improved UEFI detection linux

lib/filesystem.js

@@ -172,6 +172,7 @@ function fsOpenFiles(callback) {
             let lines = stdout.toString().split('\n');
             result.max = parseInt(util.getValue(lines, 'kern.maxfiles', ':'), 10);
             result.allocated = parseInt(util.getValue(lines, 'kern.num_files', ':'), 10);
+            result.available = result.max - result.allocated;
           }
           if (callback) {
             callback(result);
@@ -401,12 +402,17 @@ function blockDevices(callback) {
             }
             resolve(data);
           });
-
         } catch (e) {
           if (callback) { callback(data); }
           resolve(data);
         }
       }
+      if (_freebsd || _openbsd || _netbsd) {
+        // will follow
+        if (callback) { callback(null); }
+        resolve(null);
+      }
+
     });
   });
 }

lib/osinfo.js

@@ -353,7 +353,13 @@ function isUefiLinux() {
         if (!err) {
           resolve(true);
         } else {
-          resolve(false);
+          exec('dmesg | grep -E "EFI v|UEFI"', function (error, stdout) {
+            if (!error) {
+              const lines = stdout.toString().split('\n');
+              return (lines.length > 0);
+            }
+            resolve(false);
+          });
         }
       });
     });