Annotation of loncom/LONCAPA.pm, revision 1.19

1.1       albertel    1: # The LearningOnline Network
                      2: # Base routines
                      3: #
1.19    ! albertel    4: # $Id: LONCAPA.pm,v 1.18 2006/12/06 22:22:36 albertel Exp $
1.1       albertel    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;
1.2       www        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 $loncapa_max_wait_time = 13;
                     40: 
1.14      albertel   41: 
                     42: use vars qw($match_domain   $match_not_domain
                     43: 	    $match_username $match_not_username
1.16      albertel   44: 	    $match_courseid $match_not_courseid
                     45: 	    $match_name
1.14      albertel   46: 	    $match_handle   $match_not_handle);
                     47: 
1.1       albertel   48: require Exporter;
                     49: our @ISA = qw (Exporter);
1.14      albertel   50: our @EXPORT = qw(&add_get_param    &escape            &unescape       
                     51: 		 &tie_domain_hash  &untie_domain_hash &tie_user_hash
                     52: 		 &untie_user_hash  &propath);
                     53: our @EXPORT_OK = qw($match_domain   $match_not_domain
                     54: 		    $match_username $match_not_username
1.16      albertel   55: 		    $match_courseid $match_not_courseid
                     56: 		    $match_name
1.14      albertel   57: 		    $match_handle   $match_not_handle);
                     58: our %EXPORT_TAGS = ( 'match' =>[qw($match_domain   $match_not_domain
                     59: 				   $match_username $match_not_username
1.16      albertel   60: 				   $match_courseid $match_not_courseid
                     61: 				   $match_name
1.14      albertel   62: 				   $match_handle   $match_not_handle)],);
1.2       www        63: my %perlvar;
1.1       albertel   64: 
1.8       foxr       65: 
                     66: 
1.2       www        67: # Inputs are a url, and a hash ref of
1.1       albertel   68: # form name => value pairs
                     69: # takes care of properly adding the form name elements and values to the 
                     70: # the url doing proper escaping of the values and joining with ? or & as 
                     71: # needed
                     72: 
                     73: sub add_get_param {
                     74:     my ($url,$form_data) = @_;
                     75:     my $needs_question_mark = ($url !~ /\?/);
                     76: 
                     77:     while (my ($name,$value) = each(%$form_data)) {
                     78: 	if ($needs_question_mark) {
                     79: 	    $url.='?';
                     80: 	    $needs_question_mark = 0;
                     81: 	} else { 
                     82: 	    $url.='&';
                     83: 	}
                     84: 	$url.=$name.'='.&escape($form_data->{$name});
                     85:     }
                     86:     return $url;
                     87: }
                     88: 
                     89: # -------------------------------------------------------- Escape Special Chars
                     90: 
                     91: sub escape {
                     92:     my $str=shift;
                     93:     $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
                     94:     return $str;
                     95: }
                     96: 
                     97: # ----------------------------------------------------- Un-Escape Special Chars
                     98: 
                     99: sub unescape {
                    100:     my $str=shift;
                    101:     $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
                    102:     return $str;
                    103: }
                    104: 
1.14      albertel  105: $match_domain     = $LONCAPA::domain_re     = qr{[\w\-.]+};
                    106: $match_not_domain = $LONCAPA::not_domain_re = qr{[^\w\-.]+};
                    107: sub clean_domain {
                    108:     my ($domain) = @_;
                    109:     $domain =~ s/$match_not_domain//g;
                    110:     return $domain;
                    111: }
                    112: 
1.17      albertel  113: $match_username     = $LONCAPA::username_re     = qr{[a-zA-Z\_][\w\-.]+};
1.14      albertel  114: $match_not_username = $LONCAPA::not_username_re = qr{[^\w\-.]+};
                    115: sub clean_username {
                    116:     my ($username) = @_;
1.16      albertel  117:     $username =~ s/^\d+//;
1.14      albertel  118:     $username =~ s/$match_not_username//g;
                    119:     return $username;
                    120: }
                    121: 
1.16      albertel  122: 
                    123: $match_courseid     = $LONCAPA::courseid_re     = qr{\d[\w\-.]+};
                    124: $match_not_courseid = $LONCAPA::not_courseid_re = qr{[^\w\-.]+};
                    125: 
1.18      albertel  126: $match_name         = $LONCAPA::name = qr{$match_username|$match_courseid};
1.16      albertel  127: sub clean_name {
                    128:     my ($name) = @_;
                    129:     $name =~ s/$match_not_username//g;
