%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2018. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(release_handler).
-behaviour(gen_server).

-include_lib("kernel/include/file.hrl").

%% External exports
-export([start_link/0,
	 create_RELEASES/1, create_RELEASES/2, create_RELEASES/4,
	 unpack_release/1,
	 check_install_release/1, check_install_release/2,
	 install_release/1, install_release/2, new_emulator_upgrade/2,
	 remove_release/1, which_releases/0, which_releases/1,
	 make_permanent/1, reboot_old_release/1,
	 set_unpacked/2, set_removed/1, install_file/2]).
-export([upgrade_app/2, downgrade_app/2, downgrade_app/3,
	 upgrade_script/2, downgrade_script/3,
	 eval_appup_script/4]).

%% Internal exports
-export([init/1, handle_call/3, handle_info/2, terminate/2,
	 handle_cast/2, code_change/3]).

%% Internal exports, a client release_handler may call this functions.
-export([do_write_release/3, do_copy_file/2, do_copy_files/2,
	 do_copy_files/1, do_rename_files/1, do_remove_files/1,
	 remove_file/1, do_write_file/2, do_write_file/3,
	 do_ensure_RELEASES/1]).

-record(state, {unpurged = [],
		root,
		rel_dir,
		releases,
		timer,
		start_prg,
		masters = false,
		client_dir = false,
	        static_emulator = false,
		pre_sync_nodes = []}).

%%-----------------------------------------------------------------
%% status      action                next_status
%% =============================================
%%   -         unpack                unpacked
%% unpacked    install               current
%%             remove                -
%% current     make_permanent        permanent
%%             install other         old
%%             restart node          unpacked
%%             remove                -
%% permanent   make other permanent  old
%%             install               permanent
%% old         reboot_old            permanent
%%             install               current
%%             remove                -
%%-----------------------------------------------------------------
%% libs = [{Lib, Vsn, Dir}]
-record(release, {name, vsn, erts_vsn, libs = [], status}).

-define(timeout, 10000).

%%-----------------------------------------------------------------
%% The version set on the temporary release that will be used when the
%% emulator is upgraded.
-define(tmp_vsn(__BaseVsn__), "__new_emulator__"++__BaseVsn__).




%%-----------------------------------------------------------------
%% Assumes the following file structure:
%% root --- lib --- Appl-Vsn1 --- <src>
%%       |       |             |- ebin
%%       |       |             |_ priv
%%       |       |_ Appl-Vsn2
%%       |
%%       |- bin --- start (default; {sasl, start_prg} overrides
%%       |       |- run_erl
%%       |       |- start_erl (reads start_erl.data)
%%       |       |_ <to_erl>
%%       |
%%       |- erts-EVsn1 --- bin --- <jam44>
%%       |                      |- <epmd>
%%       |                      |_ erl
%%       |- erts-EVsn2
%%       |
%%       |- clients --- ClientName1 --- bin -- start
%%         <clients use same lib and erts as master>
%%       |           |               |_ releases --- start_erl.data
%%       |           |                           |_ Vsn1 -- start.boot
%%       |           |_ ClientName2
%%       |
%%       |- clients --- Type1 --- lib
%%         <clients use own lib and erts>
%%       |           |         |- erts-EVsn
%%       |           |         |- bin -- start
%%       |           |         |_ ClientName1 -- releases -- start_erl.data
%%       |           |                                    |_ start.boot (static)
%%       |           |                                    |_ Vsn1
%%       |           |_ Type2 
%%       |
%%       |- releases --- RELEASES
%%       |            |_ <Vsn1.tar.Z>
%%       |            |
%%       |            |- start_erl.data (generated by rh)
%%       |            |
%%       |            |_ Vsn1 --- start.boot
%%       |            |        |- <sys.config>
%%       |            |        |_ relup
%%       |            |_ Vsn2        
%%       |
%%       |- log --- erlang.log.N (1 .. 5)
%%
%% where <Name> means 'for example Name', and root is
%% init:get_argument(root)
%%
%% It is configurable where the start file is located, and what it
%% is called.
%%   The paramater is {sasl, start_prg} = File
%% It is also configurable where the releases directory is located.
%% Default is $ROOT/releases.  $RELDIR overrids, and
%% {sasl, releases_dir} overrides both.
%%-----------------------------------------------------------------
start_link() ->
    gen_server:start_link({local, release_handler}, ?MODULE, [], []).

%%-----------------------------------------------------------------
%% Args: ReleaseName is the name of the package file
%%       (without .tar.Z (.tar on non unix systems))
%% Purpose: Copies all files in the release package to their
%%          directories.  Checks that all required libs and erts
%%          files are present.
%% Returns: {ok, Vsn} | {error, Reason}
%%          Reason = {existing_release, Vsn} |
%%                   {no_such_file, File} |
%%                   {bad_rel_file, RelFile} |
%%                   {file_missing, FileName} |  (in the tar package)
%%                   exit_reason()
%%-----------------------------------------------------------------
unpack_release(ReleaseName) ->
    call({unpack_release, ReleaseName}).
    
%%-----------------------------------------------------------------
%% Purpose: Checks the relup script for the specified version.
%%          The release must be unpacked.
%%          Options = [purge] - all old code that can be soft purged
%%          will be purged if all checks succeeds. This can be usefull
%%          in order to reduce time needed in the following call to
%%          install_release.
%% Returns: {ok, FromVsn, Descr} | {error, Reason}
%%          Reason = {illegal_option, IllegalOpt} |
%%                   {already_installed, Vsn} |
%%                   {bad_relup_file, RelFile} |
%%                   {no_such_release, Vsn} |
%%                   {no_such_from_vsn, Vsn} |
%%                   exit_reason()
%%-----------------------------------------------------------------
check_install_release(Vsn) ->
    check_install_release(Vsn, []).

check_install_release(Vsn, Opts) ->
    case check_check_install_options(Opts, false) of
	{ok,Purge} ->
	    call({check_install_release, Vsn, Purge});
	Error ->
	    Error
    end.

check_check_install_options([purge|Opts], _) ->
    check_check_install_options(Opts, true);
check_check_install_options([Illegal|_],_Purge) ->
    {error,{illegal_option,Illegal}};
check_check_install_options([],Purge) ->
    {ok,Purge}.


%%-----------------------------------------------------------------
%% Purpose: Executes the relup script for the specified version.
%%          The release must be unpacked.
%% Returns: {ok, FromVsn, Descr} |
%%          {continue_after_restart, FromVsn, Descr} |
%%          {error, Reason}
%%          Reason = {already_installed, Vsn} |
%%                   {bad_relup_file, RelFile} |
%%                   {no_such_release, Vsn} |
%%                   {no_such_from_vsn, Vsn} |
%%                   {could_not_create_hybrid_boot,Why} |
%%                   {missing_base_app,Vsn,App} |
%%                   {illegal_option, Opt}} |
%%                   exit_reason()
%%-----------------------------------------------------------------
install_release(Vsn) ->
    call({install_release, Vsn, restart, []}).


install_release(Vsn, Opt) ->
    case check_install_options(Opt, restart, []) of
	{ok, ErrorAction, InstallOpt} ->
	    call({install_release, Vsn, ErrorAction, InstallOpt});
	Error ->
	    Error
    end.

check_install_options([Opt | Opts], ErrAct, InstOpts) ->
    case install_option(Opt) of
	{error_action, EAct} ->
	    check_install_options(Opts, EAct, InstOpts);
	true ->
	    check_install_options(Opts, ErrAct, [Opt | InstOpts]);
	false ->
	    {error, {illegal_option, Opt}}
    end;
check_install_options([], ErrAct, InstOpts) ->
    {ok, ErrAct, InstOpts}.

install_option(Opt = {error_action, reboot}) -> Opt;
install_option(Opt = {error_action, restart}) -> Opt;
install_option({code_change_timeout, TimeOut}) ->
    check_timeout(TimeOut);
install_option({suspend_timeout, TimeOut}) ->
    check_timeout(TimeOut);
install_option({update_paths, Bool}) when Bool==true; Bool==false ->
    true;
install_option(_Opt) -> false.

check_timeout(infinity) -> true;
check_timeout(Int) when is_integer(Int), Int > 0 -> true;
check_timeout(_Else) -> false.

%%-----------------------------------------------------------------
%% Purpose: Called by boot script after emulator is restarted due to
%%          new erts version.
%% Returns: Same as install_release/2
%%          If this crashes, the emulator restart will fail
%%          (since the function is called from the boot script)
%%          and there will be a rollback.
%%-----------------------------------------------------------------
new_emulator_upgrade(Vsn, Opts) ->
    Result = call({install_release, Vsn, reboot, Opts}),
    error_logger:info_msg(
      "~w:install_release(~p,~p) completed after node restart "
      "with new emulator version~nResult: ~p~n",[?MODULE,Vsn,Opts,Result]),
    Result.

%%-----------------------------------------------------------------
%% Purpose: Makes the specified release version be the one that is
%%          used when the system starts (or restarts).
%%          The release must be installed (not unpacked).
%% Returns: ok | {error, Reason}
%%          Reason = {bad_status, Status} |
%%                   {no_such_release, Vsn} |
%%                   exit_reason()
%%-----------------------------------------------------------------
make_permanent(Vsn) ->
    call({make_permanent, Vsn}).

%%-----------------------------------------------------------------
%% Purpose: Reboots the system from an old release.
%%-----------------------------------------------------------------
reboot_old_release(Vsn) ->
    call({reboot_old_release, Vsn}).

%%-----------------------------------------------------------------
%% Purpose: Deletes all files and directories used by the release
%%          version, that are not used by any other release.
%%          The release must not be permanent.
%% Returns: ok | {error, Reason}
%%          Reason = {permanent, Vsn} |
%%-----------------------------------------------------------------
remove_release(Vsn) ->
    call({remove_release, Vsn}).

%%-----------------------------------------------------------------
%% Args: RelFile = string()
%%       Libs = [{Lib, LibVsn, Dir}]
%%       Lib = LibVsn = Dir = string()
%% Purpose: Tells the release handler that a release has been
%%          unpacked, without using the function unpack_release/1.
%%          RelFile is an absolute file name including the extension
%%          .rel.
%%          The release dir will be created.  The necessary files can
%%          be installed by calling install_file/2.
%%          The release_handler remebers where all libs are located.
%%          If remove_release is called later,
%%          those libs are removed as well (if no other releases uses
%%          them).
%% Returns: ok | {error, Reason}
%%-----------------------------------------------------------------
set_unpacked(RelFile, LibDirs) ->
    call({set_unpacked, RelFile, LibDirs}).

%%-----------------------------------------------------------------
%% Args: Vsn = string()
%% Purpose: Makes it possible to handle removal of releases
%%          outside the release_handler.
%%          This function won't delete any files at all.
%% Returns: ok | {error, Reason}
%%-----------------------------------------------------------------
set_removed(Vsn) ->
    call({set_removed, Vsn}).

