[RFC 02/14] efi_loader: library function efi_dp_merge

[Ilias Apalodimas]

Hi Heinrich,

On Fri, 26 Apr 2024 at 17:13, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
> Provide a function to append a device_path to a list of device paths
> that is separated by final end nodes.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  include/efi_loader.h             |  3 +++
>  lib/efi_loader/efi_device_path.c | 31 +++++++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+)
>
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 9600941aa32..a7d7b8324f1 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -944,6 +944,9 @@ struct efi_load_option {
>
>  struct efi_device_path *efi_dp_from_lo(struct efi_load_option *lo,
>                                        const efi_guid_t *guid);
> +struct efi_device_path *efi_dp_merge(const struct efi_device_path *dp1,
> +                                    efi_uintn_t *size,
> +                                    const struct efi_device_path *dp2);
>  struct efi_device_path *efi_dp_concat(const struct efi_device_path *dp1,
>                                       const struct efi_device_path *dp2,
>                                       bool split_end_node);
> diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
> index 46aa59b9e40..16cbe41d32f 100644
> --- a/lib/efi_loader/efi_device_path.c
> +++ b/lib/efi_loader/efi_device_path.c
> @@ -270,6 +270,37 @@ struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp)
>         return ndp;
>  }
>
> +/**
> + * efi_dp_merge() - Concatenate two device paths separated by final end node
> + *
> + * @dp1:       first device path
> + * @size:      pointer to length of @dp1, total size on return
> + * @dp2:       second device path
> + *
> + * Return:     concatenated device path or NULL
> + */
> +struct efi_device_path *efi_dp_merge(const struct efi_device_path *dp1,
> +                                    efi_uintn_t *size,
> +                                    const struct efi_device_path *dp2)
> +{
> +       efi_uintn_t len, len1, len2;
> +       struct efi_device_path *dp;
> +       u8 *p;
> +
> +       len1 = *size;
> +       len2 = efi_dp_size(dp2) + sizeof(END);
> +       len = len1 + len2;
> +       dp = efi_alloc(len);
> +       if (!dp)
> +               return NULL;
> +       memcpy(dp, dp1, len1);
> +       p = (u8 *)dp + len1;
> +       memcpy(p, dp2, len2);
> +       *size = len;

Can't we just use efi_dp_concat()?

Thanks
/Ilias
> +
> +       return dp;
> +}
> +
>  /**
>   * efi_dp_concat() - Concatenate two device paths and add and terminate them
>   *                   with an end node.
> --
> 2.43.0
>