/* $Id$ Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@cs.vu.nl WWW: http://www.swi-prolog.org Copyright (C): 1985-2009, University of 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 Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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(shlib, [ load_foreign_library/1, % :LibFile load_foreign_library/2, % :LibFile, +InstallFunc unload_foreign_library/1, % +LibFile unload_foreign_library/2, % +LibFile, +UninstallFunc current_foreign_library/2, % ?LibFile, ?Public reload_foreign_libraries/0, % Directives use_foreign_library/1, % :LibFile use_foreign_library/2 % :LibFile, +InstallFunc ]). :- use_module(library(lists), [reverse/2]). :- set_prolog_flag(generate_debug_info, false). /** Utility library for loading foreign objects (DLLs, shared objects) This section discusses the functionality of the (autoload) library(shlib), providing an interface to manage shared libraries. We describe the procedure for using a foreign resource (DLL in Windows and shared object in Unix) called =mylib=. First, one must assemble the resource and make it compatible to SWI-Prolog. The details for this vary between platforms. The plld(1) utility can be used to deal with this in a portable manner. The typical commandline is: == plld -o mylib file.{c,o,cc,C} ... == Make sure that one of the files provides a global function =|install_mylib()|= that initialises the module using calls to PL_register_foreign(). Here is a simple example file mylib.c, which creates a Windows MessageBox: == #include #include static foreign_t pl_say_hello(term_t to) { char *a; if ( PL_get_atom_chars(to, &a) ) { MessageBox(NULL, a, "DLL test", MB_OK|MB_TASKMODAL); PL_succeed; } PL_fail; } install_t install_mylib() { PL_register_foreign("say_hello", 1, pl_say_hello, 0); } == Now write a file mylib.pl: == :- module(mylib, [ say_hello/1 ]). :- use_foreign_library(foreign(mylib)). == The file mylib.pl can be loaded as a normal Prolog file and provides the predicate defined in C. */ :- meta_predicate load_foreign_library(:), load_foreign_library(:, +), use_foreign_library(:), use_foreign_library(:, +). :- dynamic loading/1, % Lib error/2, % File, Error foreign_predicate/2, % Lib, Pred current_library/5. % Lib, Entry, Path, Module, Handle :- volatile % Do not store in state loading/1, error/2, foreign_predicate/2, current_library/5. :- ( current_prolog_flag(open_shared_object, true) -> true ; print_message(warning, shlib(not_supported)) % error? ). /******************************* * DISPATCHING * *******************************/ /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Windows: If libpl.dll is compiled for debugging, prefer loading D.dll to allow for debugging. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ find_library(Spec, Lib) :- current_prolog_flag(windows, true), false, current_prolog_flag(kernel_compile_mode, debug), libd_spec(Spec, SpecD), catch(find_library2(SpecD, Lib), _, fail). find_library(Spec, Lib) :- find_library2(Spec, Lib). find_library2(Spec, Lib) :- absolute_file_name(Spec, [ file_type(executable), access(read), file_errors(fail) ], Lib), !. find_library2(Spec, Spec) :- atom(Spec), !. % use machines finding schema find_library2(foreign(Spec), Spec) :- atom(Spec), !. % use machines finding schema find_library2(Spec, _) :- throw(error(existence_error(source_sink, Spec), _)). libd_spec(Name, NameD) :- atomic(Name), file_name_extension(Base, Ext, Name), atom_concat(Base, 'D', BaseD), file_name_extension(BaseD, Ext, NameD). libd_spec(Spec, SpecD) :- compound(Spec), Spec =.. [Alias,Name], libd_spec(Name, NameD), SpecD =.. [Alias,NameD]. libd_spec(Spec, Spec). % delay errors base(Path, Base) :- atomic(Path), !, file_base_name(Path, File), file_name_extension(Base, _Ext, File). base(Path, Base) :- Path =.. [_,Arg], base(Arg, Base). entry(_, Function, Function) :- Function \= default(_), !. entry(Spec, default(FuncBase), Function) :- base(Spec, Base), atomic_list_concat([FuncBase, Base], '_', Function). entry(_, default(Function), Function). /******************************* * (UN)LOADING * *******************************/ %% load_foreign_library(:FileSpec) is det. %% load_foreign_library(:FileSpec, +Entry:atom) is det. % % Load a _|shared object|_ or _DLL_. After loading the Entry % function is called without arguments. The default entry function % is composed from =install_=, followed by the file base-name. % E.g., the load-call below calls the function % =|install_mylib()|=. If the platform prefixes extern functions % with =_=, this prefix is added before calling. % % == % ... % load_foreign_library(foreign(mylib)), % ... % == % % @param FileSpec is a specification for absolute_file_name/3. If searching % the file fails, the plain name is passed to the OS to try the default % method of the OS for locating foreign objects. The default definition % of file_search_path/2 searches /lib/ on Unix and % /bin on Windows. % % @see use_foreign_library/1,2 are intended for use in