From ab6e1bd2d8c3c2e4fe5add90033cb18ad43ee481 Mon Sep 17 00:00:00 2001
From: Philipp Schuster <philipp.schuster@cyberus-technology.de>
Date: Wed, 21 May 2025 13:32:31 +0200
Subject: [PATCH] misc: ch-remote: streamline #[source] and Error impl

This streamlines the Error implementation in the Cloud Hypervisor code
base to match the remaining parts so that everything follows the agreed
conventions. These are leftovers missed in the previous commits.

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
---
 src/bin/ch-remote.rs | 78 ++++++++++++++++++++------------------------
 1 file changed, 35 insertions(+), 43 deletions(-)

diff --git a/src/bin/ch-remote.rs b/src/bin/ch-remote.rs
index f807189d3..ba3692838 100644
--- a/src/bin/ch-remote.rs
+++ b/src/bin/ch-remote.rs
@@ -6,7 +6,7 @@
 use std::io::Read;
 use std::marker::PhantomData;
 use std::os::unix::net::UnixStream;
-use std::{fmt, process};
+use std::process;
 
 use api_client::{
     simple_api_command, simple_api_command_with_fds, simple_api_full_command,
@@ -14,6 +14,7 @@ use api_client::{
 };
 use clap::{Arg, ArgAction, ArgMatches, Command};
 use option_parser::{ByteSized, ByteSizedParseError};
+use thiserror::Error;
 use vmm::config::RestoreConfig;
 use vmm::vm_config::{
     DeviceConfig, DiskConfig, FsConfig, NetConfig, PmemConfig, UserDeviceConfig, VdpaConfig,
@@ -24,50 +25,41 @@ use zbus::{proxy, zvariant::Optional};
 
 type ApiResult = Result<(), Error>;
 
-#[derive(Debug)]
+#[derive(Error, Debug)]
 enum Error {
-    HttpApiClient(ApiClientError),
+    #[error("http client error: {0}")]
+    HttpApiClient(#[source] ApiClientError),
     #[cfg(feature = "dbus_api")]
-    DBusApiClient(zbus::Error),
-    InvalidCpuCount(std::num::ParseIntError),
-    InvalidMemorySize(ByteSizedParseError),
-    InvalidBalloonSize(ByteSizedParseError),
-    AddDeviceConfig(vmm::config::Error),
-    AddDiskConfig(vmm::config::Error),
-    AddFsConfig(vmm::config::Error),
-    AddPmemConfig(vmm::config::Error),
-    AddNetConfig(vmm::config::Error),
-    AddUserDeviceConfig(vmm::config::Error),
-    AddVdpaConfig(vmm::config::Error),
-    AddVsockConfig(vmm::config::Error),
-    Restore(vmm::config::Error),
-    ReadingStdin(std::io::Error),
-    ReadingFile(std::io::Error),
-}
-
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use Error::*;
-        match self {
-            HttpApiClient(e) => e.fmt(f),
-            #[cfg(feature = "dbus_api")]
-            DBusApiClient(e) => write!(f, "Error D-Bus proxy: {e}"),
-            InvalidCpuCount(e) => write!(f, "Error parsing CPU count: {e}"),
-            InvalidMemorySize(e) => write!(f, "Error parsing memory size: {e:?}"),
-            InvalidBalloonSize(e) => write!(f, "Error parsing balloon size: {e:?}"),
-            AddDeviceConfig(e) => write!(f, "Error parsing device syntax: {e}"),
-            AddDiskConfig(e) => write!(f, "Error parsing disk syntax: {e}"),
-            AddFsConfig(e) => write!(f, "Error parsing filesystem syntax: {e}"),
-            AddPmemConfig(e) => write!(f, "Error parsing persistent memory syntax: {e}"),
-            AddNetConfig(e) => write!(f, "Error parsing network syntax: {e}"),
-            AddUserDeviceConfig(e) => write!(f, "Error parsing user device syntax: {e}"),
-            AddVdpaConfig(e) => write!(f, "Error parsing vDPA device syntax: {e}"),
-            AddVsockConfig(e) => write!(f, "Error parsing vsock syntax: {e}"),
-            Restore(e) => write!(f, "Error parsing restore syntax: {e}"),
-            ReadingStdin(e) => write!(f, "Error reading from stdin: {e}"),
-            ReadingFile(e) => write!(f, "Error reading from file: {e}"),
-        }
-    }
+    #[error("dbus api client error: {0}")]
+    DBusApiClient(#[source] zbus::Error),
+    #[error("Error parsing CPU count: {0}")]
+    InvalidCpuCount(#[source] std::num::ParseIntError),
+    #[error("Error parsing memory size: {0}")]
+    InvalidMemorySize(#[source] ByteSizedParseError),
+    #[error("Error parsing balloon size: {0}")]
+    InvalidBalloonSize(#[source] ByteSizedParseError),
+    #[error("Error parsing device syntax: {0}")]
+    AddDeviceConfig(#[source] vmm::config::Error),
+    #[error("Error parsing disk syntax: {0}")]
+    AddDiskConfig(#[source] vmm::config::Error),
+    #[error("Error parsing filesystem syntax: {0}")]
+    AddFsConfig(#[source] vmm::config::Error),
+    #[error("Error parsing persistent memory syntax: {0}")]
+    AddPmemConfig(#[source] vmm::config::Error),
+    #[error("Error parsing network syntax: {0}")]
+    AddNetConfig(#[source] vmm::config::Error),
+    #[error("Error parsing user device syntax: {0}")]
+    AddUserDeviceConfig(#[source] vmm::config::Error),
+    #[error("Error parsing vDPA device syntax: {0}")]
+    AddVdpaConfig(#[source] vmm::config::Error),
+    #[error("Error parsing vsock syntax: {0}")]
+    AddVsockConfig(#[source] vmm::config::Error),
+    #[error("Error parsing restore syntax: {0}")]
+    Restore(#[source] vmm::config::Error),
+    #[error("Error reading from stdin: {0}")]
+    ReadingStdin(#[source] std::io::Error),
+    #[error("Error reading from file: {0}")]
+    ReadingFile(#[source] std::io::Error),
 }
 
 enum TargetApi<'a> {