--- loncom/LONCAPA.pm	2009/05/13 14:01:10	1.28
+++ loncom/LONCAPA.pm	2019/08/25 02:43:33	1.36
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # Base routines
 #
-# $Id: LONCAPA.pm,v 1.28 2009/05/13 14:01:10 raeburn Exp $
+# $Id: LONCAPA.pm,v 1.36 2019/08/25 02:43:33 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -37,13 +37,31 @@ 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   $match_not_handle);
@@ -52,22 +70,103 @@ require Exporter;
 our @ISA = qw (Exporter);
 our @EXPORT = qw(&add_get_param    &escape            &unescape       
 		 &tie_domain_hash  &untie_domain_hash &tie_user_hash
-		 &untie_user_hash  &propath);
+		 &untie_user_hash  &propath &tie_course);
 our @EXPORT_OK = qw($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);
+		    $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 $distro;
+}
+
+# Return the default password length. Can be overridden in a domain
+# by specifying a larger value (integer) in the domain configuration.
+
+sub passwd_min {
+    return 7;
+}
+
+#----------------------------------------------------------------------
+#
+#  some of these subs need a bit of documentation
+
 sub add_get_param {
     my ($url,$form_data) = @_;
     my $needs_question_mark = ($url !~ /\?/);
@@ -100,8 +199,16 @@ sub unescape {
     return $str;
 }
 
-$match_domain     = $LONCAPA::domain_re     = qr{[\w\-.]+};
-$match_not_domain = $LONCAPA::not_domain_re = qr{[^\w\-.]+};
+$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;
@@ -119,6 +226,7 @@ sub clean_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) = @_;
@@ -151,6 +259,47 @@ sub clean_handle {
     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 {
@@ -161,8 +310,7 @@ sub propath {
     $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
     my $proname="$perlvar{'lonUsersDir'}/$udom/$subdir/$uname";
     return $proname;
-} 
-
+}
 
 sub tie_domain_hash {
     my ($domain,$namespace,$how,$loghead,$logtail) = @_;
@@ -363,6 +511,7 @@ sub _do_hash_untie {
     }
 }
 
+
 BEGIN {
     %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
 }
@@ -453,6 +602,37 @@ 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
@@ -461,8 +641,17 @@ routines if you just have a filename ret
 
 =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()