OXYGENHUB
# 6706bdcfb63e oxygen / crates / oxy-core / src / repo / sync.rs
44.3 KiB · Rust · last changed Lazy blobs: clone --max-blob / filter.max-blob, absent-blob registry fetched on first read, objects endpoint (spec 0.6e) 1 month ago source blame history raw
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//! Serving and talking to remotes (spec §10.2, §16).
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use super::*;
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/// What a fetch brought in.
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#[derive(Debug, Clone, PartialEq, Eq, Default)]
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pub struct FetchReport {
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    /// Bookmark name, its heads, and how many changes were new.
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    pub refs: Vec<(String, Vec<ChangeHash>, usize)>,
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    /// Tags adopted from the remote.
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    pub new_tags: usize,
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    /// The remote has never presented a policy, so nothing was verified
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    /// against one (spec §14.5: warn loudly).
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    pub unverified: bool,
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}
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct PullReport {
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    pub heads: Vec<ChangeHash>,
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    pub changed: bool,
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    pub checked_out: bool,
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}
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impl Repo {
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    // ------------------------------------------------------------ serving (spec §16)
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    fn ref_attest_path(&self, bookmark: &str) -> PathBuf {
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        self.oxy.join("attest").join(bookmark)
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    }
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    /// The latest reference attestation stored for a bookmark.
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    pub fn latest_ref_attest(&self, bookmark: &str) -> Result<Option<(ObjectRef, SignedAttest)>> {
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        match fs::read_to_string(self.ref_attest_path(bookmark)) {
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            Ok(h) => {
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                let r = ObjectRef::from_hex(h.trim()).ok_or_else(|| RepoError::Msg("corrupt attestation pointer".into()))?;
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                Ok(Some((r, SignedAttest { attest: self.store.get_attest(&r)?, sigs: self.store.signatures(&r)? })))
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            }
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            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(None),
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            Err(e) => Err(e.into()),
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        }
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    }
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    fn set_ref_attest(&self, bookmark: &str, r: &ObjectRef) -> Result<()> {
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        fs::create_dir_all(self.oxy.join("attest"))?;
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        write_atomic(&self.ref_attest_path(bookmark), r.to_hex().as_bytes())
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    }
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    pub fn remote_refs(&self) -> Result<RefsResponse> {
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        let view = self.view()?;
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        let mut out = Vec::new();
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        for (name, state) in &view.bookmarks {
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            let latest = self.latest_ref_attest(name)?.map(|(_, a)| a);
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            let last_serial = latest.as_ref().and_then(|a| match a.attest.body {
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                AttestBody::Ref { serial, .. } => Some(serial),
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                _ => None,
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            });
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            let attestation = latest.filter(|a| matches!(&a.attest.body, AttestBody::Ref { new_state, .. } if new_state == state));
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            out.push(RemoteRef { name: name.clone(), state: *state, heads: self.store.get_state(state)?.heads, attestation, last_serial });
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        }
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        Ok(RefsResponse { refs: out, policy: self.current_policy()?.map(|(_, sp)| sp), tags: self.tag_refs()? })
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    }
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    /// Every change reachable from `heads` that is in the store.
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    fn closure_in_store(&self, heads: &[ChangeHash]) -> Result<BTreeSet<ChangeHash>> {
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        let mut seen = BTreeSet::new();
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        let mut stack: Vec<ChangeHash> = heads.to_vec();
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        while let Some(h) = stack.pop() {
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            if seen.contains(&h) || !self.store.has(&h) {
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                continue;
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            }
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            seen.insert(h);
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            stack.extend(self.store.get_change(&h)?.deps);
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        }
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        Ok(seen)
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    }
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    /// The changes within `depth` dependency steps of `heads` (spec §17),
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    /// nearest first; depth 1 is the heads themselves.
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    pub fn shallow_changes(&self, heads: &[ChangeHash], depth: u32) -> Result<Vec<ChangeHash>> {
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        let mut out = Vec::new();
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        let mut seen: BTreeSet<ChangeHash> = BTreeSet::new();
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        let mut layer: Vec<ChangeHash> = heads.to_vec();
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        for _ in 0..depth.max(1) {
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            let mut next = Vec::new();
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            for h in layer {
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                if !seen.insert(h) || !self.store.has(&h) {
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                    continue;
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                }
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                let c = self.store.get_change(&h)?;
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                next.extend(c.deps.iter().copied());
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                out.push(h);
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            }
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            if next.is_empty() {
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                break;
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            }
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            layer = next;
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        }
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        out.reverse();
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        Ok(out)
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    }
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    fn shallow_path(&self) -> PathBuf {
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        self.oxy.join("shallow")
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    }
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    /// The shallow boundary: dependencies this repository does not hold (spec §17).
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    pub fn boundary(&self) -> BTreeSet<ChangeHash> {
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        fs::read_to_string(self.shallow_path()).map(|t| t.lines().filter_map(ObjectRef::from_hex).collect()).unwrap_or_default()
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    }
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    pub fn is_shallow(&self) -> bool {
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        !self.boundary().is_empty()
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    }
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    fn write_boundary(&self, boundary: &BTreeSet<ChangeHash>) -> Result<()> {
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        if boundary.is_empty() {
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            let _ = fs::remove_file(self.shallow_path());
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            return Ok(());
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        }
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        let text: String = boundary.iter().map(|h| format!("{}\n", h.to_hex())).collect();
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        write_atomic(&self.shallow_path(), text.as_bytes())
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    }
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    /// Recompute the boundary from what is stored: every dependency of a
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    /// stored change that is not itself stored.
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    fn refresh_boundary(&self, imported: &[ChangeHash]) -> Result<()> {
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        let mut boundary = self.boundary();
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        boundary.retain(|h| !self.store.has(h));
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        for h in imported {
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            for d in self.store.get_change(h)?.deps {
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                if !self.store.has(&d) {
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                    boundary.insert(d);
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                }
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            }
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        }
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        self.write_boundary(&boundary)
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    }
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    /// Fetch `depth` more levels of history below the shallow boundary.
