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Trap array out-of-bound index access error.

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This commit is contained in:
Stephen Chung 2020-02-23 13:59:50 +08:00
parent c4a2e3bd44
commit 829621a3d4
1 changed files with 42 additions and 8 deletions
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50
src/engine.rs
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@ -15,6 +15,7 @@ use crate::parser::{lex, parse, Expr, FnDef, Stmt};
pub enum EvalAltResult { pub enum EvalAltResult {
ErrorFunctionNotFound(String), ErrorFunctionNotFound(String),
ErrorFunctionArgMismatch, ErrorFunctionArgMismatch,
ErrorArrayOutOfBounds(usize, i64),
ErrorIndexMismatch, ErrorIndexMismatch,
ErrorIfGuardMismatch, ErrorIfGuardMismatch,
ErrorVariableNotFound(String), ErrorVariableNotFound(String),
@ -45,6 +46,9 @@ impl PartialEq for EvalAltResult {
(&ErrorFunctionNotFound(ref a), &ErrorFunctionNotFound(ref b)) => a == b, (&ErrorFunctionNotFound(ref a), &ErrorFunctionNotFound(ref b)) => a == b,
(&ErrorFunctionArgMismatch, &ErrorFunctionArgMismatch) => true, (&ErrorFunctionArgMismatch, &ErrorFunctionArgMismatch) => true,
(&ErrorIndexMismatch, &ErrorIndexMismatch) => true, (&ErrorIndexMismatch, &ErrorIndexMismatch) => true,
(&ErrorArrayOutOfBounds(max1, index1), &ErrorArrayOutOfBounds(max2, index2)) => {
max1 == max2 && index1 == index2
}
(&ErrorIfGuardMismatch, &ErrorIfGuardMismatch) => true, (&ErrorIfGuardMismatch, &ErrorIfGuardMismatch) => true,
(&ErrorVariableNotFound(ref a), &ErrorVariableNotFound(ref b)) => a == b, (&ErrorVariableNotFound(ref a), &ErrorVariableNotFound(ref b)) => a == b,
(&ErrorAssignmentToUnknownLHS, &ErrorAssignmentToUnknownLHS) => true, (&ErrorAssignmentToUnknownLHS, &ErrorAssignmentToUnknownLHS) => true,
@ -62,7 +66,12 @@ impl Error for EvalAltResult {
match *self { match *self {
EvalAltResult::ErrorFunctionNotFound(_) => "Function not found", EvalAltResult::ErrorFunctionNotFound(_) => "Function not found",
EvalAltResult::ErrorFunctionArgMismatch => "Function argument types do not match", EvalAltResult::ErrorFunctionArgMismatch => "Function argument types do not match",
EvalAltResult::ErrorIndexMismatch => "Index does not match array", EvalAltResult::ErrorIndexMismatch => "Array access expects integer index",
EvalAltResult::ErrorArrayOutOfBounds(_, index) if index < 0 => {
"Array access expects non-negative index"
}
EvalAltResult::ErrorArrayOutOfBounds(max, _) if max == 0 => "Access of empty array",
EvalAltResult::ErrorArrayOutOfBounds(_, _) => "Array index out of bounds",
EvalAltResult::ErrorIfGuardMismatch => "If guards expect boolean expression", EvalAltResult::ErrorIfGuardMismatch => "If guards expect boolean expression",
EvalAltResult::ErrorVariableNotFound(_) => "Variable not found", EvalAltResult::ErrorVariableNotFound(_) => "Variable not found",
EvalAltResult::ErrorAssignmentToUnknownLHS => { EvalAltResult::ErrorAssignmentToUnknownLHS => {
@ -88,7 +97,18 @@ impl fmt::Display for EvalAltResult {
if let Some(s) = self.as_str() { if let Some(s) = self.as_str() {
