tools/format: add struct to pretty print bytes

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/tools/format.rs

@@ -46,3 +46,49 @@ pub fn render_bool_with_default_true(value: &Value, _record: &Value) -> Result<S
     let value = value.as_bool().unwrap_or(true);
     Ok((if value { "1" } else { "0" }).to_string())
 }
+
+pub struct HumanByte {
+    b: usize,
+}
+impl std::fmt::Display for HumanByte {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.b < 1024 {
+            return write!(f, "{} B", self.b);
+        }
+        let kb: f64 = self.b as f64 / 1024.0;
+        if kb < 1024.0 {
+            return write!(f, "{:.2} KiB", kb);
+        }
+        let mb: f64 = kb / 1024.0;
+        if mb < 1024.0 {
+            return write!(f, "{:.2} MiB", mb);
+        }
+        let gb: f64 = mb / 1024.0;
+        if gb < 1024.0 {
+            return write!(f, "{:.2} GiB", gb);
+        }
+        let tb: f64 = gb / 1024.0;
+        if tb < 1024.0 {
+            return write!(f, "{:.2} TiB", tb);
+        }
+        let pb: f64 = tb / 1024.0;
+        return write!(f, "{:.2} PiB", pb);
+    }
+}
+impl From<usize> for HumanByte {
+    fn from(v: usize) -> Self {
+        HumanByte { b: v }
+    }
+}
+
+#[test]
+fn correct_byte_convert() {
+    fn convert(b: usize) -> String {
+         HumanByte::from(b).to_string()
+    }
+    assert_eq!(convert(1023), "1023 B");
+    assert_eq!(convert(1<<10), "1.00 KiB");
+    assert_eq!(convert(1<<20), "1.00 MiB");
+    assert_eq!(convert((1<<30) + (103 * 1<<20)), "1.10 GiB");
+    assert_eq!(convert((2<<50) + (500 * 1<<40)), "2.49 PiB");
+}