fix(get): Don't crash on bad negative bounds

Author: epage

src/path/mod.rs

@@ -40,11 +40,11 @@ impl std::fmt::Display for ParseError {
 
 impl std::error::Error for ParseError {}
 
-fn sindex_to_uindex(index: isize, len: usize) -> usize {
+fn sindex_to_uindex(index: isize, len: usize) -> Option<usize> {
     if index >= 0 {
-        index as usize
+        Some(index as usize)
     } else {
-        len - index.unsigned_abs()
+        len.checked_sub(index.unsigned_abs())
     }
 }
 
@@ -80,7 +80,7 @@ impl Expression {
             Self::Subscript(expr, index) => match expr.get(root) {
                 Some(value) => match value.kind {
                     ValueKind::Array(ref array) => {
-                        let index = sindex_to_uindex(index, array.len());
+                        let index = sindex_to_uindex(index, array.len())?;
 
                         if index >= array.len() {
                             None
@@ -141,7 +141,7 @@ impl Expression {
 
                     match value.kind {
                         ValueKind::Array(ref mut array) => {
-                            let index = sindex_to_uindex(index, array.len());
+                            let index = sindex_to_uindex(index, array.len())?;
 
                             if index >= array.len() {
                                 array.resize(index + 1, Value::new(None, ValueKind::Nil));
@@ -216,7 +216,7 @@ impl Expression {
                     }
 
                     if let ValueKind::Array(ref mut array) = parent.kind {
-                        let uindex = sindex_to_uindex(index, array.len());
+                        let uindex = sindex_to_uindex(index, array.len()).unwrap();
                         if uindex >= array.len() {
                             array.resize(uindex + 1, Value::new(None, ValueKind::Nil));
                         }

tests/testsuite/errors.rs

@@ -28,7 +28,6 @@ fn test_error_path_index_bounds() {
 
 #[test]
 #[cfg(feature = "json")]
-#[should_panic]
 fn test_error_path_index_negative_bounds() {
     let c = Config::builder()
         .add_source(File::from_str(
@@ -46,7 +45,7 @@ fn test_error_path_index_negative_bounds() {
     assert!(res.is_err());
     assert_data_eq!(
         res.unwrap_err().to_string(),
-        str![[r#"configuration property "arr[2]" not found"#]]
+        str![[r#"configuration property "arr[-1]" not found"#]]
     );
 }