From 06875127b2217808350946004e756301f8161d5a Mon Sep 17 00:00:00 2001
From: Daniel Verkamp <dverkamp@chromium.org>
Date: Wed, 18 Aug 2021 14:25:11 -0700
Subject: [PATCH] vhost: convert to ThisError and sort

BUG=b:197143586
TEST=cargo check

Change-Id: Ib3ecfa6e6c9fc88edcf592d511cacfd97b2dd195
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3105429
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
---
 Cargo.lock       |  2 ++
 vhost/Cargo.toml |  2 ++
 vhost/src/lib.rs | 50 +++++++++++++++++++++---------------------------
 3 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 23de9082c2..84bf53127f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1243,6 +1243,8 @@ dependencies = [
  "base",
  "libc",
  "net_util",
+ "remain",
+ "thiserror",
  "virtio_sys",
  "vm_memory",
 ]
diff --git a/vhost/Cargo.toml b/vhost/Cargo.toml
index 1e2253f8dd..63282b22fa 100644
--- a/vhost/Cargo.toml
+++ b/vhost/Cargo.toml
@@ -9,5 +9,7 @@ assertions = { path = "../assertions" }
 libc = "*"
 net_util = { path = "../net_util" }
 base = { path = "../base" }
+remain = "*"
+thiserror = "*"
 virtio_sys = { path = "../virtio_sys" }
 vm_memory = { path = "../vm_memory" }
diff --git a/vhost/src/lib.rs b/vhost/src/lib.rs
index 4a70599f31..c4287e3ec4 100644
--- a/vhost/src/lib.rs
+++ b/vhost/src/lib.rs
@@ -10,50 +10,44 @@ pub use crate::net::NetT;
 pub use crate::vsock::Vsock;
 
 use std::alloc::Layout;
-use std::fmt::{self, Display};
 use std::io::Error as IoError;
 use std::ptr::null;
 
 use assertions::const_assert;
 use base::{ioctl, ioctl_with_mut_ref, ioctl_with_ptr, ioctl_with_ref};
 use base::{AsRawDescriptor, Event, LayoutAllocation};
+use remain::sorted;
+use thiserror::Error;
 use vm_memory::{GuestAddress, GuestMemory, GuestMemoryError};
 
-#[derive(Debug)]
+#[sorted]
+#[derive(Error, Debug)]
 pub enum Error {
-    /// Error opening vhost device.
-    VhostOpen(IoError),
-    /// Error while running ioctl.
-    IoctlError(IoError),
-    /// Invalid queue.
-    InvalidQueue,
-    /// Invalid descriptor table address.
-    DescriptorTableAddress(GuestMemoryError),
-    /// Invalid used address.
-    UsedAddress(GuestMemoryError),
     /// Invalid available address.
+    #[error("invalid available address: {0}")]
     AvailAddress(GuestMemoryError),
+    /// Invalid descriptor table address.
+    #[error("invalid descriptor table address: {0}")]
+    DescriptorTableAddress(GuestMemoryError),
+    /// Invalid queue.
+    #[error("invalid queue")]
+    InvalidQueue,
+    /// Error while running ioctl.
+    #[error("failed to run ioctl: {0}")]
+    IoctlError(IoError),
     /// Invalid log address.
+    #[error("invalid log address: {0}")]
     LogAddress(GuestMemoryError),
+    /// Invalid used address.
+    #[error("invalid used address: {0}")]
+    UsedAddress(GuestMemoryError),
+    /// Error opening vhost device.
+    #[error("failed to open vhost device: {0}")]
+    VhostOpen(IoError),
 }
+
 pub type Result<T> = std::result::Result<T, Error>;
 
-impl Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use self::Error::*;
-
-        match self {
-            VhostOpen(e) => write!(f, "failed to open vhost device: {}", e),
-            IoctlError(e) => write!(f, "failed to run ioctl: {}", e),
-            InvalidQueue => write!(f, "invalid queue"),
-            DescriptorTableAddress(e) => write!(f, "invalid descriptor table address: {}", e),
-            UsedAddress(e) => write!(f, "invalid used address: {}", e),
-            AvailAddress(e) => write!(f, "invalid available address: {}", e),
-            LogAddress(e) => write!(f, "invalid log address: {}", e),
-        }
-    }
-}
-
 fn ioctl_result<T>() -> Result<T> {
     Err(Error::IoctlError(IoError::last_os_error()))
 }