lxc-ps to limit its search to containers

src/lxc/lxc-ps.in

@@ -35,12 +35,54 @@ our @PS_LINES;        # Output lines of the ps command
 our $LXC_DISPLAY = 0; # By default do not display container information
 our %LXC_NAMES;       # Specified container names (if any)
 
+sub get_container_names {
+	my $ref_names = shift;
+	my $lxcpath='@LXCPATH@';
+
+	open(active, "netstat -xa | grep $lxcpath |") or return;
+	while(<active>) {
+		chomp;
+		s#.*$lxcpath/(.*)/command.*#$1#;
+		push @$ref_names, $_;
+	}
+	close active;
+}
+
+sub get_cgroup {
+	my $ref_cgroup = shift;
+	my $mount_string;
+
+	$mount_string=`mount -t cgroup |grep -E -e '^lxc '`;
+	unless ($mount_string) {
+		$mount_string=`mount |grep -m1 'type cgroup'`;
+	}
+	chomp($mount_string);
+	if ($mount_string) {
+		$$ref_cgroup=`echo "$mount_string" |cut -d' ' -f3`;
+		chomp($$ref_cgroup);
+	}
+	die "unable to find mounted cgroup" unless $$ref_cgroup;
+}
 
-# Reclaim the PID index in the ps output.
-# The $PS_HEADERS must be set to the first line of ps output and must
-# contains the columns headers.
-# This function will set the $PS_PID_INDEX global or exit with an error
-# message if the PID index can't be retrieved.
+sub get_pids_in_containers {
+	my $ref_names = shift;
+	my $ref_cgroup = shift;
+	my $ref_pids = shift;
+	my @pidlist;
+
+	for (@{$ref_names}) {
+		my $task_file = "$$ref_cgroup/$_/tasks";
+
+		$LXC_NAMES{$_} = 1;
+		open(tasks, "cat $task_file 2>/dev/null |") or next;
+		while (<tasks>) {
+			chomp $_;
+			push @pidlist, $_;
+		}
+		close tasks;
+	}
+	$$ref_pids = join(',', @pidlist);
+}
 
 sub reclaim_pid_index {
     my @headers = split " ", $PS_HEADERS;
@@ -54,28 +96,18 @@ sub reclaim_pid_index {
     exit 1;
 }
 
-
-# Execute the ps command
-
 sub execute_ps {
     open(ps, "ps @_ |") or die "Cannot execute ps command: $!\n";
 
-    # Reclaim the PID index in ps output
     $PS_HEADERS = <ps>;
     reclaim_pid_index;
 
-    # Reclaim lines of ps output
     while (<ps>) {
 	push @PS_LINES, $_;
     }
     close ps;
 }
 
-
-# Get the container name (if any) associated to a given PID.
-# @param $pid The PID to use.
-# @return The container name as a string or an empty string.
-
 sub get_container {
     my $pid = shift;
     my $filename = "/proc/$pid/cgroup";
@@ -91,26 +123,16 @@ sub get_container {
     return $container;
 }
 
-
-# Display headers line.
-# The $PS_HEADERS global must be set.
-
 sub display_headers {
     printf "%-10s %s", "CONTAINER", $PS_HEADERS;
 }
 
-
-# Display command usage
-
 sub display_usage {
     print <<EOF;
 Usage: lxc-ps [--help] [--usage] [--name NAME...] [--lxc] [ps options]
 EOF
 }
 
-
-# Display command help
-
 sub display_help {
     display_usage;
     print <<EOF;
@@ -130,9 +152,6 @@ or try a 'ps --help' for further details.
 EOF
 }
 
-
-# Process lxc-ps arguments and build
-
 use Getopt::Long qw(:config no_auto_abbrev pass_through);
 
 my $arg_help  = '';
@@ -153,36 +172,30 @@ if ($arg_usage) {display_usage; exit 0;}
 
 # Should we filter processes related to containers
 if ($arg_lxc) {
-    # Display processes related to all containers
-    $LXC_DISPLAY = 1;
-    @ARGV = ('-e', @ARGV);
-} elsif (@arg_name > 0) {
-    # Display processes related to specified containers
-    $LXC_DISPLAY = 2;
-    foreach (@arg_name) {
-	$LXC_NAMES{$_} = 1;
-    }
-    @ARGV = ('-e', @ARGV);
+	$LXC_DISPLAY = 1;
+	get_container_names \@arg_name;
+}
+if (@arg_name > 0) {
+	my $cgroup;
+	my $pid_list;
+	$LXC_DISPLAY = 2;
+
+	get_cgroup \$cgroup;
+	get_pids_in_containers(\@arg_name, \$cgroup, \$pid_list);
+	if ($pid_list) {
+		@ARGV = ("-p $pid_list",@ARGV);
+	}
 }
-
-
-# Execute the ps command
 
 execute_ps @ARGV;
 
-
-# Display result with addition of container name
-
 display_headers;
 for (@PS_LINES) {
     my @a = split;
     my $container = get_container $a[$PS_PID_INDEX];
-    if ($LXC_DISPLAY == 1 and $container eq '') {next;}
     if ($LXC_DISPLAY == 2 and not $LXC_NAMES{$container}) {next;}
+    if ($LXC_DISPLAY == 1 and $container eq '') {next;}
     printf "%-10s %s", $container, $_;
 }
 
-
-# Done
-
 exit 0;