%%-----------------------------------------------------------------
%% Purpose: Makes it possible to install the start.boot,
%%          sys.config and relup files if they are not part of a 
%%          standard release package.  May be used to
%%          install files that are generated, before install_release
%%          is called.
%% Returns: ok | {error, {no_such_release, Vsn}}
%%-----------------------------------------------------------------
install_file(Vsn, File) when is_list(File) ->
    call({install_file, File, Vsn}).

%%-----------------------------------------------------------------
%% Returns: [{Name, Vsn, [LibName], Status}]
%%          Status = unpacked | current | permanent | old
%%-----------------------------------------------------------------
which_releases() ->
    call(which_releases).

%%-----------------------------------------------------------------
%% Returns: [{Name, Vsn, [LibName], Status}]
%%          Status = unpacked | current | permanent | old
%%-----------------------------------------------------------------
which_releases(Status) ->
    Releases = which_releases(),
    get_releases_with_status(Releases, Status, []).

%%-----------------------------------------------------------------
%% check_script(Script, LibDirs) -> ok | {error, Reason}
%%-----------------------------------------------------------------
check_script(Script, LibDirs) ->
    release_handler_1:check_script(Script, LibDirs).

%%-----------------------------------------------------------------
%% eval_script(Script, Apps, LibDirs, NewLibs, Opts) ->
%%                                             {ok, UnPurged} |
%%                                             restart_emulator |
%%                                             {error, Error}
%%                                             {'EXIT', Reason}
%% If sync_nodes is present, the calling process must have called
%% net_kernel:monitor_nodes(true) before calling this function.
%% No!  No other process than the release_handler can ever call this
%% function, if sync_nodes is used.
%%
%% LibDirs is a list of all applications, while NewLibs is a list of
%% applications that have changed version between the current and the
%% new release.
%% -----------------------------------------------------------------
eval_script(Script, Apps, LibDirs, NewLibs, Opts) ->
    catch release_handler_1:eval_script(Script, Apps, LibDirs, NewLibs, Opts).

%%-----------------------------------------------------------------
%% Func: create_RELEASES(Root, RelFile, LibDirs) -> ok | {error, Reason}
%% Types: Root = RelFile = string()
%% Purpose: Creates an initial RELEASES file.
%%-----------------------------------------------------------------
create_RELEASES([Root, RelFile | LibDirs]) ->
    create_RELEASES(Root, filename:join(Root, "releases"), RelFile, LibDirs).

create_RELEASES(Root, RelFile) ->
    create_RELEASES(Root, filename:join(Root, "releases"), RelFile, []).

create_RELEASES(Root, RelDir, RelFile, LibDirs) ->
    case catch check_rel(Root, RelFile, LibDirs, false) of
	{error, Reason } ->
	    {error, Reason};
	Rel ->
	    Rel2 = Rel#release{status = permanent},
	    catch write_releases(RelDir, [Rel2], false)
    end.

%%-----------------------------------------------------------------
%% Func: upgrade_app(App, Dir) -> {ok, Unpurged}
%%                              | restart_emulator
%%                              | {error, Error}
%% Types:
%%   App = atom()
%%   Dir = string() assumed to be application directory, the code
%%         located under Dir/ebin
%% Purpose: Upgrade to the version in Dir according to an appup file
%%-----------------------------------------------------------------
upgrade_app(App, NewDir) ->
    try upgrade_script(App, NewDir) of
	{ok, NewVsn, Script} ->
	    eval_appup_script(App, NewVsn, NewDir, Script)
    catch
	throw:Reason ->
	    {error, Reason}
    end.

%%-----------------------------------------------------------------
%% Func: downgrade_app(App, Dir)
%%       downgrade_app(App, Vsn, Dir) -> {ok, Unpurged}
%%                                     | restart_emulator
%%                                     | {error, Error}
%% Types:
%%   App = atom()
%%   Vsn = string(), may be omitted if Dir == App-Vsn
%%   Dir = string() assumed to be application directory, the code
%%         located under Dir/ebin
%% Purpose: Downgrade from the version in Dir according to an appup file
%%          located in the ebin dir of the _current_ version
%%-----------------------------------------------------------------
downgrade_app(App, OldDir) ->
    case string:lexemes(filename:basename(OldDir), "-") of
	[_AppS, OldVsn] ->
	    downgrade_app(App, OldVsn, OldDir);
	_ ->
	    {error, {unknown_version, App}}
    end.
downgrade_app(App, OldVsn, OldDir) ->
    try downgrade_script(App, OldVsn, OldDir) of
	{ok, Script} ->
	    eval_appup_script(App, OldVsn, OldDir, Script)
    catch
	throw:Reason ->
	    {error, Reason}
    end.

upgrade_script(App, NewDir) ->
    OldVsn = ensure_running(App),
    OldDir = code:lib_dir(App),
    {NewVsn, Script} = find_script(App, NewDir, OldVsn, up),
    OldAppl = read_app(App, OldVsn, OldDir),
    NewAppl = read_app(App, NewVsn, NewDir),
    case systools_rc:translate_scripts(up,
				       [Script],[NewAppl],[OldAppl]) of
	{ok, LowLevelScript} ->
	    {ok, NewVsn, LowLevelScript};
	{error, _SystoolsRC, Reason} ->
	    throw(Reason)
    end.

downgrade_script(App, OldVsn, OldDir) ->
    NewVsn = ensure_running(App),
    NewDir = code:lib_dir(App),
    {NewVsn, Script} = find_script(App, NewDir, OldVsn, down),
    OldAppl = read_app(App, OldVsn, OldDir),
    NewAppl = read_app(App, NewVsn, NewDir),
    case systools_rc:translate_scripts(dn,
				       [Script],[OldAppl],[NewAppl]) of
	{ok, LowLevelScript} ->
	    {ok, LowLevelScript};
	{error, _SystoolsRC, Reason} ->
	    throw(Reason)
    end.

eval_appup_script(App, ToVsn, ToDir, Script) ->
    EnvBefore = application_controller:prep_config_change(),
    AppSpecL = read_appspec(App, ToDir),
    Res = release_handler_1:eval_script(Script,
					[], % [AppSpec]
					[{App, ToVsn, ToDir}],
					[{App, ToVsn, ToDir}],
					[]), % [Opt]
    case Res of
	{ok, _Unpurged} ->
	    application_controller:change_application_data(AppSpecL,[]),
	    application_controller:config_change(EnvBefore);
	_Res ->
	    ignore
    end,
    Res.

ensure_running(App) ->
    case lists:keysearch(App, 1, application:which_applications()) of
	{value, {_App, _Descr, Vsn}} ->
	    Vsn;
	false ->
	    throw({app_not_running, App})
    end.

find_script(App, Dir, OldVsn, UpOrDown) ->
    Appup = filename:join([Dir, "ebin", atom_to_list(App)++".appup"]),
    case file:consult(Appup) of
	{ok, [{NewVsn, UpFromScripts, DownToScripts}]} ->
	    Scripts = case UpOrDown of
			  up -> UpFromScripts;
			  down -> DownToScripts
		      end,
	    case systools_relup:appup_search_for_version(OldVsn,Scripts) of
		{ok,Script} ->
		    {NewVsn,Script};
		error ->
		    throw({version_not_in_appup, OldVsn})
	    end;
	{error, enoent} ->
	    throw(no_appup_found);
	{error, Reason} ->
	    throw(Reason)
    end.

read_app(App, Vsn, Dir) ->
    AppS = atom_to_list(App),
    Path = [filename:join(Dir, "ebin")],
    case systools_make:read_application(AppS, Vsn, Path, []) of
	{ok, Appl} ->
	    Appl;
	{error, {not_found, _AppFile}} ->
	    throw({no_app_found, Vsn, Dir});
	{error, Reason} ->
	    throw(Reason)
    end.

read_appspec(App, Dir) ->
    AppS = atom_to_list(App),
    Path = [filename:join(Dir, "ebin")],
    case file:path_consult(Path, AppS++".app") of
	{ok, AppSpecL, _File} ->
	    AppSpecL;
	{error, Reason} ->
	    throw(Reason)
    end.
				      
%%-----------------------------------------------------------------
%% call(Request) -> Term
%%-----------------------------------------------------------------
call(Req) ->
    gen_server:call(release_handler, Req, infinity).


%%-----------------------------------------------------------------
%% Call-back functions from gen_server
%%-----------------------------------------------------------------
init([]) ->
    {ok, [[Root]]} = init:get_argument(root),
    {CliDir, Masters} = is_client(),
    ReleaseDir =
	case application:get_env(sasl, releases_dir) of
	    undefined ->
		case os:getenv("RELDIR") of
		    false ->
			if
			    CliDir == false ->
				filename:join([Root, "releases"]);
			    true ->
				filename:join([CliDir, "releases"])
			end;
		    RELDIR ->
			RELDIR
		end;
	    {ok, Dir} ->
		Dir
	end,
    Releases =
	case consult(filename:join(ReleaseDir, "RELEASES"), Masters) of
	    {ok, [Term]} ->
		transform_release(ReleaseDir, Term, Masters);
	    _ ->
		{Name, Vsn} = init:script_id(),
		[#release{name = Name, vsn = Vsn, status = permanent}]
	end,
    StartPrg =
	case application:get_env(start_prg) of
	    {ok, Found2} when is_list(Found2) ->
		{do_check, Found2};
	    _ ->
		{no_check, filename:join([Root, "bin", "start"])}
	end,
    Static =
	case application:get_env(static_emulator) of
	    {ok, SFlag} when is_atom(SFlag) -> SFlag;
	    _                            -> false
	end,
    {ok, #state{root = Root, rel_dir = ReleaseDir, releases = Releases,
		start_prg = StartPrg, masters = Masters,
	        client_dir = CliDir, static_emulator = Static}}.

