/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (c)  1995-2023, University of Amsterdam
                              VU University Amsterdam
                              CWI, Amsterdam
                              SWI-Prolog Solutions b.v.
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in
       the documentation and/or other materials provided with the
       distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

:- module(shlib,
          [ load_foreign_library/1,     % :LibFile
            load_foreign_library/2,     % :LibFile, +Options
            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, +Options
          ]).
:- if(current_predicate(win_add_dll_directory/2)).
:- export(win_add_dll_directory/1).
:- endif.

:- autoload(library(error),[existence_error/2]).
:- autoload(library(lists),[member/2,reverse/2]).

:- set_prolog_flag(generate_debug_info, false).

/** <module> 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
``swipl-ld(1)`` utility can be used to  deal   with  this  in a portable
manner. The typical commandline is:

```
swipl-ld -shared -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(). Below is a simple example file ``mylib.c``, which
prints a "hello" message. Note that we use SWI-Prolog's Sprintf() rather
than  C  standard  printf()  to  print    the  outout  through  Prolog's
`current_output`  stream,  making  the  example    work  in  a  windowed
environment. The standard C printf() works in a console environment, but
this bypasses Prolog's output redirection.  Also   note  the  use of the
standard C ``bool`` type, which is supported  in 9.2.x and more actively
promoted in the 9.3.x development series.

```
#include <SWI-Prolog.h>
#include <SWI-Stream.h>
#include <stdbool.h>

static foreign_t
pl_say_hello(term_t to)
{ char *s;

  if ( PL_get_chars(to, &s, CVT_ALL|REP_UTF8) )
  { Sprintf("hello %Us", s);

    return true;
  }

  return false;
}

install_t
install_mylib(void)
{ 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. The generated   ``mylib.so`` (or ``.dll``, etc.)
must be placed in a directory searched  for using the Prolog search path
`foreign` (see absolute_file_name/3). To  load   this  from  the current
directory, we can use the ``-p alias=dir`` option:

```
swipl -p foreign=. mylib.pl
?- say_hello(world).
hello world
true.
```
*/

:- meta_predicate
    load_foreign_library(:),
    load_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.

:- '$notransact'((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?
   ).

% The flag `res_keep_foreign` prevents deleting  temporary files created
% to load shared objects when set  to   `true`.  This  may be needed for
% debugging purposes.

:- create_prolog_flag(res_keep_foreign, false,
                      [ keep(true) ]).


%!  use_foreign_library(+FileSpec) is det.
%!  use_foreign_library(+FileSpec, +Options:list) 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.
%
%   As of SWI-Prolog 8.1.22, use_foreign_library/1,2 is in provided as a
%   built-in predicate that, if necessary,   loads  library(shlib). This
%   implies that these directives can be used without explicitly loading
%   library(shlib) or relying on demand loading.


                 /*******************************
                 *           DISPATCHING        *
                 *******************************/

%!  find_library(+LibSpec, -Lib, -Delete) is det.
%
%   Find a foreign library from LibSpec.  If LibSpec is available as
%   a resource, the content of the resource is copied to a temporary
%   file and Delete is unified with =true=.

find_library(Spec, TmpFile, true) :-
    '$rc_handle'(Zipper),
    term_to_atom(Spec, Name),
    setup_call_cleanup(
        zip_lock(Zipper),
        setup_call_cleanup(
            open_foreign_in_resources(Zipper, Name, In),
            setup_call_cleanup(
                tmp_file_stream(binary, TmpFile, Out),
                copy_stream_data(In, Out),
                close(Out)),
            close(In)),
        zip_unlock(Zipper)),
    !.
find_library(Spec, Lib, Copy) :-
    absolute_file_name(Spec, Lib0,
                       [ file_type(executable),
                         access(read),
                         file_errors(fail)
                       ]),
    !,
    lib_to_file(Lib0, Lib, Copy).
find_library(Spec, Spec, false) :-
    atom(Spec),
    !.                  % use machines finding schema
find_library(foreign(Spec), Spec, false) :-
    atom(Spec),
    !.                  % use machines finding schema
find_library(Spec, _, _) :-
    throw(error(existence_error(source_sink, Spec), _)).

%!  lib_to_file(+Lib0, -Lib, -Copy) is det.
%
%   If Lib0 is not a regular file  we   need  to  copy it to a temporary
%   regular file because dlopen()  and   Windows  LoadLibrary() expect a
%   file name. On some systems this can   be  avoided. Roughly using two
%   approaches (after discussion with Peter Ludemann):
%
%     - On FreeBSD there is shm_open() to create an anonymous file in
%       memory and than fdlopen() to link this.
%     - In general, we could redefine the system calls open(), etc. to
%       make dlopen() work on non-files.  This is highly non-portably
%       though.
%     - We can mount the resource zip using e.g., `fuse-zip` on Linux.
%       This however fails if we include the resources as a string in
%       the executable.
%
%   @see https://github.com/fancycode/MemoryModule for Windows

lib_to_file(Res, TmpFile, true) :-
    sub_atom(Res, 0, _, _, 'res://'),
    !,
    setup_call_cleanup(
        open(Res, read, In, [type(binary)]),
        setup_call_cleanup(
            tmp_file_stream(binary, TmpFile, Out),
            copy_stream_data(In, Out),
            close(Out)),
        close(In)).
lib_to_file(Lib, Lib, false).


