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Diff for /loncom/LONCAPA.pm between versions 1.1 and 1.36

version 1.1, 2006/05/08 22:05:54 version 1.36, 2019/08/25 02:43:33
Line 27 Line 27
 #  #
 ###  ###
   
   
   
 package LONCAPA;  package LONCAPA;
   
 use strict;  use strict;
   use lib '/home/httpd/lib/perl/';
   use LONCAPA::Configuration;
   use Fcntl qw(:flock);
   use GDBM_File;
   use POSIX;
   #use Apache::lonnet;
   
   my $loncapa_max_wait_time = 13;
   
   
   #--------------------------------------------------------------------------
   #
   #   The  constant definnitions below probably should really be in 
   #   a configuration file somewhere (loncapa.conf?) and loaded so that they can be 
   #   modified without requring source code changes:
   #
   #   COURSE_CACHE_TIME - Number of minutes after which an unaccessed
   #                       course.db or course_param.db file is considered
   #                       to be a stale cache of this info.
   #
   #   LONCAPA_TEMPDIR   - Place loncapa puts temporary files
   #
   
   my  $COURSE_CACHE_TIME =  60; # minutes course cache file is considered valid. 
   my  $LONCAPA_TEMPDIR   =  '/tmp/'; # relative to configuration{'lonTabDir'}.
   
   use vars qw($match_domain   $match_not_domain
       $match_username $match_not_username
       $match_courseid $match_not_courseid
               $match_community
       $match_name
               $match_lonid
       $match_handle   $match_not_handle);
   
 require Exporter;  require Exporter;
 our @ISA = qw (Exporter);  our @ISA = qw (Exporter);
 our @EXPORT = qw(&add_get_param &escape &unescape);  our @EXPORT = qw(&add_get_param    &escape            &unescape       
    &tie_domain_hash  &untie_domain_hash &tie_user_hash
    &untie_user_hash  &propath &tie_course);
   our @EXPORT_OK = qw($match_domain   $match_not_domain
       $match_username $match_not_username
       $match_courseid $match_not_courseid
                       $match_community
       $match_name
       $match_lonid
       $match_handle   $match_not_handle &tie_course);
   our %EXPORT_TAGS = ( 'match' =>[qw($match_domain   $match_not_domain
      $match_username $match_not_username
      $match_courseid $match_not_courseid
                                      $match_community
      $match_name
      $match_lonid
      $match_handle   $match_not_handle)],);
   my %perlvar;
   
   
   #
   # If necessary fetch and tie a user's image of the course hash 
   # to the specified hash
   # Parameters:
   #   domain   - User's domain
   #   user     - Name of user.
   #   course   - Course number.
   #   cdom     - Domain that is home to the course
   #   hash     - reference to the has to tie.
   #
   # Side effects:
   #   a gdbm file and it's associated lock file will be created in the 
   #   tmp directory tree.
   #
   # Returns:
   #   0 - failure.
   #   1 - success.
   #
   #  Note:
   #     It's possible the required user's db file is already present in the tempdir.
   #     in that case a decision must be made about whether or not to just tie to it
   #     or to fetch it again. Remember this sub could be called in the context of a user
   #     other than the one whose data are being fetched.  We don't know if that user already
   #     has a live session on this server.  What we'll do is only re-fetch if the hash atime.
   #     is older than COURSE_CACHE_TIME...that is if it's been accessed relatively recently
   #     where COURSE_CACHE_TIME defines the caching time.
   #
   #     The database files this function creates are of the form:
   #     $user@$domain_$course@$cdom.{db,lock}
   #     This differs from the prior filenames.  Therefore if a module does its own
   #     caching (That's a coding no-no) and does not use this centralized sub,
   #     multiple cache files for the same course/user will be created. 
   #  
   sub tie_course {
       my ($domain, $user, $course, $cdom, $hash) = @_;
   
