From 2fd112ac9af2407dc0bf25ae4c4bbe318172b501 Mon Sep 17 00:00:00 2001
From: Wolfgang Bumiller <w.bumiller@proxmox.com>
Date: Fri, 24 Apr 2020 14:40:17 +0200
Subject: [PATCH] add Device::from_dev_t

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
 Cargo.toml    |  4 ++++
 src/format.rs | 24 +++++++++++++++++++++---
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 6abe73b..39dcf95 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,3 +38,7 @@ async-example = [
     "tokio/io-driver",
     "tokio/macros",
 ]
+
+[dev-dependencies]
+libc = "0.2"
+anyhow = "1.0"
diff --git a/src/format.rs b/src/format.rs
index e1e3ace..92dea96 100644
--- a/src/format.rs
+++ b/src/format.rs
@@ -321,9 +321,7 @@ impl XAttr {
     }
 
     pub fn name(&self) -> &CStr {
-        unsafe {
-            CStr::from_bytes_with_nul_unchecked(&self.data[..self.name_len+1])
-        }
+        unsafe { CStr::from_bytes_with_nul_unchecked(&self.data[..self.name_len + 1]) }
     }
 
     pub fn value(&self) -> &[u8] {
@@ -367,6 +365,26 @@ impl Device {
          (self.minor & 0x0000_00ff) |
         ((self.minor & 0xffff_ff00) << 12)
     }
+
+    /// Get a `Device` from a `dev_t` value.
+    #[rustfmt::skip]
+    pub fn from_dev_t(dev: u64) -> Self {
+        // see to_dev_t
+        Self {
+            major: (dev >>  8) & 0x0000_0fff |
+                   (dev >> 32) & 0xffff_f000,
+            minor:  dev        & 0x0000_00ff |
+                   (dev >> 12) & 0xffff_ff00,
+        }
+    }
+}
+
+#[cfg(all(test, target_os = "linux"))]
+#[test]
+fn test_linux_devices() {
+    let c_dev = unsafe { ::libc::makedev(0xabcd_1234, 0xdcba_5678) };
+    let dev = Device::from_dev_t(c_dev);
+    assert_eq!(dev.to_dev_t(), c_dev);
 }
 
 #[derive(Clone, Debug)]
-- 
2.39.2