shred: correctly print zero-byte pass in verbose mode (#7800)

Fixes #7798.

Co-authored-by: Sylvestre Ledru <sylvestre@debian.org>

Author: BenWiederhake

src/uu/shred/src/shred.rs

@@ -376,8 +376,8 @@ fn get_size(size_str_opt: Option<String>) -> Option<u64> {
 fn pass_name(pass_type: &PassType) -> String {
     match pass_type {
         PassType::Random => String::from("random"),
-        PassType::Pattern(Pattern::Single(byte)) => format!("{byte:x}{byte:x}{byte:x}"),
-        PassType::Pattern(Pattern::Multi([a, b, c])) => format!("{a:x}{b:x}{c:x}"),
+        PassType::Pattern(Pattern::Single(byte)) => format!("{byte:02x}{byte:02x}{byte:02x}"),
+        PassType::Pattern(Pattern::Multi([a, b, c])) => format!("{a:02x}{b:02x}{c:02x}"),
     }
 }
 

tests/by-util/test_shred.rs

@@ -209,6 +209,17 @@ fn test_shred_fail_no_perm() {
         .stderr_contains("Couldn't rename to");
 }
 
+#[test]
+fn test_shred_verbose_pass_single_0_byte_name() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let file = "foo";
+    at.write(file, "non-empty");
+    ucmd.arg("-vn200")
+        .arg(file)
+        .succeeds()
+        .stderr_contains("/200 (000000)...\n");
+}
+
 #[test]
 fn test_shred_verbose_no_padding_1() {
     let (at, mut ucmd) = at_and_ucmd!();