Function patch_range_in 

fn patch_range_in(
    tx: &Transaction<'_>,
    zone_id: &str,
    name: &str,
    offset: i64,
    data: &[u8],
) -> Result<(), StoreError>

Write data at byte offset of a file’s stored parts, inside tx, reading and rewriting only the parts the range touches. A part shorter than the range is extended (with zeros up to offset, which callers never leave as a gap). Leaves the file’s recorded size to the caller.