1: # The LearningOnline Network
2: # Base routines
3: #
4: # $Id: LONCAPA.pm,v 1.5 2006/05/30 19:29:48 albertel Exp $
5: #
6: # Copyright Michigan State University Board of Trustees
7: #
8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
9: #
10: # LON-CAPA is free software; you can redistribute it and/or modify
11: # it under the terms of the GNU General Public License as published by
12: # the Free Software Foundation; either version 2 of the License, or
13: # (at your option) any later version.
14: #
15: # LON-CAPA is distributed in the hope that it will be useful,
16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18: # GNU General Public License for more details.
19: #
20: # You should have received a copy of the GNU General Public License
21: # along with LON-CAPA; if not, write to the Free Software
22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23: #
24: # /home/httpd/html/adm/gpl.txt
25: #
26: # http://www.lon-capa.org/
27: #
28: ###
29:
30: package LONCAPA;
31:
32: use strict;
33: use lib '/home/httpd/lib/perl/';
34: use LONCAPA::Configuration;
35: use Fcntl qw(:flock);
36: use GDBM_File;
37: use POSIX;
38:
39: my $loncapa_max_wait_time = 13;
40:
41: require Exporter;
42: our @ISA = qw (Exporter);
43: our @EXPORT = qw(&add_get_param &escape &unescape &tie_domain_hash &untie_domain_hash &tie_user_hash &untie_user_hash &propath);
44: my %perlvar;
45:
46: # Inputs are a url, and a hash ref of
47: # form name => value pairs
48: # takes care of properly adding the form name elements and values to the
49: # the url doing proper escaping of the values and joining with ? or & as
50: # needed
51:
52: sub add_get_param {
53: my ($url,$form_data) = @_;
54: my $needs_question_mark = ($url !~ /\?/);
55:
56: while (my ($name,$value) = each(%$form_data)) {
57: if ($needs_question_mark) {
58: $url.='?';
59: $needs_question_mark = 0;
60: } else {
61: $url.='&';
62: }
63: $url.=$name.'='.&escape($form_data->{$name});
64: }
65: return $url;
66: }
67:
68: # -------------------------------------------------------- Escape Special Chars
69:
70: sub escape {
71: my $str=shift;
72: $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
73: return $str;
74: }
75:
76: # ----------------------------------------------------- Un-Escape Special Chars
77:
78: sub unescape {
79: my $str=shift;
80: $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
81: return $str;
82: }
83:
84: # -------------------------------------------- Return path to profile directory
85:
86: sub propath {
87: my ($udom,$uname)=@_;
88: $udom=~s/\W//g;
89: $uname=~s/\W//g;
90: my $subdir=$uname.'__';
91: $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
92: my $proname="$perlvar{'lonUsersDir'}/$udom/$subdir/$uname";
93: return $proname;
94: }
95:
96:
97: #---------------------------------------------------------------
98: #
99: # Manipulation of hash based databases (factoring out common code
100: # for later use as we refactor.
101: #
102: # Ties a domain level resource file to a hash.
103: # If requested a history entry is created in the associated hist file.
104: #
105: # Parameters:
106: # domain - Name of the domain in which the resource file lives.
107: # namespace - Name of the hash within that domain.
108: # how - How to tie the hash (e.g. GDBM_WRCREAT()).
109: # loghead - Optional parameter, if present a log entry is created
110: # in the associated history file and this is the first part
111: # of that entry.
112: # logtail - Goes along with loghead, The actual logentry is of the
113: # form $loghead:<timestamp>:logtail.
114: # Returns:
115: # Reference to a hash bound to the db file or alternatively undef
116: # if the tie failed.
117: #
118: sub tie_domain_hash {
119: my ($domain,$namespace,$how,$loghead,$logtail) = @_;
120:
121: # Filter out any whitespace in the domain name:
122:
123: $domain =~ s/\W//g;
124:
125: # We have enough to go on to tie the hash:
126:
127: my $user_top_dir = $perlvar{'lonUsersDir'};
128: my $domain_dir = $user_top_dir."/$domain";
129: my $resource_file = $domain_dir."/$namespace";
130: return &_locking_hash_tie($resource_file,$namespace,$how,$loghead,$logtail);
131: }
132:
133: sub untie_domain_hash {
134: return &_locking_hash_untie(@_);
135: }
136: #
137: # Ties a user's resource file to a hash.
138: # If necessary, an appropriate history
139: # log file entry is made as well.
140: # This sub factors out common code from the subs that manipulate
141: # the various gdbm files that keep keyword value pairs.
142: # Parameters:
143: # domain - Name of the domain the user is in.
144: # user - Name of the 'current user'.
145: # namespace - Namespace representing the file to tie.
146: # how - What the tie is done to (e.g. GDBM_WRCREAT().
147: # loghead - Optional first part of log entry if there may be a
148: # history file.
149: # what - Optional tail of log entry if there may be a history
150: # file.
151: # Returns:
152: # hash to which the database is tied. It's up to the caller to untie.
153: # undef if the has could not be tied.
