pygrub: fix extlinux parsing

pygrub was unable to parse extlinux config files correctly, exactly
the ones like:

LABEL grsec
  KERNEL vmlinuz-3.0.10-grsec
  APPEND initrd=initramfs-3.0.10-grsec
root=UUID=cfd4a7b4-8c40-4025-b877-8205f1c622ee
modules=sd-mod,usb-storage,ext4 xen quiet

This patch fixes it, adding a new case when parsing the "append" line,
that searches for the initrd image.

Signed-off-by: Roger Pau Monne <roger.pau@entel.upc.edu>
Acked-by: Ian Campbell <ian.campbell.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>

tools/pygrub/examples/alpine-linux-2.3.2.extlinux

@@ -0,0 +1,11 @@
+DEFAULT menu.c32
+PROMPT 0
+MENU TITLE Alpine/Linux Boot Menu
+MENU HIDDEN
+MENU AUTOBOOT Alpine will be booted automatically in # seconds.
+TIMEOUT 30
+LABEL grsec
+  MENU DEFAULT
+  MENU LABEL Linux 3.0.10-grsec
+  KERNEL vmlinuz-3.0.10-grsec
+  APPEND initrd=initramfs-3.0.10-grsec root=UUID=a97ffe64-430f-4fd3-830e-4736d9a27af0 modules=sd-mod,usb-storage,ext4 quiet

tools/pygrub/src/ExtLinuxConf.py

@@ -60,6 +60,13 @@ class ExtLinuxImage(object):
 
                 # Bypass regular self.commands handling
                 com = None
+            elif arg.find("initrd="):
+                # find initrd image in append line
+                args = arg.strip().split(" ")
+                for a in args:
+                    if a.lower().startswith("initrd="):
+                        setattr(self, "initrd", a.replace("initrd=", ""))
+                        arg = arg.replace(a, "")
 
         if com is not None and self.commands.has_key(com):
             if self.commands[com] is not None:
@@ -86,10 +93,12 @@ class ExtLinuxImage(object):
         self._args = args
     def get_kernel(self):
         return self._kernel
+    def set_args(self, val):
+        self._args = val
     def get_args(self):
         return self._args
     kernel = property(get_kernel, set_kernel)
-    args = property(get_args)
+    args = property(get_args, set_args)
 
     def set_initrd(self, val):
         self._initrd = (None,val)