handle_call({unpack_release, ReleaseName}, _From, S)
  when S#state.masters == false ->
    case catch do_unpack_release(S#state.root, S#state.rel_dir,
				 ReleaseName, S#state.releases) of
	{ok, NewReleases, Vsn} -> 
	    {reply, {ok, Vsn}, S#state{releases = NewReleases}};
	{error, Reason}   ->
	    {reply, {error, Reason}, S}; 
	{'EXIT', Reason} ->
	    {reply, {error, Reason}, S}
    end;
handle_call({unpack_release, _ReleaseName}, _From, S) ->
    {reply, {error, client_node}, S};

handle_call({check_install_release, Vsn, Purge}, _From, S) ->
    case catch do_check_install_release(S#state.rel_dir,
					Vsn,
					S#state.releases,
					S#state.masters,
					Purge) of
	{ok, CurrentVsn, Descr} -> 
	    {reply, {ok, CurrentVsn, Descr}, S};
	{error, Reason}   ->
	    {reply, {error, Reason}, S}; 
	{'EXIT', Reason} ->
	    {reply, {error, Reason}, S}
    end;

handle_call({install_release, Vsn, ErrorAction, Opts}, From, S) ->
    NS = resend_sync_nodes(S),
    case catch do_install_release(S, Vsn, Opts) of
	{ok, NewReleases, [], CurrentVsn, Descr} ->
	    {reply, {ok, CurrentVsn, Descr}, NS#state{releases=NewReleases}};
	{ok, NewReleases, Unpurged, CurrentVsn, Descr} ->
	    Timer =
		case S#state.timer of
		    undefined ->
			{ok, Ref} = timer:send_interval(?timeout, timeout),
			Ref;
		    Ref -> Ref
		end,
	    NewS = NS#state{releases = NewReleases, unpurged = Unpurged,
			    timer = Timer},
	    {reply, {ok, CurrentVsn, Descr}, NewS};
	{error, Reason}   ->
	    {reply, {error, Reason}, NS}; 
	{restart_emulator, CurrentVsn, Descr} ->
	    gen_server:reply(From, {ok, CurrentVsn, Descr}),
	    init:reboot(),
	    {noreply, NS};
	{restart_new_emulator, CurrentVsn, Descr} ->
	    gen_server:reply(From, {continue_after_restart, CurrentVsn, Descr}),
	    init:reboot(),
	    {noreply, NS};
	{'EXIT', Reason} ->
	    io:format("release_handler:"
		      "install_release(Vsn=~tp Opts=~tp) failed, "
		      "Reason=~tp~n", [Vsn, Opts, Reason]),
	    gen_server:reply(From, {error, Reason}),
	    case ErrorAction of
		restart ->
		    init:restart();
		reboot ->
		    init:reboot()
	    end,
	    {noreply, NS}
    end;

handle_call({make_permanent, Vsn}, _From, S) ->
    case catch do_make_permanent(S, Vsn) of
	{ok, Releases, Unpurged} ->
	    {reply, ok, S#state{releases = Releases, unpurged = Unpurged}};
	{error, Reason}   ->
	    {reply, {error, Reason}, S}; 
	{'EXIT', Reason} ->
	    {reply, {error, Reason}, S}
    end;

handle_call({reboot_old_release, Vsn}, From, S) ->
    case catch do_reboot_old_release(S, Vsn) of
	ok ->
	    gen_server:reply(From, ok),
	    init:reboot(),
	    {noreply, S};
	{error, Reason}   ->
	    {reply, {error, Reason}, S}; 
	{'EXIT', Reason} ->
	    {reply, {error, Reason}, S}
    end;

handle_call({remove_release, Vsn}, _From, S)
  when S#state.masters == false ->
    case catch do_remove_release(S#state.root, S#state.rel_dir,
				 Vsn, S#state.releases) of
	{ok, NewReleases} -> 
	    {reply, ok, S#state{releases = NewReleases}};
	{error, Reason}   ->
	    {reply, {error, Reason}, S}; 
	{'EXIT', Reason} ->
	    {reply, {error, Reason}, S}
    end;
handle_call({remove_release, _Vsn}, _From, S) ->
    {reply, {error, client_node}, S};

handle_call({set_unpacked, RelFile, LibDirs}, _From, S) ->
    Root = S#state.root,
    case catch do_set_unpacked(Root, S#state.rel_dir, RelFile,
			       LibDirs, S#state.releases,
			       S#state.masters) of
	{ok, NewReleases, Vsn} -> 
	    {reply, {ok, Vsn}, S#state{releases = NewReleases}};
	{error, Reason}   ->
	    {reply, {error, Reason}, S}; 
	{'EXIT', Reason} ->
	    {reply, {error, Reason}, S}
    end;

handle_call({set_removed, Vsn}, _From, S) ->
    case catch do_set_removed(S#state.rel_dir, Vsn,
			      S#state.releases,
			      S#state.masters) of
	{ok, NewReleases} ->
	    {reply, ok, S#state{releases = NewReleases}};
	{error, Reason}   ->
	    {reply, {error, Reason}, S}; 
	{'EXIT', Reason} ->
	    {reply, {error, Reason}, S}
    end;

handle_call({install_file, File, Vsn}, _From, S) ->
    Reply = 
	case lists:keysearch(Vsn, #release.vsn, S#state.releases) of
	    {value, _} ->
		Dir = filename:join([S#state.rel_dir, Vsn]),
		catch copy_file(File, Dir, S#state.masters);
	    _ ->
		{error, {no_such_release, Vsn}}
	end,
    {reply, Reply, S};

handle_call(which_releases, _From, S) ->
    Reply = lists:map(fun(#release{name = Name, vsn = Vsn, libs = Libs,
				   status = Status}) ->
			      {Name, Vsn, mk_lib_name(Libs), Status}
		      end, S#state.releases),
    {reply, Reply, S}.

mk_lib_name([{LibName, Vsn, _Dir} | T]) ->
    [lists:concat([LibName, "-", Vsn]) | mk_lib_name(T)];
mk_lib_name([]) -> [].

handle_info(timeout, S) ->
    case soft_purge(S#state.unpurged) of
	[] ->
	    _ = timer:cancel(S#state.timer),
	    {noreply, S#state{unpurged = [], timer = undefined}};
	Unpurged ->
	    {noreply, S#state{unpurged = Unpurged}}
    end;

handle_info({sync_nodes, Id, Node}, S) ->
    PSN = S#state.pre_sync_nodes,
    {noreply, S#state{pre_sync_nodes = [{sync_nodes, Id, Node} | PSN]}};

handle_info(Msg, State) ->
    error_logger:info_msg("release_handler: got unknown message: ~p~n", [Msg]),
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

handle_cast(_Msg, State) ->
    {noreply, State}.
code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

%%%-----------------------------------------------------------------
%%% Internal functions
%%%-----------------------------------------------------------------
is_client() ->
    case application:get_env(masters) of
	{ok, Masters} ->
	    Alive = is_alive(),
	    case atom_list(Masters) of
		true when Alive == true ->
		    case application:get_env(client_directory) of
			{ok, ClientDir} ->
			    case int_list(ClientDir) of
				true ->
				    {ClientDir, Masters};
				_ ->
				    exit({bad_parameter, client_directory,
					  ClientDir})
			    end;
			_ ->
			    {false, false}
		    end;
		_ ->
		    exit({bad_parameter, masters, Masters})
	    end;
	_ ->
	    {false, false}
    end.

atom_list([A|T]) when is_atom(A) -> atom_list(T);
atom_list([])                    -> true;
atom_list(_)                     -> false.

int_list([I|T]) when is_integer(I) -> int_list(T);
int_list([])                       -> true;
int_list(_)                        -> false.

resend_sync_nodes(S) ->
    lists:foreach(fun(Msg) -> self() ! Msg end, S#state.pre_sync_nodes),
    S#state{pre_sync_nodes = []}.

soft_purge(Unpurged) ->
    lists:filter(fun({Mod, _PostPurgeMethod}) ->
			 case code:soft_purge(Mod) of
			     true -> false; % No proc left, don't remember Mod
			     false -> true  % Still proc left, remember it
			 end
		 end,
		 Unpurged).

brutal_purge(Unpurged) ->
    lists:filter(fun({Mod, brutal_purge}) -> code:purge(Mod), false;
		    (_) -> true
		 end,
		 Unpurged).

%%-----------------------------------------------------------------
%% The release package is a RelName.tar.Z (.tar on non unix) file
%% with the following contents:
%%   - RelName.rel   == {release, {Name, Vsn}, {erts, EVsn}, [lib()]}
%%   - <files> according to [lib()]
%%   - lib() = {LibName, LibVsn}
%% In the Dir, there exists a file called RELEASES, which contains
%% a [{Vsn, {erts, EVsn}, {libs, [{LibName, LibVsn, LibDir}]}}].
%% Note that RelDir is an absolute directory name !
%% Note that this function is not executed by a client
%% release_handler.
%%-----------------------------------------------------------------
do_unpack_release(Root, RelDir, ReleaseName, Releases) ->
    Tar = filename:join(RelDir, ReleaseName ++ ".tar.gz"),
    do_check_file(Tar, regular),
    Rel = ReleaseName ++ ".rel",
    _ = extract_rel_file(filename:join("releases", Rel), Tar, Root),
    RelFile = filename:join(RelDir, Rel),
    Release = check_rel(Root, RelFile, false),
    #release{vsn = Vsn} = Release,
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, _} -> throw({error, {existing_release, Vsn}});
	_          -> ok
    end,
    extract_tar(Root, Tar),
    NewReleases = [Release#release{status = unpacked} | Releases],
    write_releases(RelDir, NewReleases, false),

    %% Keeping this for backwards compatibility reasons with older
    %% systools:make_tar, where there is no copy of the .rel file in
    %% the releases/<vsn> dir. See OTP-9746.
    Dir = filename:join([RelDir, Vsn]),
    copy_file(RelFile, Dir, false),

    %% Clean release
    _ = file:delete(Tar),
    _ = file:delete(RelFile),

    {ok, NewReleases, Vsn}.
   
check_rel(Root, RelFile, Masters) ->
    check_rel(Root, RelFile, [], Masters).
check_rel(Root, RelFile, LibDirs, Masters) ->
    case consult(RelFile, Masters) of
	{ok, [RelData]} ->
	    check_rel_data(RelData, Root, LibDirs, Masters);
	{ok, _} ->
	    throw({error, {bad_rel_file, RelFile}});
	{error, Reason} when is_tuple(Reason) ->
	    throw({error, {bad_rel_file, RelFile}});
	{error, FileError} -> % FileError is posix atom | no_master
	    throw({error, {FileError, RelFile}})
    end.

check_rel_data({release, {Name, Vsn}, {erts, EVsn}, Libs}, Root, LibDirs,
		Masters) ->
    Libs2 =
	lists:map(fun(LibSpec) ->
			  Lib = element(1, LibSpec),
			  LibVsn = element(2, LibSpec),
			  LibName = lists:concat([Lib, "-", LibVsn]),
			  LibDir = 
			      case lists:keysearch(Lib, 1, LibDirs) of
				  {value, {_Lib, _Vsn, Dir}} ->
				      Path = filename:join(Dir,LibName),
				      check_path(Path, Masters),
				      Path;
				  _ ->
				      filename:join([Root, "lib", LibName])
			      end,
			  {Lib, LibVsn, LibDir}
		  end,
		  Libs),
    #release{name = Name, vsn = Vsn, erts_vsn = EVsn,
	     libs = Libs2, status = unpacking};
check_rel_data(RelData, _Root, _LibDirs, _Masters) ->
    throw({error, {bad_rel_data, RelData}}).

check_path(Path) ->
	check_path_response(Path, file:read_file_info(Path)).
check_path(Path, false)   -> check_path(Path);
check_path(Path, Masters) -> check_path_master(Masters, Path).

