Re: [PATCH proxmox-backup v2 2/5] datastore: data blob: refactor decoding method

[Robert Obkircher <r.obkircher@proxmox.com>]

> Improve code style and readability by using a single match statement
> instead of chained if statements and deduplicate the common digest
> verificaton, performed on the decoded blob data.
> 
> Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
>
> diff --git a/pbs-datastore/src/data_blob.rs b/pbs-datastore/src/data_blob.rs
> index 465bcb280..9fd791af5 100644
> --- a/pbs-datastore/src/data_blob.rs
> +++ b/pbs-datastore/src/data_blob.rs
> @@ -180,57 +180,57 @@ impl DataBlob {
>          config: Option<&CryptConfig>,
>          digest: Option<&[u8; 32]>,
>      ) -> Result<Vec<u8>, Error> {
> -        let magic = self.magic();
> +        let magic = *self.magic();
>  
> -        if magic == &UNCOMPRESSED_BLOB_MAGIC_1_0 {
> -            let data_start = std::mem::size_of::<DataBlobHeader>();
> -            let data = self.raw_data[data_start..].to_vec();
> -            if let Some(digest) = digest {
> -                Self::verify_digest(&data, None, digest)?;
> +        let (data, crypt_config) = match magic {
> +            UNCOMPRESSED_BLOB_MAGIC_1_0 => {
> +                let data_start = std::mem::size_of::<DataBlobHeader>();
> +                let data = self.raw_data[data_start..].to_vec();
> +                (data, None)
>              }
> -            Ok(data)
> -        } else if magic == &COMPRESSED_BLOB_MAGIC_1_0 {
> -            let data_start = std::mem::size_of::<DataBlobHeader>();
> -            let mut reader = &self.raw_data[data_start..];
> -            let data = zstd::stream::decode_all(&mut reader)?;
> -            // zstd::block::decompress is about 10% slower
> -            // let data = zstd::block::decompress(&self.raw_data[data_start..], MAX_BLOB_SIZE)?;
> -            if let Some(digest) = digest {
> -                Self::verify_digest(&data, None, digest)?;
> +            COMPRESSED_BLOB_MAGIC_1_0 => {
> +                let data_start = std::mem::size_of::<DataBlobHeader>();
> +                let mut reader = &self.raw_data[data_start..];
> +                let data = zstd::stream::decode_all(&mut reader)?;
> +                // zstd::block::decompress is about 10% slower
> +                // let data = zstd::block::decompress(&self.raw_data[data_start..], MAX_BLOB_SIZE)?;
> +                (data, None)
>              }
> -            Ok(data)
> -        } else if magic == &ENCR_COMPR_BLOB_MAGIC_1_0 || magic == &ENCRYPTED_BLOB_MAGIC_1_0 {
> -            let header_len = std::mem::size_of::<EncryptedDataBlobHeader>();
> -            let head = unsafe {
> -                (&self.raw_data[..header_len]).read_le_value::<EncryptedDataBlobHeader>()?
> -            };
> +            ENCR_COMPR_BLOB_MAGIC_1_0 | ENCRYPTED_BLOB_MAGIC_1_0 => {
> +                let header_len = std::mem::size_of::<EncryptedDataBlobHeader>();
> +                let head = unsafe {
> +                    (&self.raw_data[..header_len]).read_le_value::<EncryptedDataBlobHeader>()?
> +                };
>  
> -            if let Some(config) = config {
> -                let data = if magic == &ENCR_COMPR_BLOB_MAGIC_1_0 {
> -                    Self::decode_compressed_chunk(
> -                        config,
> -                        &self.raw_data[header_len..],
> -                        &head.iv,
> -                        &head.tag,
> -                    )?
> +                if let Some(config) = config {
nit: this could be `let Some(config) = config else { bail!(..); };`
to reduce indentation.

-- 
Robert Obkircher <r.obkircher@proxmox.com>