86 lines
2.9 KiB
Perl
86 lines
2.9 KiB
Perl
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/* Part of SWI-Prolog
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Author: Jan Wielemaker
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E-mail: J.Wielemaker@uva.nl
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WWW: http://www.swi-prolog.org
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Copyright (C): 2009, University of Amsterdam
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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As a special exception, if you link this library with other files,
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compiled with a Free Software compiler, to produce an executable, this
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library does not by itself cause the resulting executable to be covered
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by the GNU General Public License. This exception does not however
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invalidate any other reasons why the executable file might be covered by
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the GNU General Public License.
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*/
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:- module(stream_info,
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[ stream_info/1 % +Stream
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]).
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:- use_foreign_library(foreign(streaminfo)).
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%% stream_info(+Stream) is det.
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%
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% Print detailed information about a stream or a file-number to
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% the error output. The output of this command is meant for
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% experts and requires knowledge about the implementation of
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% streams. It has been added to diagnose leaking streams in
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% web-servers. For example, on linux systems we can examine
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% process file-descriptors using
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%
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% ==
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% % ls -l /proc/<pid>/fd
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% ==
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%
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% If now (say) descriptor 15 is open where it should not be, we
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% can this command to find the associated Prolog streams and print
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% as mush as possible information about the stream.
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%
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% ==
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% ?- stream_info(15).
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% ==
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%
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% @param Stream A stream-handle, alias name or (integer) system
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% file handle.
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stream_info(Stream) :-
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is_stream(Stream), !,
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forall(stream_property(Stream, P),
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print_property(P)),
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nl,
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catch('$stream_info'(Stream), E, true),
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( nonvar(E)
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-> format('~w:~t~25|~q~n', ['pending exception', E])
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; true
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).
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stream_info(FileNo) :-
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integer(FileNo), !,
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findall(S, stream_property(S, file_no(FileNo)), Streams),
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length(Streams, Len),
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format('File no ~w is connected to ~d streams~n', [FileNo, Len]),
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forall(member(Stream, Streams),
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( format('****************~nStream ~p:~n', [Stream]),
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stream_info(Stream))).
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print_property(P) :-
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P =.. [Name,Value], !,
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format('~w:~t~25|~q~n', [Name, Value]).
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print_property(input) :- !.
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print_property(output) :- !.
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print_property(P) :-
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format('~p~n', [P]).
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