%%-----------------------------------------------------------------
%% check_path at any master node.
%% If the path does not exist or is not a directory
%% at one node it should not exist at any other node either.
%%-----------------------------------------------------------------
check_path_master([Master|Ms], Path) ->
	case rpc:call(Master, file, read_file_info, [Path]) of
	{badrpc, _} -> consult_master(Ms, Path);
	Res         -> check_path_response(Path, Res)
	end;
check_path_master([], _Path) ->
	{error, no_master}.

check_path_response(_Path, {ok, Info}) when Info#file_info.type==directory ->
	ok;
check_path_response(Path, {ok, _Info}) ->
	throw({error, {not_a_directory, Path}});
check_path_response(Path, {error, _Reason}) ->
	throw({error, {no_such_directory, Path}}).

do_check_install_release(RelDir, Vsn, Releases, Masters, Purge) ->
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, #release{status = current}} ->
	    {error, {already_installed, Vsn}};
	{value, Release} ->
	    LatestRelease = get_latest_release(Releases),
	    VsnDir = filename:join([RelDir, Vsn]),
	    check_file(filename:join(VsnDir, "start.boot"), regular, Masters),
	    IsRelup = check_opt_file(filename:join(VsnDir, "relup"), regular, Masters),
	    check_opt_file(filename:join(VsnDir, "sys.config"), regular, Masters),

	    %% Check that all required libs are present
	    Libs = Release#release.libs,
	    lists:foreach(fun({_Lib, _LibVsn, LibDir}) ->
				  check_file(LibDir, directory, Masters),
				  Ebin = filename:join(LibDir, "ebin"),
				  check_file(Ebin, directory, Masters)
			  end,
			  Libs),

	    if
		IsRelup ->
		    case get_rh_script(LatestRelease, Release, RelDir, Masters) of
			{ok, {CurrentVsn, Descr, Script}} ->
			    case catch check_script(Script, Libs) of
				{ok,SoftPurgeMods} when Purge=:=true ->
				    %% Get modules with brutal_purge
				    %% instructions, but that can be
				    %% soft purged
				    {ok,BrutalPurgeMods} =
					release_handler_1:check_old_processes(
					  Script,brutal_purge),
				    lists:foreach(
				      fun(Mod) ->
					      catch erlang:purge_module(Mod)
				      end,
				      SoftPurgeMods ++ BrutalPurgeMods),
				    {ok, CurrentVsn, Descr};
				{ok,_} ->
				    {ok, CurrentVsn, Descr};
				Else ->
				    Else
			    end;
			Error ->
			    Error
		    end;
		true ->
		    {ok, Vsn, ""}
	    end;
	_ ->
	    {error, {no_such_release, Vsn}}
    end.
	    
do_install_release(#state{start_prg = StartPrg,
			  root = RootDir,
			  rel_dir = RelDir, releases = Releases,
			  masters = Masters,
			  static_emulator = Static},
		   Vsn, Opts) ->
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, #release{status = current}} ->
	    {error, {already_installed, Vsn}};
	{value, Release} ->
	    LatestRelease = get_latest_release(Releases),
	    case get_rh_script(LatestRelease, Release, RelDir, Masters) of
		{ok, {_CurrentVsn, _Descr, [restart_new_emulator|_Script]}}
		  when Static == true ->
		    throw(static_emulator);
		{ok, {CurrentVsn, Descr, [restart_new_emulator|_Script]}} ->
		    %% This will only happen if the upgrade includes
		    %% an emulator upgrade (and it is not a downgrade)
		    %% - then the new emulator must be started before
		    %% new code can be loaded.
		    %% Create a temporary release which includes new
		    %% emulator, kernel, stdlib and sasl - and old
		    %% versions of other applications.
		    {TmpVsn,TmpRelease} =
			new_emulator_make_tmp_release(LatestRelease,Release,
						      RelDir,Opts,Masters),
		    NReleases = [TmpRelease|Releases],

		    %% Then uppgrade to the temporary release.
		    %% The rest of the upgrade will continue after the restart
		    prepare_restart_new_emulator(StartPrg, RootDir,
						 RelDir, TmpVsn, TmpRelease,
						 NReleases, Masters),
		    {restart_new_emulator, CurrentVsn, Descr};
		{ok, {CurrentVsn, Descr, Script}} ->
		    %% In case there has been an emulator upgrade,
		    %% remove the temporary release
		    NReleases =
			new_emulator_rm_tmp_release(
			  LatestRelease#release.vsn,
			  LatestRelease#release.erts_vsn,
			  Vsn,RelDir,Releases,Masters),

		    %% Then execute the relup script
		    mon_nodes(true),
		    EnvBefore = application_controller:prep_config_change(),
		    Apps = change_appl_data(RelDir, Release, Masters),
		    LibDirs = Release#release.libs,
		    NewLibs = get_new_libs(LatestRelease#release.libs,
					   Release#release.libs),
		    case eval_script(Script, Apps, LibDirs, NewLibs, Opts) of
			{ok, Unpurged} ->
			    application_controller:config_change(EnvBefore),
			    mon_nodes(false),
			    NReleases1 = set_status(Vsn, current, NReleases),
			    {ok, NReleases1, Unpurged, CurrentVsn, Descr};
			restart_emulator when Static == true ->
			    throw(static_emulator);
			restart_emulator ->
			    mon_nodes(false),
			    prepare_restart_new_emulator(StartPrg, RootDir,
							 RelDir, Vsn, Release,
							 NReleases, Masters),
			    {restart_emulator, CurrentVsn, Descr};
			Else ->
			    application_controller:config_change(EnvBefore),
			    mon_nodes(false),
			    Else
		    end;
		Error ->
		    Error
	    end;
	_ ->
	    {error, {no_such_release, Vsn}}
    end.

new_emulator_make_tmp_release(CurrentRelease,ToRelease,RelDir,Opts,Masters) ->
    CurrentVsn = CurrentRelease#release.vsn,
    ToVsn = ToRelease#release.vsn,
    TmpVsn = ?tmp_vsn(CurrentVsn),
    case get_base_libs(ToRelease#release.libs) of
	{ok,{Kernel,Stdlib,Sasl},_} ->
	    case get_base_libs(CurrentRelease#release.libs) of
		{ok,_,RestLibs} ->
		    TmpErtsVsn = ToRelease#release.erts_vsn,
		    TmpLibs = [Kernel,Stdlib,Sasl|RestLibs],
		    TmpRelease = CurrentRelease#release{vsn=TmpVsn,
							erts_vsn=TmpErtsVsn,
							libs = TmpLibs,
							status = unpacked},
		    new_emulator_make_hybrid_boot(CurrentVsn,ToVsn,TmpVsn,
						  RelDir,Opts,Masters),
		    new_emulator_make_hybrid_config(CurrentVsn,ToVsn,TmpVsn,
						    RelDir,Masters),
		    {TmpVsn,TmpRelease};
		{error,{missing,Missing}} ->
		    throw({error,{missing_base_app,CurrentVsn,Missing}})
	    end;
	{error,{missing,Missing}} ->
	    throw({error,{missing_base_app,ToVsn,Missing}})
    end.

%% Get kernel, stdlib and sasl libs,
%% and also return the rest of the libs as a list.
%% Return error if any of kernel, stdlib or sasl does not exist.
get_base_libs(Libs) ->
    get_base_libs(Libs,undefined,undefined,undefined,[]).
get_base_libs([{kernel,_,_}=Kernel|Libs],undefined,Stdlib,Sasl,Rest) ->
    get_base_libs(Libs,Kernel,Stdlib,Sasl,Rest);
get_base_libs([{stdlib,_,_}=Stdlib|Libs],Kernel,undefined,Sasl,Rest) ->
    get_base_libs(Libs,Kernel,Stdlib,Sasl,Rest);
get_base_libs([{sasl,_,_}=Sasl|Libs],Kernel,Stdlib,undefined,Rest) ->
    get_base_libs(Libs,Kernel,Stdlib,Sasl,Rest);
get_base_libs([Lib|Libs],Kernel,Stdlib,Sasl,Rest) ->
    get_base_libs(Libs,Kernel,Stdlib,Sasl,[Lib|Rest]);
get_base_libs([],undefined,_Stdlib,_Sasl,_Rest) ->
    {error,{missing,kernel}};
get_base_libs([],_Kernel,undefined,_Sasl,_Rest) ->
    {error,{missing,stdlib}};
get_base_libs([],_Kernel,_Stdlib,undefined,_Rest) ->
    {error,{missing,sasl}};
get_base_libs([],Kernel,Stdlib,Sasl,Rest) ->
    {ok,{Kernel,Stdlib,Sasl},lists:reverse(Rest)}.

new_emulator_make_hybrid_boot(CurrentVsn,ToVsn,TmpVsn,RelDir,Opts,Masters) ->
    FromBootFile = filename:join([RelDir,CurrentVsn,"start.boot"]),
    ToBootFile = filename:join([RelDir,ToVsn,"start.boot"]),
    TmpBootFile = filename:join([RelDir,TmpVsn,"start.boot"]),
    ensure_dir(TmpBootFile,Masters),
    Args = [ToVsn,Opts],
    {ok,FromBoot} = read_file(FromBootFile,Masters),
    {ok,ToBoot} = read_file(ToBootFile,Masters),
    case systools_make:make_hybrid_boot(TmpVsn,FromBoot,ToBoot,Args) of
	{ok,TmpBoot} ->
	    write_file(TmpBootFile,TmpBoot,Masters);
	{error,Reason} ->
	    throw({error,{could_not_create_hybrid_boot,Reason}})
    end.

new_emulator_make_hybrid_config(CurrentVsn,ToVsn,TmpVsn,RelDir,Masters) ->
    FromFile = filename:join([RelDir,CurrentVsn,"sys.config"]),
    ToFile = filename:join([RelDir,ToVsn,"sys.config"]),
    TmpFile = filename:join([RelDir,TmpVsn,"sys.config"]),

    FromConfig =
	case consult(FromFile,Masters) of
	    {ok,[FC]} ->
		FC;
	    {error,Error1} ->
		io:format("Warning: ~w can not read ~tp: ~tp~n",
			  [?MODULE,FromFile,Error1]),
		[]
	end,

    [Kernel,Stdlib,Sasl] =
	case consult(ToFile,Masters) of
	    {ok,[ToConfig]} ->
		[lists:keyfind(App,1,ToConfig) || App <- [kernel,stdlib,sasl]];
	    {error,Error2} ->
		io:format("Warning: ~w can not read ~tp: ~tp~n",
			  [?MODULE,ToFile,Error2]),
		[false,false,false]
	end,

    Config1 = replace_config(kernel,FromConfig,Kernel),
    Config2 = replace_config(stdlib,Config1,Stdlib),
    Config3 = replace_config(sasl,Config2,Sasl),

    ConfigStr = io_lib:format("%% ~s~n~tp.~n",
                              [epp:encoding_to_string(utf8),Config3]),
    write_file(TmpFile,unicode:characters_to_binary(ConfigStr),Masters).

