1: #!/usr/bin/perl
2: #
3: # The LearningOnline Network with CAPA
4: # Connect to MAXIMA CAS
5: #
6: # $Id: lonmaxima,v 1.9 2006/03/04 06:51:02 albertel Exp $
7: #
8: # Copyright Michigan State University Board of Trustees
9: #
10: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
11: #
12: # LON-CAPA is free software; you can redistribute it and/or modify
13: # it under the terms of the GNU General Public License as published by
14: # the Free Software Foundation; either version 2 of the License, or
15: # (at your option) any later version.
16: #
17: # LON-CAPA is distributed in the hope that it will be useful,
18: # but WITHOUT ANY WARRANTY; without even the implied warranty of
19: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20: # GNU General Public License for more details.
21: #
22: # You should have received a copy of the GNU General Public License
23: # along with LON-CAPA; if not, write to the Free Software
24: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25: #
26: # /home/httpd/html/adm/gpl.txt
27: #
28:
29: #
30: # http://www.lon-capa.org/
31: #
32:
33:
34: use IPC::Open3;
35: use IO::Select;
36: use IO::Socket;
37: use IO::File;
38: use Symbol;
39: use POSIX;
40: use lib '/home/httpd/lib/perl/';
41: use LONCAPA::Configuration;
42:
43: use strict;
44:
45: # global variables
46: my $PREFORK = 5; # number of children to maintain
47: my $MAX_CLIENTS_PER_CHILD = 5; # number of clients each child should process
48: my %children = (); # keys are current child process IDs
49: my $children = 0; # current number of children
50: my $status; # string for current status
51: my $pidfile; # file containg parent process pid
52: my $port; # path to UNIX socket file
53: my %perlvar; # configuration file info
54: my $lastlog; # last string that was logged
55: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children $status
56: $pidfile $port %perlvar $lastlog);
57:
58: sub maximareply {
59: my ($cmd) = @_;
60: my $reply='';
61: my $error='';
62: my $exitstatus='';
63:
64: unless ($cmd=~/\;\n$/) { $cmd.=";\n"; }
65:
66: my ($cmd_in, $cmd_out, $cmd_err);
67: my $maximapid = open3($cmd_in, $cmd_out, $cmd_err, 'maxima');
68: $children{$maximapid} = 1;
69:
70: print $cmd_in $cmd;
71: close($cmd_in);
72:
73: &status("Command sent");
74:
75: $SIG{ALRM} = sub { kill 9 => $maximapid; };
76: alarm(5);
77:
78: my $selector = IO::Select->new();
79:
80: $selector->add($cmd_err, $cmd_out);
81:
82: while (my @ready = $selector->can_read()) {
83: foreach my $fh (@ready) {
84: if (ref($fh)
85: && ref($cmd_err)
86: && fileno($fh) == fileno($cmd_err)) {
87: $error.=<$cmd_err>;
88: } else {
89: my $line = scalar(<$cmd_out>);
90: if ($line=~/^(\(\%o|\s)/) {
91: $line=~s/^\(.*\)/ /;
92: $reply.=$line;
93: }
94: }
95: $selector->remove($fh) if eof($fh);
96: }
97: }
98: alarm(0);
99: $SIG{ALRM} = 'DEFAULT';
100: if (ref($cmd_out)) { close($cmd_out); }
101: if (ref($cmd_err)) { close($cmd_err); }
102:
103: &status("Command processed");
104: return ($reply,$error,$exitstatus);
105: }
106:
107: # ------------------------------------------------------------ Service routines
108: sub REAPER { # takes care of dead children
109: # and MAXIMA processes
110: $SIG{CHLD} = \&REAPER;
111: my $pid = wait;
112: $children--;
113: delete($children{$pid});
114: }
115:
116: sub HUNTSMAN { # signal handler for SIGINT
117: local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children
118: kill('INT' => keys(%children));
119: unlink($pidfile);
120: unlink($port);
121: &logthis('---- Shutdown ----');
122: exit; # clean up with dignity
123: }
124:
125:
126:
127: # --------------------------------------------------------------------- Logging
128:
129: sub logthis {
130: my ($message)=@_;
131: my $execdir=$perlvar{'lonDaemons'};
132: my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
133: my $now=time;
134: my $local=localtime($now);
135: $lastlog=$local.': '.$message;
136: print $fh "$local ($$): $message\n";
137: }
138:
139: # -------------------------------------------------------------- Status setting
140:
141: sub status {
142: my ($what)=@_;
143: my $now=time;
144: my $local=localtime($now);
145: $status=$local.': '.$what;
146: $0='lonmaxima: '.$what.' '.$local;
147: }
148:
149: # -------------------------------------------------------- Escape Special Chars
150:
151: sub escape {
152: my ($str)=@_;
153: $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
154: return $str;
155: }
156:
157: # ----------------------------------------------------- Un-Escape Special Chars
158:
159: sub unescape {
160: my ($str)=@_;
161: $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
162: return $str;
163: }