       #
       #  See if we need to re-fetch the course data
       #
   
       
   }
   
   # Return a string that is the path in which loncapa puts temp files:
   
   sub tempdir {
       my $result =  $perlvar{'lonDaemons'}.$LONCAPA_TEMPDIR; # to allow debugging.
       return $result;
   }
   
   # Return the default engine to use to render content of <m></m> tags unless
   # a domain, course, or user specific value exists. 
   
   sub texengine {
       return 'MathJax';
   }
   
   # Return the Linux distro where this LON-CAPA instance is running
   
   sub distro {
       my $distro;
       if (open(PIPE,"/home/httpd/perl/distprobe |")) {
           $distro = <PIPE>;
           close(PIPE);
       }
       return $distro;
   }
   
   # Return the default password length. Can be overridden in a domain
   # by specifying a larger value (integer) in the domain configuration.
   
 # Inputs are a url, adn a hash ref of  sub passwd_min {
 # form name => value pairs      return 7;
 # takes care of properly adding the form name elements and values to the   }
 # the url doing proper escaping of the values and joining with ? or & as   
 # needed  #----------------------------------------------------------------------
   #
   #  some of these subs need a bit of documentation
   
 sub add_get_param {  sub add_get_param {
     my ($url,$form_data) = @_;      my ($url,$form_data) = @_;
Line 72  sub unescape { Line 199  sub unescape {
     return $str;      return $str;
 }  }
   
   $LONCAPA::assess_re = qr{\.(problem|exam|quiz|assess|survey|form|library|task)$};
   $LONCAPA::assess_page_re = qr{\.(problem|exam|quiz|assess|survey|form|library|task|page)$};
   $LONCAPA::assess_page_seq_re = qr{\.(problem|exam|quiz|assess|survey|form|library|task|sequence|page)$};
   $LONCAPA::parse_re = qr{\.(problem|exam|quiz|assess|survey|form|library|page|xml|html|htm|xhtml|xhtm)$};
   $LONCAPA::parse_page_re = qr{\.(problem|exam|quiz|assess|survey|form|library|page|xml|html|htm|xhtml|xhtm|page)$};
   $LONCAPA::parse_page_sty_re = qr{\.(problem|exam|quiz|assess|survey|form|library|page|xml|html|htm|xhtml|xhtm|page|sty)$};
   
   
   $match_domain     = $LONCAPA::domain_re     = qr{[[:alnum:]\-.]+};
   $match_not_domain = $LONCAPA::not_domain_re = qr{[^[:alnum:]\-.]+};
   sub clean_domain {
       my ($domain) = @_;
       $domain =~ s/$match_not_domain//g;
       return $domain;
   }
   
   $match_username     = $LONCAPA::username_re     = qr{\w[\w\-.@]+};
   $match_not_username = $LONCAPA::not_username_re = qr{[^\w\-.@]+};
   sub clean_username {
       my ($username) = @_;
       $username =~ s/^\W+//;
       $username =~ s/$match_not_username//g;
       return $username;
   }
   
   
   $match_courseid     = $LONCAPA::courseid_re     = qr{\d[\w\-.]+};
   $match_community    =$LONCAPA::community_re     = qr{0[\w\-.]+};
   $match_not_courseid = $LONCAPA::not_courseid_re = qr{[^\w\-.]+};
   sub clean_courseid {
       my ($courseid) = @_;
       $courseid =~ s/^\D+//;
       $courseid =~ s/$match_not_courseid//g;
       return $courseid;
   }
   
   $match_name         = $LONCAPA::name_re = qr{$match_username|$match_courseid};
   sub clean_name {
       my ($name) = @_;
       $name =~ s/$match_not_username//g;
       return $name;
   }
   
   $match_lonid     = $LONCAPA::lonid_re     = qr{[\w\-.]+};
   
   sub split_courseid {
       my ($courseid) = @_;
       my  ($domain,$coursenum) = 
    ($courseid=~m{^/($match_domain)/($match_courseid)});
       return ($domain,$coursenum);
   }
   