%% Take the configuration for application App from the new config and
%% insert in the old config.
%% If no entry exists in the new config, then delete the entry (if it exists)
%% from the old config.
%% If entry exists in the new config, but not in the old config, then
%% add the entry.
replace_config(App,Config,false) ->
    lists:keydelete(App,1,Config);
replace_config(App,Config,AppConfig) ->
    lists:keystore(App,1,Config,AppConfig).

%% Remove all files related to the temporary release
new_emulator_rm_tmp_release(?tmp_vsn(_)=TmpVsn,EVsn,NewVsn,
			    RelDir,Releases,Masters) ->
    case os:type() of
	{win32, nt} ->
	    rename_tmp_service(EVsn,TmpVsn,NewVsn);
	_ ->
	    ok
    end,
    remove_dir(filename:join(RelDir,TmpVsn),Masters),
    lists:keydelete(TmpVsn,#release.vsn,Releases);
new_emulator_rm_tmp_release(_,_,_,_,Releases,_) ->
    Releases.

%% Rename the tempoarary service (for erts ugprade) to the real ToVsn
rename_tmp_service(EVsn,TmpVsn,NewVsn) ->
    FromName = hd(string:lexemes(atom_to_list(node()),"@")) ++ "_" ++ TmpVsn,
    ToName = hd(string:lexemes(atom_to_list(node()),"@")) ++ "_" ++ NewVsn,
    case erlsrv:get_service(EVsn,ToName) of
	{error, _Error} ->
	    ok;
	_Data ->
	    {ok,_} = erlsrv:remove_service(ToName),
	    ok
    end,
    rename_service(EVsn,FromName,ToName).


%% Rename a service and check that it succeeded
rename_service(EVsn,FromName,ToName) ->
    case erlsrv:rename_service(EVsn,FromName,ToName) of
	{ok,_} ->
	    case erlsrv:get_service(EVsn,ToName) of
		{error,Error1} ->
		    throw({error,Error1});
		_Data2 ->
		    ok
	    end;
	Error2 ->
	    throw({error,{service_rename_failed, Error2}})
    end.


%%% This code chunk updates the services in one of two ways,
%%% Either the emulator is restarted, in which case the old service
%%% is to be removed and the new enabled, or the emulator is NOT restarted
%%% in which case we try to rename the old service to the new name and try
%%% to update heart's view of what service we are really running.
do_make_services_permanent(PermanentVsn,Vsn, PermanentEVsn, EVsn) ->
    PermName = hd(string:lexemes(atom_to_list(node()),"@"))
	++ "_" ++ PermanentVsn,
    Name = hd(string:lexemes(atom_to_list(node()),"@"))
	++ "_" ++ Vsn,
    case erlsrv:get_service(EVsn,Name) of
	{error, _Error} ->
	    %% We probably do not need to replace services, just 
	    %% rename.
	    case os:getenv("ERLSRV_SERVICE_NAME") == PermName of
		true ->
		    rename_service(EVsn,PermName,Name),
		    %% The interfaces for doing this are
		    %% NOT published and may be subject to
		    %% change. Do NOT do this anywhere else!

		    os:putenv("ERLSRV_SERVICE_NAME", Name),

		    %% Restart heart port program, this
		    %% function is only to be used here.
		    heart:cycle();
		false ->
		    throw({error,service_name_missmatch})
	    end;
	Data ->
	    UpdData = erlsrv:new_service(Name, Data, []),
	    case erlsrv:store_service(EVsn,UpdData) of
		ok ->
		    {ok,_} = erlsrv:disable_service(PermanentEVsn, PermName),
		    {ok,_} = erlsrv:enable_service(EVsn, Name),
		    {ok,_} = erlsrv:remove_service(PermName),
		    %%% Read comments about these above...
		    os:putenv("ERLSRV_SERVICE_NAME", Name),
		    ok = heart:cycle();
		Error4 ->
		    throw(Error4)
	    end
    end.

do_make_permanent(#state{releases = Releases,
			 rel_dir = RelDir, unpurged = Unpurged,
			 masters = Masters,
			 static_emulator = Static},
		  Vsn) ->
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, #release{erts_vsn = EVsn, status = Status}}
	  when Status /= unpacked, Status /= old, Status /= permanent ->
	    Dir = filename:join([RelDir, Vsn]),
	    Sys =
		case catch check_file(filename:join(Dir, "sys.config"),
				      regular, Masters) of
		    ok ->     filename:join(Dir, "sys");
		    _ -> false
		end,
	    Boot = filename:join(Dir, "start.boot"),
	    check_file(Boot, regular, Masters),
	    set_permanent_files(RelDir, EVsn, Vsn, Masters, Static),
	    NewReleases = set_status(Vsn, permanent, Releases),
	    write_releases(RelDir, NewReleases, Masters),
	    case os:type() of
		{win32, nt} ->
		    {value, PermanentRelease} = 
				lists:keysearch(permanent, #release.status,
						Releases),
		    PermanentVsn = PermanentRelease#release.vsn,
		    PermanentEVsn = PermanentRelease#release.erts_vsn,
		    case catch do_make_services_permanent(PermanentVsn, 
							  Vsn, 
							  PermanentEVsn,
							  EVsn)  of
			{error,Reason} ->
			    throw({error,{service_update_failed, Reason}});
			_ ->
			    ok
		    end;
		_ ->
		    ok
	    end,
	    ok = init:make_permanent(filename:join(Dir, "start"), Sys),
	    {ok, NewReleases, brutal_purge(Unpurged)};
	{value, #release{status = permanent}} ->
	    {ok, Releases, Unpurged};
	{value, #release{status = Status}} ->
	    {error, {bad_status, Status}};
	false ->
	    {error, {no_such_release, Vsn}}
    end.


do_back_service(OldVersion, CurrentVersion,OldEVsn,CurrentEVsn) ->
    NN = hd(string:lexemes(atom_to_list(node()),"@")),
    OldName = NN ++ "_" ++ OldVersion,
    CurrentName = NN ++ "_" ++ CurrentVersion,
    UpdData = case erlsrv:get_service(CurrentEVsn,CurrentName) of
		  {error, Error} ->
		      throw({error,Error});
		  Data ->
		      erlsrv:new_service(OldName, Data, [])
	      end,
    _ = case erlsrv:store_service(OldEVsn,UpdData) of
	    ok ->
		{ok,_} = erlsrv:disable_service(CurrentEVsn,CurrentName),
		{ok,_} = erlsrv:enable_service(OldEVsn,OldName);
	    Error2 ->
		throw(Error2)
	end,
    OldErlSrv = filename:nativename(erlsrv:erlsrv(OldEVsn)),
    CurrentErlSrv = filename:nativename(erlsrv:erlsrv(CurrentEVsn)),
    case heart:set_cmd(CurrentErlSrv ++ " remove " ++ CurrentName ++ 
		       " & " ++ OldErlSrv ++ " start " ++ OldName) of
	ok ->
	    ok;
	Error3 ->
	    throw({error, {'heart:set_cmd() error', Error3}})
    end.

do_reboot_old_release(#state{releases = Releases,
			     rel_dir = RelDir, masters = Masters,
			     static_emulator = Static},
		      Vsn) ->
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, #release{erts_vsn = EVsn, status = old}} ->
	    CurrentRunning = case os:type() of
				 {win32,nt} ->
				     %% Get the current release on NT
				     case lists:keysearch(permanent, 
							  #release.status,
							  Releases) of
					 false ->
					     lists:keysearch(current,
							     #release.status,
							     Releases);
					 {value,CR} ->
					     CR
				     end;
				 _ ->
				     false
			     end,
	    set_permanent_files(RelDir, EVsn, Vsn, Masters, Static),
	    NewReleases = set_status(Vsn, permanent, Releases),
	    write_releases(RelDir, NewReleases, Masters),
	    case os:type() of
		{win32,nt} ->
		    %% Edit up the services and set a reasonable heart 
		    %% command
		    do_back_service(Vsn,CurrentRunning#release.vsn,EVsn,
				   CurrentRunning#release.erts_vsn);
		_ ->
		    ok
	    end,
	    ok;
	{value, #release{status = Status}} ->
	    {error, {bad_status, Status}};
	false ->
	    {error, {no_such_release, Vsn}}
    end.

%%-----------------------------------------------------------------
%% Depending of if the release_handler is running in normal, client or
%% client with static emulator the new system version is made permanent
%% in different ways.
%%-----------------------------------------------------------------
set_permanent_files(RelDir, EVsn, Vsn, false, _) ->
    write_start(filename:join([RelDir, "start_erl.data"]),
		EVsn ++ " " ++ Vsn,
		false);
set_permanent_files(RelDir, EVsn, Vsn, Masters, false) ->
    write_start(filename:join([RelDir, "start_erl.data"]),
		EVsn ++ " " ++ Vsn,
		Masters);
set_permanent_files(RelDir, _EVsn, Vsn, Masters, _Static) ->
    VsnDir = filename:join([RelDir, Vsn]),
    set_static_files(VsnDir, RelDir, Masters).


do_remove_service(Vsn) ->
    %% Very unconditionally remove the service.
    %% Note that the service could already have been removed when
    %% making another release permanent.
    ServiceName = hd(string:lexemes(atom_to_list(node()),"@"))
	++ "_" ++ Vsn,
    case erlsrv:get_service(ServiceName) of
	{error, _Error} ->
	    ok;
	_Data ->
	    {ok,_} = erlsrv:remove_service(ServiceName),
	    ok
    end.

do_remove_release(Root, RelDir, Vsn, Releases) ->
    % Decide which libs should be removed
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, #release{status = permanent}} ->
	    {error, {permanent, Vsn}};
	{value, #release{libs = RemoveLibs, vsn = Vsn, erts_vsn = EVsn}} ->
	    case os:type() of
		{win32, nt} ->
		    do_remove_service(Vsn);
		_ ->
		    ok
	    end,

	    NewReleases = lists:keydelete(Vsn, #release.vsn, Releases),
	    RemoveThese =
		lists:foldl(fun(#release{libs = Libs}, Remove) ->
				    diff_dir(Remove, Libs)
			    end, RemoveLibs, NewReleases),
	    lists:foreach(fun({_Lib, _LVsn, LDir}) ->
				  remove_file(LDir)
			  end, RemoveThese),
	    remove_file(filename:join([RelDir, Vsn])),
	    case lists:keysearch(EVsn, #release.erts_vsn, NewReleases) of
		{value, _} -> ok;
		false -> % Remove erts library, no more references to it
		    remove_file(filename:join(Root, "erts-" ++ EVsn))
	    end,
	    write_releases(RelDir, NewReleases, false),
	    {ok, NewReleases};
	false ->
	    {error, {no_such_release, Vsn}}
    end.

do_set_unpacked(Root, RelDir, RelFile, LibDirs, Releases, Masters) ->
    Release = check_rel(Root, RelFile, LibDirs, Masters),
    #release{vsn = Vsn} = Release,
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, _} -> throw({error, {existing_release, Vsn}});
	false -> ok
    end,
    NewReleases = [Release#release{status = unpacked} | Releases],
    VsnDir = filename:join([RelDir, Vsn]),
    make_dir(VsnDir, Masters),
    write_releases(RelDir, NewReleases, Masters),
    {ok, NewReleases, Vsn}.

do_set_removed(RelDir, Vsn, Releases, Masters) ->
    case lists:keysearch(Vsn, #release.vsn, Releases) of
	{value, #release{status = permanent}} ->
	    {error, {permanent, Vsn}};
	{value, _} ->
	    NewReleases = lists:keydelete(Vsn, #release.vsn, Releases),
	    write_releases(RelDir, NewReleases, Masters),
	    {ok, NewReleases};
	false ->
	    {error, {no_such_release, Vsn}}
    end.


