Re: [Xen-devel] [PATCH] Make PyGrub run first entry in grub config when invalid default boot option provided

[Michal Novotny <minovotn@xxxxxxxxxx>]

Hi,
thanks for advice. Here's new and corrected version of the patch. Well, 
the error here is IndexError, when an error occurs so the IndexError is 
catched and not KeyError. I have also tried it with KeyError but it was 
not working so IndexError is catched here.
Michal

Ian Jackson wrote:
> Michal Novotny writes ("[Xen-devel] [PATCH] Make PyGrub run first entry in grub 
> config when invalid default boot option provided"):
>   
> > -    img = g.cf.images[sel]
> > +    try:
> > +        img = g.cf.images[sel]
> > +    except:
> >     
> It is not correct to do this on all exceptions.  (This is a common
> mistake in Python.)  I assume that in your error case the images array
> doesn't have the relevant entry and that your code should read:
>   +        img = g.cf.images[sel]
>   +    except KeyError:
>
> Ian.
>   

diff -r e1562a36094e tools/pygrub/src/pygrub
--- a/tools/pygrub/src/pygrub   Thu Mar 19 17:04:06 2009 +0000
+++ b/tools/pygrub/src/pygrub   Fri Mar 20 15:09:31 2009 +0100
@@ -530,7 +530,11 @@
         print "No kernel image selected!"
         sys.exit(1)
 
-    img = g.cf.images[sel]
+    try:
+        img = g.cf.images[sel]
+    except IndexError:
+        img = g.cf.images[0]
+
 
     grubcfg = { "kernel": None, "ramdisk": None, "args": None }
 

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