/usr/lib/swi-prolog/library/modules.pl is in swi-prolog-nox 7.2.3-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 | /* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@cs.vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 2014, 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(modules,
[ in_temporary_module/3 % ?Module, :Setup, :Goal
]).
/** <module> Module utility predicates
*/
:- meta_predicate
in_temporary_module(?, 0, 0).
%% in_temporary_module(?Module, :Setup, :Goal)
%
% Run Goal on temporary loaded sources and discard the module and
% loaded predicates after completion. This predicate performs the
% following steps:
%
% 1. If Module is unbound, create a unique identifier for it.
% 2. Turn Module into a _temporary_ module using set_module/1.
% Note that this requires the module to be non-existent or
% empty. If Module is specified, it should typically be set
% to a unique value as obtained from e.g. uuid/1.
% 3. Run Setup in the context of Module.
% 4. If setup succeeded possible choice points are discarded
% and Goal is started.
%
% The logical result of this predicate is the same as
% `(Setup@Module -> Goal@Module)`, i.e., both Setup and Goal are
% resolved relative to the current module, but executed in the
% context of Module. If Goal must be called in Module, use
% `call(Goal)`.
%
% The module and all its predicates are destroyed after Goal
% terminates, as defined by setup_call_cleanup/3.
%
% *Discussion* This predicate is intended to load programs in an
% isolated environment and reclaim all resources. This
% unfortunately is incomplete:
%
% - Running the code may leave side effects such as creating
% records, flags, changing Prolog flags, etc. The system
% has no provisions to track this.
% - So called _functors_ (name/arity pairs) are not yet subject
% to garbage collection. Functors are both used to define
% predicates and to create compound terms.
%
% @see library(sandbox) determines whether unknown goals are safe
% to call.
% @see load_files/2 offers the option sandboxed(true) to load code
% from unknown sources safely.
in_temporary_module(Module, Setup, Goal) :-
( var(Module)
-> ( repeat,
I is random(1<<63),
atom_concat('tmp-', I, Module),
set_module(Module:class(temporary))
-> true
)
; set_module(Module:class(temporary))
),
call_cleanup(
( @(Setup, Module)
-> @(Goal, Module)
),
'$destroy_module'(Module)).
|