1 files changed, 25 insertions, 0 deletions
diff --git a/third_party/rust/walkdir/src/util.rs b/third_party/rust/walkdir/src/util.rs
new file mode 100644
index 0000000000..b9fcad8bf2
--- /dev/null
+++ b/third_party/rust/walkdir/src/util.rs
@@ -0,0 +1,25 @@
+use std::io;
+use std::path::Path;
+
+#[cfg(unix)]
+pub fn device_num<P: AsRef<Path>>(path: P) -> io::Result<u64> {
+    use std::os::unix::fs::MetadataExt;
+
+    path.as_ref().metadata().map(|md| md.dev())
+}
+
+#[cfg(windows)]
+pub fn device_num<P: AsRef<Path>>(path: P) -> io::Result<u64> {
+    use winapi_util::{file, Handle};
+
+    let h = Handle::from_path_any(path)?;
+    file::information(h).map(|info| info.volume_serial_number())
+}
+
+#[cfg(not(any(unix, windows)))]
+pub fn device_num<P: AsRef<Path>>(_: P) -> io::Result<u64> {
+    Err(io::Error::new(
+        io::ErrorKind::Other,
+        "walkdir: same_file_system option not supported on this platform",
+    ))
+}