Re: [PATCH v8 11/18] cryptodisk: Add macros GRUB_TYPE_U_MAX/MIN(type) to replace literals

[Patrick Steinhardt]

On Tue, Dec 08, 2020 at 04:45:42PM -0600, Glenn Washburn wrote:
> Add GRUB_TYPE_U_MAX/MIN(type) macros to get the max/min values for an
> unsigned number with size of type.
> 
> Signed-off-by: Glenn Washburn <development@efficientek.com>

Reviewed-by: Patrick Steinhardt <ps@pks.im>

> ---
>  grub-core/disk/cryptodisk.c | 8 ++++----
>  include/grub/types.h        | 7 +++++++
>  2 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
> index 0e955a020..5aa0c4720 100644
> --- a/grub-core/disk/cryptodisk.c
> +++ b/grub-core/disk/cryptodisk.c
> @@ -284,23 +284,23 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev,
>         iv[1] = grub_cpu_to_le32 (sector >> GRUB_TYPE_BITS (iv[0]));
>         /* FALLTHROUGH */
>       case GRUB_CRYPTODISK_MODE_IV_PLAIN:
> -       iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF);
> +       iv[0] = grub_cpu_to_le32 (sector & GRUB_TYPE_U_MAX (iv[0]));
>         break;
>       case GRUB_CRYPTODISK_MODE_IV_BYTECOUNT64:
>         iv[1] = grub_cpu_to_le32 (sector >> (GRUB_TYPE_BITS (iv[1])
>                                              - dev->log_sector_size));
>         iv[0] = grub_cpu_to_le32 ((sector << dev->log_sector_size)
> -                                 & 0xFFFFFFFF);
> +                                 & GRUB_TYPE_U_MAX (iv[0]));
>         break;
>       case GRUB_CRYPTODISK_MODE_IV_BENBI:
>         {
>           grub_uint64_t num = (sector << dev->benbi_log) + 1;
>           iv[sz - 2] = grub_cpu_to_be32 (num >> GRUB_TYPE_BITS (iv[0]));
> -         iv[sz - 1] = grub_cpu_to_be32 (num & 0xFFFFFFFF);
> +         iv[sz - 1] = grub_cpu_to_be32 (num & GRUB_TYPE_U_MAX (iv[0]));
>         }
>         break;
>       case GRUB_CRYPTODISK_MODE_IV_ESSIV:
> -       iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF);
> +       iv[0] = grub_cpu_to_le32 (sector & GRUB_TYPE_U_MAX (iv[0]));
>         err = grub_crypto_ecb_encrypt (dev->essiv_cipher, iv, iv,
>                                        dev->cipher->cipher->blocksize);
>         if (err)
> diff --git a/include/grub/types.h b/include/grub/types.h
> index 9989e3a16..b36b26a79 100644
> --- a/include/grub/types.h
> +++ b/include/grub/types.h
> @@ -161,6 +161,13 @@ typedef grub_int32_t     grub_ssize_t;
>  #endif
>  # define GRUB_LONG_MIN (-GRUB_LONG_MAX - 1)
>  
> +/*
> + * Cast to unsigned long long so that the "return value" is always a 
> consistent
> + * type and to ensure an unsigned value regardless of type parameter.
> + */
> +#define GRUB_TYPE_U_MAX(type) ((unsigned long long)((typeof (type))(~0)))
> +#define GRUB_TYPE_U_MIN(type) 0ULL
> +
>  typedef grub_uint64_t grub_properly_aligned_t;
>  
>  #define GRUB_PROPERLY_ALIGNED_ARRAY(name, size) grub_properly_aligned_t 
> name[((size) + sizeof (grub_properly_aligned_t) - 1) / sizeof 
> (grub_properly_aligned_t)]
> -- 
> 2.27.0
>

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