   $match_handle     = $LONCAPA::handle_re     = qr{[\w\-.@]+};
   $match_not_handle = $LONCAPA::not_handle_re = qr{[^\w\-.@]+};
   sub clean_handle {
       my ($handle) = @_;
       $handle =~ s/$match_not_handle//g;
       return $handle;
   }
   
   #
   # -- Ensure another process for same filesystem action is not running.
   #    lond uses for: apachereload; loncron uses for: lciptables
   #
   
   sub try_to_lock {
       my ($lockfile)=@_;
       my $currentpid;
       my $lastpid;
       # Do not manipulate lock file as root
       if ($>==0) {
           return 0;
       }
       # Try to generate lock file.
       # Wait 3 seconds.  If same process id is in
       # lock file, then assume lock file is stale, and
       # go ahead.  If process id's fluctuate, try
       # for a maximum of 10 times.
       for (0..10) {
           if (-e $lockfile) { 
               open(LOCK,"<$lockfile");
               $currentpid=<LOCK>;
               close LOCK;
               if ($currentpid==$lastpid) {
                   last;
               }
               sleep 3;
               $lastpid=$currentpid;
           } else {
               last;
           }
           if ($_==10) {
               return 0;
           }
       }
       open(LOCK,">$lockfile");
       print LOCK $$;
       close LOCK;
       return 1;
   }
   
   # -------------------------------------------- Return path to profile directory
   
   sub propath {
       my ($udom,$uname)=@_;
       $udom = &clean_domain($udom);
       $uname= &clean_name($uname);
       my $subdir=$uname.'__';
       $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
       my $proname="$perlvar{'lonUsersDir'}/$udom/$subdir/$uname";
       return $proname;
   }
   
   sub tie_domain_hash {
       my ($domain,$namespace,$how,$loghead,$logtail) = @_;
       
       # Filter out any whitespace in the domain name:
       
       $domain = &clean_domain($domain);
       
       # We have enough to go on to tie the hash:
       
       my $user_top_dir   = $perlvar{'lonUsersDir'};
       my $domain_dir     = $user_top_dir."/$domain";
       my $resource_file  = $domain_dir."/$namespace";
       return &_locking_hash_tie($resource_file,$namespace,$how,$loghead,$logtail);
   }
   
   sub untie_domain_hash {
       return &_locking_hash_untie(@_);
   }
   
   
   sub tie_user_hash {
       my ($domain,$user,$namespace,$how,$loghead,$what) = @_;
   
       $namespace=~s{/}{_}g; # / -> _
       $namespace     = &clean_username($namespace);
       my $proname    = &propath($domain, $user);
       my $file_prefix="$proname/$namespace";
       return &_locking_hash_tie($file_prefix,$namespace,$how,$loghead,$what);
   }
   
   sub untie_user_hash {
       return &_locking_hash_untie(@_);
   }
   
   
   sub locking_hash_tie {
       my ($filename,$how)=@_;
       my ($file_prefix,$namespace)=&db_filename_parts($filename);
       if ($namespace eq '') { return undef; }
       return &_locking_hash_tie($file_prefix,$namespace,$how);
   }
   
   sub locking_hash_untie {
       return &_locking_hash_untie(@_);
   }
   
   sub db_filename_parts {
       my ($filename)=@_;
       my ($file_path,$namespace)=($filename=~/^(.*)\/([^\/]+)\.db$/);
       if ($namespace eq '') { return undef; }
       return ($file_path.'/'.$namespace,$namespace);
   }
   
   # internal routines that handle the actual tieing and untieing process
   
   sub _do_hash_tie {
       my ($file_prefix,$namespace,$how,$loghead,$what) = @_;
       my %hash;
       if(tie(%hash, 'GDBM_File', "$file_prefix.db", $how, 0640)) {
    # If this is a namespace for which a history is kept,
    # make the history log entry:    
    if (($namespace !~/^nohist\_/) && (defined($loghead))) {
       my $hfh = IO::File->new(">>$file_prefix.hist"); 
       if($hfh) {
    my $now = time();
    print $hfh ("$loghead:$now:$what\n");
       }
       $hfh->close;
    }
    return \%hash;
       } else {
    return undef;
       }
   }
   
   sub _do_hash_untie {
       my ($hashref) = @_;
       my $result = untie(%$hashref);
       return $result;
   }
   
