hashsum: improve the blake2 --tag export

src/uu/hashsum/src/hashsum.rs

@@ -59,7 +59,7 @@ struct Options {
 /// greater than 512.
 fn create_blake2b(matches: &ArgMatches) -> UResult<(&'static str, Box<dyn Digest>, usize)> {
     match matches.get_one::<usize>("length") {
-        Some(0) | None => Ok(("BLAKE2", Box::new(Blake2b::new()) as Box<dyn Digest>, 512)),
+        Some(0) | None => Ok(("BLAKE2b", Box::new(Blake2b::new()) as Box<dyn Digest>, 512)),
         Some(length_in_bits) => {
             if *length_in_bits > 512 {
                 return Err(USimpleError::new(
@@ -71,7 +71,7 @@ fn create_blake2b(matches: &ArgMatches) -> UResult<(&'static str, Box<dyn Digest
             if length_in_bits % 8 == 0 {
                 let length_in_bytes = length_in_bits / 8;
                 Ok((
-                    "BLAKE2",
+                    "BLAKE2b",
                     Box::new(Blake2b::with_output_bytes(length_in_bytes)),
                     *length_in_bits,
                 ))
@@ -327,7 +327,7 @@ pub fn uumain(mut args: impl uucore::Args) -> UResult<()> {
     //        least somewhat better from a user's perspective.
     let matches = command.try_get_matches_from(args)?;
 
-    let (name, algo, bits) = detect_algo(&binary_name, &matches)?;
+    let (algoname, algo, bits) = detect_algo(&binary_name, &matches)?;
 
     let binary = if matches.get_flag("binary") {
         true
@@ -355,7 +355,7 @@ pub fn uumain(mut args: impl uucore::Args) -> UResult<()> {
     }
 
     let opts = Options {
-        algoname: name,
+        algoname,
         digest: algo,
         output_bits: bits,
         binary,
@@ -792,17 +792,22 @@ where
             .map_err_context(|| "failed to read input".to_string())?;
             let (escaped_filename, prefix) = escape_filename(filename);
             if options.tag {
-                println!(
-                    "{}{} ({}) = {}",
-                    prefix, options.algoname, escaped_filename, sum
-                );
+                if options.algoname == "BLAKE2b" && options.digest.output_bits() != 512 {
+                    // special case for BLAKE2b with non-default output length
+                    println!(
+                        "BLAKE2b-{} ({escaped_filename}) = {sum}",
+                        options.digest.output_bits()
+                    );
+                } else {
+                    println!("{prefix}{} ({escaped_filename}) = {sum}", options.algoname);
+                }
             } else if options.nonames {
                 println!("{sum}");
             } else if options.zero {
                 // with zero, we don't escape the filename
-                print!("{} {}{}\0", sum, binary_marker, filename.display());
+                print!("{sum} {binary_marker}{}\0", filename.display());
             } else {
-                println!("{}{} {}{}", prefix, sum, binary_marker, escaped_filename);
+                println!("{prefix}{sum} {binary_marker}{escaped_filename}");
             }
         }
         if bad_format > 0 && failed_cksum == 0 && correct_format == 0 && !options.status {

tests/by-util/test_hashsum.rs

@@ -243,6 +243,30 @@ fn test_invalid_b2sum_length_option_too_large() {
         .code_is(1);
 }
 
+#[test]
+fn test_check_b2sum_tag_output() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+
+    at.touch("f");
+
+    scene
+        .ccmd("b2sum")
+        .arg("--length=0")
+        .arg("--tag")
+        .arg("f")
+        .succeeds()
+        .stdout_only("BLAKE2b (f) = 786a02f742015903c6c6fd852552d272912f4740e15847618a86e217f71f5419d25e1031afee585313896444934eb04b903a685b1448b755d56f701afe9be2ce\n");
+
+    scene
+        .ccmd("b2sum")
+        .arg("--length=128")
+        .arg("--tag")
+        .arg("f")
+        .succeeds()
+        .stdout_only("BLAKE2b-128 (f) = cae66941d9efbd404e4d88758ea67670\n");
+}
+
 #[test]
 fn test_check_file_not_found_warning() {
     let scene = TestScenario::new(util_name!());