Fix some panics related to BigInt operations (#884)

* Fix some panics related to BigInt operations

* Address review comments

* Address review comments

boa/src/builtins/bigint/mod.rs

@@ -173,9 +173,17 @@ impl BigInt {
     pub(crate) fn as_int_n(_this: &Value, args: &[Value], ctx: &mut Context) -> Result<Value> {
         let (modulo, bits) = Self::calculate_as_uint_n(args, ctx)?;
 
-        if bits > 0 && modulo >= BigInt::from(2).pow(&BigInt::from(bits as i64 - 1)) {
+        if bits > 0
+            && modulo
+                >= BigInt::from(2)
+                    .pow(&BigInt::from(bits as i64 - 1))
+                    .expect("the exponent must be positive")
+        {
             Ok(Value::from(
-                modulo - BigInt::from(2).pow(&BigInt::from(bits as i64)),
+                modulo
+                    - BigInt::from(2)
+                        .pow(&BigInt::from(bits as i64))
+                        .expect("the exponent must be positive"),
             ))
         } else {
             Ok(Value::from(modulo))
@@ -214,10 +222,11 @@ impl BigInt {
         let bigint = bigint_arg.to_bigint(ctx)?;
 
         Ok((
-            bigint
+            bigint.as_inner().clone().mod_floor(
-                .as_inner()
+                &BigInt::from(2)
-                .clone()
+                    .pow(&BigInt::from(bits as i64))
-                .mod_floor(&BigInt::from(2).pow(&BigInt::from(bits as i64))),
+                    .expect("the exponent must be positive"),
+            ),
             bits,
         ))
     }

boa/src/builtins/bigint/operations.rs

@@ -7,15 +7,46 @@ use super::BigInt;
 
 impl BigInt {
     #[inline]
-    pub fn pow(self, other: &Self) -> Self {
+    pub fn pow(self, other: &Self) -> Result<Self, String> {
-        Self(
+        Ok(Self(self.0.pow(
-            self.0.pow(
+            other.0.to_biguint().ok_or("BigInt negative exponent")?,
-                other
+        )))
-                    .0
+    }
-                    .to_biguint()
+
-                    .expect("RangeError: \"BigInt negative exponent\""),
+    #[inline]
-            ),
+    pub fn shift_right(mut self, other: Self) -> Result<Self, String> {
-        )
+        use std::ops::ShlAssign;
+        use std::ops::ShrAssign;
+
+        if let Some(n) = other.0.to_i32() {
+            if n > 0 {
+                self.0.shr_assign(n as usize)
+            } else {
+                self.0.shl_assign(n.abs() as usize)
+            }
+
+            Ok(self)
+        } else {
+            Err("Maximum BigInt size exceeded".into())
+        }
+    }
+
+    #[inline]
+    pub fn shift_left(mut self, other: Self) -> Result<Self, String> {
+        use std::ops::ShlAssign;
+        use std::ops::ShrAssign;
+
+        if let Some(n) = other.0.to_i32() {
+            if n > 0 {
+                self.0.shl_assign(n as usize)
+            } else {
+                self.0.shr_assign(n.abs() as usize)
+            }
+
+            Ok(self)
+        } else {
+            Err("Maximum BigInt size exceeded".into())
+        }
     }
 
     /// Floored integer modulo.
@@ -55,48 +86,6 @@ impl_bigint_operator!(BitAnd, bitand, BitAndAssign, bitand_assign);
 impl_bigint_operator!(BitOr, bitor, BitOrAssign, bitor_assign);
 impl_bigint_operator!(BitXor, bitxor, BitXorAssign, bitxor_assign);
 
-impl std::ops::Shr for BigInt {
-    type Output = Self;
-
-    fn shr(mut self, other: Self) -> Self::Output {
-        use std::ops::ShlAssign;
-        use std::ops::ShrAssign;
-
-        if let Some(n) = other.0.to_i32() {
-            if n > 0 {
-                self.0.shr_assign(n as usize)
-            } else {
-                self.0.shl_assign(n.abs() as usize)
-            }
-
-            return self;
-        }
-
-        panic!("RangeError: Maximum BigInt size exceeded");
-    }
-}
-
-impl std::ops::Shl for BigInt {
-    type Output = Self;
-
-    fn shl(mut self, other: Self) -> Self::Output {
-        use std::ops::ShlAssign;
-        use std::ops::ShrAssign;
-
-        if let Some(n) = other.0.to_i32() {
-            if n > 0 {
-                self.0.shl_assign(n as usize)
-            } else {
-                self.0.shr_assign(n.abs() as usize)
-            }
-
-            return self;
-        }
-
-        panic!("RangeError: Maximum BigInt size exceeded");
-    }
-}
-
 impl std::ops::Neg for BigInt {
     type Output = Self;
 

