From f444ef6ccf2c8f750bb93456d12b7d969034f52a Mon Sep 17 00:00:00 2001
From: Sebastien Boeuf <sebastien.boeuf@intel.com>
Date: Fri, 24 Jan 2020 08:58:21 +0100
Subject: [PATCH] vfio: Fix map_err losing the inner error

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
---
 vfio/src/vfio_device.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/vfio/src/vfio_device.rs b/vfio/src/vfio_device.rs
index 9c40c5189..0e2076a67 100644
--- a/vfio/src/vfio_device.rs
+++ b/vfio/src/vfio_device.rs
@@ -13,6 +13,7 @@ use std::fmt;
 use std::fs::{File, OpenOptions};
 use std::io;
 use std::mem;
+use std::num;
 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
 use std::os::unix::prelude::FileExt;
 use std::path::{Path, PathBuf};
@@ -48,6 +49,8 @@ pub enum VfioError {
     IommuDmaUnmap,
     VfioDeviceGetIrqInfo,
     VfioDeviceSetIrq,
+    ReadLink(io::Error),
+    ParseInt(num::ParseIntError),
 }
 pub type Result<T> = std::result::Result<T, VfioError>;
 
@@ -96,6 +99,8 @@ impl fmt::Display for VfioError {
             }
             VfioError::VfioDeviceGetIrqInfo => write!(f, "failed to get vfio device irq info"),
             VfioError::VfioDeviceSetIrq => write!(f, "failed to set vfio deviece irq"),
+            VfioError::ReadLink(e) => write!(f, "failed to read link from path: {}", e),
+            VfioError::ParseInt(e) => write!(f, "failed to parse integer: {}", e),
         }
     }
 }
@@ -593,12 +598,10 @@ impl VfioDevice {
         iommu_attached: bool,
     ) -> Result<Self> {
         let uuid_path: PathBuf = [sysfspath, Path::new("iommu_group")].iter().collect();
-        let group_path = uuid_path.read_link().map_err(|_| VfioError::InvalidPath)?;
+        let group_path = uuid_path.read_link().map_err(VfioError::ReadLink)?;
         let group_osstr = group_path.file_name().ok_or(VfioError::InvalidPath)?;
         let group_str = group_osstr.to_str().ok_or(VfioError::InvalidPath)?;
-        let group_id = group_str
-            .parse::<u32>()
-            .map_err(|_| VfioError::InvalidPath)?;
+        let group_id = group_str.parse::<u32>().map_err(VfioError::ParseInt)?;
 
         let group = VfioGroup::new(group_id, device_fd)?;
         let device_info = group.get_device(sysfspath)?;