block: add DiskFile::physical_size()

This is a pre-requisite for the bug fix in the following commit.

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

block/src/qcow/mod.rs

@@ -1811,6 +1811,12 @@ impl BlockBackend for QcowFile {
     fn logical_size(&self) -> std::result::Result<u64, crate::Error> {
         Ok(self.virtual_size())
     }
+
+    fn physical_size(&self) -> std::result::Result<u64, crate::Error> {
+        self.raw_file
+            .physical_size()
+            .map_err(crate::Error::GetFileMetadata)
+    }
 }
 
 // Returns an Error if the given offset doesn't align to a cluster boundary.

block/src/qcow/qcow_raw_file.rs

@@ -179,6 +179,10 @@ impl QcowRawFile {
         self.file.seek(SeekFrom::Start(address))?;
         self.file.write_all(&data[0..cluster_size])
     }
+
+    pub fn physical_size(&self) -> Result<u64, std::io::Error> {
+        self.file.metadata().map(|m| m.len())
+    }
 }
 
 impl Clone for QcowRawFile {

block/src/qcow/raw_file.rs

@@ -357,6 +357,10 @@ impl BlockBackend for RawFile {
     fn logical_size(&self) -> std::result::Result<u64, crate::Error> {
         Ok(self.metadata().map_err(crate::Error::RawFileError)?.len())
     }
+
+    fn physical_size(&self) -> std::result::Result<u64, crate::Error> {
+        Ok(self.metadata().map_err(crate::Error::RawFileError)?.len())
+    }
 }
 
 impl Clone for RawFile {