Re: [PATCH v7] probe: Support probing for partition UUID with --part-uuid

[Daniel Kiper]

CC-ing Paul.

On Wed, May 15, 2019 at 09:04:43PM +0200, Jacob Kroon wrote:
> Linux supports root=PARTUUID=<partuuid> boot argument, so add
> support for probing it. Compared to the fs UUID, the partition
> UUID does not change when reformatting a partition.
>
> For now, only disks using a GPT partition table are supported.
>
> Signed-off-by: Jacob Kroon <address@hidden>

Reviewed-by: Daniel Kiper <address@hidden>

Paul, is your RB valid for v7?

> ---
>  docs/grub.texi             |  4 +++-
>  grub-core/commands/probe.c | 34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+), 1 deletion(-)
>
> Changes since v6:
>  * Mention GPT restriction in manual
>
> diff --git a/docs/grub.texi b/docs/grub.texi
> index 308b25074..fc12fc775 100644
> --- a/docs/grub.texi
> +++ b/docs/grub.texi
> @@ -4771,9 +4771,11 @@ a rest.
>  @node probe
>  @subsection probe
>
> address@hidden Command probe address@hidden var] 
> @option{--driver}|@option{--partmap}|@option{--fs}|@option{--fs-uuid}|@option{--label}
>  device
> address@hidden Command probe address@hidden var] 
> @option{--driver}|@option{--partmap}|@option{--fs}|@option{--fs-uuid}|@option{--label}|@option{--part-uuid}
>  device
>  Retrieve device information. If option @option{--set} is given, assign result
>  to variable @var{var}, otherwise print information on the screen.
> +
> +The option @option{--part-uuid} is currently only implemented for 
> GPT-formatted disks.
>  @end deffn
>
>
> diff --git a/grub-core/commands/probe.c b/grub-core/commands/probe.c
> index 95d272287..d2e7f662e 100644
> --- a/grub-core/commands/probe.c
> +++ b/grub-core/commands/probe.c
> @@ -24,6 +24,7 @@
>  #include <grub/device.h>
>  #include <grub/disk.h>
>  #include <grub/partition.h>
> +#include <grub/gpt_partition.h>
>  #include <grub/net.h>
>  #include <grub/fs.h>
>  #include <grub/file.h>
> @@ -45,6 +46,7 @@ static const struct grub_arg_option options[] =
>      {"fs",           'f', 0, N_("Determine filesystem type."), 0, 0},
>      {"fs-uuid",              'u', 0, N_("Determine filesystem UUID."), 0, 0},
>      {"label",                'l', 0, N_("Determine filesystem label."), 0, 
> 0},
> +    {"part-uuid",    0,   0, N_("Determine partition UUID."), 0, 0},
>      {0, 0, 0, 0, 0, 0}
>    };
>
> @@ -98,6 +100,38 @@ grub_cmd_probe (grub_extcmd_context_t ctxt, int argc, 
> char **args)
>        grub_device_close (dev);
>        return GRUB_ERR_NONE;
>      }
> +  if (state[6].set)
> +    {
> +      /* AAAABBBB-CCCC-DDDD-EEEE-FFFFFFFFFFFF + null terminator */
> +      char val[37] = "none";
> +      if (dev->disk && dev->disk->partition &&
> +       grub_strcmp(dev->disk->partition->partmap->name, "gpt") == 0)
> +     {
> +       struct grub_gpt_partentry entry;
> +       struct grub_partition *p = dev->disk->partition;
> +       grub_disk_t disk = grub_disk_open(dev->disk->name);
> +       if (!disk)
> +         return grub_errno;
> +       if (grub_disk_read(disk, p->offset, p->index, sizeof(entry), &entry))
> +         return grub_errno;
> +       grub_disk_close(disk);
> +       grub_gpt_part_guid_t *guid = &entry.guid;
> +       grub_snprintf (val, sizeof(val),
> +                      "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
> +                      grub_le_to_cpu32 (guid->data1),
> +                      grub_le_to_cpu16 (guid->data2),
> +                      grub_le_to_cpu16 (guid->data3),
> +                      guid->data4[0], guid->data4[1], guid->data4[2],
> +                      guid->data4[3], guid->data4[4], guid->data4[5],
> +                      guid->data4[6], guid->data4[7]);
> +     }
> +      if (state[0].set)
> +     grub_env_set (state[0].arg, val);
> +      else
> +     grub_printf ("%s", val);
> +      grub_device_close (dev);
> +      return GRUB_ERR_NONE;
> +    }
>    fs = grub_fs_probe (dev);
>    if (! fs)
>      return grub_errno;
> --
> 2.20.1