%%-----------------------------------------------------------------
%% A relup file consists of:
%%   {Vsn, [{FromVsn, Descr, RhScript}], [{ToVsn, Descr, RhScript}]}.
%% It describes how to get to this release from previous releases,
%% and how to get from this release to previous releases.
%% We can get from a FromVsn that's a substring of CurrentVsn (e.g.
%% 1.1 is a substring of 1.1.1, but not 1.2), but when we get to
%% ToVsn, we must have an exact match.
%%
%% We do not put any semantics into the version strings, i.e. we
%% don't know if going from Vsn1 to Vsn2 represents a upgrade or
%% a downgrade.  For both upgrades and downgrades, the relup file
%% is located in the directory of the latest version.  Since we
%% do not which version is latest, we first suppose that ToVsn > 
%% CurrentVsn, i.e. we perform an upgrade.  If we don't find the
%% corresponding relup instructions, we check if it's possible to
%% downgrade from CurrentVsn to ToVsn.
%%-----------------------------------------------------------------
get_rh_script(#release{vsn = ?tmp_vsn(CurrentVsn)},
	      #release{vsn = ToVsn},
	      RelDir,
	      Masters) ->
    {ok,{Vsn,Descr,[restart_new_emulator|Script]}} =
	do_get_rh_script(CurrentVsn,ToVsn,RelDir,Masters),
    {ok,{Vsn,Descr,Script}};
get_rh_script(#release{vsn = CurrentVsn},
	      #release{vsn = ToVsn},
	      RelDir,
	      Masters) ->
    do_get_rh_script(CurrentVsn,ToVsn,RelDir,Masters).

do_get_rh_script(CurrentVsn, ToVsn, RelDir, Masters) ->
    Relup = filename:join([RelDir, ToVsn, "relup"]),
    case try_upgrade(ToVsn, CurrentVsn, Relup, Masters) of
	{ok, RhScript} ->
	    {ok, RhScript};
	_ ->
	    Relup2 = filename:join([RelDir, CurrentVsn,"relup"]),
	    case try_downgrade(ToVsn, CurrentVsn, Relup2, Masters) of
		{ok, RhScript} ->
		    {ok, RhScript};
		_ ->
		    throw({error, {no_matching_relup, ToVsn, CurrentVsn}})
	    end
    end.

try_upgrade(ToVsn, CurrentVsn, Relup, Masters) ->
    case consult(Relup, Masters) of
	{ok, [{ToVsn, ListOfRhScripts, _}]} ->
	    case lists:keysearch(CurrentVsn, 1, ListOfRhScripts) of
		{value, RhScript} -> 
		    {ok, RhScript};
		_ -> 
		    error
	    end;
	{ok, _} ->
	    throw({error, {bad_relup_file, Relup}});
	{error, Reason} when is_tuple(Reason) ->
	    throw({error, {bad_relup_file, Relup}});
	{error, enoent} ->
	    error;
	{error, FileError} -> % FileError is posix atom | no_master
	    throw({error, {FileError, Relup}})
    end.

try_downgrade(ToVsn, CurrentVsn, Relup, Masters) ->
    case consult(Relup, Masters) of
	{ok, [{CurrentVsn, _, ListOfRhScripts}]} ->
	    case lists:keysearch(ToVsn, 1, ListOfRhScripts) of
		{value, RhScript} ->
		    {ok, RhScript};
		_ ->
		    error
	    end;
	{ok, _} ->
	    throw({error, {bad_relup_file, Relup}});
	{error, Reason} when is_tuple(Reason) ->
	    throw({error, {bad_relup_file, Relup}});
	{error, FileError} -> % FileError is posix atom | no_master
	    throw({error, {FileError, Relup}})
    end.


%% Status = current | tmp_current | permanent
set_status(Vsn, Status, Releases) ->
    lists:zf(fun(Release) when Release#release.vsn == Vsn,
		               Release#release.status == permanent ->
		     %% If a permanent rel is installed, it keeps its
		     %% permanent status (not changed to current).
		     %% The current becomes old though.
		     true;
		(Release) when Release#release.vsn == Vsn ->	
		     {true, Release#release{status = Status}};	
		(Release) when Release#release.status == Status ->
		     {true, Release#release{status = old}};
		(_) ->
		     true
	     end, Releases).

get_latest_release(Releases) ->
    case lists:keysearch(current, #release.status, Releases) of
	{value, Release} ->
	    Release;
	false ->
	    {value, Release} = 
		lists:keysearch(permanent, #release.status, Releases),
	    Release
    end.

%% Returns: [{Lib, Vsn, Dir}] to be removed
diff_dir([H | T], L) ->
    case memlib(H, L) of
	true -> diff_dir(T, L);
	false -> [H | diff_dir(T, L)]
    end;
diff_dir([], _) -> [].

memlib({Lib, Vsn, _Dir}, [{Lib, Vsn, _Dir2} | _T]) -> true;
memlib(Lib, [_H | T]) -> memlib(Lib, T);
memlib(_Lib, []) -> false.
			 
%% recursively remove file or directory
remove_file(File) ->
    case file:read_link_info(File) of
	{ok, Info} when Info#file_info.type==directory ->
	    case file:list_dir(File) of
		{ok, Files} ->
		    lists:foreach(fun(File2) ->
					 remove_file(filename:join(File,File2))
				  end, Files),
		    case file:del_dir(File) of
			ok -> ok;
			{error, Reason} -> throw({error, Reason})
		    end;
		{error, Reason} ->
		    throw({error, Reason})
	    end;
	{ok, _Info} ->
	    case file:delete(File) of
		ok -> ok;
		{error, Reason} -> throw({error, Reason})
	    end;
	{error, _Reason} ->
	    throw({error, {no_such_file, File}})

    end.

do_write_file(File, Str) ->
    do_write_file(File, Str, []).
do_write_file(File, Str, FileOpts) ->
    case file:open(File, [write | FileOpts]) of
	{ok, Fd} ->
	    io:put_chars(Fd, Str),
	    ok = file:close(Fd);
	{error, Reason} ->
	    {error, {Reason, File}}
    end.

%%-----------------------------------------------------------------
%% Change current applications (specifically, update their version,
%% description and env.)
%%-----------------------------------------------------------------
change_appl_data(RelDir, #release{vsn = Vsn}, Masters) ->
    Dir = filename:join([RelDir, Vsn]),
    BootFile = filename:join(Dir, "start.boot"),
    case read_file(BootFile, Masters) of
	{ok, Bin} ->
	    Config = case consult(filename:join(Dir, "sys.config"), Masters) of
			 {ok, [Conf]} -> Conf;
			 _ -> []
		     end,
	    Appls = get_appls(binary_to_term(Bin)),
	    case application_controller:change_application_data(Appls,Config) of
		ok -> Appls;
		{error, Reason} -> exit({change_appl_data, Reason})
	    end;
	{error, _Reason} ->
	    throw({error, {no_such_file, BootFile}})
    end.

%%-----------------------------------------------------------------
%% This function is dependent on the application functions and
%% the start script syntax.
%%-----------------------------------------------------------------
get_appls({script, _, Script}) -> get_appls(Script, []).

%% kernel is taken care of separately
get_appls([{kernelProcess, application_controller, 
	    {application_controller, start, [App]}} |T], Res) ->
    get_appls(T, [App | Res]);
%% other applications but kernel
get_appls([{apply, {application, load, [App]}} |T], Res) ->
    get_appls(T, [App | Res]);
get_appls([_ | T], Res) ->
    get_appls(T, Res);
get_appls([], Res) ->
    Res.


mon_nodes(true) ->
    ok = net_kernel:monitor_nodes(true);
mon_nodes(false) ->
    ok = net_kernel:monitor_nodes(false),
    flush().

flush() ->
    receive
	{nodedown, _} -> flush();
	{nodeup, _} -> flush()
    after
	0 -> ok
    end.

prepare_restart_nt(#release{erts_vsn = EVsn, vsn = Vsn},
		   #release{erts_vsn = PermEVsn, vsn = PermVsn},
		   DataFileName) ->
    CurrentServiceName = hd(string:lexemes(atom_to_list(node()),"@"))
	++ "_" ++ PermVsn,
    FutureServiceName = hd(string:lexemes(atom_to_list(node()),"@"))
	++ "_" ++ Vsn,
    CurrentService = case erlsrv:get_service(PermEVsn,CurrentServiceName) of
			 {error, _} = Error1 ->
			     throw(Error1);
			 CS ->
			     CS
		     end,
    FutureService =  erlsrv:new_service(FutureServiceName,
					CurrentService,
					filename:nativename(DataFileName),
					%% This is rather icky... On a
					%% non permanent service, the 
					%% ERLSRV_SERVICE_NAME is 
					%% actually that of an old service,
					%% to make heart commands work...
					CurrentServiceName),
    
    case erlsrv:store_service(EVsn, FutureService) of
	{error, _} = Error2 ->
	    throw(Error2);
	_X ->
	    {ok,_} = erlsrv:disable_service(EVsn, FutureServiceName),
	    ErlSrv = filename:nativename(erlsrv:erlsrv(EVsn)),
	    StartDisabled = ErlSrv ++ " start_disabled " ++ FutureServiceName,
	    case heart:set_cmd(StartDisabled) of
		ok ->
		    ok;
		Error3 ->
		    throw({error, {'heart:set_cmd() error', Error3}})
	    end
    end.
    
