Function convert_copy

block/src/qcow/mod.rs:2194–2223

(reader: &mut R, writer: &mut W, offset: u64, size: u64)

}

fn convert_copy<R, W>(reader: &mut R, writer: &mut W, offset: u64, size: u64) -> BlockResult<()>
where
    R: Read + Seek,
    W: Write + Seek,
{
    const CHUNK_SIZE: usize = 65536;
    let mut buf = [0; CHUNK_SIZE];
    let mut read_count = 0;
    reader
        .seek(SeekFrom::Start(offset))
        .map_err(|e| BlockError::new(BlockErrorKind::Io, Error::SeekingFile(e)))?;
    writer
        .seek(SeekFrom::Start(offset))
        .map_err(|e| BlockError::new(BlockErrorKind::Io, Error::SeekingFile(e)))?;
    loop {
        let this_count = min(CHUNK_SIZE as u64, size - read_count) as usize;
        let nread = reader
            .read(&mut buf[..this_count])
            .map_err(|e| BlockError::new(BlockErrorKind::Io, Error::ReadingData(e)))?;
        writer
            .write(&buf[..nread])
            .map_err(|e| BlockError::new(BlockErrorKind::Io, Error::WritingData(e)))?;
        read_count += nread as u64;
        if nread == 0 || read_count == size {
            break;
        }
    }

    Ok(())
}

fn convert_reader_writer<R, W>(reader: &mut R, writer: &mut W, size: u64) -> BlockResult<()>
where