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    pub fn deepen(&self, remote_name: &str, depth: u32) -> Result<usize> {
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        let boundary = self.boundary();
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        if boundary.is_empty() {
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            return Ok(0);
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        }
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        let remote = self.open_named_remote(remote_name)?;
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        let wanted = remote.shallow(&boundary.iter().copied().collect::<Vec<_>>(), depth)?;
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        let bundle = remote.fetch(&wanted, self.config.max_blob)?;
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        let imported = self.import_bundle_shallow(&bundle, false)?;
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        if self.config.max_blob.is_some() {
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            self.register_missing_blobs(&imported, remote_name)?;
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        }
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        self.refresh_boundary(&imported)?;
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        Ok(imported.len())
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    }
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    /// `closure(want) \ closure(have)`, dependencies first (spec §16.2).
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    pub fn negotiate(&self, have: &[ChangeHash], want: &[ChangeHash]) -> Result<Vec<ChangeHash>> {
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        let have = self.closure_in_store(have)?;
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        // In a shallow repository the walk stops at the boundary, whose
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        // changes the remote is assumed to hold.
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        let boundary = self.boundary();
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        let mut out = Vec::new();
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        let mut done: BTreeSet<ChangeHash> = have.clone();
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        done.extend(boundary.iter().copied());
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        // Iterative post-order DFS.
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        let mut stack: Vec<(ChangeHash, bool)> = want.iter().rev().map(|h| (*h, false)).collect();
167 
        while let Some((h, expanded)) = stack.pop() {
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            if done.contains(&h) {
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                continue;
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            }
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            if !self.store.has(&h) {
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                return fail(format!("change {} is not in this repository", h.short(12)));
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            }
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            if expanded {
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                done.insert(h);
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                out.push(h);
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                continue;
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            }
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            stack.push((h, true));
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            for d in self.store.get_change(&h)?.deps {
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                if !done.contains(&d) {
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                    stack.push((d, false));
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                }
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            }
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        }
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        Ok(out)
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    }
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    /// Bundle changes (in the given dependency order) with their signatures,
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    /// seals, identities, blobs, chunks.
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    pub fn bundle_for(&self, changes: &[ChangeHash]) -> Result<Bundle> {
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        self.bundle_for_filtered(changes, None)
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    }
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    /// Objects by reference for the `objects` endpoint; a blob brings its chunks.
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    pub fn objects_for(&self, refs: &[ObjectRef]) -> Result<Vec<(ObjectType, Vec<u8>)>> {
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        let mut out = Vec::new();
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        for r in refs {
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            let (ty, body) = match self.store.get(r) {
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                Ok(x) => x,
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                Err(StoreError::NotFound(_)) => continue,
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                Err(e) => return Err(e.into()),
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            };
204 
            if ty == ObjectType::Blob {
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                for c in Blob::decode(&body)?.chunks {
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                    if let Ok((cty, cb)) = self.store.get(&c) {
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                        out.push((cty, cb));
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                    }
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                }
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            }
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            out.push((ty, body));
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        }
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        Ok(out)
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    }
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    /// Like `bundle_for`, leaving out blobs larger than `max_blob` bytes
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    /// (and their chunks) so the receiver fetches them lazily (spec §13.5).
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    pub fn bundle_for_filtered(&self, changes: &[ChangeHash], max_blob: Option<u64>) -> Result<Bundle> {
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        let mut bundle = Bundle::default();
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        let mut objects: BTreeSet<ObjectRef> = BTreeSet::new();
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        let mut seals: BTreeSet<ObjectRef> = BTreeSet::new();
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        let add_object = |r: &ObjectRef, objects: &mut BTreeSet<ObjectRef>| {
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            if !r.is_zero() && self.store.has(r) {
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                objects.insert(*r);
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            }
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        };
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        for h in changes {
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            let c = self.store.get_change(h)?;
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            let sigs = self.store.signatures(h)?;
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            add_object(&c.author, &mut objects);
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            for s in &sigs {
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                add_object(&s.key, &mut objects);
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            }
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            for e in &c.edits {
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                if let Edit::Replace { old, new, .. } = e {
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                    for b in [old, new].into_iter().flatten() {
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                        if self.store.has(b) {
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                            if let Ok(blob) = Blob::decode(&self.store.get_typed(b, ObjectType::Blob)?) {
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                                if max_blob.is_some_and(|m| blob.length > m) {
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                                    continue;
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                                }
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                                objects.insert(*b);
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                                objects.extend(blob.chunks.iter().copied());
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                            }
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                        }
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                    }
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                }
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            }
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            for s in self.store.seals_for(h)? {
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                seals.insert(s);
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            }
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            bundle.changes.push((c, sigs));
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        }
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        for r in seals {
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            let attest = self.store.get_attest(&r)?;
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            let sigs = self.store.signatures(&r)?;
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            for s in &sigs {
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                add_object(&s.key, &mut objects);
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            }
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            bundle.attests.push(SignedAttest { attest, sigs });
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        }
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        for r in objects {
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            let (ty, body) = self.store.get(&r)?;
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            bundle.objects.push((ty, body));
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        }
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        Ok(bundle)
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    }
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    /// Store a bundle's contents. With `strict`, every change must
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    /// authenticate (signature or seal by its author or a delegate).
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    pub fn import_bundle(&self, bundle: &Bundle, strict: bool) -> Result<Vec<ChangeHash>> {
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        self.import_bundle_inner(bundle, strict, false)
273 
    }
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    /// Like `import_bundle`, accepting changes whose dependencies are absent
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    /// (they join the shallow boundary).
