objectstore/packed: Use constants/functions from format/pack

5 files changed, 23 insertions, 85 deletions

diff --git a/objectstore/packed/delta_base.go b/objectstore/packed/delta_base.go
index fd9b96d5..b1113be7 100644
--- a/objectstore/packed/delta_base.go
+++ b/objectstore/packed/delta_base.go
@@ -3,6 +3,7 @@ package packed
 import (
 	"fmt"
 
+	packfmt "codeberg.org/lindenii/furgit/format/pack"
 	"codeberg.org/lindenii/furgit/objecttype"
 )
 
@@ -24,7 +25,7 @@ func (store *Store) deltaResolveBase(plan deltaPlan) (objecttype.Type, []byte, e
 	if err != nil {
 		return objecttype.TypeInvalid, nil, err
 	}
-	if !isBaseObjectType(meta.ty) {
+	if !packfmt.IsBaseObjectType(meta.ty) {
 		return objecttype.TypeInvalid, nil, fmt.Errorf("objectstore/packed: delta plan base is not a base object")
 	}
 	base, err := inflateAt(pack, meta.dataOffset, meta.size)
diff --git a/objectstore/packed/delta_plan.go b/objectstore/packed/delta_plan.go
index 58e0fc0c..07dd5c77 100644
--- a/objectstore/packed/delta_plan.go
+++ b/objectstore/packed/delta_plan.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	deltaapply "codeberg.org/lindenii/furgit/format/delta/apply"
+	packfmt "codeberg.org/lindenii/furgit/format/pack"
 	"codeberg.org/lindenii/furgit/objecttype"
 )
 
@@ -46,7 +47,7 @@ func (store *Store) deltaPlanFor(start location) (deltaPlan, error) {
 			return deltaPlan{}, err
 		}
 		if plan.declaredSize < 0 {
-			if isBaseObjectType(meta.ty) {
+			if packfmt.IsBaseObjectType(meta.ty) {
 				plan.declaredSize = meta.size
 			} else {
 				declaredSize, err := deltaDeclaredSizeAt(pack, meta.dataOffset)
@@ -57,7 +58,7 @@ func (store *Store) deltaPlanFor(start location) (deltaPlan, error) {
 			}
 		}
 
-		if isBaseObjectType(meta.ty) {
+		if packfmt.IsBaseObjectType(meta.ty) {
 			plan.baseLoc = current
 			plan.baseType = meta.ty
 			return plan, nil
diff --git a/objectstore/packed/entry_parse.go b/objectstore/packed/entry_parse.go
index 76fcb754..69ef80e6 100644
--- a/objectstore/packed/entry_parse.go
+++ b/objectstore/packed/entry_parse.go
@@ -3,6 +3,7 @@ package packed
 import (
 	"fmt"
 
+	packfmt "codeberg.org/lindenii/furgit/format/pack"
 	"codeberg.org/lindenii/furgit/internal/intconv"
 	"codeberg.org/lindenii/furgit/objectid"
 	"codeberg.org/lindenii/furgit/objecttype"
@@ -33,93 +34,28 @@ func parseEntryMeta(pack *packFile, algo objectid.Algorithm, offset uint64) (ent
 	if err != nil {
 		return zero, fmt.Errorf("objectstore/packed: pack %q offset conversion: %w", pack.name, err)
 	}
-	first := pack.data[pos]
-	pos++
-
-	meta := entryMeta{
-		ty:   objecttype.Type((first >> 4) & 0x07),
-		size: int64(first & 0x0f),
+	entry, err := packfmt.ParseEntry(pack.data[pos:], algo.Size())
+	if err != nil {
+		return zero, fmt.Errorf("objectstore/packed: pack %q: %w", pack.name, err)
 	}
 