164:
165: # ------------------------ grabs exception and records it to log before exiting
166: sub catchexception {
167: my ($signal)=@_;
168: $SIG{QUIT}='DEFAULT';
169: $SIG{__DIE__}='DEFAULT';
170: chomp($signal);
171: &logthis("<font color=\"red\">CRITICAL: "
172: ."ABNORMAL EXIT. Child $$ died through "
173: ."\"$signal\"</font>");
174: die("Signal abend");
175: }
176:
177:
178:
179: # ---------------------------------------------------------------- Main program
180: # -------------------------------- Set signal handlers to record abnormal exits
181:
182:
183: $SIG{'QUIT'}=\&catchexception;
184: $SIG{__DIE__}=\&catchexception;
185:
186: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
187: &status("Read loncapa.conf and loncapa_apache.conf");
188: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
189:
190: # ----------------------------- Make sure this process is running from user=www
191: my $wwwid=getpwnam('www');
192: if ($wwwid!=$<) {
193: my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
194: my $subj="LON: User ID mismatch";
195: system("echo 'User ID mismatch. lonmaxima must be run as user www.' |\
196: mailto $emailto -s '$subj' > /dev/null");
197: exit 1;
198: }
199:
200: # --------------------------------------------- Check if other instance running
201:
202: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
203:
204: if (-e $pidfile) {
205: my $lfh=IO::File->new("$pidfile");
206: my $pide=<$lfh>;
207: chomp($pide);
208: if (kill(0 => $pide)) { die "already running"; }
209: }
210:
211: # ------------------------------------------------------- Listen to UNIX socket
212: &status("Opening socket");
213:
214: $port = "$perlvar{'lonSockDir'}/maximasock";
215:
216: unlink($port);
217:
218:
219: my $server = IO::Socket::UNIX->new(Local => $port,
220: Type => SOCK_STREAM,
221: Listen => 10 );
222: if (!$server) {
223: my $st=120+int(rand(240));
224:
225: &logthis("<font color=blue>WARNING: ".
226: "Can't make server socket ($st secs): .. exiting</font>");
227:
228: sleep($st);
229: exit;
230: }
231:
232:
233: # ---------------------------------------------------- Fork once and dissociate
234:
235: my $fpid=fork;
236: exit if $fpid;
237: die("Couldn't fork: $!") unless defined($fpid);
238:
239: POSIX::setsid() or die "Can't start new session: $!";
240:
241: # ------------------------------------------------------- Write our PID on disk
242:
243: my $execdir=$perlvar{'lonDaemons'};
244: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
245: print PIDSAVE "$$\n";
246: close(PIDSAVE);
247: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
248: &status('Starting');
249:
250:
251: # Fork off our children.
252: for (1 .. $PREFORK) {
253: &make_new_child($server);
254: }
255:
256: # Install signal handlers.
257: $SIG{CHLD} = \&REAPER;
258: $SIG{INT} = $SIG{TERM} = \&HUNTSMAN;
259:
260: # And maintain the population.
261: while (1) {
262: &status('Parent process, sleeping');
263: sleep; # wait for a signal (i.e., child's death)
264: for (my $i = $children; $i < $PREFORK; $i++) {
265: &status('Parent process, starting child');
266: &make_new_child($server); # top up the child pool
267: }
268: }
269:
270: sub make_new_child {
271: my ($server) = @_;
272:
273: # block signal for fork
274: my $sigset = POSIX::SigSet->new(SIGINT);
275: sigprocmask(SIG_BLOCK, $sigset)
276: or die("Can't block SIGINT for fork: $!\n");
277:
278: die("fork: $!") unless defined(my $pid = fork);
279:
280: if ($pid) {
281: # Parent records the child's birth and returns.
282: sigprocmask(SIG_UNBLOCK, $sigset)
283: or die("Can't unblock SIGINT for fork: $!\n");
284: $children{$pid} = 1;
285: $children++;
286: return;
287: } else {
288: # Child can *not* return from this subroutine.
289: $SIG{INT} = 'DEFAULT'; # make SIGINT kill us as it did before
290:
291: # unblock signals
292: sigprocmask(SIG_UNBLOCK, $sigset)
293: or die("Can't unblock SIGINT for fork: $!\n");
294:
295: &process_requests($server);
296:
297: # tidy up gracefully and finish
298:
299: # this exit is VERY important, otherwise the child will become
300: # a producer of more and more children, forking yourself into
301: # process death.
302: exit;
303: }
304: }
305:
306: sub process_requests {
307: my ($server) = @_;
308: # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
309: for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
310: &status('Accepting connections');
311: my $client = $server->accept() or last;
312: while (my $cmd=<$client>) {
313: &status('Processing command');
314: print $client &escape((&maximareply(&unescape($cmd)))[0])."\n";
315: }
316: }
317: }
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