--- loncom/lonnet/perl/lonnet.pm	2001/01/05 20:45:09	1.87
+++ loncom/lonnet/perl/lonnet.pm	2001/01/09 22:27:07	1.91
@@ -83,7 +83,7 @@
 # 11/2,11/14,11/15,11/16,11/20,11/21,11/22,11/25,11/27,
 # 12/02,12/12,12/13,12/14,12/28,12/29 Gerd Kortemeyer
 # 05/01/01 Guy Albertelli
-# 05/01 Gerd Kortemeyer
+# 05/01,06/01,09/01 Gerd Kortemeyer
 
 package Apache::lonnet;
 
@@ -97,6 +97,7 @@ use IO::Socket;
 use GDBM_File;
 use Apache::Constants qw(:common :http);
 use HTML::TokeParser;
+use Fcntl qw(:flock);
 
 # --------------------------------------------------------------------- Logging
 
@@ -179,6 +180,11 @@ sub reconlonc {
 
 sub critical {
     my ($cmd,$server)=@_;
+    unless ($hostname{$server}) {
+        &logthis("<font color=blue>WARNING:".
+               " Critical message to unknown server ($server)</font>");
+        return 'no_such_host';
+    }
     my $answer=reply($cmd,$server);
     if ($answer eq 'con_lost') {
         my $pingreply=reply('ping',$server);
@@ -228,6 +234,7 @@ sub critical {
 
 sub appenv {
     my %newenv=@_;
+    my ($in,$out);
     map {
 	if (($newenv{$_}=~/^user\.role/) || ($newenv{$_}=~/^user\.priv/)) {
             &logthis("<font color=blue>WARNING: ".
@@ -243,8 +250,19 @@ sub appenv {
      unless ($fh=Apache::File->new("$ENV{'user.environment'}")) {
 	return 'error';
      }
+     unless (flock($fh,LOCK_SH)) {
+         &logthis("<font color=blue>WARNING: ".
+                  'Could not obtain shared lock in appenv: '.$!);
+         $fh->close();
+         return 'error: '.$!;
+     }
+     &logthis("<font color=green>appenv LOCK_SH gotten");
      @oldenv=<$fh>;
+     $in=$#oldenv+1;
+     &logthis("<font color=green>appenv LOCK_SH to be closed");
+     $fh->close();
     }
+    &logthis("<font color=green>Number of elements read appenv: ".$in."from".join(" ",caller));
     for (my $i=0; $i<=$#oldenv; $i++) {
         chomp($oldenv[$i]);
         if ($oldenv[$i] ne '') {
@@ -260,12 +278,22 @@ sub appenv {
 	return 'error';
      }
      my $newname;
-     flock($fh,'LOCK_EX');
-     foreach $newname (keys %newenv) {
+     unless (flock($fh,LOCK_EX)) {
+         &logthis("<font color=blue>WARNING: ".
+                  'Could not obtain exclusive lock in appenv: '.$!);
+         $fh->close();
+         return 'error: '.$!;
+     }
+     &logthis("<font color=green>appenv LOCK_EX gotten");
+     $out=0;
+     foreach $newname (sort keys %newenv) {
 	 print $fh "$newname=$newenv{$newname}\n";
+	 $out++;
      }
+     &logthis("<font color=green>appenv LOCK_EX to be closed");
      $fh->close();
     }
+    &logthis("<font color=green>Number of elements read appenv: ".$in." number out:".$out."from".join(" ",caller));
     return 'ok';
 }
 # ----------------------------------------------------- Delete from Environment
@@ -284,14 +312,26 @@ sub delenv {
      unless ($fh=Apache::File->new("$ENV{'user.environment'}")) {
 	return 'error';
      }
+     unless (flock($fh,LOCK_SH)) {
+         &logthis("<font color=blue>WARNING: ".
+                  'Could not obtain shared lock in delenv: '.$!);
+         $fh->close();
+         return 'error: '.$!;
+     }
      @oldenv=<$fh>;
+     $fh->close();
     }
     {
      my $fh;
      unless ($fh=Apache::File->new(">$ENV{'user.environment'}")) {
 	return 'error';
      }
-     flock($fh,'LOCK_EX');
+     unless (flock($fh,LOCK_EX)) {
+         &logthis("<font color=blue>WARNING: ".
+                  'Could not obtain exclusive lock in delenv: '.$!);
+         $fh->close();
+         return 'error: '.$!;
+     }
      map {
 	 unless ($_=~/^$delthis/) { print $fh $_; }
      } @oldenv;