Fix incorrect wording about function failure time on unsafe ops - these
are now caught by the validator. And a small visit from the perl style police:
check the return value from open().

doc/src/sgml/plperl.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.47 2005/10/18 22:53:54 adunstan Exp $
+$PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.48 2005/10/24 15:39:50 adunstan Exp $
 -->
 
  <chapter id="plperl">
@@ -554,12 +554,16 @@ $$ LANGUAGE plperl;
    system operations are not allowed for security reasons:
 <programlisting>
 CREATE FUNCTION badfunc() RETURNS integer AS $$
-    open(TEMP, "&gt;/tmp/badfile");
-    print TEMP "Gotcha!\n";
+    my $tmpfile = "/tmp/badfile";
+    open my $fh, '&gt;', $tmpfile
+        or elog(ERROR, qq{Could not open the file "$tmpfile": $!});
+    print $fh "Testing writing to a file\n";
+    close $fh or elog(ERROR, qq{Could not close the file "$tmpfile": $!});
     return 1;
 $$ LANGUAGE plperl;
 </programlisting>
-   The creation of the function will succeed, but executing it will not.
+	The creation of this function will fail as its use of a forbidden
+	operation will be be caught by the validator.
   </para>
 
   <para>