Re: [RFC PATCH 0/2] grub-probe: improve message when disk cannot be opened

[Antonio Ospite]

On Tue, 23 Aug 2016 12:17:26 +0200
Antonio Ospite <address@hidden> wrote:

> Hi,
> 
> right now when running grub-probe and the disk cannot be opened the
> error message can be misleading, it always says "disk not found" but in
> some case the disk may exist but the user has no permissions to open
> it, see https://savannah.gnu.org/bugs/?42409
>

Ping.

Now that grub 2.02 has been released maybe there is a chance that
someone looks at this issue?

The two patches from this thread still apply to the current master
branch.

I can resend them if needed.

Thanks,
   Antonio

> The message can be improved by propagating informations about the cause
> of the failure from the bottom layers.
> 
> Please take a look at the patches in this series, I marked them RFC
> because I am new to grub code and I am not sure that all the error paths
> set a meaningful message, but I wanted some code to base the discussion
> on.
> 
> Patch 1/2 aims to prevent overriding the error messages from the
> disk->open() methods called in grub_disk_open().
> 
> Patch 2/2 exposes to the user the —now more informative— message from
> grub_disk_open().
> 
> Before these changes I was getting this output when running grub-probe
> with insufficient permissions:
> 
>   $ LANG=C ./grub-probe /
>   ./grub-probe: warning: disk does not exist, so falling back to partition 
> device /dev/sda1.
>   ./grub-probe: warning: disk does not exist, so falling back to partition 
> device /dev/sda1.
>   ./grub-probe: warning: disk does not exist, so falling back to partition 
> device /dev/sda1.
>   ./grub-probe: error: disk `hostdisk//dev/sda1' not found.
> 
> 
> After the patches the reason of the failure is clearer:
> 
>   $ LANG=C ./grub-probe /
>   ./grub-probe: warning: cannot open `/dev/sda': Permission denied, so 
> falling back to partition device /dev/sda1.
>   ./grub-probe: warning: cannot open `/dev/sda': Permission denied, so 
> falling back to partition device /dev/sda1.
>   ./grub-probe: warning: cannot open `/dev/sda': Permission denied, so 
> falling back to partition device /dev/sda1.
>   ./grub-probe: error: cannot open `/dev/sda1': Permission denied.
> 
> 
> As I said, this is the final effect I am aiming for but I am not 100%
> sure my solution is complete.
> 
> Thanks,
>    Antonio
> 
> 
> Antonio Ospite (2):
>   * grub-core/kern/disk.c: don't override grub_errmsg when
>     grub_disk_open fails
>   * util/getroot.c: improve error message when a disk cannot be opened
> 
>  grub-core/kern/disk.c |  3 +--
>  util/getroot.c        | 15 +++++++++------
>  2 files changed, 10 insertions(+), 8 deletions(-)
> 

-- 
Antonio Ospite
https://ao2.it
https://twitter.com/ao2it

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