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detect division by zero in typed propagation

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This commit is contained in:
dark64 2023-06-13 00:36:57 +02:00
parent cd15f020e0
commit 791a9b66d5
1 changed files with 34 additions and 10 deletions
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40
zokrates_analysis/src/propagation.rs
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@ -33,6 +33,7 @@ pub enum Error {
InvalidValue(String),
OutOfBounds(u128, u128),
VariableLength(String),
DivisionByZero,
}
impl fmt::Display for Error {
@ -47,6 +48,9 @@ impl fmt::Display for Error {
index, size
),
Error::VariableLength(message) => write!(f, "{}", message),
Error::DivisionByZero => {
write!(f, "Division by zero detected during static analysis",)
}
}
}
}
@ -924,12 +928,16 @@ impl<'ast, T: Field> ResultFolder<'ast, T> for Propagator<'ast, T> {
let left = self.fold_field_expression(*e.left)?;
let right = self.fold_field_expression(*e.right)?;
Ok(match (left, right) {
(FieldElementExpression::Value(n1), FieldElementExpression::Value(n2)) => {
FieldElementExpression::Value(ValueExpression::new(n1.value / n2.value))
match (left, right) {
(_, FieldElementExpression::Value(n)) if n.value == T::from(0) => {
Err(Error::DivisionByZero)
}
(e, FieldElementExpression::Value(n)) if n.value == T::from(1) => Ok(e),
(FieldElementExpression::Value(n1), FieldElementExpression::Value(n2)) => Ok(
FieldElementExpression::Value(ValueExpression::new(n1.value / n2.value)),
),
(e1, e2) => Ok(e1 / e2),
}
(e1, e2) => e1 / e2,
})
}
FieldElementExpression::Neg(e) => match self.fold_field_expression(*e.inner)? {
FieldElementExpression::Value(n) => {
@ -1571,14 +1579,30 @@ mod tests {
#[test]
fn div() {
let e = FieldElementExpression::div(
let mut propagator = Propagator::default();
assert_eq!(
propagator.fold_field_expression(FieldElementExpression::div(
FieldElementExpression::value(Bn128Field::from(6)),
FieldElementExpression::value(Bn128Field::from(2)),
)),
Ok(FieldElementExpression::value(Bn128Field::from(3)))
);
assert_eq!(
Propagator::default().fold_field_expression(e),
Ok(FieldElementExpression::value(Bn128Field::from(3)))
propagator.fold_field_expression(FieldElementExpression::div(
FieldElementExpression::identifier("a".into()),
FieldElementExpression::value(Bn128Field::from(1)),
)),
Ok(FieldElementExpression::identifier("a".into()))
);
assert_eq!(
propagator.fold_field_expression(FieldElementExpression::div(
FieldElementExpression::value(Bn128Field::from(6)),
FieldElementExpression::value(Bn128Field::from(0)),
)),
Err(Error::DivisionByZero)
);
}