write!(f, "{}: {}", self.description(), s) write!(f, "{}: {}", self.description(), s)
} else { } else {
write!(f, "{}", self.description()) match self {
EvalAltResult::ErrorArrayOutOfBounds(_, index) if *index < 0 => {
write!(f, "{}: {} < 0", self.description(), index)
}
EvalAltResult::ErrorArrayOutOfBounds(max, _) if *max == 0 => {
write!(f, "{}", self.description())
}
EvalAltResult::ErrorArrayOutOfBounds(max, index) => {
write!(f, "{} (max {}): {}", self.description(), max - 1, index)
}
_ => write!(f, "{}", self.description()),
}
} }
} }
} }
@ -292,9 +312,15 @@ impl Engine {
let mut val = self.call_fn_raw(get_fn_name, vec![this_ptr])?; let mut val = self.call_fn_raw(get_fn_name, vec![this_ptr])?;
((*val).downcast_mut() as Option<&mut Vec<Box<dyn Any>>>) ((*val).downcast_mut() as Option<&mut Vec<Box<dyn Any>>>)
.and_then(|arr| idx.downcast_ref::<i64>().map(|idx| (arr, *idx as usize))) .and_then(|arr| idx.downcast_ref::<i64>().map(|idx| (arr, *idx)))
.map(|(arr, idx)| arr[idx].clone())
.ok_or(EvalAltResult::ErrorIndexMismatch) .ok_or(EvalAltResult::ErrorIndexMismatch)
.and_then(|(arr, idx)| match idx {
x if x < 0 => Err(EvalAltResult::ErrorArrayOutOfBounds(0, x)),
x => arr
.get(x as usize)
.cloned()
.ok_or(EvalAltResult::ErrorArrayOutOfBounds(arr.len(), x)),
})
} }
Expr::Dot(ref inner_lhs, ref inner_rhs) => match **inner_lhs { Expr::Dot(ref inner_lhs, ref inner_rhs) => match **inner_lhs {
Expr::Identifier(ref id) => { Expr::Identifier(ref id) => {
@ -335,11 +361,19 @@ impl Engine {
.eval_expr(scope, idx)? .eval_expr(scope, idx)?
.downcast::<i64>() .downcast::<i64>()
.map_err(|_| EvalAltResult::ErrorIndexMismatch)?; .map_err(|_| EvalAltResult::ErrorIndexMismatch)?;
let idx = *idx_boxed as usize; let idx_raw = *idx_boxed;
let idx = match idx_raw {
x if x < 0 => return Err(EvalAltResult::ErrorArrayOutOfBounds(0, x)),
x => x as usize,
};
let (idx_sc, val) = Self::search_scope(scope, id, |val| { let (idx_sc, val) = Self::search_scope(scope, id, |val| {
((*val).downcast_mut() as Option<&mut Vec<Box<dyn Any>>>) ((*val).downcast_mut() as Option<&mut Vec<Box<dyn Any>>>)
.map(|arr| arr[idx].clone())
.ok_or(EvalAltResult::ErrorIndexMismatch) .ok_or(EvalAltResult::ErrorIndexMismatch)
.and_then(|arr| {
arr.get(idx)
.cloned()
.ok_or(EvalAltResult::ErrorArrayOutOfBounds(arr.len(), idx_raw))
})
})?; })?;
Ok((idx_sc, idx, val)) Ok((idx_sc, idx, val))
@ -475,11 +509,11 @@ impl Engine {
for &mut (ref name, ref mut val) in &mut scope.iter_mut().rev() { for &mut (ref name, ref mut val) in &mut scope.iter_mut().rev() {
if *id == *name { if *id == *name {
if let Some(i) = idx.downcast_ref::<i64>() { if let Some(&i) = idx.downcast_ref::<i64>() {
if let Some(arr_typed) = if let Some(arr_typed) =
(*val).downcast_mut() as Option<&mut Vec<Box<dyn Any>>> (*val).downcast_mut() as Option<&mut Vec<Box<dyn Any>>>
{ {
arr_typed[*i as usize] = rhs_val; arr_typed[i as usize] = rhs_val;
return Ok(Box::new(())); return Ok(Box::new(()));
} else { } else {
return Err(EvalAltResult::ErrorIndexMismatch); return Err(EvalAltResult::ErrorIndexMismatch);