PXB-1615 WIP Updates for Percona XtraBackup

Changes made should be working but to properly test them, I need to set
up a development API with the new items for XtraBackup in the DB.

lib/VersionCheck.pm

@@ -153,14 +153,16 @@ sub version_check {
          return;
       }
       PTDEBUG && _d('Using', $protocol);
+      my $url = $args{url}                       # testing
+                || $ENV{PERCONA_VERSION_CHECK_URL}  # testing
+                || "$protocol://v.percona.com";
+      PTDEBUG && _d('API URL:', $url);
 
       # Get list of programs to check from Percona.
       my $advice = pingback(
          instances => $instances_to_check,
          protocol  => $protocol,
-         url       => $args{url}                       # testing
-                   || $ENV{PERCONA_VERSION_CHECK_URL}  # testing
-                   || "$protocol://v.percona.com",
+         url       => $url,
       );
       if ( $advice ) {
          PTDEBUG && _d('Advice:', Dumper($advice));
@@ -342,9 +344,14 @@ sub get_uuid {
     my $filename = $ENV{"HOME"} . $uuid_file;
     my $uuid = _generate_uuid();
 
-    open(my $fh, '>', $filename) or die "Could not open file '$filename' $!";
-    print $fh $uuid;
-    close $fh;
+    my $fh;
+    eval {
+        open($fh, '>', $filename);
+    };
+    if (!$EVAL_ERROR) {
+        print $fh $uuid;
+        close $fh;
+    }
 
     return $uuid;
 }   
@@ -434,8 +441,9 @@ sub pingback {
       general_id => get_uuid(),
    );
 
+   my $tool_name = $ENV{XTRABACKUP_VERSION} ? "Percona XtraBackup" : File::Basename::basename($0);
    my $client_response = {
-      headers => { "X-Percona-Toolkit-Tool" => File::Basename::basename($0) },
+      headers => { "X-Percona-Toolkit-Tool" => $tool_name },
       content => $client_content,
    };
    PTDEBUG && _d('Client response:', Dumper($client_response));
@@ -528,6 +536,7 @@ my %sub_for_type = (
    perl_version        => \&get_perl_version,
    perl_module_version => \&get_perl_module_version,
    mysql_variable      => \&get_mysql_variable,
+   xtrabackup          => \&get_xtrabackup_version,
 );
 
 sub valid_item {
@@ -659,6 +668,10 @@ sub get_perl_version {
    return $version;
 }
 
+sub get_xtrabackup_version {
+    return $ENV{XTRABACKUP_VERSION};
+}
+
 sub get_perl_module_version {
    my (%args) = @_;
    my $item = $args{item};