dd: do not show zero multiplier warning when zero is the multiplicand (#11673)

* dd: do not show zero multiplier warning when zero is the multiplicand

* tests/dd: test zero multiplier warning when zero is the multiplicand

Author: iburaky2

src/uu/dd/src/parseargs.rs

@@ -524,8 +524,8 @@ pub fn parse_bytes_with_opt_multiplier(s: &str) -> Result<u64, ParseError> {
         parse_bytes_no_x(s, parts[0])
     } else {
         let mut total: u64 = 1;
-        for part in parts {
-            if part == "0" {
+        for (i, part) in parts.iter().enumerate() {
+            if *part == "0" && i != parts.len() - 1 {
                 show_zero_multiplier_warning();
             }
             let num = parse_bytes_no_x(s, part)?;

tests/by-util/test_dd.rs

@@ -263,6 +263,13 @@ fn test_zero_multiplier_warning() {
             .succeeds()
             .no_stdout()
             .stderr_contains("warning: '0x' is a zero multiplier; use '00x' if that is intended");
+
+        new_ucmd!()
+            .args(&[format!("{arg}=0x0x0").as_str(), "status=none"])
+            .pipe_in("")
+            .succeeds()
+            .no_stdout()
+            .stderr_is("dd: warning: '0x' is a zero multiplier; use '00x' if that is intended\ndd: warning: '0x' is a zero multiplier; use '00x' if that is intended\n");
     }
 }