277 
    pub fn import_bundle_shallow(&self, bundle: &Bundle, strict: bool) -> Result<Vec<ChangeHash>> {
278 
        self.import_bundle_inner(bundle, strict, true)
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    }
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    fn import_bundle_inner(&self, bundle: &Bundle, strict: bool, shallow: bool) -> Result<Vec<ChangeHash>> {
282 
        for (ty, body) in &bundle.objects {
283 
            match ty {
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                ObjectType::Chunk | ObjectType::Blob | ObjectType::Identity | ObjectType::State | ObjectType::Checkpoint => {
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                    self.store.put(*ty, body)?;
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                }
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                other => return fail(format!("bundle may not carry {} objects", other.name())),
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            }
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        }
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        for sa in &bundle.attests {
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            let r = self.store.put_attest(&sa.attest)?;
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            for sig in &sa.sigs {
293 
                self.store.put_signature(&r, sig)?;
294 
            }
295 
            if let AttestBody::Seal { hashes } = &sa.attest.body {
296 
                for h in hashes {
297 
                    self.store.index_seal(h, &r)?;
298 
                }
299 
            }
300 
        }
301 
        let incoming: BTreeSet<ChangeHash> = bundle.changes.iter().map(|(c, _)| c.hash()).collect();
302 
        let boundary = self.boundary();
303 
        let mut imported = Vec::new();
304 
        for (c, sigs) in &bundle.changes {
305 
            let h = c.hash();
306 
            for d in &c.deps {
307 
                if !self.store.has(d) && !incoming.contains(d) && !shallow && !boundary.contains(d) {
308 
                    return fail(format!("change {} depends on {}, which is neither stored nor in the bundle", h.short(12), d.short(12)));
309 
                }
310 
            }
311 
            self.store.put_change(c)?;
312 
            for sig in sigs {
313 
                self.store.put_signature(&h, sig)?;
314 
            }
315 
            imported.push(h);
316 
        }
317 
        if strict {
318 
            for h in &imported {
319 
                if !matches!(self.authenticate_change(h)?, SignatureStatus::Valid { .. }) {
320 
                    return fail(format!("change {} is not authenticated by its author", h.short(12)));
321 
                }
322 
            }
323 
        }
324 
        Ok(imported)
325 
    }
326
327 
    /// Verify a reference attestation against an update it claims to describe.
328 
    /// `allow_equal` lets a client re-read the attestation it already has; a
329 
    /// server receiving a push requires a strictly greater serial.
330 
    fn check_ref_attest(&self, sa: &SignedAttest, name: &str, old_state: &ObjectRef, new_state: &ObjectRef, last_serial: Option<u64>, allow_equal: bool) -> std::result::Result<u64, String> {
331 
        let AttestBody::Ref { name: n, old_state: o, new_state: nw, serial } = &sa.attest.body else {
332 
            return Err("attestation is not a ref attestation".into());
333 
        };
334 
        if n != name || o != old_state || nw != new_state {
335 
            return Err("attestation does not describe this update".into());
336 
        }
337 
        if sa.attest.repo != self.id().map_err(|e| e.to_string())? {
338 
            return Err("attestation is for a different repository".into());
339 
        }
340 
        if let Some(last) = last_serial {
341 
            if *serial < last || (*serial == last && !allow_equal) {
342 
                return Err(format!("attestation serial {serial} is not greater than the last seen {last}"));
343 
            }
344 
        }
345 
        let r = sa.attest.hash();
346 
        let sig = sa.sigs.first().ok_or("attestation carries no signature")?;
347 
        let id = self.store.get_identity(&sig.key).map_err(|_| format!("unknown key {}", sig.key.short(12)))?;
348 
        verify_signature(&id, sig, Domain::Attest, &r).map_err(|e| e.to_string())?;
349 
        Ok(*serial)
350 
    }
351
352 
    /// Accept a push (spec §16.4). Without a trust policy every repository
353 
    /// is unverified, so unsigned changes and unattested updates are accepted;
354 
    /// attestations that are present must still be valid. With a policy,
355 
    /// every change and update is checked against it. A newer policy in the
356 
    /// push is applied first when it is signed by the current roots.
357 
    pub fn receive_push(&self, bundle: Bundle, updates: Vec<RefUpdate>, policy: Option<SignedPolicy>, tags: Vec<crate::protocol::TagRef>) -> Result<Vec<RefResult>> {
358 
        let mut results = Vec::new();
359 
        if let Some(sp) = policy {
360 
            let current = self.current_policy()?.map(|(_, c)| c.policy);
361 
            match self.check_policy(&sp, current.as_ref()) {
362 
                Ok(()) => {
363 
                    self.set_policy(&sp, &format!("push received: policy serial {}", sp.policy.serial))?;
364 
                    results.push(RefResult { name: "policy".into(), ok: true, reason: format!("serial {}", sp.policy.serial) });
365 
                }
366 
                Err(e) => {
367 
                    results.push(RefResult { name: "policy".into(), ok: false, reason: e });
368 
                    for u in updates {
369 
                        results.push(RefResult { name: u.name, ok: false, reason: "policy update was rejected".into() });
370 
                    }
371 
                    return Ok(results);
372 
                }
373 
            }
374 
        }
375 
        let policy = self.current_policy()?.map(|(_, sp)| sp.policy);
376 
        if let Err(e) = self.import_bundle(&bundle, policy.is_some()) {
377 
            for u in updates {
378 
                results.push(RefResult { name: u.name, ok: false, reason: e.to_string() });
379 
            }
380 
            return Ok(results);
381 
        }
382 
        let (op_ref, op) = self.head_op()?;
383 
        let mut view = op.view.clone();
384 
        let mut names = Vec::new();
385 
        for u in updates {
386 
            let outcome = self.apply_update(&mut view, &u, policy.as_ref());
387 
            let (ok, reason) = match outcome {
388 
                Ok(()) => (true, String::new()),
389 
                Err(e) => (false, e),
390 
            };
391 
            if ok {
392 
                names.push(u.name.clone());
393 
