release_handler.erl

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	    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 = CurrentVsn},
	      #release{vsn = Vsn},
	      RelDir,
	      Masters) ->
    Relup = filename:join([RelDir, Vsn, "relup"]),
    case try_upgrade(Vsn, CurrentVsn, Relup, Masters) of
	{ok, RhScript} ->
	    {ok, RhScript};
	_ ->
	    Relup2 = filename:join([RelDir, CurrentVsn,"relup"]),
	    case try_downgrade(Vsn, CurrentVsn, Relup2, Masters) of
		{ok, RhScript} ->
		    {ok, RhScript};
		_ ->
		    throw({error, {no_matching_relup, Vsn, 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_file_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) ->
    case file:open(File, write) of
	{ok, Fd} ->
	    io:put_chars(Fd, Str),
	    file:close(Fd),
	    ok;
	{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) ->
    net_kernel:monitor_nodes(true);
mon_nodes(false) ->
    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:tokens(atom_to_list(node()),"@")) 
	++ "_" ++ PermVsn,
    FutureServiceName = hd(string:tokens(atom_to_list(node()),"@")) 
	++ "_" ++ Vsn,
    CurrentService = case erlsrv:get_service(PermEVsn,CurrentServiceName) of
			 {error, Reason} ->
			     throw({error, Reason});
			 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, Rison} ->
	    throw({error,Rison});
	_ ->
	    erlsrv:disable_service(EVsn, FutureServiceName),
	    ErlSrv = filename:nativename(erlsrv:erlsrv(EVsn)),
	    case heart:set_cmd(ErlSrv ++ " enable " ++ FutureServiceName ++
			       " & " ++ ErlSrv ++ " start " ++ 
			       FutureServiceName ++
			       " & " ++ ErlSrv ++ " disable " ++ 
			       FutureServiceName) of
		ok ->
		    ok;
		Error ->
		    throw({error, {'heart:set_cmd() error', Error}})
	    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, 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} ->
	    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, false) ->
    DataFile = filename:join([RelDir, "new_start_erl.data"]),
    case do_write_file(DataFile, Data) of
	ok    -> DataFile;
	Error -> throw(Error)
    end;
write_new_start_erl(Data, RelDir, Masters) ->
    DataFile = filename:join([RelDir, "new_start_erl.data"]),
    case at_all_masters(Masters, ?MODULE, do_write_file,
			[DataFile, Data]) of
	ok    -> DataFile;
	Error -> throw(Error)
    end.

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

%%-----------------------------------------------------------------
%% 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: ~p 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).