                    130:     return $name;
                    131: }
                    132: 
                    133: sub split_courseid {
                    134:     my ($courseid) = @_;
                    135:     my  ($domain,$coursenum) = 
                    136: 	($courseid=~m{^/($match_domain)/($match_courseid)});
                    137:     return ($domain,$coursenum);
                    138: }
                    139: 
1.14      albertel  140: $match_handle     = $LONCAPA::handle_re     = qr{[\w\-.]+};
                    141: $match_not_handle = $LONCAPA::not_handle_re = qr{[^\w\-.]+};
                    142: sub clean_handle {
                    143:     my ($handle) = @_;
                    144:     $handle =~ s/$match_not_handle//g;
                    145:     return $handle;
                    146: }
                    147: 
1.2       www       148: # -------------------------------------------- Return path to profile directory
                    149: 
                    150: sub propath {
                    151:     my ($udom,$uname)=@_;
1.14      albertel  152:     $udom = &clean_domain($udom);
1.16      albertel  153:     $uname= &clean_name($uname);
1.2       www       154:     my $subdir=$uname.'__';
                    155:     $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
                    156:     my $proname="$perlvar{'lonUsersDir'}/$udom/$subdir/$uname";
                    157:     return $proname;
                    158: } 
                    159: 
                    160: 
                    161: #---------------------------------------------------------------
                    162: #
                    163: # Manipulation of hash based databases (factoring out common code
                    164: # for later use as we refactor.
                    165: #
                    166: #  Ties a domain level resource file to a hash.
                    167: #  If requested a history entry is created in the associated hist file.
                    168: #
                    169: #  Parameters:
                    170: #     domain    - Name of the domain in which the resource file lives.
                    171: #     namespace - Name of the hash within that domain.
                    172: #     how       - How to tie the hash (e.g. GDBM_WRCREAT()).
                    173: #     loghead   - Optional parameter, if present a log entry is created
                    174: #                 in the associated history file and this is the first part
                    175: #                  of that entry.
                    176: #     logtail   - Goes along with loghead,  The actual logentry is of the
                    177: #                 form $loghead:<timestamp>:logtail.
                    178: # Returns:
                    179: #    Reference to a hash bound to the db file or alternatively undef
                    180: #    if the tie failed.
                    181: #
                    182: sub tie_domain_hash {
                    183:     my ($domain,$namespace,$how,$loghead,$logtail) = @_;
                    184:     
                    185:     # Filter out any whitespace in the domain name:
                    186:     
1.14      albertel  187:     $domain = &clean_domain($domain);
1.2       www       188:     
                    189:     # We have enough to go on to tie the hash:
                    190:     
                    191:     my $user_top_dir   = $perlvar{'lonUsersDir'};
                    192:     my $domain_dir     = $user_top_dir."/$domain";
                    193:     my $resource_file  = $domain_dir."/$namespace";
                    194:     return &_locking_hash_tie($resource_file,$namespace,$how,$loghead,$logtail);
                    195: }
                    196: 
                    197: sub untie_domain_hash {
                    198:     return &_locking_hash_untie(@_);
                    199: }
                    200: #
                    201: #   Ties a user's resource file to a hash.  
                    202: #   If necessary, an appropriate history
                    203: #   log file entry is made as well.
                    204: #   This sub factors out common code from the subs that manipulate
                    205: #   the various gdbm files that keep keyword value pairs.
                    206: # Parameters:
                    207: #   domain       - Name of the domain the user is in.
                    208: #   user         - Name of the 'current user'.
                    209: #   namespace    - Namespace representing the file to tie.
                    210: #   how          - What the tie is done to (e.g. GDBM_WRCREAT().
                    211: #   loghead      - Optional first part of log entry if there may be a
                    212: #                  history file.
                    213: #   what         - Optional tail of log entry if there may be a history
                    214: #                  file.
                    215: # Returns:
                    216: #   hash to which the database is tied.  It's up to the caller to untie.
                    217: #   undef if the has could not be tied.
