[gnome-boxes] installer: More robust drivers selection

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 87b0d6b24ccbac155ce8fa4ebb5ce2268c6b91b0
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Mon Feb 25 14:31:57 2013 +0100

    installer: More robust drivers selection
    
    This patch ensures that we:
    
    1. Don't add/setup same driver more than once.
    2. Prefer same arch over compatible ones.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=694211

 src/unattended-installer.vala |   23 +++++++++++++++++------
 1 files changed, 17 insertions(+), 6 deletions(-)
---
diff --git a/src/unattended-installer.vala b/src/unattended-installer.vala
index 191a7f0..98eaf8f 100644
--- a/src/unattended-installer.vala
+++ b/src/unattended-installer.vala
@@ -770,7 +770,7 @@ private class Boxes.UnattendedInstaller: InstallerMedia {
     }
 
     private GLib.List<DeviceDriver> get_drivers (DriverTestFunction test_func) {
-        var drivers = new GLib.List<DeviceDriver> ();
+        var drivers = new GLib.HashTable<string,DeviceDriver> (str_hash, str_equal);
 
         foreach (var d in os.get_device_drivers ().get_elements ()) {
             var driver = d as DeviceDriver;
@@ -779,13 +779,24 @@ private class Boxes.UnattendedInstaller: InstallerMedia {
                 continue;
 
             var compatibility = compare_cpu_architectures (os_media.architecture, driver.get_architecture 
());
-            if (compatibility == CPUArchCompatibity.IDENTICAL || compatibility == 
CPUArchCompatibity.COMPATIBLE)
-                // We don't entertain compatiblity when word-size is different because 32-bit drivers
-                // are not guaranteed to work on 64-bit architectures in all OSs.
-                drivers.append (driver);
-        }
-
-        return drivers;
+            var location = driver.get_location ();
+            if (compatibility == CPUArchCompatibity.IDENTICAL)
+                drivers.replace (location, driver);
+            else if (compatibility == CPUArchCompatibity.COMPATIBLE && drivers.lookup (location) == null)
+                drivers.insert (location, driver);
+            // We don't entertain compatibility when word-size is different because 32-bit drivers
+            // are not guaranteed to work on 64-bit architectures in all OSs.
+        }
+
+        // We can't just return drivers.get_values () as we don't own the list returned by this call and 
drivers
+        // hashtable is destroyed at the end of this function. Also we can't just use drivers.get_values 
().copy ()
+        // as we need a deep copy of drivers.
+        var ret = new GLib.List<DeviceDriver> ();
+        foreach (var driver in drivers.get_values ())
+            ret.prepend (driver);
+        ret.reverse ();
+
+        return ret;
     }
 
     private delegate bool ScriptTestFunction (InstallScript script);