            }
394 
            results.push(RefResult { name: u.name, ok, reason });
395 
        }
396 
        for t in &tags {
397 
            let name = format!("tags/{}", t.name);
398 
            match self.adopt_tag(&mut view, t, policy.as_ref()) {
399 
                Ok(()) => {
400 
                    names.push(name.clone());
401 
                    results.push(RefResult { name, ok: true, reason: String::new() });
402 
                }
403 
                Err(e) => results.push(RefResult { name, ok: false, reason: e }),
404 
            }
405 
        }
406 
        if !names.is_empty() {
407 
            self.record_op(&[op_ref], &format!("push received: {}", names.join(" ")), view)?;
408 
        }
409 
        Ok(results)
410 
    }
411
412 
    fn apply_update(&self, view: &mut View, u: &RefUpdate, policy: Option<&crate::policy::Policy>) -> std::result::Result<(), String> {
413 
        if u.name == "policy" {
414 
            return Err("the policy reference is updated by sending a policy, not a bookmark update".into());
415 
        }
416 
        let empty = self.store.put_state(&StateObject::new(vec![])).map_err(|e| e.to_string())?;
417 
        let current = view.bookmarks.get(&u.name).copied().unwrap_or(empty);
418 
        if current != u.old_state {
419 
            return Err("stale: the remote bookmark has moved; pull first".into());
420 
        }
421 
        let new_state = self.store.get_state(&u.new_state).map_err(|_| "new state object is missing".to_string())?;
422 
        for h in &new_state.heads {
423 
            if !self.store.has(h) {
424 
                return Err(format!("head {} is missing", h.short(12)));
425 
            }
426 
        }
427 
        if !u.force {
428 
            let old_heads = self.store.get_state(&current).map_err(|e| e.to_string())?.heads;
429 
            let closure = self.closure_in_store(&new_state.heads).map_err(|e| e.to_string())?;
430 
            if let Some(h) = old_heads.iter().find(|h| !closure.contains(h)) {
431 
                return Err(format!("not a fast-forward: current head {} would be dropped (use --force)", h.short(12)));
432 
            }
433 
        }
434 
        if let Some(p) = policy {
435 
            let Some(sa) = &u.attestation else {
436 
                return Err(format!("{:?} requires a signed reference attestation under this repository's policy", u.name));
437 
            };
438 
            let signer = sa.sigs.first().map(|s| s.key).ok_or("attestation carries no signature")?;
439 
            if !p.authorizes(&signer, &u.name) {
440 
                return Err(format!("key {} may not update {:?} under this repository's policy", signer.short(12), u.name));
441 
            }
442 
            let old_heads = self.store.get_state(&current).map_err(|e| e.to_string())?.heads;
443 
            self.state_allowed(&old_heads, &new_state.heads, p, &u.name)?;
444 
        }
445 
        if let Some(sa) = &u.attestation {
446 
            let last = self.latest_ref_attest(&u.name).map_err(|e| e.to_string())?.and_then(|(_, a)| match a.attest.body {
447 
                AttestBody::Ref { serial, .. } => Some(serial),
448 
                _ => None,
449 
            });
450 
            self.check_ref_attest(sa, &u.name, &u.old_state, &u.new_state, last, false)?;
451 
            let r = self.store.put_attest(&sa.attest).map_err(|e| e.to_string())?;
452 
            for sig in &sa.sigs {
453 
                self.store.put_signature(&r, sig).map_err(|e| e.to_string())?;
454 
            }
455 
            self.set_ref_attest(&u.name, &r).map_err(|e| e.to_string())?;
456 
        }
457 
        view.bookmarks.insert(u.name.clone(), u.new_state);
458 
        Ok(())
459 
    }
460
461 
    // ------------------------------------------------------------ client side
462
463 
    fn remote_url(&self, name: &str) -> Result<String> {
464 
        self.config.remotes.get(name).cloned().ok_or_else(|| RepoError::Msg(format!("no remote named {name:?}; add one with `oxy remote add`")))
465 
    }
466
467 
    /// Credentials and trust for a remote: `remote.<name>.token` (else
468 
    /// `$OXY_TOKEN`) and `remote.<name>.ca` (else `$OXY_CA`).
469 
    fn remote_options(&self, name: &str) -> RemoteOptions {
470 
        RemoteOptions {
471 
            token: self.config.remote_tokens.get(name).cloned().or_else(|| std::env::var("OXY_TOKEN").ok()),
472 
            ca: self.config.remote_cas.get(name).map(PathBuf::from).or_else(|| std::env::var("OXY_CA").ok().map(PathBuf::from)),
473 
        }
474 
    }
475
476 
    fn open_named_remote(&self, name: &str) -> Result<Box<dyn crate::protocol::Remote>> {
477 
        open_remote(&self.remote_url(name)?, &self.remote_options(name))
478 
    }
479
480 
    fn serial_path(&self, remote: &str, bookmark: &str) -> PathBuf {
481 
        self.oxy.join("remotes").join(remote).join(format!("{bookmark}.serial"))
482 
    }
483
484 
    fn last_seen_serial(&self, remote: &str, bookmark: &str) -> Option<u64> {
485 
        fs::read_to_string(self.serial_path(remote, bookmark)).ok().and_then(|s| s.trim().parse().ok())
486 
    }
487
488 
    fn record_serial(&self, remote: &str, bookmark: &str, serial: u64) -> Result<()> {
489 
        let p = self.serial_path(remote, bookmark);
490 
        fs::create_dir_all(p.parent().unwrap())?;
491 
        write_atomic(&p, serial.to_string().as_bytes())
492 
    }
493
494 
    fn policy_serial_path(&self, remote: &str) -> PathBuf {
495 
        self.oxy.join("remotes").join(remote).join("policy.serial")
496 
    }
497
498 
    /// The highest policy serial `remote` has ever presented.
499 
    fn remote_policy_serial(&self, remote: &str) -> Option<u64> {
500 
        fs::read_to_string(self.policy_serial_path(remote)).ok().and_then(|s| s.trim().parse().ok())
501 
    }
502
503 
    fn record_policy_serial(&self, remote: &str, serial: u64) -> Result<()> {
504 
        let p = self.policy_serial_path(remote);
505 
        fs::create_dir_all(p.parent().unwrap())?;
506 
        write_atomic(&p, serial.to_string().as_bytes())
507 
    }
508
509 
    fn lazy_dir(&self) -> PathBuf {
510 
        self.oxy.join("lazy")
511 
    }
512
513 
    /// Remember that `blob` was withheld by `remote` (spec §13.5).
514 
    fn register_lazy(&self, blob: &ObjectRef, remote: &str) -> Result<()> {
515 
        fs::create_dir_all(self.lazy_dir())?;
516 
        write_atomic(&self.lazy_dir().join(blob.to_hex()), remote.as_bytes())
517 
    }
518
519 
    /// Which remote promised an absent blob, if any.
520 
    pub fn lazy_remote(&self, blob: &ObjectRef) -> Option<String> {
521 
        fs::read_to_string(self.lazy_dir().join(blob.to_hex())).ok().map(|s| s.trim().to_string())
522 
    }
523
524 
    /// Fetch an absent blob (and its chunks) from the remote that promised it.
