use bstr::BString; use crate::{    extension::{FsMonitor, Signature},    util::{read_u32, read_u64, split_at_byte_exclusive},}; #[derive(Clone)]pub enum Token {    V1 { nanos_since_1970: u64 },    V2 { token: BString },} pub const SIGNATURE: Signature = *b"FSMN"; pub fn decode(data: &[u8]) -> Option<FsMonitor> {    let (version, data) = read_u32(data)?;    let (token, data) = match version {        1 => {            let (nanos_since_1970, data) = read_u64(data)?;            (Token::V1 { nanos_since_1970 }, data)        }        2 => {            let (token, data) = split_at_byte_exclusive(data, 0)?;            (Token::V2 { token: token.into() }, data)        }        _ => return None,    };     let (ewah_size, data) = read_u32(data)?;    let (entry_dirty, data) = git_bitmap::ewah::decode(&data[..ewah_size as usize]).ok()?;     if !data.is_empty() {        return None;    }     FsMonitor { token, entry_dirty }.into()}