   {
       my $sym;
       my @pushed_syms;
   
       sub clean_sym {
    undef($sym);
       }
       sub push_locking_hash_tie {
    if (!defined($sym)) {
       die("Invalid used of push_locking_hash_tie, should only be called after a lock has occurred and before and unlock.");
    }
    push(@pushed_syms,$sym);
    undef($sym);
       }
   
       sub pop_locking_hash_tie {
    if (defined($sym)) {
       die("Invalid nested used of pop_locking_hash_tie, should only be called after a unlock has occurred.");
    }
    $sym = pop(@pushed_syms);
       }
   
       sub _locking_hash_tie {
    my ($file_prefix,$namespace,$how,$loghead,$what) = @_;
    if (defined($sym)) {
       die('Nested locking attempted without proper use of push_locking_hash_tie, this is unsupported');
    }
   
           my $lock_type=LOCK_SH;
   # Are we reading or writing?
           if ($how eq &GDBM_READER()) {
   # We are reading
              if (!open($sym,"$file_prefix.db.lock")) {
   # We don't have a lock file. This could mean
   # - that there is no such db-file
   # - that it does not have a lock file yet
                  if ((! -e "$file_prefix.db") && (! -e "$file_prefix.db.gz")) {
   # No such file. Forget it.                
                      $! = 2;
      &clean_sym();
                      return undef;
                  }
   # Apparently just no lock file yet. Make one
                  open($sym,">>$file_prefix.db.lock");
              }
   # Do a shared lock
              if (!&flock_sym(LOCK_SH)) { 
          &clean_sym();
          return undef; 
      } 
   # If this is compressed, we will actually need an exclusive lock
      if (-e "$file_prefix.db.gz") {
          if (!&flock_sym(LOCK_EX)) {
      &clean_sym();
      return undef;
          }
      }
           } elsif ($how eq &GDBM_WRCREAT()) {
   # We are writing
              open($sym,">>$file_prefix.db.lock");
   # Writing needs exclusive lock
              if (!&flock_sym(LOCK_EX)) {
          &clean_sym();
          return undef;
      }
           } else {
              die("Unknown method $how for $file_prefix");
           }
   # The file is ours!
   # If it is archived, un-archive it now
          if (-e "$file_prefix.db.gz") {
              system("gunzip $file_prefix.db.gz");
      if (-e "$file_prefix.hist.gz") {
          system("gunzip $file_prefix.hist.gz");
      }
          }
   # Change access mode to non-blocking
          $how=$how|&GDBM_NOLOCK();
   # Go ahead and tie the hash
         my $result = 
       &_do_hash_tie($file_prefix,$namespace,$how,$loghead,$what);
    if (!$result) {
       &clean_sym();
    }
    return $result;
       }
   
       sub flock_sym {
           my ($lock_type)=@_;
    my $failed=0;
    eval {
       local $SIG{__DIE__}='DEFAULT';
       local $SIG{ALRM}=sub {
    $failed=1;
    die("failed lock");
       };
       alarm($loncapa_max_wait_time);
       flock($sym,$lock_type);
       alarm(0);
    };
    if ($failed) {
       $! = 100; # throwing error # 100
       return undef;
    } else {
       return 1;
    }
       }
   
       sub _locking_hash_untie {
    my ($hashref) = @_;
    my $result = untie(%$hashref);
    flock($sym,LOCK_UN);
    close($sym);
    &clean_sym();
    return $result;
       }
   }
   
   
   BEGIN {
       %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
   }
   
 1;  1;
   
