Reject '+' sign in print page ranges (#4931)

crates/print/src/range.rs

@@ -51,6 +51,10 @@ fn page_of(tok: &str, count: usize, labels: &Labels) -> Result<usize, PrintError
     if let Some(i) = labels.get(t) {
         return Ok(i);
     }
+    // `usize::from_str` accepts a leading '+', which is not part of a page number.
+    if !t.bytes().all(|b| b.is_ascii_digit()) {
+        return Err(PrintError::NotAPage(t.to_string()));
+    }
     match t.parse::<usize>() {
         Ok(n) if n >= 1 && n <= count => Ok(n - 1),
         Ok(n) => Err(PrintError::OutOfRange(n, count)),
@@ -176,6 +180,13 @@ mod tests {
         assert!(select_pages(0, Some("-"), &[], Subset::All, false).is_err());
     }
 
+    #[test]
+    fn plus_sign_is_not_a_page() {
+        for r in ["+3", "+2-4", "2-+4"] {
+            assert!(matches!(select_pages(5, Some(r), &[], Subset::All, false), Err(PrintError::NotAPage(_))), "accepted {r}");
+        }
+    }
+
     #[test]
     fn open_ended_range_covers_all_pages() {
         assert_eq!(select_pages(5, Some("-"), &[], Subset::All, false).unwrap(), vec![0, 1, 2, 3, 4]);