Remove the sysv IPC shared memory code in favor of using files instead.

This fixes an issue with resmon not correctly cleaning up the shared memory
segments when it dies.

Currently no locking is done on the file to prevent reading of a partial
status dump. This needs fixing.

Also, the file is deleted immediately after opening. This deals with the issue
of having a stale file around if resmon dies and also limits the ability of
somebody to inject invalid data into the file.

git-svn-id: https://labs.omniti.com/resmon/branches/resmon2@367 8c0face9-b7db-6ec6-c4b3-d5f7145c7d55

lib/Resmon/Status.pm

@@ -8,50 +8,53 @@ use IO::File;
 use IO::Socket;
 use Socket;
 use Fcntl qw/:flock/;
-use IPC::SysV qw /IPC_PRIVATE IPC_CREAT IPC_RMID S_IRWXU S_IRWXG S_IRWXO/;
 use Data::Dumper;
 
-my $SEGSIZE = 1024*256;
 my $KEEPALIVE_TIMEOUT = 5;
 my $REQUEST_TIMEOUT = 60;
 sub new {
     my $class = shift;
     my $file = shift;
+    my $fh = IO::File->new(".$file.state", "+>");
+    # Delete the just opened file - it stays open, but doesn't show on disk
+    unlink ".$file.state";
     return bless {
-        file => $file
+        file => $file,
+        shared_state => $fh
     }, $class;
 }
 
 sub get_shared_state {
     my $self = shift;
-    my $blob;
-    my $len;
-    return unless(defined($self->{shared_state}));
-    # Lock shared segment
-    # Read in
-    shmread($self->{shared_state}, $len, 0, length(pack('i', 0)));
-    $len = unpack('i', $len);
-    shmread($self->{shared_state}, $blob, length(pack('i', 0)), $len);
-    # unlock
-    my $VAR1;
-    eval $blob;
-    die $@ if ($@);
-    $self->{store} = $VAR1;
+    my $fh = $self->{shared_state};
+    if (defined $fh) {
+        my $VAR1;
+        $fh->seek(0, 0);
+        my $blob;
+        {
+            local $/ = undef;
+            $blob = <$fh>;
+        }
+        eval $blob;
+        die $@ if ($@);
+        $self->{store} = $VAR1;
+    } else {
+        die "Unable to read shared state";
+    };
     return $self->{store};
 }
 
 sub store_shared_state {
     my $self = shift;
-    return unless(defined($self->{shared_state}));
-    my $blob = Dumper($self->{store});
-
-    # Lock shared segment
-    # Write state and flush
-    shmwrite($self->{shared_state}, pack('i', length($blob)),
-        0, length(pack('i', 0))) || die "$!";
-    shmwrite($self->{shared_state}, $blob, length(pack('i', 0)),
-        length($blob)) || die "$!";
-    # unlock
+    my $fh = $self->{shared_state};
+    if (defined($fh)) {
+        $fh->truncate(0);
+        $fh->seek(0,0);
+        print $fh Dumper($self->{store});
+        $fh->flush();
+    } else {
+        die "Unable to store shared state";
+    };
 }
 
 sub xml_kv_dump {
@@ -467,11 +470,6 @@ sub open {
     $self->{swap_on_close} = 1; # move this to a non .swap version on close
     chmod 0644, "$self->{file}.swap";
 
-    unless(defined($self->{shared_state})) {
-        $self->{shared_state} = shmget(IPC_PRIVATE, $SEGSIZE,
-            IPC_CREAT|S_IRWXU|S_IRWXG|S_IRWXO);
-        die "$0: $!" unless (defined $self->{shared_state});
-    }
     return 1;
 }
 
@@ -530,8 +528,5 @@ sub DESTROY {
         kill 9, $child if(kill 0, $child);
         waitpid(-1,WNOHANG);
     }
-    if(defined($self->{shared_state})) {
-        shmctl($self->{shared_state}, IPC_RMID, 0);
-    }
 }
 1;