 __END__  __END__
Line 80  __END__ Line 524  __END__
   
 =head1 NAME  =head1 NAME
   
   Apache::LONCAPA
   
 LONCAPA - Basic routines  LONCAPA - Basic routines
   
 =head1 SYNOPSIS  =head1 SYNOPSIS
Line 88  Generally useful routines Line 534  Generally useful routines
   
 =head1 EXPORTED SUBROUTINES  =head1 EXPORTED SUBROUTINES
   
 =over 4  =over
   
 =item *  =item escape()
   
 escape() : unpack non-word characters into CGI-compatible hex codes  unpack non-word characters into CGI-compatible hex codes
   
 =item *  =item unescape()
   
 unescape() : pack CGI-compatible hex codes into actual non-word ASCII character   pack CGI-compatible hex codes into actual non-word ASCII character
   
 =item *  =item  add_get_param()
   
 add_get_param() :  Append escaped form elements (name=value etc.) to a url.
    
  Inputs:  url (with or without exit GET from parameters), hash ref of   Inputs:  url (with or without exit GET from parameters), hash ref of
               form name => value pairs                form name => value pairs
   
  Return: url with properly added the form name elements and values to the    Return: url with form name elements and values appended to the 
          the url doing proper escaping of the values and joining with ? or &           the url, doing proper escaping of the values and joining with ? or &
          as needed           as needed
   
   =item clean_handle()
   
   =item propath()
   
   =item untie_domain_hash()
   
   =item tie_domain_hash()
   
   Manipulation of hash based databases (factoring out common code
   for later use as we refactor.
   
    Ties a domain level resource file to a hash.
    If requested a history entry is created in the associated hist file.
   
    Parameters:
       domain    - Name of the domain in which the resource file lives.
       namespace - Name of the hash within that domain.
       how       - How to tie the hash (e.g. GDBM_WRCREAT()).
       loghead   - Optional parameter, if present a log entry is created
                   in the associated history file and this is the first part
                    of that entry.
       logtail   - Goes along with loghead,  The actual logentry is of the
                   form $loghead:<timestamp>:logtail.
   Returns:
      Reference to a hash bound to the db file or alternatively undef
      if the tie failed.
   
   =item tie_user_hash()
   
     Ties a user's resource file to a hash.  
     If necessary, an appropriate history
     log file entry is made as well.
     This sub factors out common code from the subs that manipulate
     the various gdbm files that keep keyword value pairs.
   Parameters:
     domain       - Name of the domain the user is in.
     user         - Name of the 'current user'.
     namespace    - Namespace representing the file to tie.
     how          - What the tie is done to (e.g. GDBM_WRCREAT().
     loghead      - Optional first part of log entry if there may be a
                    history file.
     what         - Optional tail of log entry if there may be a history
                    file.
   Returns:
     hash to which the database is tied.  It's up to the caller to untie.
     undef if the has could not be tied.
   
   =item tie_course
   
   Caches the course database into the temp directory in the context of a specific
   user and ties it to a hash.
   Parameters:
      domain    - Domain the user is in.
      user      - Username of the user.
      course    - Course specification
      cdom      - The course domain.
      hash      - Reference to the hash to tie.
   
   Returns:
       1        - Success
       0        - Failure.
   
   =item tie_course_params
   
   Caches the course parameter database into the temp directory in the context
   of a specific user and ties it to a hash.
   Parameters:
      domain   - Domain the user is in.
      user     - Username of the user.
      course   - course specification.
      cdom     - The course domain.
      hash     - reference to the hash to tie.
   
   Returns:
      1        - Success.
      0        - Failure./
   
   
   =item locking_hash_tie()
   
   routines if you just have a filename return tied hashref or undef
   
   =item locking_hash_untie()
   
   =item db_filename_parts()
   
   =back
   
   =item tempdir()
   
   Returns the file system path to the place loncapa temporary files should be placed/found.
   
   
   =head1 INTERNAL SUBROUTINES
   
   =over 
   
   =item _do_hash_tie()
   
   =item _do_hash_untie()
   
 =back  =back
   
   =cut
   
Removed from v.1.1  
changed lines
  Added in v.1.36

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