From d2882b1d85b296d06e430af0981076c028382487 Mon Sep 17 00:00:00 2001
From: Tim Zhang <tim@hyper.sh>
Date: Fri, 13 Nov 2020 17:03:16 +0800
Subject: [PATCH] Print cause when println!("{}")

> Print like following:
unable to write to a control group file caused by: Os { code: 22, kind: InvalidInput, message: "Invalid argument" }) }

Signed-off-by: Tim Zhang <tim@hyper.sh>
---
 src/error.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/error.rs b/src/error.rs
index a8cd65c..26c86a8 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -66,7 +66,11 @@ impl fmt::Display for Error {
             ErrorKind::Other => "an unknown error".to_string(),
         };
 
-        write!(f, "{}", msg)
+        if let Some(cause) = &self.cause {
+            write!(f, "{} caused by: {:?}", msg, cause)
+        } else {
+            write!(f, "{}", msg)
+        }
     }
 }