cksum: Back support for -a blake3 and -a shake*

Author: oech3

src/uu/cksum/src/cksum.rs

@@ -88,9 +88,13 @@ fn maybe_sanitize_length(
             sanitize_sha2_sha3_length_str(algo, s_len).map(Some)
         }
 
-        // For BLAKE2b, if a length is provided, validate it.
+        // For BLAKE2b and SKAKE, if a length is provided, validate it.
         (Some(AlgoKind::Blake2b), Some(len)) => calculate_blake2b_length_str(len),
-
+        (Some(AlgoKind::Shake128 | AlgoKind::Shake256), Some(s_len)) => {
+            let len = s_len.parse::<usize>()
+                .map_err(|_| ChecksumError::InvalidLength(s_len.to_string()))?;
+            Ok(Some(len))
+        }
         // For any other provided algorithm, check if length is 0.
         // Otherwise, this is an error.
         (_, Some(len)) if len.parse::<u32>() == Ok(0_u32) => Ok(None),

src/uucore/src/lib/features/checksum/mod.rs

@@ -86,7 +86,7 @@ pub enum AlgoKind {
     Sha384,
     Sha512,
 
-    // Not available in cksum
+    // Extension
     Shake128,
     Shake256,
     Blake3,
@@ -114,6 +114,11 @@ impl AlgoKind {
             ALGORITHM_OPTIONS_SHA256 => Sha256,
             ALGORITHM_OPTIONS_SHA384 => Sha384,
             ALGORITHM_OPTIONS_SHA512 => Sha512,
+
+            // Extension
+            ALGORITHM_OPTIONS_BLAKE3 => Blake3,
+            ALGORITHM_OPTIONS_SHAKE128 => Shake128,
+            ALGORITHM_OPTIONS_SHAKE256 => Shake256,
             _ => return Err(ChecksumError::UnknownAlgorithm(algo.as_ref().to_string()).into()),
         })
     }