525 
    pub(crate) fn fetch_lazy_blob(&self, blob: &ObjectRef) -> Result<()> {
526 
        let Some(remote_name) = self.lazy_remote(blob) else {
527 
            return Err(RepoError::Store(StoreError::NotFound(*blob)));
528 
        };
529 
        let remote = self.open_named_remote(&remote_name)?;
530 
        let objects = remote.objects(&[*blob])?;
531 
        for (ty, body) in objects {
532 
            if matches!(ty, ObjectType::Blob | ObjectType::Chunk) {
533 
                self.store.put(ty, &body)?;
534 
            }
535 
        }
536 
        if !self.store.has(blob) {
537 
            return fail(format!("{remote_name} did not send blob {}", blob.short(12)));
538 
        }
539 
        let _ = fs::remove_file(self.lazy_dir().join(blob.to_hex()));
540 
        Ok(())
541 
    }
542
543 
    /// After importing from `remote`, record every blob the changes reference
544 
    /// that the store lacks as lazily available from that remote.
545 
    fn register_missing_blobs(&self, changes: &[ChangeHash], remote: &str) -> Result<usize> {
546 
        let mut n = 0;
547 
        for h in changes {
548 
            let c = self.store.get_change(h)?;
549 
            for e in &c.edits {
550 
                if let Edit::Replace { old, new, .. } = e {
551 
                    for b in [old, new].into_iter().flatten() {
552 
                        if !self.store.has(b) {
553 
                            self.register_lazy(b, remote)?;
554 
                            n += 1;
555 
                        }
556 
                    }
557 
                }
558 
            }
559 
        }
560 
        Ok(n)
561 
    }
562
563 
    /// Every head this repository knows: bookmarks, remote tracking, working copy.
564 
    fn known_heads(&self, view: &View) -> Result<Vec<ChangeHash>> {
565 
        let mut have: BTreeSet<ChangeHash> = BTreeSet::new();
566 
        for st in view.bookmarks.values().chain(view.remotes.values().flat_map(|b| b.values())) {
567 
            if let Ok(s) = self.store.get_state(st) {
568 
                have.extend(s.heads);
569 
            }
570 
        }
571 
        have.extend(view.workspaces.values().copied());
572 
        Ok(have.into_iter().collect())
573 
    }
574
575 
    /// Fetch every bookmark of a remote into `remotes/<name>/bookmarks/*` (spec §10.2).
576 
    pub fn fetch(&self, remote_name: &str) -> Result<FetchReport> {
577 
        let remote = self.open_named_remote(remote_name)?;
578 
        if remote.repo_id()? != self.id()? {
579 
            return fail(format!("remote {remote_name:?} is a different repository (repository IDs differ)"));
580 
        }
581 
        let resp = remote.refs()?;
582 
        // Trust policy (spec §14.5). Adopt the remote's policy when it is newer
583 
        // and signed by roots we trust, or on first contact. A remote that
584 
        // once presented a policy may never present none or an older one:
585 
        // that is a downgrade. A remote that never presented one is
586 
        // unverified, and this fetch is checked only as far as possible.
587 
        let local_policy = self.current_policy()?.map(|(_, sp)| sp.policy);
588 
        let seen = self.remote_policy_serial(remote_name);
589 
        let mut unverified = false;
590 
        match &resp.policy {
591 
            Some(sp) => {
592 
                if seen.is_some_and(|s| sp.policy.serial < s) {
593 
                    return fail(format!("{remote_name} presents policy serial {} but presented {} before: refusing the downgrade", sp.policy.serial, seen.unwrap()));
594 
                }
595 
                match &local_policy {
596 
                    Some(l) if sp.policy.serial < l.serial => {}
597 
                    Some(l) if sp.policy.serial == l.serial => {
598 
                        if sp.policy.hash() != l.hash() {
599 
                            return fail(format!("{remote_name} presents a different policy with the same serial {}", l.serial));
600 
                        }
601 
                    }
602 
                    local => {
603 
                        self.check_policy(sp, local.as_ref()).map_err(|e| RepoError::Msg(format!("policy from {remote_name}: {e}")))?;
604 
                        self.set_policy(sp, &format!("oxy fetch {remote_name} (policy serial {})", sp.policy.serial))?;
605 
                    }
606 
                }
607 
                self.record_policy_serial(remote_name, sp.policy.serial)?;
608 
            }
609 
            None => {
610 
                if seen.is_some() {
611 
                    return fail(format!("{remote_name} presented a policy before but has none now: refusing the downgrade"));
612 
                }
613 
                unverified = true;
614 
            }
615 
        }
616 
        let policy = if unverified { None } else { self.current_policy()?.map(|(_, sp)| sp.policy) };
617 
        let (op_ref, op) = self.head_op()?;
618 
        let mut view = op.view.clone();
619 
        let have = self.known_heads(&view)?;
620 
        let mut report = Vec::new();
621 
        let max_blob = self.config.max_blob;
622 
        for r in resp.refs {
623 
            let needed = remote.negotiate(&have, &r.heads)?;
624 
            let bundle = remote.fetch(&needed, max_blob)?;
625 
            // Changes are not individually re-verified here: the bookmark's
626 
            // attestation (checked below) binds its whole state, and the
627 
            // receiver of the push verified the added changes at that time.