open_foreign_in_resources(Zipper, ForeignSpecAtom, Stream) :-
    term_to_atom(foreign(Name), ForeignSpecAtom),
    zipper_members_(Zipper, Entries),
    entries_for_name(Entries, Name, Entries1),
    compatible_architecture_lib(Entries1, Name, CompatibleLib),
    zipper_goto(Zipper, file(CompatibleLib)),
    zipper_open_current(Zipper, Stream,
                        [ type(binary),
                          release(true)
                        ]).

%!  zipper_members_(+Zipper, -Members) is det.
%
%   Simplified version of zipper_members/2 from library(zip). We already
%   have a lock  on  the  zipper  and   by  moving  this  here  we avoid
%   dependency on another library.
%
%   @tbd: should we cache this?

zipper_members_(Zipper, Members) :-
    zipper_goto(Zipper, first),
    zip_members__(Zipper, Members).

zip_members__(Zipper, [Name|T]) :-
    zip_file_info_(Zipper, Name, _Attrs),
    (   zipper_goto(Zipper, next)
    ->  zip_members__(Zipper, T)
    ;   T = []
    ).


%!  compatible_architecture_lib(+Entries, +Name, -CompatibleLib) is det.
%
%   Entries is a list of entries  in   the  zip  file, which are already
%   filtered to match the  shared  library   identified  by  `Name`. The
%   filtering is done by entries_for_name/3.
%
%   CompatibleLib is the name of the  entry   in  the  zip file which is
%   compatible with the  current  architecture.   The  compatibility  is
%   determined according to the description in qsave_program/2 using the
%   qsave:compat_arch/2 hook.
%
%   The entries are of the form 'shlib(Arch, Name)'

compatible_architecture_lib([], _, _) :- !, fail.
compatible_architecture_lib(Entries, Name, CompatibleLib) :-
    current_prolog_flag(arch, HostArch),
    (   member(shlib(EntryArch, Name), Entries),
        qsave_compat_arch1(HostArch, EntryArch)
    ->  term_to_atom(shlib(EntryArch, Name), CompatibleLib)
    ;   existence_error(arch_compatible_with(Name), HostArch)
    ).

qsave_compat_arch1(Arch1, Arch2) :-
    qsave:compat_arch(Arch1, Arch2), !.
qsave_compat_arch1(Arch1, Arch2) :-
    qsave:compat_arch(Arch2, Arch1), !.

%!  qsave:compat_arch(Arch1, Arch2) is semidet.
%
%   User definable hook to establish if   Arch1 is compatible with Arch2
%   when running a shared object. It is used in saved states produced by
%   qsave_program/2 to determine which shared object to load at runtime.
%
%   @see `foreign` option in qsave_program/2 for more information.

:- multifile qsave:compat_arch/2.

qsave:compat_arch(A,A).

entries_for_name([], _, []).
entries_for_name([H0|T0], Name, [H|T]) :-
    shlib_atom_to_term(H0, H),
    match_filespec(Name, H),
    !,
    entries_for_name(T0, Name, T).
entries_for_name([_|T0], Name, T) :-
    entries_for_name(T0, Name, T).

shlib_atom_to_term(Atom, shlib(Arch, Name)) :-
    sub_atom(Atom, 0, _, _, 'shlib('),
    !,
    term_to_atom(shlib(Arch,Name), Atom).
shlib_atom_to_term(Atom, Atom).

match_filespec(Name, shlib(_,Name)).

base(Path, Base) :-
    atomic(Path),
    !,
    file_base_name(Path, File),
    file_name_extension(Base, _Ext, File).
base(_/Path, Base) :-
    !,
    base(Path, Base).
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, +Options:list) 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. Options provided are below.  Other   options  are passed to
%   open_shared_object/3.
%
%     - install(+Function)
%       Installation function to use.  Default is default(install),
%       which derives the function from FileSpec.
%
%   ```
%       ...
%       load_foreign_library(foreign(mylib)),
%       ...
%   ```
%
%   @arg  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 <prolog home>/lib/<arch> on Unix and
%         <prolog home>/bin on Windows.
%
%   @see  use_foreign_library/1,2 are intended for use in directives.

load_foreign_library(Library) :-
    load_foreign_library(Library, []).

load_foreign_library(Module:LibFile, InstallOrOptions) :-
    (   is_list(InstallOrOptions)
    ->  Options = InstallOrOptions
    ;   Options = [install(InstallOrOptions)]
    ),
    with_mutex('$foreign',
               load_foreign_library(LibFile, Module, Options)).