directives. load_foreign_library(Library) :- load_foreign_library(Library, default(install)). load_foreign_library(Module:LibFile, Entry) :- with_mutex('$foreign', load_foreign_library(LibFile, Module, Entry)). load_foreign_library(LibFile, _Module, _) :- current_library(LibFile, _, _, _, _), !. load_foreign_library(LibFile, Module, DefEntry) :- retractall(error(_, _)), find_library(LibFile, Path), asserta(loading(LibFile)), catch(Module:open_shared_object(Path, Handle), E, true), ( nonvar(E) -> assert(error(Path, E)), fail ; true ), !, ( ( entry(LibFile, DefEntry, Entry), Module:call_shared_object_function(Handle, Entry) -> true ; DefEntry == default(install) ) -> retractall(loading(LibFile)), assert_shlib(LibFile, Entry, Path, Module, Handle) ; retractall(loading(LibFile)), close_shared_object(Handle), print_message(error, shlib(LibFile, call_entry(DefEntry))), fail ). load_foreign_library(LibFile, _, _) :- retractall(loading(LibFile)), ( error(_Path, E) -> retractall(error(_, _)), throw(E) ; throw(error(existence_error(foreign_library, LibFile), _)) ). %% use_foreign_library(+FileSpec) is det. %% use_foreign_library(+FileSpec, +Entry:atom) is det. % % Load and install a foreign library as load_foreign_library/1,2 % and register the installation using initialization/2 with the % option =now=. This is similar to using: % % == % :- initialization(load_foreign_library(foreign(mylib))). % == % % but using the initialization/1 wrapper causes the library to be % loaded _after_ loading of the file in which it appears is % completed, while use_foreign_library/1 loads the library % _immediately_. I.e. the difference is only relevant if the % remainder of the file uses functionality of the C-library. use_foreign_library(FileSpec) :- initialization(load_foreign_library(FileSpec), now). use_foreign_library(FileSpec, Entry) :- initialization(load_foreign_library(FileSpec, Entry), now). %% unload_foreign_library(+FileSpec) is det. %% unload_foreign_library(+FileSpec, +Exit:atom) is det. % % Unload a _|shared object|_ or _DLL_. After calling the Exit % function, the shared object is removed from the process. The % default exit function is composed from =uninstall_=, followed by % the file base-name. unload_foreign_library(LibFile) :- unload_foreign_library(LibFile, default(uninstall)). unload_foreign_library(LibFile, DefUninstall) :- with_mutex('$foreign', do_unload(LibFile, DefUninstall)). do_unload(LibFile, DefUninstall) :- current_library(LibFile, _, _, Module, Handle), retractall(current_library(LibFile, _, _, _, _)), ( entry(LibFile, DefUninstall, Uninstall), Module:call_shared_object_function(Handle, Uninstall) -> true ; true ), abolish_foreign(LibFile), close_shared_object(Handle). abolish_foreign(LibFile) :- ( retract(foreign_predicate(LibFile, Module:Head)), functor(Head, Name, Arity), abolish(Module:Name, Arity), fail ; true ). system:'$foreign_registered'(M, H) :- ( loading(Lib) -> true ; Lib = '' ), assert(foreign_predicate(Lib, M:H)). assert_shlib(File, Entry, Path, Module, Handle) :- retractall(current_library(File, _, _, _, _)), asserta(current_library(File, Entry, Path, Module, Handle)). /******************************* * ADMINISTRATION * *******************************/ %% current_foreign_library(?File, ?Public) % % Query currently loaded shared libraries. current_foreign_library(File, Public) :- current_library(File, _Entry, _Path, _Module, _Handle), findall(Pred, foreign_predicate(File, Pred), Public). /******************************* * RELOAD * *******************************/ %% reload_foreign_libraries % % Reload all foreign libraries loaded (after restore of a state % created using qsave_program/2. reload_foreign_libraries :- findall(lib(File, Entry, Module), ( retract(current_library(File, Entry, _, Module, _)), File \== - ), Libs), reverse(Libs, Reversed), reload_libraries(Reversed). reload_libraries([]). reload_libraries([lib(File, Entry, Module)|T]) :- ( load_foreign_library(File, Module, Entry) -> true ; print_message(error, shlib(File, load_failed)) ), reload_libraries(T). /******************************* * CLEANUP (WINDOWS ...) * *******************************/ /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Called from Halt() in pl-os.c (if it is defined), *after* all at_halt/1 hooks have been executed, and after dieIO(), closing and flushing all files has been called. On Unix, this is not very useful, and can only lead to conflicts. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ unload_all_foreign_libraries :- current_prolog_flag(unix, true), !. unload_all_foreign_libraries :- forall(current_library(File, _, _, _, _), unload_foreign(File)). %% unload_foreign(+File) % % Unload the given foreign file and all `spontaneous' foreign % predicates created afterwards. Handling these spontaneous % predicates is a bit hard, as we do not know who created them and % on which library they depend. unload_foreign(File) :- unload_foreign_library(File), ( clause(foreign_predicate(Lib, M:H), true, Ref), ( Lib == '' -> functor(H, Name, Arity), abolish(M:Name, Arity), erase(Ref), fail ; ! ) -> true ; true ). /******************************* * MESSAGES * *******************************/ :- multifile prolog:message/3. prolog:message(shlib(LibFile, call_entry(DefEntry))) --> [ '~w: Failed to call entry-point ~w'-[LibFile, DefEntry] ]. prolog:message(shlib(LibFile, load_failed)) --> [ '~w: Failed to load file'-[LibFile] ]. prolog:message(shlib(not_supported)) --> [ 'Emulator does not support foreign libraries' ].