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yap-6.3/packages/clib/filesex.pl
2011-03-10 11:05:53 +00:00

203 lines
6.7 KiB
Prolog

/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@cs.vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 2002-2010, 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 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(files_ex,
[ set_time_file/3, % +File, -OldTimes, +NewTimes
link_file/3, % +OldPath, +NewPath, +Type
relative_file_name/3, % +AbsPath, +RelTo, -RelPath
directory_file_path/3, % +Dir, +File, -Path
copy_file/2, % +From, +To
make_directory_path/1 % +Directory
]).
/** <module> Extended operations on files
This module provides additional operations on files. This covers both
more obscure and possible non-portable low-level operations and
high-level utilities.
*/
:- use_foreign_library(foreign(files), install_files).
%% set_time_file(+File, -OldTimes, +NewTimes) is det.
%
% Query and set POSIX time attributes of a file. Both OldTimes and
% NewTimes are lists of option-terms. Times are represented in
% SWI-Prolog's standard floating point numbers. New times may be
% specified as =now= to indicate the current time. Defined options
% are:
%
% * access(Time)
% Describes the time of last access of the file. This value
% can be read and written.
%
% * modified(Time)
% Describes the time the contents of the file was last
% modified. This value can be read and written.
%
% * changed(Time)
% Describes the time the file-structure itself was changed by
% adding (link()) or removing (unlink()) names.
%
% Below are some example queries. The first retrieves the
% access-time, while the second sets the last-modified time to the
% current time.
%
% ==
% ?- set_time_file(foo, [acess(Access)], []).
% ?- set_time_file(foo, [], [modified(now)]).
% ==
%
% @bug Setting times does not work on Windows.
%% link_file(+OldPath, +NewPath, +Type) is det.
%
% Create a link in the filesystem from NewPath to OldPath. Type
% defines the type of link and is one of =hard= or =symbolic=.
%
% With some limitations, these functions also work on Windows.
% First of all, the unerlying filesystem must support links. This
% requires NTFS. Second, symbolic links are only supported in
% Vista and later.
%
% @error domain_error(link_type, Type) if the requested link-type
% is unknown or not supported on the target OS.
%% relative_file_name(+Path:atom, +RelTo:atom, -RelPath:atom) is det.
%
% True when RelPath is a relative path to AbsPath, relative to
% RelTo. Path and RelTo are first handed to absolute_file_name/2,
% which makes the absolute *and* canonical. Below is an example:
%
% ==
% ?- relative_file_name('/home/janw/nice',
% '/home/janw/deep/dir/file', Path).
% Path = '../../nice'.
% ==
%
% @param All paths must be in canonical POSIX notation, i.e.,
% using / to separate segments in the path. See
% prolog_to_os_filename/2.
% @bug This predicate is defined as a _syntactical_ operation.
relative_file_name(Path, RelTo, RelPath) :-
absolute_file_name(Path, AbsPath),
absolute_file_name(RelTo, AbsRelTo),
atomic_list_concat(PL, /, AbsPath),
atomic_list_concat(RL, /, AbsRelTo),
delete_common_prefix(PL, RL, PL1, PL2),
to_dot_dot(PL2, DotDot, PL1),
atomic_list_concat(DotDot, /, RelPath).
delete_common_prefix([H|T01], [H|T02], T1, T2) :- !,
delete_common_prefix(T01, T02, T1, T2).
delete_common_prefix(T1, T2, T1, T2).
to_dot_dot([], Tail, Tail).
to_dot_dot([_], Tail, Tail) :- !.
to_dot_dot([_|T0], ['..'|T], Tail) :-
to_dot_dot(T0, T, Tail).
%% directory_file_path(+Directory, +File, -Path) is det.
%% directory_file_path(?Directory, ?File, +Path) is det.
%
% True when Path is the full path-name for File in Dir. This is
% comparable to atom_concat(Directory, File, Path), but it ensures
% there is exactly one / between the two parts. Notes:
%
% * In mode (+,+,-), if File is given and absolute, Path
% is unified to File.
% * Mode (-,-,+) uses file_directory_name/2 and file_base_name/2
directory_file_path(Dir, File, Path) :-
nonvar(Dir), nonvar(File), !,
( is_absolute_file_name(File)
-> Path = File
; sub_atom(Dir, _, _, 0, /)
-> atom_concat(Dir, File, Path)
; atomic_list_concat([Dir, /, File], Path)
).
directory_file_path(Dir, File, Path) :-
nonvar(Path), !,
( nonvar(Dir)
-> ( sub_atom(Dir, _, _, 0, /)
-> atom_concat(Dir, File, Path)
; atom_concat(Dir, /, TheDir),
atom_concat(TheDir, File, Path)
)
; nonvar(File)
-> atom_concat(Dir, File, Path)
; file_directory_name(Path, Dir),
file_base_name(Path, File)
).
directory_file_path(_, _, _) :-
throw(error(instantiation_error(_), _)).
%% copy_file(From, To) is det.
%
% Copy a file into a new file or directory. The data is copied as
% binary data.
copy_file(From, To) :-
destination_file(To, From, Dest),
setup_call_cleanup(open(Dest, write, Out, [type(binary)]),
copy_from(From, Out),
close(Out)).
copy_from(File, Stream) :-
setup_call_cleanup(open(File, read, In, [type(binary)]),
copy_stream_data(In, Stream),
close(In)).
destination_file(Dir, File, Dest) :-
exists_directory(Dir), !,
atomic_list_concat([Dir, File], /, Dest).
destination_file(Dest, _, Dest).
%% make_directory_path(+Dir) is det.
%
% Create Dir and all required components (like mkdir -p). Can
% raise various file-specific exceptions.
make_directory_path(Dir) :-
make_directory_path_2(Dir), !.
make_directory_path(Dir) :-
permission_error(create, directory, Dir).
make_directory_path_2(Dir) :-
exists_directory(Dir), !.
make_directory_path_2(Dir) :-
Dir \== (/), !,
file_directory_name(Dir, Parent),
make_directory_path_2(Parent),
make_directory(Dir).