use crate::data::File;use git_features::progress::Progress;use git_hash::SIZE_OF_SHA1_DIGEST as SHA1_SIZE;use std::sync::atomic::AtomicBool; /// Returned by [`File::verify_checksum()`]#[derive(thiserror::Error, Debug)]#[allow(missing_docs)]pub enum Error {    #[error("pack checksum mismatch: expected {expected}, got {actual}")]    Mismatch {        expected: git_hash::ObjectId,        actual: git_hash::ObjectId,    },    #[error("could not read pack file")]    Io(#[from] std::io::Error),} /// Checksums and verify checksumsimpl File {    /// The checksum in the trailer of this pack data file    pub fn checksum(&self) -> git_hash::ObjectId {        git_hash::ObjectId::from_20_bytes(&self.data[self.data.len() - SHA1_SIZE..])    }     /// Verifies that the checksum of the packfile over all bytes preceding it indeed matches the actual checksum,    /// returning the actual checksum equivalent to the return value of [`checksum()`][File::checksum()] if there    /// is no mismatch.    ///    /// Note that if no `progress` is desired, one can pass [`git_features::progress::Discard`].    ///    /// Have a look at [`index::File::verify_integrity(…)`][crate::index::File::verify_integrity()] for an    /// even more thorough integrity check.    pub fn verify_checksum(        &self,        mut progress: impl Progress,        should_interrupt: &AtomicBool,    ) -> Result<git_hash::ObjectId, Error> {        let right_before_trailer = self.data.len() - SHA1_SIZE;        let actual = match git_features::hash::bytes_of_file(            &self.path,            right_before_trailer,            git_hash::Kind::Sha1,            &mut progress,            should_interrupt,        ) {            Ok(id) => id,            Err(_io_err) => {                let start = std::time::Instant::now();                let mut hasher = git_features::hash::Sha1::default();                hasher.update(&self.data[..right_before_trailer]);                progress.inc_by(right_before_trailer);                progress.show_throughput(start);                git_hash::ObjectId::new_sha1(hasher.digest())            }        };         let expected = self.checksum();        if actual == expected {            Ok(actual)        } else {            Err(Error::Mismatch { actual, expected })        }    }}