Remove use of ops::Mul and ops::Neg since they can fail (#811)

Author: jonasbb

serde_with/src/utils/duration.rs

@@ -28,13 +28,17 @@ impl Sign {
         *self == Sign::Negative
     }
 
-    pub(crate) fn apply<T>(&self, value: T) -> T
-    where
-        T: core::ops::Neg<Output = T>,
-    {
+    pub(crate) fn apply_f64(&self, value: f64) -> f64 {
         match *self {
             Sign::Positive => value,
-            Sign::Negative => value.neg(),
+            Sign::Negative => -value,
+        }
+    }
+
+    pub(crate) fn apply_i64(&self, value: i64) -> Option<i64> {
+        match *self {
+            Sign::Positive => Some(value),
+            Sign::Negative => value.checked_neg(),
         }
     }
 }
@@ -53,6 +57,16 @@ impl DurationSigned {
         }
     }
 
+    pub(crate) fn checked_mul(mut self, rhs: u32) -> Option<Self> {
+        self.duration = self.duration.checked_mul(rhs)?;
+        Some(self)
+    }
+
+    pub(crate) fn checked_div(mut self, rhs: u32) -> Option<Self> {
+        self.duration = self.duration.checked_div(rhs)?;
+        Some(self)
+    }
+
     #[cfg(any(feature = "chrono_0_4", feature = "time_0_3"))]
     pub(crate) fn with_duration(sign: Sign, duration: Duration) -> Self {
         Self { sign, duration }
@@ -107,24 +121,6 @@ impl From<&SystemTime> for DurationSigned {
     }
 }
 
-impl core::ops::Mul<u32> for DurationSigned {
-    type Output = DurationSigned;
-
-    fn mul(mut self, rhs: u32) -> Self::Output {
-        self.duration *= rhs;
-        self
-    }
-}
-
-impl core::ops::Div<u32> for DurationSigned {
-    type Output = DurationSigned;
-
-    fn div(mut self, rhs: u32) -> Self::Output {
-        self.duration /= rhs;
-        self
-    }
-}
-
 impl<STRICTNESS> SerializeAs<DurationSigned> for DurationSeconds<u64, STRICTNESS>
 where
     STRICTNESS: Strictness,
@@ -163,11 +159,15 @@ where
     {
         let mut secs = source
             .sign
-            .apply(i64::try_from(source.duration.as_secs()).map_err(|_| {
+            .apply_i64(i64::try_from(source.duration.as_secs()).map_err(|_| {
                 SerError::custom("The Duration of Timestamp is outside the supported range.")
-            })?);
+            })?)
+            .ok_or_else(|| {
+                S::Error::custom("The Duration of Timestamp is outside the supported range.")
+            })?;
 
         // Properly round the value
+        // TODO check for overflows BUG771
         if source.duration.subsec_millis() >= 500 {
             if source.sign.is_positive() {
                 secs += 1;
@@ -189,7 +189,7 @@ where
     {
         // as conversions are necessary for floats
         #[allow(clippy::as_conversions)]
-        let mut secs = source.sign.apply(source.duration.as_secs() as f64);
+        let mut secs = source.sign.apply_f64(source.duration.as_secs() as f64);
 
         // Properly round the value
         if source.duration.subsec_millis() >= 500 {
@@ -214,9 +214,12 @@ where
     {
         let mut secs = source
             .sign
-            .apply(i64::try_from(source.duration.as_secs()).map_err(|_| {
+            .apply_i64(i64::try_from(source.duration.as_secs()).map_err(|_| {
                 SerError::custom("The Duration of Timestamp is outside the supported range.")
-            })?);
+            })?)
+            .ok_or_else(|| {
+                S::Error::custom("The Duration of Timestamp is outside the supported range.")
+            })?;
 
         // Properly round the value
         if source.duration.subsec_millis() >= 500 {
@@ -240,7 +243,7 @@ where
     {
         source
             .sign
-            .apply(source.duration.as_secs_f64())
+            .apply_f64(source.duration.as_secs_f64())
             .serialize(serializer)
     }
 }
@@ -256,7 +259,7 @@ where
     {
         source
             .sign
-            .apply(source.duration.as_secs_f64())
+            .apply_f64(source.duration.as_secs_f64())
             .to_string()
             .serialize(serializer)
     }
@@ -276,7 +279,8 @@ macro_rules! duration_impls {
             where
                 S: Serializer,
             {
-                $inner::<FORMAT, STRICTNESS>::serialize_as(&(*source * $factor), serializer)
+                let value = source.checked_mul($factor).ok_or_else(|| S::Error::custom("Failed to serialize value as the value cannot be represented."))?;
+                $inner::<FORMAT, STRICTNESS>::serialize_as(&value, serializer)
             }
         }
 
@@ -291,7 +295,8 @@ macro_rules! duration_impls {
                 D: Deserializer<'de>,
             {
                 let dur = $inner::<FORMAT, STRICTNESS>::deserialize_as(deserializer)?;
-                Ok(dur / $factor)
+                let dur = dur.checked_div($factor).ok_or_else(|| D::Error::custom("Failed to deserialize value as the value cannot be represented."))?;
+                Ok(dur)
             }
         }