[gnome-boxes] installer-media: Fetch original volume ID from udev

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 43cc58069cb6c06b872de6f12d2d2831263ed02b
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Tue Feb 19 03:47:29 2013 +0200

    installer-media: Fetch original volume ID from udev
    
    udev replaces spaces (' ') with underscores ('_') in 'ID_FS_LABEL'
    property. Since there is no way to know if an underscore was
    originally a space or not in the source volume ID, we better use
    'ID_FS_LABEL_ENC' instead. In that property spaces are escaped by '\x20'
    and hence we can be much more certain about it being originally a space.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=694141

 src/installer-media.vala |   21 ++++++++++++++++++++-
 1 files changed, 20 insertions(+), 1 deletions(-)
---
diff --git a/src/installer-media.vala b/src/installer-media.vala
index 278d4da..23dc996 100644
--- a/src/installer-media.vala
+++ b/src/installer-media.vala
@@ -146,7 +146,7 @@ private class Boxes.InstallerMedia : GLib.Object {
         if (!device.get_property_as_boolean ("OSINFO_BOOTABLE"))
             throw new OSDatabaseError.NON_BOOTABLE ("Media %s is not bootable.", device_file);
 
-        label = device.get_property ("ID_FS_LABEL");
+        label = get_decoded_udev_property (device, "ID_FS_LABEL_ENC");
 
         var os_id = device.get_property ("OSINFO_INSTALLER") ?? device.get_property ("OSINFO_LIVE");
 
@@ -159,6 +159,25 @@ private class Boxes.InstallerMedia : GLib.Object {
         }
     }
 
+    private string? get_decoded_udev_property (GUdev.Device device, string property_name) {
+        var encoded = device.get_property (property_name);
+
+        var decoded = "";
+        for (var i = 0; i < encoded.length; ) {
+           uint8 x;
+
+           if (encoded[i:encoded.length].scanf ("\\x%02x", out x) > 0) {
+               decoded += ((char) x).to_string ();
+               i += 4;
+           } else {
+               decoded += encoded[i].to_string ();
+               i++;
+           }
+        }
+
+        return decoded;
+    }
+
     private void setup_label (string? label = null) {
         if (label != null)
             this.label = label;