#sections{type = guess_type(Line2)}};
+		Sections#sections.shebang =:= undefined ->
+		    %% No shebang. Skip the first line
+		    {HeaderSz1, LineNo, Fd,
+		     Sections#sections{type = guess_type(Line2)}};
+		Line2Type =:= comment ->
+		    %% Skip shebang on first line and comment on second
+		    {HeaderSz2, LineNo + 2, Fd,
+		     Sections#sections{type = guess_type(Line3),
+				       comment = Line2}};
+		true ->
 		    %% Just skip shebang on first line
-		    {HeaderSz1, LineNo + 1, guess_type(Line2)}
+		    {HeaderSz1, LineNo + 1, Fd,
+		     Sections#sections{type = guess_type(Line2)}}
 	    end
     end.
-        
+
 classify_line(Line) ->
     case Line of
         [$\#, $\! | _] ->
@@ -313,8 +560,10 @@ classify_line(Line) ->
 	    archive;
 	[$F, $O, $R, $1 | _] ->
 	    beam;
-	[$\%, $\%, $\! | _] ->
+	[$%, $%, $\! | _] ->
 	    emu_args;
+	[$% | _] ->
+	    comment;
 	 _ ->
 	    undefined
    end.
@@ -336,8 +585,8 @@ get_line(P) ->
 
 parse_archive(S, File, HeaderSz) ->
     case file:read_file(File) of
-	{ok, <<_FirstLine:HeaderSz/binary, Bin/binary>>} ->
-	    Mod = 
+	{ok, <<_Header:HeaderSz/binary, Bin/binary>>} ->
+	    Mod =
 		case init:get_argument(escript) of
 		    {ok, [["main", M]]} ->
 			%% Use explicit module name
@@ -345,14 +594,14 @@ parse_archive(S, File, HeaderSz) ->
 		    _ ->
 			%% Use escript name without extension as module name
 			RevBase = lists:reverse(filename:basename(File)),
-			RevBase2 = 
+			RevBase2 =
 			    case lists:dropwhile(fun(X) -> X =/= $. end, RevBase) of
                                 [$. | Rest] -> Rest;
                                 [] -> RevBase
                             end,
                         list_to_atom(lists:reverse(RevBase2))
 		end,
-	    
+
 	    S#state{source = archive,
 		    mode = run,
 		    module = Mod,
@@ -365,7 +614,7 @@ parse_archive(S, File, HeaderSz) ->
 
 
 parse_beam(S, File, HeaderSz, CheckOnly) ->
-    {ok, <<_FirstLine:HeaderSz/binary, Bin/binary>>} =
+    {ok, <<_Header:HeaderSz/binary, Bin/binary>>} =
         file:read_file(File),
     case beam_lib:chunks(Bin, [exports]) of
 	{ok, {Module, [{exports, Exports}]}} ->
@@ -399,7 +648,7 @@ parse_source(S, File, Fd, StartLine, HeaderSz, CheckOnly) ->
             {ok, FileForm} = epp:parse_erl_form(Epp),
             OptModRes = epp:parse_erl_form(Epp),
             S2 = S#state{source = text, module = Module},
-            S3 = 
+            S3 =
                 case OptModRes of
                     {ok, {attribute,_, module, M} = Form} ->
                         epp_parse_file(Epp, S2#state{module = M}, [Form, FileForm]);
@@ -448,12 +697,12 @@ check_source(S, CheckOnly) ->
 
 pre_def_macros(File) ->
     {MegaSecs, Secs, MicroSecs} = erlang:now(),
-    Replace = fun(Char) -> 
+    Replace = fun(Char) ->
 		      case Char of
 			  $\. -> $\_;
                           _ -> Char
                       end
-              end, 
+              end,
     CleanBase = lists:map(Replace, filename:basename(File)),
     ModuleStr =
 	CleanBase ++ "__" ++
@@ -642,8 +891,8 @@ eval_exprs([E|Es], Bs0, Lf, Ef, RBs) ->
     eval_exprs(Es, Bs, Lf, Ef, RBs).
 
 format_exception(Class, Reason) ->
-    PF = fun(Term, I) -> 
-                 io_lib:format("~." ++ integer_to_list(I) ++ "P", [Term, 50]) 
+    PF = fun(Term, I) ->
+                 io_lib:format("~." ++ integer_to_list(I) ++ "P", [Term, 50])
          end,
     StackTrace = erlang:get_stacktrace(),
     StackFun = fun(M, _F, _A) -> (M =:= erl_eval) or (M =:= ?MODULE) end,
@@ -651,7 +900,7 @@ format_exception(Class, Reason) ->
 
 fatal(Str) ->
     throw(Str).
-                                
+
 my_halt(Reason) ->
     case process_info(group_leader(), status) of
         {_,waiting} ->
@@ -675,7 +924,7 @@ hidden_apply(App, M, F, Args) ->
 		    Arity = length(Args),
 		    Text = io_lib:format("Call to ~w:~w/~w in application ~w failed.\n",
 					 [M, F, Arity, App]),
-		    fatal(Text);		    
+		    fatal(Text);
 		Stk ->
 		    erlang:raise(error, undef, Stk)
 	    end