hashsum: add --zero option (#4612) (#4632)

* `hashsum`: add `--zero`  option (#4612)

src/uu/hashsum/src/hashsum.rs

@@ -47,6 +47,7 @@ struct Options {
     strict: bool,
     warn: bool,
     output_bits: usize,
+    zero: bool,
 }
 
 #[allow(clippy::cognitive_complexity)]
@@ -269,6 +270,7 @@ pub fn uumain(mut args: impl uucore::Args) -> UResult<()> {
     let quiet = matches.get_flag("quiet") || status;
     let strict = matches.get_flag("strict");
     let warn = matches.get_flag("warn") && !status;
+    let zero = matches.get_flag("zero");
 
     let opts = Options {
         algoname: name,
@@ -282,6 +284,7 @@ pub fn uumain(mut args: impl uucore::Args) -> UResult<()> {
         quiet,
         strict,
         warn,
+        zero,
     };
 
     match matches.get_many::<OsString>("FILE") {
@@ -359,6 +362,13 @@ pub fn uu_app_common() -> Command {
                 .help("warn about improperly formatted checksum lines")
                 .action(ArgAction::SetTrue),
         )
+        .arg(
+            Arg::new("zero")
+                .short('z')
+                .long("zero")
+                .help("end each output line with NUL, not newline")
+                .action(ArgAction::SetTrue),
+        )
         .arg(
             Arg::new("FILE")
                 .index(1)
@@ -613,6 +623,8 @@ where
                 println!("{} ({}) = {}", options.algoname, filename.display(), sum);
             } else if options.nonames {
                 println!("{sum}");
+            } else if options.zero {
+                print!("{} {}{}\0", sum, binary_marker, filename.display());
             } else {
                 println!("{} {}{}", sum, binary_marker, filename.display());
             }

tests/by-util/test_hashsum.rs

@@ -53,6 +53,14 @@ macro_rules! test_digest {
                 .stdout_is("input.txt: OK\n");
         }
 
+        #[test]
+        fn test_zero() {
+            let ts = TestScenario::new("hashsum");
+            assert_eq!(ts.fixtures.read(EXPECTED_FILE),
+                       get_hash!(ts.ucmd().arg(DIGEST_ARG).arg(BITS_ARG).arg("--zero").arg("input.txt").succeeds().no_stderr().stdout_str()));
+        }
+
+
         #[cfg(windows)]
         #[test]
         fn test_text_mode() {