154: #
155: sub tie_user_hash {
156: my ($domain,$user,$namespace,$how,$loghead,$what) = @_;
157:
158: $namespace=~s/\//\_/g; # / -> _
159: $namespace=~s/\W//g; # whitespace eliminated.
160: my $proname = &propath($domain, $user);
161:
162: my $file_prefix="$proname/$namespace";
163: return &_locking_hash_tie($file_prefix,$namespace,$how,$loghead,$what);
164: }
165:
166: sub untie_user_hash {
167: return &_locking_hash_untie(@_);
168: }
169:
170: # internal routines that handle the actual tieing and untieing process
171:
172: sub _do_hash_tie {
173: my ($file_prefix,$namespace,$how,$loghead,$what) = @_;
174: my %hash;
175: if(tie(%hash, 'GDBM_File', "$file_prefix.db", $how, 0640)) {
176: # If this is a namespace for which a history is kept,
177: # make the history log entry:
178: if (($namespace !~/^nohist\_/) && (defined($loghead))) {
179: my $hfh = IO::File->new(">>$file_prefix.hist");
180: if($hfh) {
181: my $now = time();
182: print $hfh ("$loghead:$now:$what\n");
183: }
184: $hfh->close;
185: }
186: return \%hash;
187: } else {
188: return undef;
189: }
190: }
191:
192: sub _do_hash_untie {
193: my ($hashref) = @_;
194: my $result = untie(%$hashref);
195: return $result;
196: }
197:
198: {
199: my $sym;
200:
201: sub _locking_hash_tie {
202: my ($file_prefix,$namespace,$how,$loghead,$what) = @_;
203: my $lock_type=LOCK_SH;
204: # Are we reading or writing?
205: if ($how eq &GDBM_READER()) {
206: # We are reading
207: if (!open($sym,"$file_prefix.db.lock")) {
208: # We don't have a lock file. This could mean
209: # - that there is no such db-file
210: # - that it does not have a lock file yet
211: if ((! -e "$file_prefix.db") && (! -e "$file_prefix.db.gz")) {
212: # No such file. Forget it.
213: $! = 2;
214: return undef;
215: }
216: # Apparently just no lock file yet. Make one
217: open($sym,">>$file_prefix.db.lock");
218: }
219: # Do a shared lock
220: if (!&flock_sym(LOCK_SH)) { return undef; }
221: # If this is compressed, we will actually need an exclusive lock
222: if (-e "$file_prefix.db.gz") {
223: if (!&flock_sym(LOCK_EX)) { return undef; }
224: }
225: } elsif ($how eq &GDBM_WRCREAT()) {
226: # We are writing
227: open($sym,">>$file_prefix.db.lock");
228: # Writing needs exclusive lock
229: if (!&flock_sym(LOCK_EX)) { return undef; }
230: } else {
231: die("Unknown method $how for $file_prefix");
232: }
233: # The file is ours!
234: # If it is archived, un-archive it now
235: if (-e "$file_prefix.db.gz") {
236: system("gunzip $file_prefix.db.gz");
237: if (-e "$file_prefix.hist.gz") {
238: system("gunzip $file_prefix.hist.gz");
239: }
240: }
241: # Change access mode to non-blocking
242: $how=$how|&GDBM_NOLOCK();
243: # Go ahead and tie the hash
244: return &_do_hash_tie($file_prefix,$namespace,$how,$loghead,$what);
245: }
246:
247: sub flock_sym {
248: my ($lock_type)=@_;
249: my $failed=0;
250: eval {
251: local $SIG{__DIE__}='DEFAULT';
252: local $SIG{ALRM}=sub {
253: $failed=1;
254: die("failed lock");
255: };
256: alarm($loncapa_max_wait_time);
257: flock($sym,$lock_type);
258: alarm(0);
259: };
260: if ($failed) {
261: $! = 100; # throwing error # 100
262: return undef;
263: } else {
264: return 1;
265: }
266: }
267:
268: sub _locking_hash_untie {
269: my ($hashref) = @_;
270: my $result = untie(%$hashref);
271: flock($sym,LOCK_UN);
272: close($sym);
273: undef($sym);
274: return $result;
275: }
276: }
277:
278: BEGIN {
279: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
280: }
281:
282: 1;
283:
284: __END__
285:
286: =pod
287:
288: =head1 NAME
289:
290: LONCAPA - Basic routines
291:
292: =head1 SYNOPSIS
293:
294: Generally useful routines
295:
296: =head1 EXPORTED SUBROUTINES
297:
298: =over 4
299:
300: =item *
301:
302: escape() : unpack non-word characters into CGI-compatible hex codes
303:
304: =item *
305:
306: unescape() : pack CGI-compatible hex codes into actual non-word ASCII character
307:
308: =item *
309:
310: add_get_param() :
311: Inputs: url (with or without exit GET from parameters), hash ref of
312: form name => value pairs
313:
314: Return: url with properly added the form name elements and values to the
315: the url doing proper escaping of the values and joining with ? or &
316: as needed
317:
318: =back
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