628 
            let imported = self.import_bundle(&bundle, false)?;
629 
            if max_blob.is_some() {
630 
                self.register_missing_blobs(&imported, remote_name)?;
631 
            }
632 
            for h in &r.heads {
633 
                if !self.store.has(h) {
634 
                    return fail(format!("remote did not send head {}", h.short(12)));
635 
                }
636 
            }
637 
            let state = self.store.put_state(&StateObject::new(r.heads.clone()))?;
638 
            if state != r.state {
639 
                return fail(format!("remote state {} does not match its heads", r.state.short(12)));
640 
            }
641 
            if let Some(p) = &policy {
642 
                let Some(sa) = &r.attestation else {
643 
                    return fail(format!("{remote_name}/{} has no attestation, which its policy requires", r.name));
644 
                };
645 
                let signer = sa.sigs.first().map(|s| s.key).ok_or_else(|| RepoError::Msg("attestation carries no signature".into()))?;
646 
                if !p.authorizes(&signer, &r.name) {
647 
                    return fail(format!("{remote_name}/{}: attested by {}, which the policy does not authorize", r.name, signer.short(12)));
648 
                }
649 
            }
650 
            if let Some(sa) = &r.attestation {
651 
                let AttestBody::Ref { old_state, new_state, .. } = &sa.attest.body else {
652 
                    return fail("remote sent a non-ref attestation for a bookmark");
653 
                };
654 
                let (old_state, new_state) = (*old_state, *new_state);
655 
                let serial = self
656 
                    .check_ref_attest(sa, &r.name, &old_state, &new_state, self.last_seen_serial(remote_name, &r.name), true)
657 
                    .map_err(|e| RepoError::Msg(format!("attestation for {}/{}: {e}", remote_name, r.name)))?;
658 
                if new_state != r.state {
659 
                    return fail(format!("attestation for {}/{} does not cover its current state", remote_name, r.name));
660 
                }
661 
                let ar = self.store.put_attest(&sa.attest)?;
662 
                for sig in &sa.sigs {
663 
                    self.store.put_signature(&ar, sig)?;
664 
                }
665 
                self.record_serial(remote_name, &r.name, serial)?;
666 
            }
667 
            view.remotes.entry(remote_name.to_string()).or_default().insert(r.name.clone(), state);
668 
            report.push((r.name, r.heads, imported.len()));
669 
        }
670 
        let mut new_tags = 0;
671 
        for t in &resp.tags {
672 
            if view.tags.contains_key(&t.name) {
673 
                continue;
674 
            }
675 
            // The tag's changes must be here: fetch them if the bookmarks did not bring them.
676 
            let missing: Vec<ChangeHash> = t.heads.iter().filter(|h| !self.store.has(h)).copied().collect();
677 
            if !missing.is_empty() {
678 
                let needed = remote.negotiate(&self.known_heads(&view)?, &missing)?;
679 
                let bundle = remote.fetch(&needed, max_blob)?;
680 
                self.import_bundle(&bundle, false)?;
681 
            }
682 
            self.store.put_state(&StateObject::new(t.heads.clone()))?;
683 
            self.adopt_tag(&mut view, t, policy.as_ref()).map_err(|e| RepoError::Msg(format!("{remote_name} {}: {e}", t.name)))?;
684 
            new_tags += 1;
685 
        }
686 
        if view != op.view {
687 
            self.record_op(&[op_ref], &format!("oxy fetch {remote_name}"), view)?;
688 
        }
689 
        let _ = self.run_hook(
690 
            "post-fetch",
691 
            &format!(
692 
                "{{\"event\":\"post-fetch\",\"remote\":{},\"bookmarks\":{}}}",
693 
                json_str(remote_name),
694 
                json_array(report.iter().map(|(n, heads, _)| format!("{{\"name\":{},\"heads\":{}}}", json_str(n), json_array(heads.iter().map(|h| json_str(&h.to_hex()))))))
695 
            ),
696 
        );
697 
        Ok(FetchReport { refs: report, unverified, new_tags })
698 
    }
699
700 
    /// Shallow fetch of the remote's bookmark: its checkpoint as our base,
701 
    /// the changes within `depth` steps of its heads, and the boundary below.
702 
    pub fn fetch_shallow(&self, remote_name: &str, depth: u32) -> Result<usize> {
703 
        let remote = self.open_named_remote(remote_name)?;
704 
        if remote.repo_id()? != self.id()? {
705 
            return fail(format!("remote {remote_name:?} is a different repository (repository IDs differ)"));
706 
        }
707 
        let resp = remote.refs()?;
708 
        let bookmark = self.config.bookmark.clone();
709 
        if let Some(sp) = &resp.policy {
710 
            let local = self.current_policy()?.map(|(_, sp)| sp.policy);
711 
            self.check_policy(sp, local.as_ref()).map_err(|e| RepoError::Msg(format!("policy from {remote_name}: {e}")))?;
712 
            self.set_policy(sp, &format!("oxy clone --depth (policy serial {})", sp.policy.serial))?;
713 
            self.record_policy_serial(remote_name, sp.policy.serial)?;
714 
        }
715 
        let Some(r) = resp.refs.into_iter().find(|r| r.name == bookmark) else {
716 
            return fail(format!("{remote_name} has no bookmark {bookmark:?}"));
717 
        };
718 
        if r.heads.is_empty() {
719 
            return Ok(0);
720 
        }
721 
        // Base: the remote's checkpoint of exactly these heads.
722 
        let cp_bundle = remote.checkpoint(&r.heads)?;
723 
        let mut cp_ref = None;
724 
        for (ty, body) in &cp_bundle.objects {
725 
            let put = self.store.put(*ty, body)?;
726 
            if *ty == ObjectType::Checkpoint {
727 
                cp_ref = Some(put);
728 
            }
729 
        }
730 
        let Some(cp_ref) = cp_ref else { return fail(format!("{remote_name} sent no checkpoint")) };
731 
        self.install_checkpoint(&bookmark, &cp_ref)?;
732 
        // History window.
733 
        let wanted = remote.shallow(&r.heads, depth)?;
734 
        let bundle = remote.fetch(&wanted, self.config.max_blob)?;
735 
        let imported = self.import_bundle_shallow(&bundle, false)?;
736 
        if self.config.max_blob.is_some() {
737 
            self.register_missing_blobs(&imported, remote_name)?;
738 
        }
739 
        self.refresh_boundary(&imported)?;
740 
        if let Some(sa) = &r.attestation {
741 
            let ar = self.store.put_attest(&sa.attest)?;
742 
            for sig in &sa.sigs {
743 
                self.store.put_signature(&ar, sig)?;
744 
            }
745 
            if let AttestBody::Ref { serial, .. } = sa.attest.body {
746 
                self.record_serial(remote_name, &r.name, serial)?;
747 
            }
748 
        }
749 
        let state = self.store.put_state(&StateObject::new(r.heads.clone()))?;
750 
        let (op_ref, op) = self.head_op()?;
751 
        let mut view = op.view.clone();
752 
        view.remotes.entry(remote_name.to_string()).or_default().insert(r.name.clone(), state);
753 
        self.record_op(&[op_ref], &format!("oxy fetch {remote_name} --depth {depth}"), view)?;
754 
        Ok(imported.len())
755 
    }
756
757 
    /// Fetch, then take the union of the local bookmark's state with the
758 
    /// remote's: no merge change, conflicts become reified (spec §9.4).
