Implement bounded Binary LLSD codec

crates/libremetaverse-types/src/compat.rs

@@ -16,9 +16,9 @@ use std::sync::{
 
 pub trait Collection<T> {}
 
-pub trait ReadWrite: std::io::Read + std::io::Write {}
+pub trait ReadWrite: std::io::Read + std::io::Write + std::io::Seek {}
 
-impl<T: std::io::Read + std::io::Write> ReadWrite for T {}
+impl<T: std::io::Read + std::io::Write + std::io::Seek> ReadWrite for T {}
 
 #[derive(Clone, Debug)]
 pub enum Object {

crates/libremetaverse-types/src/shim.rs

@@ -55,6 +55,13 @@ pub enum Error {
     InvalidOperation,
     /// An index or destination buffer boundary was exceeded.
     IndexOutOfRange,
+    /// Structured input was malformed at a byte or character position.
+    Parse {
+        /// Zero-based offset at which validation failed.
+        position: usize,
+        /// Static parser context suitable for diagnostics and fuzz triage.
+        context: &'static str,
+    },
     /// An operation observed a requested cancellation.
     Cancelled,
     /// An HTTP request completed with an unsuccessful response.
@@ -73,6 +80,7 @@ impl Error {
             | Self::Argument
             | Self::InvalidOperation
             | Self::IndexOutOfRange
+            | Self::Parse { .. }
             | Self::Cancelled
             | Self::HttpRequest
             | Self::Socket => None,
@@ -96,6 +104,9 @@ impl fmt::Display for Error {
                 formatter.write_str("operation was invalid for the current state")
             }
             Self::IndexOutOfRange => formatter.write_str("index was out of range"),
+            Self::Parse { position, context } => {
+                write!(formatter, "parse error at offset {position}: {context}")
+            }
             Self::Cancelled => formatter.write_str("operation was cancelled"),
             Self::HttpRequest => formatter.write_str("HTTP request failed"),
             Self::Socket => formatter.write_str("socket operation failed"),