gnucompability(fold): uutils fold accept width 0 but gnu fold rejects it (#12744)

src/uu/fold/src/fold.rs

@@ -64,12 +64,21 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     };
 
     let width = match poss_width {
-        Some(inp_width) => inp_width.parse::<usize>().map_err(|e| {
-            USimpleError::new(
-                1,
-                translate!("fold-error-illegal-width", "width" => inp_width.quote(), "error" => e),
-            )
-        })?,
+        Some(inp_width) => match inp_width.parse::<usize>() {
+            Ok(0) => {
+                return Err(USimpleError::new(
+                    1,
+                    translate!("fold-error-illegal-width", "width" => inp_width.quote()),
+                ));
+            }
+            Ok(parsed_width) => parsed_width,
+            Err(e) => {
+                return Err(USimpleError::new(
+                    1,
+                    translate!("fold-error-illegal-width", "width" => inp_width.quote(), "error" => e),
+                ));
+            }
+        },
         None => 80,
     };
 

tests/by-util/test_fold.rs

@@ -1033,3 +1033,12 @@ fn test_character_mode_special_chars() {
             .stdout_is(expected);
     }
 }
+
+#[test]
+fn test_width_zero() {
+    new_ucmd!()
+        .arg("-w")
+        .arg("0")
+        .fails_with_code(1)
+        .stderr_is("fold: illegal width value\n");
+}