759 
    pub fn pull(&self, remote_name: &str) -> Result<PullReport> {
760 
        self.fetch(remote_name)?;
761 
        let (op_ref, op) = self.head_op()?;
762 
        let bookmark = self.config.bookmark.clone();
763 
        let local = self.heads_of(&op.view, &bookmark)?;
764 
        let Some(remote_state) = op.view.remotes.get(remote_name).and_then(|b| b.get(&bookmark)).copied() else {
765 
            return Ok(PullReport { heads: local, changed: false, checked_out: false });
766 
        };
767 
        let remote_heads = self.store.get_state(&remote_state)?.heads;
768 
        let mut all = local.clone();
769 
        all.extend(remote_heads);
770 
        let st = self.load_state(&all)?;
771 
        let mut heads = st.maximal(&all);
772 
        heads.sort();
773 
        let mut sorted_local = local.clone();
774 
        sorted_local.sort();
775 
        if heads == sorted_local {
776 
            return Ok(PullReport { heads, changed: false, checked_out: false });
777 
        }
778 
        let mut view = op.view.clone();
779 
        view.bookmarks.insert(bookmark.clone(), self.store.put_state(&StateObject::new(heads.clone()))?);
780 
        self.record_op(&[op_ref], &format!("oxy pull {remote_name}"), view)?;
781 
        // Follow along if the working copy was clean and on the old heads.
782 
        let snap = self.snapshot("oxy pull")?;
783 
        let clean = snap.wc.tree_ops.is_empty() && snap.wc.edits.is_empty();
784 
        let mut base = snap.base.maximal(&snap.wc.deps);
785 
        base.sort();
786 
        let mut checked_out = false;
787 
        if clean && base == sorted_local {
788 
            self.checkout(&heads, false, "oxy pull (checkout)")?;
789 
            checked_out = true;
790 
        }
791 
        Ok(PullReport { heads, changed: true, checked_out })
792 
    }
793
794 
    /// Push the current bookmark (spec §16.3), sealing this author's unsigned
795 
    /// changes and attesting the reference when a key is available.
796 
    pub fn push(&self, remote_name: &str, force: bool) -> Result<Vec<RefResult>> {
797 
        let (op_ref, op) = self.head_op()?;
798 
        let bookmark = self.config.bookmark.clone();
799 
        let local_heads = self.heads_of(&op.view, &bookmark)?;
800 
        // pre-push hook: may veto before the remote is contacted.
801 
        self.run_hook(
802 
            "pre-push",
803 
            &format!("{{\"event\":\"pre-push\",\"remote\":{},\"bookmark\":{},\"heads\":{}}}", json_str(remote_name), json_str(&bookmark), json_array(local_heads.iter().map(|h| json_str(&h.to_hex())))),
804 
        )?;
805 
        let remote = self.open_named_remote(remote_name)?;
806 
        if remote.repo_id()? != self.id()? {
807 
            return fail(format!("remote {remote_name:?} is a different repository (repository IDs differ)"));
808 
        }
809 
        let resp = remote.refs()?;
810 
        let local_policy = self.current_policy()?.map(|(_, sp)| sp);
811 
        let policy_to_send = match (&local_policy, &resp.policy) {
812 
            (Some(l), Some(r)) if l.policy.serial > r.policy.serial => Some(l.clone()),
813 
            (Some(l), None) => Some(l.clone()),
814 
            (Some(l), Some(r)) if l.policy.serial < r.policy.serial => {
815 
                return fail(format!("{remote_name} has a newer policy (serial {}); fetch first", r.policy.serial));
816 
            }
817 
            _ => None,
818 
        };
819 
        let remote_has_policy = resp.policy.is_some() || policy_to_send.is_some();
820 
        if remote_has_policy && self.secret_key()?.is_none() {
821 
            return fail(format!("{remote_name} enforces a trust policy; pushing needs an identity (`oxy identity create`)"));
822 
        }
823 
        let remote_tags: BTreeSet<String> = resp.tags.iter().map(|t| t.name.clone()).collect();
824 
        let tags_to_send: Vec<crate::protocol::TagRef> = self.tag_refs()?.into_iter().filter(|t| !remote_tags.contains(&t.name)).collect();
825 
        let refs = resp.refs;
826 
        let empty = self.store.put_state(&StateObject::new(vec![]))?;
827 
        let (remote_state, remote_heads, last_serial) = match refs.iter().find(|r| r.name == bookmark) {
828 
            Some(r) => (r.state, r.heads.clone(), r.last_serial),
829 
            None => (empty, vec![], None),
830 
        };
831 
        let new_state = self.store.put_state(&StateObject::new(local_heads.clone()))?;
832 
        // A push that carries a policy re-attests the bookmark even when its
833 
        // state is unchanged, so the current attestation is always by a key
834 
        // the current policy authorizes (a revoked key's attestation would
835 
        // otherwise be refused by every later fetch).
836 
        if new_state == remote_state && policy_to_send.is_none() && tags_to_send.is_empty() {
837 
            return Ok(vec![RefResult { name: bookmark, ok: true, reason: "already up to date".into() }]);
838 
        }
839 
        for h in &remote_heads {
840 
            if !self.store.has(h) {
841 
                return fail(format!("the remote has change {} which you do not; pull first", h.short(12)));
842 
            }
843 
        }
844 
        if !force {
845 
            let closure = self.closure_in_store(&local_heads)?;
846 
            if let Some(h) = remote_heads.iter().find(|h| !closure.contains(h)) {
847 
                return fail(format!("not a fast-forward: remote head {} is not in your state; pull first or use --force", h.short(12)));
848 
            }
849 
        }
850 
        let to_send = self.negotiate(&remote_heads, &local_heads)?;
851 
        let mut bundle = self.bundle_for(&to_send)?;
852 
        let key = self.secret_key()?.map(|(k, _)| k);
853 
        if let Some(key) = key {
854 
            // Seal this author's changes that carry no valid authenticator.
