Support excluding filesystems with -x

https://github.com/bootandy/dust/issues/50

Add optional -x flag to limit search to the current filesystem.

Add (untested) support for windows for the equivalent of inode and
device.

src/utils/platform.rs

@@ -1,4 +1,5 @@
 use jwalk::DirEntry;
+use std::fs;
 
 #[cfg(target_family = "unix")]
 fn get_block_size() -> u64 {
@@ -20,7 +21,16 @@ pub fn get_metadata(d: &DirEntry, use_apparent_size: bool) -> Option<(u64, Optio
     })
 }
 
-#[cfg(not(target_family = "unix"))]
+#[cfg(target_family = "windows")]
+pub fn get_metadata(d: &DirEntry, use_apparent_size: bool) -> Option<(u64, Option<(u64, u64)>)> {
+    use std::os::windows::fs::MetadataExt;
+    d.metadata.as_ref().unwrap().as_ref().ok().map(|md| {
+        let windows_equivalent_of_inode = Some((md.file_index(), md.volume_serial_number()));
+        (md.file_size(), windows_equivalent_of_inode)
+    })
+}
+
+#[cfg(all(not(target_family = "windows"), not(target_family = "unix")))]
 pub fn get_metadata(d: &DirEntry, _apparent: bool) -> Option<(u64, Option<(u64, u64)>)> {
     d.metadata
         .as_ref()
@@ -29,3 +39,22 @@ pub fn get_metadata(d: &DirEntry, _apparent: bool) -> Option<(u64, Option<(u64,
         .ok()
         .map(|md| (md.len(), None))
 }
+
+#[cfg(target_family = "unix")]
+pub fn get_filesystem(file_path: &str) -> Option<u64> {
+    use std::os::unix::fs::MetadataExt;
+    let metadata = fs::metadata(file_path).unwrap();
+    Some(metadata.dev())
+}
+
+#[cfg(target_family = "windows")]
+pub fn get_device(file_path: &str) -> Option<u64> {
+    use std::os::windows::fs::MetadataExt;
+    let metadata = fs::metadata(file_path).unwrap();
+    Some(metadata.volume_serial_number())
+}
+
+#[cfg(all(not(target_family = "windows"), not(target_family = "unix")))]
+pub fn get_device(file_path: &str) -> Option<u64> {
+    None
+}