refactor: validate Fdt on construction

src/error.rs

@@ -8,16 +8,14 @@
 
 //! Error types for the `dtoolkit` crate.
 
-use core::fmt::{self, Display, Formatter};
-
 use thiserror::Error;
 
-/// An error that can occur when parsing or accessing a device tree.
-#[derive(Clone, Debug, Eq, Error, PartialEq)]
-pub enum FdtError {
-    /// There was an error parsing the device tree.
-    #[error("{0}")]
-    Parse(#[from] FdtParseError),
+/// An error that can occur when accessing a standard node or property.
+#[derive(Copy, Clone, Debug, Eq, Error, PartialEq)]
+pub enum StandardError {
+    /// There was an error when converting the property value.
+    #[error("error occurred when converting the property value: {0}")]
+    PropertyConversion(#[from] PropertyError),
     /// The `status` property of a node had an invalid value.
     #[error("Invalid status value")]
     InvalidStatus,
@@ -30,17 +28,6 @@ pub enum FdtError {
     /// The required `/memory` node wasn't found.
     #[error("/memory node missing")]
     MemoryMissing,
-    /// The size of a prop-encoded-array property wasn't a multiple of the
-    /// expected element size.
-    #[error(
-        "prop-encoded-array property was {size} bytes, but should have been a multiple of {chunk} cells"
-    )]
-    PropEncodedArraySizeMismatch {
-        /// The size in bytes of the prop-encoded-array property.
-        size: usize,
-        /// The number of 4 byte cells expected in each element of the array.
-        chunk: usize,
-    },
     /// Tried to convert part of a prop-encoded-array property to a type which
     /// was too small.
     #[error("prop-encoded-array field too big for chosen type ({cells} cells)")]
@@ -53,6 +40,7 @@ pub enum FdtError {
 /// An error that can occur when parsing a device tree.
 #[derive(Clone, Debug, Eq, Error, PartialEq)]
 #[non_exhaustive]
+#[error("{kind} at offset {offset}")]
 pub struct FdtParseError {
     offset: usize,
     /// The type of the error that has occurred.
@@ -65,11 +53,6 @@ impl FdtParseError {
     }
 }
 
-impl Display for FdtParseError {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "{} at offset {}", self.kind, self.offset)
-    }
-}
 /// The kind of an error that can occur when parsing a device tree.
 #[derive(Clone, Debug, Eq, Error, PartialEq)]
 #[non_exhaustive]
@@ -103,3 +86,26 @@ pub enum FdtErrorKind {
     #[error("Memory reservation block has an entry that is unaligned or has invalid size")]
     MemReserveInvalid,
 }
+
+/// An error that can occur when parsing a property.
+#[derive(Debug, Clone, Copy, Error, PartialEq, Eq)]
+#[non_exhaustive]
+pub enum PropertyError {
+    /// The property's value has an invalid length for the requested conversion.
+    #[error("property has an invalid length")]
+    InvalidLength,
+    /// The property's value is not a valid string.
+    #[error("property is not a valid string")]
+    InvalidString,
+    /// The size of a prop-encoded-array property wasn't a multiple of the
+    /// expected element size.
+    #[error(
+        "prop-encoded-array property was {size} bytes, but should have been a multiple of {chunk} cells"
+    )]
+    PropEncodedArraySizeMismatch {
+        /// The size in bytes of the prop-encoded-array property.
+        size: usize,
+        /// The number of 4 byte cells expected in each element of the array.
+        chunk: usize,
+    },
+}