Fix scoreboard remainder overflow for large divisors

crates/horizon-client/src/scoreboard_cmd.rs

@@ -797,7 +797,14 @@ pub fn apply_operation(op: &str, a: i32, b: i32) -> CmdResult<(i32, i32)> {
             if b == 0 {
                 return Err(div0());
             }
-            (a.wrapping_rem(b).wrapping_add(b).wrapping_rem(b), b)
+            let remainder = a.wrapping_rem(b);
+            // Floor remainder has the divisor's sign; only correct opposite signs.
+            let remainder = if remainder != 0 && ((remainder < 0) != (b < 0)) {
+                remainder + b
+            } else {
+                remainder
+            };
+            (remainder, b)
         }
         "<" => (a.min(b), b),
         ">" => (a.max(b), b),

crates/horizon-client/src/scoreboard_cmd_tests.rs

@@ -210,6 +210,47 @@ fn division_wraps_minimum_integer_by_negative_one() {
     );
 }
 
+#[test]
+fn remainder_handles_integer_boundaries() {
+    for (dividend, divisor, expected) in [
+        (i32::MAX - 1, i32::MAX, i32::MAX - 1),
+        (7, -3, -2),
+        (-7, 3, 2),
+        (i32::MIN, -1, 0),
+        (-1, i32::MIN, -1),
+        (1, i32::MIN, i32::MIN + 1),
+        (0, i32::MAX, 0),
+    ] {
+        let mut m = mock();
+        run(&mut m, "scoreboard objectives add boundary dummy").unwrap();
+        run(
+            &mut m,
+            &format!("scoreboard players set left boundary {dividend}"),
+        )
+        .unwrap();
+        run(
+            &mut m,
+            &format!("scoreboard players set right boundary {divisor}"),
+        )
+        .unwrap();
+        run(
+            &mut m,
+            "scoreboard players operation left boundary %= right boundary",
+        )
+        .unwrap();
+        assert_eq!(
+            run(&mut m, "scoreboard players get left boundary").unwrap(),
+            expected,
+            "{dividend} %= {divisor}"
+        );
+        assert_eq!(
+            run(&mut m, "scoreboard players get right boundary").unwrap(),
+            divisor
+        );
+    }
+    assert!(apply_operation("%=", 1, 0).is_err());
+}
+
 #[test]
 fn triggers() {
     let mut m = mock();

tools/command_exec_corpus.py

@@ -1191,8 +1191,21 @@ def compute():
     ]
 
 
+def scoreboard_remainder_boundaries():
+    operations = setup('/scoreboard objectives add boundary dummy')
+    for dividend, divisor in [(2147483646, 2147483647), (7, -3), (-2147483648, -1)]:
+        operations += setup(f'/scoreboard players set left boundary {dividend}',
+                            f'/scoreboard players set right boundary {divisor}')
+        operations += [cmd('/scoreboard players operation left boundary %= right boundary'),
+                       cmd('/scoreboard players get left boundary'),
+                       cmd('/scoreboard players get right boundary')]
+    operations += setup('/scoreboard objectives remove boundary')
+    return operations
+
+
 def social():
     return [
+        *scoreboard_remainder_boundaries(),
         *setup('/scoreboard objectives add trig trigger', '/scoreboard objectives add plain dummy'),
         cmd('/trigger trig'),
         cmd('/scoreboard players enable @s trig'),