objectstore/packed: Split

1 files changed, 100 insertions, 0 deletions

diff --git a/objectstore/packed/store_open_pack.go b/objectstore/packed/store_open_pack.go
new file mode 100644
index 00000000..f101b624
--- /dev/null
+++ b/objectstore/packed/store_open_pack.go
@@ -0,0 +1,100 @@
+package packed
+
+import "fmt"
+
+// openPack returns one opened and validated pack handle.
+func (store *Store) openPack(name string) (*packFile, error) {
+	store.stateMu.RLock()
+
+	pack, ok := store.packs[name]
+	if ok {
+		store.stateMu.RUnlock()
+
+		return pack, nil
+	}
+
+	store.stateMu.RUnlock()
+
+	file, err := store.root.Open(name)
+	if err != nil {
+		return nil, err
+	}
+
+	info, err := file.Stat()
+	if err != nil {
+		_ = file.Close()
+
+		return nil, err
+	}
+
+	pack, err = openPackFile(name, file, info.Size())
+	if err != nil {
+		_ = file.Close()
+
+		return nil, err
+	}
+
+	err = store.verifyPackMatchesIndexes(pack)
+	if err != nil {
+		_ = pack.close()
+
+		return nil, err
+	}
+
+	store.stateMu.Lock()
+
+	existing, ok := store.packs[name]
+	if ok {
+		store.stateMu.Unlock()
+
+		_ = pack.close()
+
+		return existing, nil
+	}
+
+	store.packs[name] = pack
+	store.stateMu.Unlock()
+
+	return pack, nil
+}
+
+// verifyPackMatchesIndexes checks that one opened pack's trailer hash matches
+// every loaded index that references the same pack name.
+func (store *Store) verifyPackMatchesIndexes(pack *packFile) error {
+	err := store.ensureCandidates()
+	if err != nil {
+		return err
+	}
+
+	candidate, ok := store.candidateForPack(pack.name)
+	if !ok {
+		return fmt.Errorf("objectstore/packed: missing index for pack %q", pack.name)
+	}
+
+	index, err := store.openIndex(candidate)
+	if err != nil {
+		return err
+	}
+
+	err = verifyMappedPackMatchesMappedIdx(pack.data, index.data, store.algo)
+	if err != nil {
+		return fmt.Errorf("objectstore/packed: pack %q does not match idx %q: %w", pack.name, index.idxName, err)
+	}
+
+	return nil
+}
+
+// entryMetaAt parses one pack entry header at location.
+func (store *Store) entryMetaAt(loc location) (*packFile, entryMeta, error) {
+	pack, err := store.openPack(loc.packName)
+	if err != nil {
+		return nil, entryMeta{}, err
+	}
+
+	meta, err := parseEntryMeta(pack, store.algo, loc.offset)
+	if err != nil {
+		return nil, entryMeta{}, err
+	}
+
+	return pack, meta, nil
+}