855 
            let mut unsigned = Vec::new();
856 
            for h in &to_send {
857 
                let c = self.store.get_change(h)?;
858 
                if c.author == key && !matches!(self.authenticate_change(h)?, SignatureStatus::Valid { .. }) {
859 
                    unsigned.push(*h);
860 
                }
861 
            }
862 
            for chunk in unsigned.chunks(crate::attest::MAX_SEAL_HASHES) {
863 
                let sa = self.sign_attest(&Attest::seal(self.id()?, chunk.to_vec()))?;
864 
                bundle.attests.push(sa);
865 
            }
866 
            bundle = self.bundle_for(&to_send)?;
867 
        }
868 
        bundle.objects.push((ObjectType::State, StateObject::new(local_heads.clone()).encode()));
869 
        let attestation = match key {
870 
            Some(_) => Some(self.sign_attest(&Attest {
871 
                repo: self.id()?,
872 
                hlc: Hlc::now(),
873 
                body: AttestBody::Ref { name: bookmark.clone(), old_state: remote_state, new_state, serial: last_serial.unwrap_or(0) + 1 },
874 
            })?),
875 
            None => None,
876 
        };
877 
        let serial = attestation.as_ref().and_then(|a| match a.attest.body {
878 
            AttestBody::Ref { serial, .. } => Some(serial),
879 
            _ => None,
880 
        });
881 
        let sent_serial = policy_to_send.as_ref().map(|p| p.policy.serial);
882 
        // Tag states must be present on the remote: bundle their changes too.
883 
        for t in &tags_to_send {
884 
            let extra = self.negotiate(&remote_heads, &t.heads)?;
885 
            let extra: Vec<ChangeHash> = extra.into_iter().filter(|h| !to_send.contains(h)).collect();
886 
            if !extra.is_empty() {
887 
                let more = self.bundle_for(&extra)?;
888 
                bundle.changes.extend(more.changes);
889 
                bundle.attests.extend(more.attests);
890 
                bundle.objects.extend(more.objects);
891 
            }
892 
            bundle.objects.push((ObjectType::State, StateObject::new(t.heads.clone()).encode()));
893 
        }
894 
        let results = remote.push(bundle, vec![RefUpdate { name: bookmark.clone(), old_state: remote_state, new_state, force, attestation }], policy_to_send, tags_to_send)?;
895 
        if let (Some(serial), true) = (sent_serial, results.iter().any(|r| r.ok && r.name == "policy")) {
896 
            self.record_policy_serial(remote_name, serial)?;
897 
        }
898 
        if results.iter().any(|r| r.ok && r.name == bookmark) {
899 
            let mut view = op.view.clone();
900 
            view.remotes.entry(remote_name.to_string()).or_default().insert(bookmark.clone(), new_state);
901 
            self.record_op(&[op_ref], &format!("oxy push {remote_name}"), view)?;
902 
            if let Some(s) = serial {
903 
                self.record_serial(remote_name, &bookmark, s)?;
904 
            }
905 
        }
906 
        Ok(results)
907 
    }
908
909 
    /// Clone a remote into `dest`: same repository ID, `origin` remote,
910 
    /// bookmark set to the remote's, working copy checked out.
911 
    pub fn clone(url: &str, dest: &Path) -> Result<Repo> {
912 
        Self::clone_with(url, dest, None, &[])
913 
    }
914
915 
    /// Clone, leaving blobs above `max_blob` bytes to be fetched on first
916 
    /// read, and materializing only `sparse` paths (which implies lazy blobs
917 
    /// unless a size is given, so out-of-scope binaries are never fetched).
918 
    pub fn clone_with(url: &str, dest: &Path, max_blob: Option<u64>, sparse: &[String]) -> Result<Repo> {
919 
        Self::clone_full(url, dest, max_blob, sparse, None)
920 
    }
921
922 
    /// Shallow clone (spec §17): a checkpoint of the bookmark's heads plus the
923 
    /// changes within `depth` steps of them; the rest is the boundary.
924 
    pub fn clone_shallow(url: &str, dest: &Path, depth: u32, max_blob: Option<u64>, sparse: &[String]) -> Result<Repo> {
925 
        Self::clone_full(url, dest, max_blob, sparse, Some(depth))
926 
    }
927
928 
    fn clone_full(url: &str, dest: &Path, max_blob: Option<u64>, sparse: &[String], depth: Option<u32>) -> Result<Repo> {
929 
        let options = RemoteOptions {
930 
            token: std::env::var("OXY_TOKEN").ok(),
931 
            ca: std::env::var("OXY_CA").ok().map(PathBuf::from),
932 
        };
933 
        let remote = open_remote(url, &options)?;
934 
        let id = remote.repo_id()?;
935 
        let mut repo = Repo::init_with_id(dest, id)?;
936 
        repo.config.set("remote.origin.url", url)?;
937 
        if let Some(m) = max_blob {
938 
            repo.config.set("filter.max-blob", &m.to_string())?;
939 
        } else if !sparse.is_empty() {
940 
            repo.config.set("filter.max-blob", "0")?;
941 
        }
942 
        if !sparse.is_empty() {
943 
            repo.config.set("filter.paths", &sparse.join(","))?;
944 
        }
945 
        repo.save_config()?;
946 
        if let Some(depth) = depth {
947 
            repo.fetch_shallow("origin", depth)?;
948 
        } else {
949 
            repo.fetch("origin")?;
950 
        }
951 
        let (op_ref, op) = repo.head_op()?;
952 
        let bookmark = repo.config.bookmark.clone();
953 
        if let Some(state) = op.view.remotes.get("origin").and_then(|b| b.get(&bookmark)).copied() {
954 
            let heads = repo.store.get_state(&state)?.heads;
955 
            let mut view = op.view.clone();
956 
            view.bookmarks.insert(bookmark, state);
957 
            repo.record_op(&[op_ref], &format!("oxy clone {url}"), view)?;
958 
            repo.checkout(&heads, false, "oxy clone (checkout)")?;
959 
        }
960 
        Ok(repo)
961 
    }
962 
}