Add '-b'/'--apparent-size' option

This commit changes `diskus` default behavior: we now report "disk
usage" instead of "apparent size" in analogy to "du -sh".

At the same time however, we introduce a new `--apparent-size` option
which can be used to switch back to "apparent size".

closes #25

1 files changed, 23 insertions, 0 deletions

diff --git a/src/filesize.rs b/src/filesize.rs
new file mode 100644
index 0000000..0ac4c7e
--- /dev/null
+++ b/src/filesize.rs
@@ -0,0 +1,23 @@
+#[derive(Debug, Clone, Copy)]
+pub enum FilesizeType {
+    DiskUsage,
+    ApparentSize,
+}
+
+impl FilesizeType {
+    #[cfg(not(windows))]
+    pub fn size(self, metadata: &std::fs::Metadata) -> u64 {
+        use std::os::unix::fs::MetadataExt;
+
+        match self {
+            Self::ApparentSize => metadata.len(),
+            // block size is always 512 byte, see stat(2) manpage
+            Self::DiskUsage => metadata.blocks() * 512,
+        }
+    }
+
+    #[cfg(windows)]
+    pub fn size(self, metadata: &std::fs::Metadata) -> u64 {
+        metadata.len()
+    }
+}