shuf: handle --input-range with huge number ranges

This requires special handling, because we cannot always generate all
possible strings beforehand, e.g. in the case of "-n 2 -i 0-2147483647".

tests/by-util/test_shuf.rs

@@ -88,6 +88,99 @@ fn test_zero_termination_multi() {
     assert_eq!(result_seq, input_seq, "Output is not a permutation");
 }
 
+#[test]
+fn test_very_large_range() {
+    let num_samples = 10;
+    let result = new_ucmd!()
+        .arg("-n")
+        .arg(&num_samples.to_string())
+        .arg("-i0-1234567890")
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<isize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), num_samples, "Miscounted output length!");
+    assert!(
+        result_seq.iter().all(|x| (0..=1234567890).contains(x)),
+        "Output includes element not from range: {}",
+        result.stdout_str()
+    );
+}
+
+#[test]
+fn test_very_large_range_offset() {
+    let num_samples = 10;
+    let result = new_ucmd!()
+        .arg("-n")
+        .arg(&num_samples.to_string())
+        .arg("-i1234567890-2147483647")
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<isize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), num_samples, "Miscounted output length!");
+    assert!(
+        result_seq
+            .iter()
+            .all(|x| (1234567890..=2147483647).contains(x)),
+        "Output includes element not from range: {}",
+        result.stdout_str()
+    );
+}
+
+#[test]
+fn test_very_high_range_full() {
+    let input_seq = vec![
+        2147483641, 2147483642, 2147483643, 2147483644, 2147483645, 2147483646, 2147483647,
+    ];
+    let result = new_ucmd!().arg("-i2147483641-2147483647").succeeds();
+    result.no_stderr();
+
+    let mut result_seq: Vec<isize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    result_seq.sort_unstable();
+    assert_eq!(result_seq, input_seq, "Output is not a permutation");
+}
+
+#[test]
+fn test_range_repeat() {
+    let num_samples = 500;
+    let result = new_ucmd!()
+        .arg("-r")
+        .arg("-n")
+        .arg(&num_samples.to_string())
+        .arg("-i12-34")
+        .succeeds();
+    result.no_stderr();
+
+    let result_seq: Vec<isize> = result
+        .stdout_str()
+        .split('\n')
+        .filter(|x| !x.is_empty())
+        .map(|x| x.parse().unwrap())
+        .collect();
+    assert_eq!(result_seq.len(), num_samples, "Miscounted output length!");
+    assert!(
+        result_seq.iter().all(|x| (12..=34).contains(x)),
+        "Output includes element not from range: {}",
+        result.stdout_str()
+    );
+}
+
 #[test]
 fn test_empty_input() {
     let result = new_ucmd!().pipe_in(vec![]).succeeds();