Method seek

block/src/vhdx/mod.rs:168–201

Wrapper function to satisfy Seek trait implementation for VHDx disk. Updates the offset field in the Vhdx struct.

(&mut self, pos: SeekFrom)

    /// Wrapper function to satisfy Seek trait implementation for VHDx disk.
    /// Updates the offset field in the Vhdx struct.
    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
        let new_offset: Option<u64> = match pos {
            SeekFrom::Start(off) => Some(off),
            SeekFrom::End(off) => {
                if off < 0 {
                    0i64.checked_sub(off).and_then(|increment| {
                        self.virtual_disk_size().checked_sub(increment as u64)
                    })
                } else {
                    self.virtual_disk_size().checked_add(off as u64)
                }
            }
            SeekFrom::Current(off) => {
                if off < 0 {
                    0i64.checked_sub(off)
                        .and_then(|increment| self.current_offset.checked_sub(increment as u64))
                } else {
                    self.current_offset.checked_add(off as u64)
                }
            }
        };

        if let Some(o) = new_offset
            && o <= self.virtual_disk_size()
        {
            self.current_offset = o;
            return Ok(o);
        }

        Err(std::io::Error::new(
            std::io::ErrorKind::InvalidData,
            "Failed seek operation",
        ))
    }
}

impl BlockBackend for Vhdx {