[PATCH 1/3] disk: efi: Move logic to get a GPT entry into a helper function

[Ilias Apalodimas]

On Fri, 13 Jun 2025 at 11:58, Javier Martinez Canillas
<javierm at redhat.com> wrote:
>
> Factor out the logic to get the Partition Table Entry (PTE) of a given
> partition into a helper function, since it could be used by other code.
>
> Signed-off-by: Javier Martinez Canillas <javierm at redhat.com>
> ---
>
>  disk/part_efi.c | 67 +++++++++++++++++++++++++++++--------------------
>  1 file changed, 40 insertions(+), 27 deletions(-)
>
> diff --git a/disk/part_efi.c b/disk/part_efi.c
> index 932d058c184c..c7d79e253958 100644
> --- a/disk/part_efi.c
> +++ b/disk/part_efi.c
> @@ -216,6 +216,34 @@ int get_disk_guid(struct blk_desc *desc, char *guid)
>         return 0;
>  }
>
> +static int part_get_gpt_pte(struct blk_desc *desc, int part, gpt_entry *gpt_e)
> +{
> +       ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_head, 1, desc->blksz);
> +       gpt_entry *gpt_pte = NULL;
> +
> +       /* "part" argument must be at least 1 */
> +       if (part < 1) {
> +               log_debug("Invalid Argument(s)\n");

I think this should be a log_err an match the comment above

> +               return -EINVAL;
> +       }
> +
> +       /* This function validates AND fills in the GPT header and PTE */
> +       if (find_valid_gpt(desc, gpt_head, &gpt_pte) != 1)
> +               return -EINVAL;
> +
> +       if (part > le32_to_cpu(gpt_head->num_partition_entries) ||
> +           !is_pte_valid(&gpt_pte[part - 1])) {
> +               log_debug("Invalid partition number %d\n", part);

I haven't read the reat yet, but isn't this something we want visible
as a normal error?

> +               free(gpt_pte);
> +               return -EPERM;
> +       }
> +
> +       memcpy(gpt_e, &gpt_pte[part - 1], sizeof(*gpt_e));
> +
> +       free(gpt_pte);
> +       return 0;
> +}
> +
>  static void __maybe_unused part_print_efi(struct blk_desc *desc)
>  {
>         ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_head, 1, desc->blksz);
> @@ -261,45 +289,32 @@ static void __maybe_unused part_print_efi(struct blk_desc *desc)
>  static int __maybe_unused part_get_info_efi(struct blk_desc *desc, int part,
>                                             struct disk_partition *info)
[..]

Rest looks good

Thanks
/Ilias