                    218: #
                    219: sub tie_user_hash {
                    220:     my ($domain,$user,$namespace,$how,$loghead,$what) = @_;
                    221: 
1.15      albertel  222:     $namespace=~s{/}{_}g;	# / -> _
                    223:     $namespace     = &clean_username($namespace);
                    224:     my $proname    = &propath($domain, $user);
1.2       www       225:     my $file_prefix="$proname/$namespace";
                    226:     return &_locking_hash_tie($file_prefix,$namespace,$how,$loghead,$what);
                    227: }
                    228: 
                    229: sub untie_user_hash {
                    230:     return &_locking_hash_untie(@_);
                    231: }
                    232: 
1.6       www       233: # routines if you just have a filename
                    234: # return tied hashref or undef
                    235: 
                    236: sub locking_hash_tie {
                    237:     my ($filename,$how)=@_;
                    238:     my ($file_prefix,$namespace)=&db_filename_parts($filename);
1.7       albertel  239:     if ($namespace eq '') { return undef; }
1.6       www       240:     return &_locking_hash_tie($file_prefix,$namespace,$how);
                    241: }
                    242: 
                    243: sub locking_hash_untie {
                    244:     return &_locking_hash_untie(@_);
                    245: }
                    246: 
                    247: sub db_filename_parts {
                    248:     my ($filename)=@_;
                    249:     my ($file_path,$namespace)=($filename=~/^(.*)\/([^\/]+)\.db$/);
1.7       albertel  250:     if ($namespace eq '') { return undef; }
1.6       www       251:     return ($file_path.'/'.$namespace,$namespace);
                    252: }
                    253: 
1.2       www       254: # internal routines that handle the actual tieing and untieing process
                    255: 
                    256: sub _do_hash_tie {
                    257:     my ($file_prefix,$namespace,$how,$loghead,$what) = @_;
                    258:     my %hash;
                    259:     if(tie(%hash, 'GDBM_File', "$file_prefix.db", $how, 0640)) {
                    260: 	# If this is a namespace for which a history is kept,
                    261: 	# make the history log entry:    
                    262: 	if (($namespace !~/^nohist\_/) && (defined($loghead))) {
                    263: 	    my $hfh = IO::File->new(">>$file_prefix.hist"); 
                    264: 	    if($hfh) {
1.5       albertel  265: 		my $now = time();
                    266: 		print $hfh ("$loghead:$now:$what\n");
1.2       www       267: 	    }
                    268: 	    $hfh->close;
                    269: 	}
                    270: 	return \%hash;
                    271:     } else {
                    272: 	return undef;
                    273:     }
                    274: }
                    275: 
                    276: sub _do_hash_untie {
                    277:     my ($hashref) = @_;
                    278:     my $result = untie(%$hashref);
                    279:     return $result;
                    280: }
                    281: 
                    282: {
                    283:     my $sym;
1.10      albertel  284:     my @pushed_syms;
1.11      albertel  285: 
                    286:     sub clean_sym {
                    287: 	undef($sym);
                    288:     }
1.10      albertel  289:     sub push_locking_hash_tie {
                    290: 	if (!defined($sym)) {
                    291: 	    die("Invalid used of push_locking_hash_tie, should only be called after a lock has occurred and before and unlock.");
                    292: 	}
                    293: 	push(@pushed_syms,$sym);
                    294: 	undef($sym);
                    295:     }
                    296: 
                    297:     sub pop_locking_hash_tie {
                    298: 	if (defined($sym)) {
                    299: 	    die("Invalid nested used of pop_locking_hash_tie, should only be called after a unlock has occurred.");
                    300: 	}
                    301: 	$sym = pop(@pushed_syms);
                    302:     }
1.2       www       303: 
                    304:     sub _locking_hash_tie {
                    305: 	my ($file_prefix,$namespace,$how,$loghead,$what) = @_;
1.9       albertel  306: 	if (defined($sym)) {
1.11      albertel  307: 	    die('Nested locking attempted without proper use of push_locking_hash_tie, this is unsupported');
1.9       albertel  308: 	}
                    309: 
1.2       www       310:         my $lock_type=LOCK_SH;
                    311: # Are we reading or writing?
                    312:         if ($how eq &GDBM_READER()) {
                    313: # We are reading
                    314:            if (!open($sym,"$file_prefix.db.lock")) {
                    315: # We don't have a lock file. This could mean
                    316: # - that there is no such db-file
                    317: # - that it does not have a lock file yet
                    318:                if ((! -e "$file_prefix.db") && (! -e "$file_prefix.db.gz")) {
                    319: # No such file. Forget it.                
