/* $Id$
Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2011, University of Amsterdam
VU University Amsterdam
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(prolog_hotfix,
[ load_hotfixes/1 % +Directory
]).
:- use_module(library(lists)).
:- use_module(library(option)).
:- use_module(library(readutil)).
:- use_module(library(apply)).
:- use_module(library(prolog_source)).
/** <module> Load hotfixes into executables
This library was developed to deal with hotfixing products that are
distributed as a Prolog saved state. It assumes the vendor is willing to
distribute hotfixes as Prolog source files. These files are placed into
a directory. The predicate load_hotfixes/1 replaces files that are
loaded into the saved state.
Resolution of the file to load is based on the module if the hotfix file
provides a module. If the hotfix file is not a module file and there are
multiple loaded source files with the same name from different
directories, the hotfix directory must create the minimal directory
structure to make the paths unique. If omitted, this library will prompt
the user for the file that must be replaced.
@tbd This could be extended in several ways:
* Load hotfixes from a (encrypted) zip file
* Use digital signatures and load over HTTP
* Replace individual predicates
@author Jan Wielemaker
*/
%% load_hotfixes(+Dir) is det.
%
% Load all hotfixes that have not yet been applied into the
% current state.
load_hotfixes(Dir) :-
absolute_file_name(Dir, DirPath,
[ file_type(directory),
access(read)
]),
phrase(prolog_source_files([DirPath]), Files),
ensure_dirsep(DirPath, Common),
maplist(apply_hotfix(Common), Files).
%% prolog_source_files(+Dirs)// is det.
%
% Find all Prolog source files in the given directory.
prolog_source_files([]) --> !.
prolog_source_files([H|T]) --> !,
prolog_source_files(H),
prolog_source_files(T).
prolog_source_files(F) -->
{ exists_file(F),
file_name_extension(_, Ext, F),
user:prolog_file_type(Ext, prolog)
}, !,
[F].
prolog_source_files(Dir) -->
{ exists_directory(Dir), !,
atom_concat(Dir, '/*', Pattern),
expand_file_name(Pattern, Members)
},
prolog_source_files(Members).
prolog_source_files(_) -->
[].
%% apply_hotfix(+HotfixDir, +File) is det.
%
% Locate the hotfix and load it if it is newer. First step to find
% the file we must replace is using the module name, as these are
% guaranteed to be unique in the Prolog process. If that fails, we
% use the filename, but now we can get multiple files with the
% same name loaded from different directories as candidates.
% Finally, if no file matches, we load the file into the =user=
% module.
apply_hotfix(_HotfixDir, File) :-
file_module(File, Module),
module_property(Module, file(Loaded)),
'$time_source_file'(Loaded, Time, _Type), !,
time_file(File, HotfixTime),
( HotfixTime =\= Time
-> load_hotfix(File, Loaded)
; true
).
apply_hotfix(HotfixDir, File) :-
atom_concat(HotfixDir, Local, File),
atom_concat(/, Local, SlashLocal),
findall(Loaded-Time,
( '$time_source_file'(Loaded, Time, user),
sub_atom(Loaded, _, _, 0, SlashLocal)
),
Pairs),
Pairs \== [], !,
( Pairs = [Loaded-Time]
-> true
; select_file_to_reload(Pairs, Local, Loaded-Time)
),
time_file(File, HotfixTime),
( HotfixTime =\= Time
-> load_hotfix(File, Loaded)
; true
).
apply_hotfix(_HotfixDir, File) :-
user:consult(File).
%% ensure_dirsep(+Dir, -DirSlash) is det.
ensure_dirsep(Dir0, Dir) :-
( sub_atom(Dir0, _, _, 0, /)
-> Dir = Dir0
; atom_concat(Dir0, /, Dir)
).
%% load_hotfix(+HotfixFile, +Loaded) is det.
%
% Reload the HotfixFile, pretending we are reloading Loaded.
%
% @see make:reload_file/1
load_hotfix(File, Loaded) :-
time_file(File, Modified),
setup_call_cleanup(
open(File, read, In),
load_hotfix_from_stream(Loaded, In, Modified),
close(In)).
load_hotfix_from_stream(Loaded, In, Modified) :-
FixOptions = [ stream(In),
modified(Modified),
register(false)
],
set_stream(In, file_name(Loaded)),
findall(M-Opts,
source_file_property(Loaded, load_context(M, _, Opts)),
Modules),
( Modules = [First-OptsFirst|Rest]
-> merge_options(FixOptions, OptsFirst, FirstOptions),
load_stream(First:Loaded, FirstOptions),
forall(member(Context-Opts, Rest),
( merge_options([if(not_loaded)|FirstOptions], Opts, ORest),
load_stream(Context:Loaded, ORest)
))
; load_stream(user:Loaded, FixOptions)
).
load_stream(Source, Options) :-
option(stream(In), Options),
setup_call_cleanup(
stream_property(In, position(Pos)),
load_files(Source, Options),
set_stream_position(In, Pos)).
%% select_file_to_reload(+Pairs, +Local, -Pair) is det.
select_file_to_reload(Pairs, Local, Pair) :-
format(user_error,
'Hotfix ~w matches multiple loaded files.~n~n',
[Local]),
forall(nth1(I, Pairs, File-_),
format(user_error, '~t~d~6| ~w~n', [I, File])),
repeat,
format(user_error, '~nPlease select (\'s\' skips hotfix)? ', []),
read_line_to_codes(user_input, Line),
( Line == end_of_file
-> halt(1)
; atom_codes(s, Line)
-> !, fail
; catch(number_codes(N, Line), _, fail)
),
nth1(N, Pairs, Pair), !.
%% file_module(+File, -Module) is semidet.
%
% True if Module is the module defined in File.
file_module(File, Module) :-
catch(file_module_guarded(File, Module), _, fail).
file_module_guarded(File, Module) :-
setup_call_cleanup(
prolog_open_source(File, In),
prolog_read_source_term(In, _, Expanded, []),
prolog_close_source(In)),
Expanded = (:- module(Module, _)).