load_foreign_library(LibFile, _Module, _) :-
    current_library(LibFile, _, _, _, _),
    !.
load_foreign_library(LibFile, Module, Options) :-
    retractall(error(_, _)),
    find_library(LibFile, Path, Delete),
    asserta(loading(LibFile)),
    retractall(foreign_predicate(LibFile, _)),
    catch(Module:open_shared_object(Path, Handle, Options), E, true),
    (   nonvar(E)
    ->  delete_foreign_lib(Delete, Path),
        assert(error(Path, E)),
        fail
    ;   delete_foreign_lib(Delete, Path)
    ),
    !,
    '$option'(install(DefEntry), Options, default(install)),
    (   entry(LibFile, DefEntry, Entry),
        Module:call_shared_object_function(Handle, Entry)
    ->  retractall(loading(LibFile)),
        assert_shlib(LibFile, Entry, Path, Module, Handle)
    ;   foreign_predicate(LibFile, _)
    ->  retractall(loading(LibFile)),    % C++ object installed predicates
        assert_shlib(LibFile, 'C++', Path, Module, Handle)
    ;   retractall(loading(LibFile)),
        retractall(foreign_predicate(LibFile, _)),
        close_shared_object(Handle),
        findall(Entry, entry(LibFile, DefEntry, Entry), Entries),
        throw(error(existence_error(foreign_install_function,
                                    install(Path, Entries)),
                    _))
    ).
load_foreign_library(LibFile, _, _) :-
    retractall(loading(LibFile)),
    (   error(_Path, E)
    ->  retractall(error(_, _)),
        throw(E)
    ;   throw(error(existence_error(foreign_library, LibFile), _))
    ).

delete_foreign_lib(true, Path) :-
    \+ current_prolog_flag(res_keep_foreign, true),
    !,
    catch(delete_file(Path), _, true).
delete_foreign_lib(_, _).


%!  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 = '<spontaneous>'
    ),
    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(unload_foreign_libraries, true),
    !,
    forall(current_library(File, _, _, _, _),
           unload_foreign(File)).
unload_all_foreign_libraries.

%!  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 == '<spontaneous>'
        ->  functor(H, Name, Arity),
            abolish(M:Name, Arity),
            erase(Ref),
            fail
        ;   !
        )
    ->  true
    ;   true
    ).


:- if(current_predicate(win_add_dll_directory/2)).

%!  win_add_dll_directory(+AbsDir) is det.
%
%   Add AbsDir to the directories where   dependent DLLs are searched on
%   Windows systems. This  call  uses   the  AddDllDirectory()  API when
%   provided. On older Windows systems it extends ``%PATH%``.
%
%   @error existence_error(directory, AbsDir) if the target directory
%   does not exist.
%   @error domain_error(absolute_file_name, AbsDir) if AbsDir is not an
%   absolute file name.

win_add_dll_directory(Dir) :-
    win_add_dll_directory(Dir, _),
    !.
win_add_dll_directory(Dir) :-
    prolog_to_os_filename(Dir, OSDir),
    getenv('PATH', Path0),
    atomic_list_concat([Path0, OSDir], ';', Path),
    setenv('PATH', Path).

% Environments such as MSYS2 and  CONDA   install  DLLs in some separate
% directory. We add these directories to   the  search path for indirect
% dependencies from ours foreign plugins.

add_dll_directories :-
    current_prolog_flag(msys2, true),
    !,
    env_add_dll_dir('MINGW_PREFIX', '/bin').
add_dll_directories :-
    current_prolog_flag(conda, true),
    !,
    env_add_dll_dir('CONDA_PREFIX', '/Library/bin'),
    ignore(env_add_dll_dir('PREFIX', '/Library/bin')).
add_dll_directories.

env_add_dll_dir(Var, Postfix) :-
    getenv(Var, Prefix),
    atom_concat(Prefix, Postfix, Dir),
    win_add_dll_directory(Dir).

:- initialization
    add_dll_directories.

:- endif.

		 /*******************************
		 *          SEARCH PATH		*
		 *******************************/

:- dynamic
    user:file_search_path/2.
:- multifile
    user:file_search_path/2.

user:file_search_path(foreign, swi(ArchLib)) :-
    current_prolog_flag(arch, Arch),
    atom_concat('lib/', Arch, ArchLib).
user:file_search_path(foreign, swi(SoLib)) :-
    (   current_prolog_flag(windows, true)
    ->  SoLib = bin
    ;   SoLib = lib
    ).


                 /*******************************
                 *            MESSAGES          *
                 *******************************/

:- multifile
    prolog:message//1,
    prolog:error_message//1.

prolog:message(shlib(LibFile, load_failed)) -->
    [ '~w: Failed to load file'-[LibFile] ].
prolog:message(shlib(not_supported)) -->
    [ 'Emulator does not support foreign libraries' ].

prolog:error_message(existence_error(foreign_install_function,
                                     install(Lib, List))) -->
    [ 'No install function in ~q'-[Lib], nl,
      '\tTried: ~q'-[List]
    ].