                    320:                    $! = 2;
1.11      albertel  321: 		   &clean_sym();
1.2       www       322:                    return undef;
                    323:                }
                    324: # Apparently just no lock file yet. Make one
                    325:                open($sym,">>$file_prefix.db.lock");
                    326:            }
                    327: # Do a shared lock
1.9       albertel  328:            if (!&flock_sym(LOCK_SH)) { 
1.11      albertel  329: 	       &clean_sym();
1.9       albertel  330: 	       return undef; 
                    331: 	   } 
1.2       www       332: # If this is compressed, we will actually need an exclusive lock
                    333: 	   if (-e "$file_prefix.db.gz") {
1.9       albertel  334: 	       if (!&flock_sym(LOCK_EX)) {
1.11      albertel  335: 		   &clean_sym();
1.9       albertel  336: 		   return undef;
                    337: 	       }
1.2       www       338: 	   }
                    339:         } elsif ($how eq &GDBM_WRCREAT()) {
                    340: # We are writing
                    341:            open($sym,">>$file_prefix.db.lock");
                    342: # Writing needs exclusive lock
1.9       albertel  343:            if (!&flock_sym(LOCK_EX)) {
1.11      albertel  344: 	       &clean_sym();
1.9       albertel  345: 	       return undef;
                    346: 	   }
1.2       www       347:         } else {
1.5       albertel  348:            die("Unknown method $how for $file_prefix");
1.2       www       349:         }
                    350: # The file is ours!
                    351: # If it is archived, un-archive it now
                    352:        if (-e "$file_prefix.db.gz") {
                    353:            system("gunzip $file_prefix.db.gz");
                    354: 	   if (-e "$file_prefix.hist.gz") {
                    355: 	       system("gunzip $file_prefix.hist.gz");
                    356: 	   }
                    357:        }
                    358: # Change access mode to non-blocking
                    359:        $how=$how|&GDBM_NOLOCK();
                    360: # Go ahead and tie the hash
1.13      albertel  361:       	my $result = 
                    362: 	    &_do_hash_tie($file_prefix,$namespace,$how,$loghead,$what);
                    363: 	if (!$result) {
                    364: 	    &clean_sym();
                    365: 	}
                    366: 	return $result;
1.2       www       367:     }
                    368: 
                    369:     sub flock_sym {
                    370:         my ($lock_type)=@_;
                    371: 	my $failed=0;
                    372: 	eval {
                    373: 	    local $SIG{__DIE__}='DEFAULT';
                    374: 	    local $SIG{ALRM}=sub {
                    375: 		$failed=1;
                    376: 		die("failed lock");
                    377: 	    };
                    378: 	    alarm($loncapa_max_wait_time);
                    379: 	    flock($sym,$lock_type);
                    380: 	    alarm(0);
                    381: 	};
                    382: 	if ($failed) {
                    383: 	    $! = 100; # throwing error # 100
                    384: 	    return undef;
                    385: 	} else {
                    386: 	    return 1;
                    387: 	}
                    388:     }
                    389: 
                    390:     sub _locking_hash_untie {
                    391: 	my ($hashref) = @_;
                    392: 	my $result = untie(%$hashref);
                    393: 	flock($sym,LOCK_UN);
                    394: 	close($sym);
1.11      albertel  395: 	&clean_sym();
1.2       www       396: 	return $result;
                    397:     }
                    398: }
                    399: 
                    400: BEGIN {
1.4       albertel  401:     %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
1.2       www       402: }
                    403: 
1.1       albertel  404: 1;
                    405: 
                    406: __END__
                    407: 
                    408: =pod
                    409: 
                    410: =head1 NAME
                    411: 
                    412: LONCAPA - Basic routines
                    413: 
                    414: =head1 SYNOPSIS
                    415: 
                    416: Generally useful routines
                    417: 
                    418: =head1 EXPORTED SUBROUTINES
                    419: 
                    420: =over 4
                    421: 
                    422: =item *
                    423: 
                    424: escape() : unpack non-word characters into CGI-compatible hex codes
                    425: 
                    426: =item *
                    427: 
                    428: unescape() : pack CGI-compatible hex codes into actual non-word ASCII character
                    429: 
                    430: =item *
                    431: 
                    432: add_get_param() :
                    433:  Inputs:  url (with or without exit GET from parameters), hash ref of
                    434:               form name => value pairs
                    435: 
                    436:  Return: url with properly added the form name elements and values to the 
                    437:          the url doing proper escaping of the values and joining with ? or &
                    438:          as needed
                    439: 
                    440: =back

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