1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org 6 Copyright (c) 2013-2020, VU University Amsterdam 7 CWI Amsterdam 8 All rights reserved. 9 10 Redistribution and use in source and binary forms, with or without 11 modification, are permitted provided that the following conditions 12 are met: 13 14 1. Redistributions of source code must retain the above copyright 15 notice, this list of conditions and the following disclaimer. 16 17 2. Redistributions in binary form must reproduce the above copyright 18 notice, this list of conditions and the following disclaimer in 19 the documentation and/or other materials provided with the 20 distribution. 21 22 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 23 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 24 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 25 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 26 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 27 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 28 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 29 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 30 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 32 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33 POSSIBILITY OF SUCH DAMAGE. 34*/ 35 36:- module(syslog, 37 [ openlog/3, % +Ident, +Options, +Facility 38 syslog/2, % +Priority, +Message 39 syslog/3, % +Priority, +Format, +Args 40 closelog/0 41 ]). 42:- autoload(library(lists),[member/2]). 43 44/** <module> Unix syslog interface 45 46This library provides an interface to the Unix syslog() facility. The 47interface is an almost direct translation of the POSIX syslog API, with 48two additions: 49 50 - syslog/3 exploits format/3 to format syslog messages 51 - The library integrates into library(debug) using 52 prolog:debug_print_hook/3, where debug _topics_ are mapped to 53 syslog _priorities_ and remaining debug _topics_ are mapped 54 to the syslog _priority_ =debug=. 55 56Note that this interface makes no attempt to abstract over logging 57facilities of operating systems. We expect that such abstractions will 58be implemented at the Prolog level using multiple integrations into 59library(debug). 60 61@see detach_IO/1 to detach normal I/O of the process and remove it 62 from the process group. 63@see fork/1 to create a daemon process. 64@see library(uid) to manage user identifiers (e.g., drop root 65 privileges). 66*/ 67 68:- use_foreign_library(foreign(syslog)). 69 70:- dynamic syslog/1. 71 72%! openlog(+Ident:atom, +Options:list(atom), +Facility:atom) is det. 73% 74% Open system log. This predicate provides a direct interface into 75% the openlog() library call. If the library call is successful, 76% it runs at_halt(closelog) to ensure closing the system log on 77% clean exit. 78% 79% @param Ident prepended to every message, and is typically set 80% to the program name. 81% @param Options is a list of options. Values are corresponding 82% C options, after removing =LOG_= and translation to 83% lower case: =cons=, =ndelay=, =nowait=, =odelay=, 84% =perror=, =pid=. 85% @param Facility is one of =auth=, =authpriv=, =cron=, =daemon=, 86% =ftp=, =kern=, =local0= ... =local7=, =lpr=, =mail=, 87% =news=, =syslog=, =user= or =uucp=. 88 89openlog(Ident, Options, Facility) :- 90 '$openlog'(Ident, Options, Facility), 91 asserta(syslog(Ident)), 92 at_halt(closelog). 93 94%! syslog(+Priority, +Message) is det. 95% 96% Send a message to the system log. Note that syslog/2 implicitly 97% opens a connection to the system log if such a connection has 98% not been opened explicitly using openlog/3. 99% 100% @param Priority is one of =emerg=, =alert=, =crit=, =err=, 101% =warning=, =notice=, =info= or =debug=. 102 103%! syslog(+Priority, +Format, +Args) is det. 104% 105% Send a formatted message to the system log if system logging is 106% opened using openlog/3. This predicate combined format/3 with 107% syslog/2. If there is no open syslog connection, syslog/3 calls 108% print_message/2. 109 110syslog(Priority, Format, Args) :- 111 syslog(_), 112 !, 113 format(string(Msg), Format, Args), 114 syslog(Priority, Msg). 115syslog(Priority, Format, Args) :- 116 syslog_priority(Priority, Kind), 117 print_message(Kind, format(Format, Args)). 118 119%! closelog is det. 120% 121% Close the system log. 122 123closelog :- 124 retractall(syslog(_)), 125 '$closelog'. 126 127 128 /******************************* 129 * DEBUG INTEGRATION * 130 *******************************/ 131 132:- multifile 133 prolog:debug_print_hook/3. 134 135%! prolog:debug_print_hook(+Topic, +Format, +Args) is semidet. 136% 137% Integration of debug/3 with the syslog facility. If syslog is 138% enabled, debug/3 is re-routed to use the syslog facilities. If 139% the _topic_ of the debug message matches one of the sylog 140% _priority_ values (see syslog/2), the message is sent with the 141% corresponding syslog priority. Otherwise it it sent with the 142% =debug= priority. 143 144prologdebug_print_hook(Topic, Format, Args) :- 145 syslog(_), 146 debug_priority(Topic, Priority), 147 syslog(Priority, Format, Args). 148 149debug_priority(Topic, Priority) :- 150 ( syslog_priority(Topic, _Kind) 151 -> Priority = Topic 152 ; Priority = debug 153 ). 154 155syslog_priority(emerg, error). 156syslog_priority(alert, warning). 157syslog_priority(crit, error). 158syslog_priority(err, error). 159syslog_priority(warning, warning). 160syslog_priority(notice, informational). 161syslog_priority(info, informational). 162syslog_priority(debug, debug). 163 164 165 /******************************* 166 * MESSAGE INTEGRATION * 167 *******************************/ 168 169user:message_hook(Term, Kind, _) :- 170 syslog(_), 171 kind_syslog_priority(Kind, Level), 172 message_to_string(Term, Message), 173 atomic_list_concat(Lines, '\n', Message), 174 forall(member(Line, Lines), 175 syslog(Level, Line)), 176 fail. 177 178kind_syslog_priority(error, err). 179kind_syslog_priority(warning, warning). 180kind_syslog_priority(informational, info)