-	shift := uint(4)
-	b := first
-	for b&0x80 != 0 {
-		if pos >= len(pack.data) {
-			return zero, fmt.Errorf("objectstore/packed: pack %q truncated entry header", pack.name)
-		}
-		b = pack.data[pos]
-		pos++
-		meta.size |= int64(b&0x7f) << shift
-		shift += 7
-	}
-	if meta.size < 0 {
-		return zero, fmt.Errorf("objectstore/packed: pack %q entry has negative size", pack.name)
+	meta := entryMeta{
+		ty:         entry.Type,
+		size:       entry.Size,
+		dataOffset: pos + entry.DataOffset,
 	}
-
 	switch meta.ty {
-	case objecttype.TypeCommit, objecttype.TypeTree, objecttype.TypeBlob, objecttype.TypeTag:
-		// Base object entries have no extra header fields.
 	case objecttype.TypeRefDelta:
-		hashSize := algo.Size()
-		if pos+hashSize > len(pack.data) {
-			return zero, fmt.Errorf("objectstore/packed: pack %q truncated ref-delta base id", pack.name)
-		}
-		baseID, err := objectid.FromBytes(algo, pack.data[pos:pos+hashSize])
+		baseID, err := objectid.FromBytes(algo, entry.RefBaseID)
 		if err != nil {
-			return zero, err
+			return zero, fmt.Errorf("objectstore/packed: pack %q invalid ref-delta base id: %w", pack.name, err)
 		}
 		meta.baseRefID = baseID
-		pos += hashSize
 	case objecttype.TypeOfsDelta:
-		dist, consumed, err := parseOfsDeltaDistance(pack.data[pos:])
-		if err != nil {
-			return zero, err
-		}
-		pos += consumed
-		if offset <= dist {
+		if offset <= entry.OfsBaseDistance {
 			return zero, fmt.Errorf("objectstore/packed: pack %q has invalid ofs-delta base", pack.name)
 		}
-		meta.baseOfs = offset - dist
-	case objecttype.TypeInvalid, objecttype.TypeFuture:
-		return zero, fmt.Errorf("objectstore/packed: pack %q has unsupported object type %d", pack.name, meta.ty)
-	default:
-		return zero, fmt.Errorf("objectstore/packed: pack %q has unsupported object type %d", pack.name, meta.ty)
-	}
-
-	meta.dataOffset = pos
-	if meta.dataOffset > len(pack.data) {
-		return zero, fmt.Errorf("objectstore/packed: pack %q entry data offset out of bounds", pack.name)
+		meta.baseOfs = offset - entry.OfsBaseDistance
 	}
 	return meta, nil
 }
-
-// parseOfsDeltaDistance parses one ofs-delta backward distance.
-func parseOfsDeltaDistance(buf []byte) (uint64, int, error) {
-	if len(buf) == 0 {
-		return 0, 0, fmt.Errorf("objectstore/packed: malformed ofs-delta distance")
-	}
-	b := buf[0]
-	dist := uint64(b & 0x7f)
-	consumed := 1
-	for b&0x80 != 0 {
-		if consumed >= len(buf) {
-			return 0, 0, fmt.Errorf("objectstore/packed: malformed ofs-delta distance")
-		}
-		b = buf[consumed]
-		consumed++
-		dist = ((dist + 1) << 7) + uint64(b&0x7f)
-	}
-	return dist, consumed, nil
-}
-
-// isBaseObjectType reports whether ty is one of the four canonical object types.
-func isBaseObjectType(ty objecttype.Type) bool {
-	switch ty {
-	case objecttype.TypeCommit, objecttype.TypeTree, objecttype.TypeBlob, objecttype.TypeTag:
-		return true
-	case objecttype.TypeInvalid, objecttype.TypeFuture, objecttype.TypeOfsDelta, objecttype.TypeRefDelta:
-		return false
-	default:
-		return false
-	}
-}
diff --git a/objectstore/packed/pack.go b/objectstore/packed/pack.go
index 00950159..9af4c860 100644
--- a/objectstore/packed/pack.go
+++ b/objectstore/packed/pack.go
@@ -6,11 +6,10 @@ import (
 	"os"
 	"syscall"
 
+	packfmt "codeberg.org/lindenii/furgit/format/pack"
 	"codeberg.org/lindenii/furgit/internal/intconv"
 )
 
-const packSignature = 0x5041434b
-
 // packFile stores one mapped and validated .pack file.
 type packFile struct {
 	// name is the .pack basename.
@@ -37,12 +36,12 @@ func openPackFile(name string, file *os.File, size int64) (*packFile, error) {
 	if err != nil {
 		return nil, err
 	}
-	if binary.BigEndian.Uint32(data[:4]) != packSignature {
+	if binary.BigEndian.Uint32(data[:4]) != packfmt.Signature {
 		_ = syscall.Munmap(data)
 		return nil, fmt.Errorf("objectstore/packed: pack %q invalid signature", name)
 	}
 	version := binary.BigEndian.Uint32(data[4:8])
-	if version != 2 && version != 3 {
+	if !packfmt.VersionSupported(version) {
 		_ = syscall.Munmap(data)
 		return nil, fmt.Errorf("objectstore/packed: pack %q unsupported version %d", name, version)
 	}
diff --git a/objectstore/packed/read_reader.go b/objectstore/packed/read_reader.go
index bcafe975..a1f24799 100644
--- a/objectstore/packed/read_reader.go
+++ b/objectstore/packed/read_reader.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 
+	packfmt "codeberg.org/lindenii/furgit/format/pack"
 	"codeberg.org/lindenii/furgit/internal/iolimit"
 	"codeberg.org/lindenii/furgit/objectheader"
 	"codeberg.org/lindenii/furgit/objectid"
@@ -40,7 +41,7 @@ func (store *Store) ReadReaderContent(id objectid.ObjectID) (objecttype.Type, in
 	if err != nil {
 		return objecttype.TypeInvalid, 0, nil, err
 	}
-	if isBaseObjectType(meta.ty) {
+	if packfmt.IsBaseObjectType(meta.ty) {
 		zr, err := zlibReaderAt(pack, meta.dataOffset)
 		if err != nil {
 			return objecttype.TypeInvalid, 0, nil, err
@@ -71,7 +72,7 @@ func (store *Store) ReadReaderFull(id objectid.ObjectID) (io.ReadCloser, error)
 	if err != nil {
 		return nil, err
 	}
-	if isBaseObjectType(meta.ty) {
+	if packfmt.IsBaseObjectType(meta.ty) {
 		header, ok := objectheader.Encode(meta.ty, meta.size)
 		if !ok {
 			return nil, fmt.Errorf("objectstore/packed: failed to encode object header for type %d", meta.ty)