%%-----------------------------------------------------------------
%% Set things up for restarting the new emulator.  The actual
%% restart is performed by calling init:reboot() higher up.
%%-----------------------------------------------------------------
prepare_restart_new_emulator(StartPrg, RootDir, RelDir,
			     Vsn, Release, Releases, Masters) ->
    {value, PRelease} = lists:keysearch(permanent, #release.status,Releases),
    NReleases1 = set_status(Vsn, current, Releases),
    NReleases2 = set_status(Vsn,tmp_current,NReleases1),
    write_releases(RelDir, NReleases2, Masters),
    prepare_restart_new_emulator(StartPrg, RootDir, RelDir,
				 Release, PRelease, Masters).

prepare_restart_new_emulator(StartPrg, RootDir, RelDir,
			     Release, PRelease, Masters) ->
    #release{erts_vsn = EVsn, vsn = Vsn} = Release,
    Data = EVsn ++ " " ++ Vsn,
    DataFile = write_new_start_erl(Data, RelDir, Masters),
    %% Tell heart to use DataFile instead of start_erl.data
    case os:type() of
	{win32,nt} ->
	    write_ini_file(RootDir,EVsn,Masters),
	    prepare_restart_nt(Release,PRelease,DataFile); 
	{unix,_} ->
	    StartP = check_start_prg(StartPrg, Masters),
	    case heart:set_cmd(StartP ++ " " ++ DataFile) of
		ok ->
		    ok;
		Error ->
		    throw({error, {'heart:set_cmd() error', Error}})
	    end
    end.

check_start_prg({do_check, StartPrg}, Masters) ->
    check_file(StartPrg, regular, Masters),
    StartPrg;
check_start_prg({_, StartPrg}, _) ->
    StartPrg.

write_new_start_erl(Data, RelDir, Masters) ->
    DataFile = filename:join([RelDir, "new_start_erl.data"]),
    write_file(DataFile, Data, Masters),
    DataFile.

%%-----------------------------------------------------------------
%% When a new emulator shall be restarted, the current release
%% is written with status tmp_current.  When the new emulator
%% is started, this function is called.  The tmp_current release
%% gets status unpacked on disk, and current in memory.  If a reboot
%% is made (due to a crash), the release is just unpacked.  If a crash
%% occurs before a call to transform_release is made, the old emulator
%% is started, and transform_release is called for it.  The tmp_current
%% release is changed to unpacked.
%% If the release is made permanent, this is written to disk.
%%-----------------------------------------------------------------
transform_release(ReleaseDir, Releases, Masters) ->
    case init:script_id() of
	{Name, ?tmp_vsn(_)=TmpVsn} ->
	    %% This is was a reboot due to a new emulator version. The
	    %% current release is a temporary internal release, which
	    %% must be removed. It is the "real new release" that is
	    %% set to unpacked on disk and current in memory.
	    DReleases = lists:keydelete(TmpVsn,#release.vsn,Releases),
	    write_releases(ReleaseDir, DReleases, Masters),
	    set_current({Name,TmpVsn},Releases);
	ScriptId ->
	    F = fun(Release) when Release#release.status == tmp_current ->
			Release#release{status = unpacked};
		   (Release) -> Release
		end,
	    case lists:map(F, Releases) of
		Releases ->
		    Releases;
		DReleases ->
		    write_releases(ReleaseDir, DReleases, Masters),
		    set_current(ScriptId, Releases)
	    end
    end.

set_current(ScriptId, Releases) ->
    F1 = fun(Release) when Release#release.status == tmp_current ->
		 case ScriptId of
		     {_Name,Vsn} when Release#release.vsn == Vsn ->
			 Release#release{status = current};
		     _ ->
			 Release#release{status = unpacked}
		 end;
	    (Release) -> Release
	 end,
    lists:map(F1, Releases).

%%-----------------------------------------------------------------
%% Functions handling files, RELEASES, start_erl.data etc.
%% This functions consider if the release_handler is a client and
%% in that case performs the operations at all master nodes or at
%% none (in case of failure).
%%-----------------------------------------------------------------

check_opt_file(FileName, Type, Masters) ->
    case catch check_file(FileName, Type, Masters) of
	ok ->
	    true;
	_Error ->
	    io:format("Warning: ~tp missing (optional)~n", [FileName]),
	    false
    end.

check_file(FileName, Type, false) ->
    do_check_file(FileName, Type);
check_file(FileName, Type, Masters) ->
    check_file_masters(FileName, Type, Masters).

%% Check that file exists at all masters.
check_file_masters(FileName, Type, [Master|Masters]) ->
    do_check_file(Master, FileName, Type),
    check_file_masters(FileName, Type, Masters);
check_file_masters(_FileName, _Type, []) ->
    ok.

%% Type == regular | directory
do_check_file(FileName, Type) ->
    case file:read_file_info(FileName) of
	{ok, Info} when Info#file_info.type==Type -> ok;
	{error, _Reason} -> throw({error, {no_such_file, FileName}})
    end.

do_check_file(Master, FileName, Type) ->
    case rpc:call(Master, file, read_file_info, [FileName]) of
	{ok, Info} when Info#file_info.type==Type -> ok;
	_ -> throw({error, {no_such_file, {Master, FileName}}})
    end.

%%-----------------------------------------------------------------
%% If Rel doesn't exists in tar it could have been created
%% by the user in another way, i.e. ignore this here.
%%-----------------------------------------------------------------
extract_rel_file(Rel, Tar, Root) ->
    _ = erl_tar:extract(Tar, [{files, [Rel]}, {cwd, Root}, compressed]).

extract_tar(Root, Tar) ->
    case erl_tar:extract(Tar, [keep_old_files, {cwd, Root}, compressed]) of
	ok ->
	    ok;
	{error, {Name, Reason}} ->		% New erl_tar (R3A).
	    throw({error, {cannot_extract_file, Name, Reason}})
    end.

write_releases(Dir, Releases, Masters) ->
    %% We must never write 'current' to disk, since this will confuse
    %% us after a node restart - since we would then have a permanent
    %% release running, but state set to current for a non-running
    %% release.
    NewReleases = lists:zf(fun(Release) when Release#release.status == current ->
				   {true, Release#release{status = unpacked}};
			      (_) ->
				   true
			   end, Releases),
    write_releases_1(Dir, NewReleases, Masters).


write_releases_1(Dir, NewReleases, false) ->
    case do_write_release(Dir, "RELEASES", NewReleases) of
	ok    -> ok;
	Error -> throw(Error)
    end;
write_releases_1(Dir, NewReleases, Masters) ->
    all_masters(Masters),
    write_releases_m(Dir, NewReleases, Masters).

do_write_release(Dir, RELEASES, NewReleases) ->
    case file:open(filename:join(Dir, RELEASES), [write,{encoding,utf8}]) of
	{ok, Fd} ->
	    ok = io:format(Fd, "%% ~s~n~tp.~n",
                           [epp:encoding_to_string(utf8),NewReleases]),
	    ok = file:close(Fd);
	{error, Reason} ->
	    {error, Reason}
    end.

%%-----------------------------------------------------------------
%% Write the "RELEASES" file at all master nodes.
%%   1. Save "RELEASES.backup" at all nodes.
%%   2. Save "RELEASES.change" at all nodes.
%%   3. Update the "RELEASES.change" file at all nodes.
%%   4. Move "RELEASES.change" to "RELEASES".
%%   5. Remove "RELEASES.backup" at all nodes.
%%
%% If one of the steps above fails, all steps is recovered from
%% (as long as possible), except for 5 which is allowed to fail.
%%-----------------------------------------------------------------
write_releases_m(Dir, NewReleases, Masters) ->
    RelFile = filename:join(Dir, "RELEASES"),
    Backup = filename:join(Dir, "RELEASES.backup"),
    Change = filename:join(Dir, "RELEASES.change"),
    ensure_RELEASES_exists(Masters, RelFile),
    case at_all_masters(Masters, ?MODULE, do_copy_files,
			[RelFile, [Backup, Change]]) of
	ok ->
	    case at_all_masters(Masters, ?MODULE, do_write_release,
				[Dir, "RELEASES.change", NewReleases]) of
		ok ->
		    case at_all_masters(Masters, file, rename,
					[Change, RelFile]) of
			ok ->
			    remove_files(all, [Backup, Change], Masters),
			    ok;
			{error, {Master, R}} ->
			    takewhile(Master, Masters, file, rename,
				      [Backup, RelFile]),
			    remove_files(all, [Backup, Change], Masters),
			    throw({error, {Master, R, move_releases}})
		    end;
		{error, {Master, R}} ->
		    remove_files(all, [Backup, Change], Masters),
		    throw({error, {Master, R, update_releases}})
	    end;
	{error, {Master, R}} ->
	    remove_files(Master, [Backup, Change], Masters),
	    throw({error, {Master, R, backup_releases}})
    end.

ensure_RELEASES_exists(Masters, RelFile) ->
    case at_all_masters(Masters, ?MODULE, do_ensure_RELEASES, [RelFile]) of
	ok ->
	    ok;
	{error, {Master, R}} ->
	    throw({error, {Master, R, ensure_RELEASES_exists}})
    end.

copy_file(File, Dir, false) ->
    case do_copy_file(File, Dir) of
	ok    -> ok;
	Error -> throw(Error)
    end;
copy_file(File, Dir, Masters) ->
    all_masters(Masters),
    copy_file_m(File, Dir, Masters).

%%-----------------------------------------------------------------
%% copy File to Dir at every master node.
%% If an error occurs at a node, the total copy failed.
%% We do not have to cleanup in case of failure as this
%% copy_file is harmless.
%%-----------------------------------------------------------------
copy_file_m(File, Dir, [Master|Masters]) ->
    case rpc:call(Master, ?MODULE, do_copy_file, [File, Dir]) of
	ok                   -> copy_file_m(File, Dir, Masters);
	{error, {Reason, F}} -> throw({error, {Master, Reason, F}});
	Other                -> throw({error, {Master, Other, File}})
    end;
copy_file_m(_File, _Dir, []) ->
    ok.

do_copy_file(File, Dir) ->
    File2 = filename:join(Dir, filename:basename(File)),
    do_copy_file1(File, File2).

do_copy_file1(File, File2) ->
    case file:read_file(File) of
	{ok, Bin} ->
	    case file:write_file(File2, Bin) of
		ok -> ok;
		{error, Reason} ->
		    {error, {Reason, File2}}
	    end;
	{error, Reason} ->
	    {error, {Reason, File}}
    end.

%%-----------------------------------------------------------------
%% Copy File to a list of files.
%%-----------------------------------------------------------------
do_copy_files(File, [ToFile|ToFiles]) ->
    case do_copy_file1(File, ToFile) of
	ok    -> do_copy_files(File, ToFiles);
	Error -> Error
    end;
do_copy_files(_, []) ->
    ok.

%%-----------------------------------------------------------------
%% Copy each Src file to Dest file in the list of files.
%%-----------------------------------------------------------------
do_copy_files([{Src, Dest}|Files]) ->
    case do_copy_file1(Src, Dest) of
	ok    -> do_copy_files(Files);
	Error -> Error
    end;
do_copy_files([]) ->
    ok.

%%-----------------------------------------------------------------
%% Rename each Src file to Dest file in the list of files.
%%-----------------------------------------------------------------
do_rename_files([{Src, Dest}|Files]) ->
    case file:rename(Src, Dest) of
	ok    -> do_rename_files(Files);
	Error -> Error
    end;
do_rename_files([]) ->
    ok.