boa/src/builtins/bigint/tests.rs

@@ -202,6 +202,41 @@ fn pow() {
     );
 }
 
+#[test]
+fn pow_negative_exponent() {
+    let mut engine = Context::new();
+
+    assert_throws(&mut engine, "10n ** (-10n)", "RangeError");
+}
+
+#[test]
+fn shl() {
+    let mut engine = Context::new();
+
+    assert_eq!(forward(&mut engine, "8n << 2n"), "32n");
+}
+
+#[test]
+fn shl_out_of_range() {
+    let mut engine = Context::new();
+
+    assert_throws(&mut engine, "1000n << 1000000000000000n", "RangeError");
+}
+
+#[test]
+fn shr() {
+    let mut engine = Context::new();
+
+    assert_eq!(forward(&mut engine, "8n >> 2n"), "2n");
+}
+
+#[test]
+fn shr_out_of_range() {
+    let mut engine = Context::new();
+
+    assert_throws(&mut engine, "1000n >> 1000000000000000n", "RangeError");
+}
+
 #[test]
 fn to_string() {
     let mut engine = Context::new();

boa/src/value/operations.rs

@@ -176,14 +176,22 @@ impl Value {
             (Self::Integer(x), Self::Rational(y)) => Self::rational(f64::from(*x).powf(*y)),
             (Self::Rational(x), Self::Integer(y)) => Self::rational(x.powi(*y)),
 
-            (Self::BigInt(ref a), Self::BigInt(ref b)) => Self::bigint(a.as_inner().clone().pow(b)),
+            (Self::BigInt(ref a), Self::BigInt(ref b)) => Self::bigint(
+                a.as_inner()
+                    .clone()
+                    .pow(b)
+                    .map_err(|msg| ctx.construct_range_error(msg))?,
+            ),
 
             // Slow path:
             (_, _) => match (self.to_numeric(ctx)?, other.to_numeric(ctx)?) {
                 (Numeric::Number(a), Numeric::Number(b)) => Self::rational(a.powf(b)),
-                (Numeric::BigInt(ref a), Numeric::BigInt(ref b)) => {
+                (Numeric::BigInt(ref a), Numeric::BigInt(ref b)) => Self::bigint(
-                    Self::bigint(a.as_inner().clone().pow(b))
+                    a.as_inner()
-                }
+                        .clone()
+                        .pow(b)
+                        .map_err(|msg| ctx.construct_range_error(msg))?,
+                ),
                 (_, _) => {
                     return ctx.throw_type_error(
                         "cannot mix BigInt and other types, use explicit conversions",
@@ -304,18 +312,24 @@ impl Value {
                 Self::integer(f64_to_int32(*x).wrapping_shl(*y as u32))
             }
 
-            (Self::BigInt(ref a), Self::BigInt(ref b)) => {
+            (Self::BigInt(ref a), Self::BigInt(ref b)) => Self::bigint(
-                Self::bigint(a.as_inner().clone() << b.as_inner().clone())
+                a.as_inner()
-            }
+                    .clone()
+                    .shift_left(b.as_inner().clone())
+                    .map_err(|msg| ctx.construct_range_error(&msg))?,
+            ),
 
             // Slow path:
             (_, _) => match (self.to_numeric(ctx)?, other.to_numeric(ctx)?) {
                 (Numeric::Number(x), Numeric::Number(y)) => {
                     Self::integer(f64_to_int32(x).wrapping_shl(f64_to_uint32(y)))
                 }
-                (Numeric::BigInt(ref x), Numeric::BigInt(ref y)) => {
+                (Numeric::BigInt(ref x), Numeric::BigInt(ref y)) => Self::bigint(
-                    Self::bigint(x.as_inner().clone() << y.as_inner().clone())
+                    x.as_inner()
-                }
+                        .clone()
+                        .shift_left(y.as_inner().clone())
+                        .map_err(|msg| ctx.construct_range_error(&msg))?,
+                ),
                 (_, _) => {
                     return ctx.throw_type_error(
                         "cannot mix BigInt and other types, use explicit conversions",
@@ -340,18 +354,24 @@ impl Value {
                 Self::integer(f64_to_int32(*x).wrapping_shr(*y as u32))
             }
 
-            (Self::BigInt(ref a), Self::BigInt(ref b)) => {
+            (Self::BigInt(ref a), Self::BigInt(ref b)) => Self::bigint(
-                Self::bigint(a.as_inner().clone() >> b.as_inner().clone())
+                a.as_inner()
-            }
+                    .clone()
+                    .shift_right(b.as_inner().clone())
+                    .map_err(|msg| ctx.construct_range_error(&msg))?,
+            ),
 
             // Slow path:
             (_, _) => match (self.to_numeric(ctx)?, other.to_numeric(ctx)?) {
                 (Numeric::Number(x), Numeric::Number(y)) => {
                     Self::integer(f64_to_int32(x).wrapping_shr(f64_to_uint32(y)))
                 }
-                (Numeric::BigInt(ref x), Numeric::BigInt(ref y)) => {
+                (Numeric::BigInt(ref x), Numeric::BigInt(ref y)) => Self::bigint(
-                    Self::bigint(x.as_inner().clone() >> y.as_inner().clone())
+                    x.as_inner()
-                }
+                        .clone()
+                        .shift_right(y.as_inner().clone())
+                        .map_err(|msg| ctx.construct_range_error(&msg))?,
+                ),
                 (_, _) => {
                     return ctx.throw_type_error(
                         "cannot mix BigInt and other types, use explicit conversions",