Re: assertion PED_LE64_TO_CPU (gpt->AlternateLBA) <= disk->dev->length failed

[Joel Granados]

Hey list:

This message seems ok to me. While I look at the patch I ask myself if it would 
not be better a PED_EXCEPTION_ERROR instead of the warning.  And, moreover, 
what occurs if the user selects ignore as apposed to cancel?

Additionally a test case here would be *great* but how do you actually make the 
gpt table point to a point that is farther away than the device.  mmmm.  maybe 
creating a label in a device with X size, then copying the first blocks to a 
device that is smaller than the other. and then executing some parted command.

Regards
----- "Petr Uzel" <address@hidden> wrote:

> On Tue, Aug 26, 2008 at 12:27:21PM -0600, Bjorn Helgaas wrote:
> > > Yes, that is probably the root of the problem.
> > > The assertion is Parted's way of warning you that your
> > > disk/partition table is corrupted in a surprising/unusual way.
> > > Can you suggest a better way to handle this sort of failure?
> > 
> > My preference would be:
> > 
> >   - Since there's a valid GPT at the beginning of the image, and
> only
> >     the secondary copy is missing, warn that the secondary copy is
> >     missing or corrupted and continue.
> 
> What about this fix? Just a proposal...
> 
> From c44a42e6a15388bf87de873fbca07796c0139b69 Mon Sep 17 00:00:00
> 2001
> From: Petr Uzel <address@hidden>
> Date: Wed, 5 Nov 2008 10:17:07 +0100
> Subject: [PATCH] print warning instead of crash on corrupted GPT
> 
> ---
>  libparted/labels/gpt.c |   14 ++++++++++++--
>  1 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/libparted/labels/gpt.c b/libparted/labels/gpt.c
> index 13d2e88..c20d729 100644
> --- a/libparted/labels/gpt.c
> +++ b/libparted/labels/gpt.c
> @@ -824,8 +824,18 @@ gpt_read (PedDisk * disk)
>               goto error;
>  
>       if (_read_header (disk->dev, &gpt, 1)) {
> -             PED_ASSERT ((PedSector) PED_LE64_TO_CPU (gpt->AlternateLBA)
> -                             <= disk->dev->length - 1, goto error_free_gpt);
> +             if ((PedSector) PED_LE64_TO_CPU (gpt->AlternateLBA)
> +                             > disk->dev->length - 1) {
> +                     if (ped_exception_throw (
> +                             PED_EXCEPTION_WARNING,
> +                             PED_EXCEPTION_IGNORE_CANCEL,
> +             _("The primary GPT table states that the backup GPT table is "
> +               "located at the position that is beyond the end of the disk. "
> +               "This means that the GPT structure is corrupted."))
> +                                 == PED_EXCEPTION_CANCEL)
> +                             goto error_free_gpt;
> +             }
> +
>               if ((PedSector) PED_LE64_TO_CPU (gpt->AlternateLBA)
>                               < disk->dev->length - 1) {
>                       char* zeros = ped_malloc (pth_get_size (disk->dev));
> -- 
> 1.6.0.2
> 
> 
> -- 
> Best regards / s pozdravem
> 
> Petr Uzel, Packages maintainer
> ---------------------------------------------------------------------
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-- 
Joel Andres Granados
Red Hat / Brno Czech Republic