%%-----------------------------------------------------------------
%% Remove a list of files. Ignore failure.
%%-----------------------------------------------------------------
do_remove_files([File|Files]) ->
    _ = file:delete(File),
    do_remove_files(Files);
do_remove_files([]) ->
    ok.


%%-----------------------------------------------------------------
%% Ensure that the RELEASES file exists.
%% If not create an empty RELEASES file.
%%-----------------------------------------------------------------
do_ensure_RELEASES(RelFile) ->
    case file:read_file_info(RelFile) of
	{ok, _} -> ok;
	_       -> do_write_file(RelFile, "[]. ") 
    end.

%%-----------------------------------------------------------------
%% Make a directory, ignore failures (captured later).
%%-----------------------------------------------------------------
make_dir(Dir, false) ->
    _ = file:make_dir(Dir),
    ok;
make_dir(Dir, Masters) ->
    lists:foreach(fun(Master) -> rpc:call(Master, file, make_dir, [Dir]) end,
		  Masters).

%%-----------------------------------------------------------------
%% Check that all masters are alive.
%%-----------------------------------------------------------------
all_masters(Masters) ->
    case rpc:multicall(Masters, erlang, info, [version]) of
	{_, []}       -> ok;
	{_, BadNodes} -> throw({error, {bad_masters, BadNodes}})
    end.

%%-----------------------------------------------------------------
%% Evaluate {M,F,A} at all masters.
%% {M,F,A} is supposed to return ok. Otherwise at_all_masters
%% returns {error, {Master, Other}}.
%%-----------------------------------------------------------------
at_all_masters([Master|Masters], M, F, A) ->
    case rpc:call(Master, M, F, A) of
	ok    -> at_all_masters(Masters, M, F, A);
	Error -> {error, {Master, Error}}
    end;
at_all_masters([], _, _, _) ->
    ok.

%%-----------------------------------------------------------------
%% Evaluate {M,F,A} at all masters until Master is found.
%% Ignore {M,F,A} return value.
%%-----------------------------------------------------------------
takewhile(Master, Masters, M, F, A) ->
    _ = lists:takewhile(fun(Ma) when Ma == Master ->
				false;
			   (Ma) ->
				rpc:call(Ma, M, F, A),
				true
			end, Masters),
    ok.

consult(File, false)   -> file:consult(File);
consult(File, Masters) -> consult_master(Masters, File).

%%-----------------------------------------------------------------
%% consult the File at any master node.
%% If the file does not exist at one node it should
%% not exist at any other node either.
%%-----------------------------------------------------------------
consult_master([Master|Ms], File) ->
    case rpc:call(Master, file, consult, [File]) of
	{badrpc, _} -> consult_master(Ms, File);
	Res         -> Res
    end;
consult_master([], _File) ->
    {error, no_master}.

read_file(File, false) ->
    file:read_file(File);
read_file(File, Masters) ->
    read_master(Masters, File).

write_file(File, Data, false) ->
    case file:write_file(File, Data) of
	ok    -> ok;
	Error -> throw(Error)
    end;
write_file(File, Data, Masters) ->
    case at_all_masters(Masters, file, write_file, [File, Data]) of
	ok    -> ok;
	Error -> throw(Error)
    end.

ensure_dir(File, false) ->
    case filelib:ensure_dir(File) of
	ok -> ok;
	Error -> throw(Error)
    end;
ensure_dir(File, Masters) ->
    case at_all_masters(Masters,filelib,ensure_dir,[File]) of
	ok -> ok;
	Error -> throw(Error)
    end.

remove_dir(Dir, false) ->
    remove_file(Dir);
remove_dir(Dir, Masters) ->
    case at_all_masters(Masters,?MODULE,remove_file,[Dir]) of
	ok -> ok;
	Error -> throw(Error)
    end.


%% Ignore status of each delete !
remove_files(Master, Files, Masters) ->
    takewhile(Master, Masters, ?MODULE, do_remove_files, [Files]).

%%-----------------------------------------------------------------
%% read the File at any master node.
%% If the file does not exist at one node it should
%% not exist at any other node either.
%%-----------------------------------------------------------------
read_master([Master|Ms], File) ->
    case rpc:call(Master, file, read_file, [File]) of
	{badrpc, _} -> read_master(Ms, File);
	Res         -> Res
    end;
read_master([], _File) ->
    {error, no_master}.

%%-----------------------------------------------------------------
%% Write start_erl.data.
%%-----------------------------------------------------------------
write_start(File, Data, false) ->
    case do_write_file(File, Data) of
	ok    -> ok;
	Error -> throw(Error)
    end;
write_start(File, Data, Masters) ->
    all_masters(Masters),
    safe_write_file_m(File, Data, Masters).


%%-----------------------------------------------------------------
%% Copy the "start.boot" and "sys.config" from SrcDir to DestDir at all
%% master nodes.
%%   1. Save DestDir/"start.backup" and DestDir/"sys.backup" at all nodes.
%%   2. Copy files at all nodes.
%%   3. Remove backup files at all nodes.
%%
%% If one of the steps above fails, all steps is recovered from
%% (as long as possible), except for 3 which is allowed to fail.
%%-----------------------------------------------------------------
set_static_files(SrcDir, DestDir, Masters) ->
    all_masters(Masters),
    Boot = "start.boot",
    Config = "sys.config",
    SrcBoot = filename:join(SrcDir, Boot),
    DestBoot = filename:join(DestDir, Boot),
    BackupBoot = filename:join(DestDir, "start.backup"),
    SrcConf = filename:join(SrcDir, Config),
    DestConf = filename:join(DestDir, Config),
    BackupConf = filename:join(DestDir, "sys.backup"),

    case at_all_masters(Masters, ?MODULE, do_copy_files,
			[[{DestBoot, BackupBoot},
			  {DestConf, BackupConf}]]) of
	ok ->
	    case at_all_masters(Masters, ?MODULE, do_copy_files,
				[[{SrcBoot, DestBoot},
				  {SrcConf, DestConf}]]) of
		ok ->
		    remove_files(all, [BackupBoot, BackupConf], Masters),
		    ok;
		{error, {Master, R}} ->
		    takewhile(Master, Masters, ?MODULE, do_rename_files,
			      [{BackupBoot, DestBoot},
			       {BackupConf, DestConf}]),
		    remove_files(all, [BackupBoot, BackupConf], Masters),
		    throw({error, {Master, R, copy_start_config}})
	    end;
	{error, {Master, R}} ->
	    remove_files(Master, [BackupBoot, BackupConf], Masters),
	    throw({error, {Master, R, backup_start_config}})
    end.

%%-----------------------------------------------------------------
%% Write erl.ini
%% Writes the erl.ini file used by erl.exe when (re)starting the erlang node.
%% At first installation, this is done by Install.exe, which means that if
%% the format of this file for some reason is changed, then Install.c must
%% also be updated (and probably some other c-files which read erl.ini)
%%-----------------------------------------------------------------
write_ini_file(RootDir,EVsn,Masters) ->
   BinDir = filename:join([RootDir,"erts-"++EVsn,"bin"]),
   Str0 = io_lib:format("[erlang]~n"
                        "Bindir=~ts~n"
                        "Progname=erl~n"
                        "Rootdir=~ts~n",
		        [filename:nativename(BinDir),
		         filename:nativename(RootDir)]),
   Str = re:replace(Str0,"\\\\","\\\\\\\\",[{return,list},global,unicode]),
   IniFile = filename:join(BinDir,"erl.ini"),
   do_write_ini_file(IniFile,Str,Masters).

do_write_ini_file(File,Data,false) ->
    case do_write_file(File, Data, [{encoding,utf8}]) of
	ok    -> ok;
	Error -> throw(Error)
    end;
do_write_ini_file(File,Data,Masters) ->
    all_masters(Masters),
    safe_write_file_m(File, Data, [{encoding,utf8}], Masters).


%%-----------------------------------------------------------------
%% Write the given file at all master nodes.
%%   1. Save <File>.backup at all nodes.
%%   2. Write <File>.change at all nodes.
%%   3. Move <File>.change to <File>
%%   4. Remove <File>.backup at all nodes.
%%
%% If one of the steps above fails, all steps are recovered from
%% (as long as possible), except for 4 which is allowed to fail.
%%-----------------------------------------------------------------
safe_write_file_m(File, Data, Masters) ->
    safe_write_file_m(File, Data, [], Masters).
safe_write_file_m(File, Data, FileOpts, Masters) ->
    Backup = File ++ ".backup",
    Change = File ++ ".change",
    case at_all_masters(Masters, ?MODULE, do_copy_files,
			[File, [Backup]]) of
	ok ->
	    case at_all_masters(Masters, ?MODULE, do_write_file,
				[Change, Data, FileOpts]) of
		ok ->
		    case at_all_masters(Masters, file, rename,
					[Change, File]) of
			ok ->
			    remove_files(all, [Backup, Change], Masters),
			    ok;
			{error, {Master, R}} ->
			    takewhile(Master, Masters, file, rename,
				      [Backup, File]),
			    remove_files(all, [Backup, Change], Masters),
			    throw({error, {Master, R, rename,
					   filename:basename(Change),
					   filename:basename(File)}})
		    end;
		{error, {Master, R}} ->
		    remove_files(all, [Backup, Change], Masters),
		    throw({error, {Master, R, write, filename:basename(Change)}})
	    end;
	{error, {Master, R}} ->
	    remove_files(Master, [Backup], Masters),
	    throw({error, {Master, R, backup,
			   filename:basename(File),
			   filename:basename(Backup)}})
    end.

%%-----------------------------------------------------------------
%% Figure out which applications that have changed version between the
%% two releases. The paths for these applications must always be
%% updated, even if the relup script does not load any modules. See
%% OTP-9402.
%%
%% A different situation is when the same application version is used
%% in old and new release, but the path has changed. This is not
%% handled here - instead it must be explicitely indicated by the
%% 'update_paths' option to release_handler:install_release/2 if the
%% code path shall be updated then.
%% -----------------------------------------------------------------
get_new_libs([{App,Vsn,_LibDir}|CurrentLibs], NewLibs) ->
    case lists:keyfind(App,1,NewLibs) of
	{App,NewVsn,_} = LibInfo when NewVsn =/= Vsn ->
	    [LibInfo | get_new_libs(CurrentLibs,NewLibs)];
	_ ->
	    get_new_libs(CurrentLibs,NewLibs)
    end;
get_new_libs([],_) ->
    [].

%%-----------------------------------------------------------------
%% Return a list of releases witch a specific status
%%-----------------------------------------------------------------
get_releases_with_status([], _, Acc) ->
    Acc;
get_releases_with_status([ {_, _, _, ReleaseStatus } = Head | Tail],
                         Status, Acc) when ReleaseStatus == Status ->
    get_releases_with_status(Tail, Status, [Head | Acc]);
get_releases_with_status([_ | Tail], Status, Acc) ->
    get_releases_with_status(Tail, Status, Acc).
