chore: use thiserror for seccomp::FilterError

Please see issue #3278 for context on this activity

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

Cargo.lock

@@ -16,6 +16,7 @@ bench = false
 event-manager = "0.3.0"
 libc = "0.2.146"
 serde_json = "1.0.78"
+thiserror = "1.0.32"
 timerfd = "1.3.0"
 
 api_server = { path = "../api_server" }

src/firecracker/Cargo.toml

@@ -1,6 +1,5 @@
 // Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
-use std::fmt;
 use std::fs::File;
 use std::io::{BufReader, Read};
 
@@ -16,35 +15,22 @@ const THREAD_CATEGORIES: [&str; 3] = ["vmm", "api", "vcpu"];
 const DESERIALIZATION_BYTES_LIMIT: Option<u64> = Some(100_000);
 
 /// Error retrieving seccomp filters.
-#[derive(fmt::Debug)]
+#[derive(Debug, thiserror::Error)]
 pub enum FilterError {
     /// Filter deserialitaion error.
+    #[error("Filter deserialization failed: {0}")]
     Deserialization(DeserializationError),
     /// Invalid thread categories.
+    #[error("Invalid thread categories: {0}")]
     ThreadCategories(String),
     /// Missing Thread Category.
+    #[error("Missing thread category: {0}")]
     MissingThreadCategory(String),
     /// File open error.
+    #[error("Filter file open error: {0}")]
     FileOpen(std::io::Error),
 }
 
-impl fmt::Display for FilterError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use self::FilterError::*;
-
-        match *self {
-            Deserialization(ref err) => write!(f, "Filter deserialization failed: {}", err),
-            ThreadCategories(ref categories) => {
-                write!(f, "Invalid thread categories: {}", categories)
-            }
-            MissingThreadCategory(ref category) => {
-                write!(f, "Missing thread category: {}", category)
-            }
-            FileOpen(ref err) => write!(f, "Filter file open error: {}", err),
-        }
-    }
-}
-
 /// Seccomp filter configuration.
 pub enum SeccompConfig {
     /// Seccomp filtering disabled.