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package furgit
import (
"bytes"
"errors"
"fmt"
"strconv"
)
// ObjType mirrors Git's object type tags.
type ObjType uint8
const (
ObjInvalid ObjType = 0
ObjCommit ObjType = 1
ObjTree ObjType = 2
ObjBlob ObjType = 3
ObjTag ObjType = 4
ObjFuture ObjType = 5
ObjOfsDelta ObjType = 6
ObjRefDelta ObjType = 7
)
const (
objNameBlob = "blob"
objNameTree = "tree"
objNameCommit = "commit"
objNameTag = "tag"
)
// Object describes any Git object variant.
type Object interface {
ObjType() ObjType
}
type objectBase struct {
Hash Hash
}
func computeRawHash(data []byte) Hash {
var id Hash
sum := newHash(data)
copy(id[:], sum[:])
return id
}
func headerForType(ty ObjType, body []byte) ([]byte, error) {
var tyStr string
switch ty {
case ObjBlob:
tyStr = objNameBlob
case ObjTree:
tyStr = objNameTree
case ObjCommit:
tyStr = objNameCommit
case ObjTag:
tyStr = objNameTag
case ObjInvalid, ObjFuture, ObjOfsDelta, ObjRefDelta:
return nil, fmt.Errorf("furgit: object: unsupported type %d", ty)
default:
return nil, fmt.Errorf("furgit: object: unsupported type %d", ty)
}
size := strconv.Itoa(len(body))
var buf bytes.Buffer
buf.Grow(len(tyStr) + len(size) + 1)
buf.WriteString(tyStr)
buf.WriteByte(' ')
buf.WriteString(size)
buf.WriteByte(0)
return buf.Bytes(), nil
}
func verifyRawObject(buf []byte, want Hash) bool {
return computeRawHash(buf) == want
}
func verifyTypedObject(ty ObjType, body []byte, want Hash) bool {
header, err := headerForType(ty, body)
if err != nil {
return false
}
raw := make([]byte, len(header)+len(body))
copy(raw, header)
copy(raw[len(header):], body)
return computeRawHash(raw) == want
}
func parseObjectBody(ty ObjType, id Hash, body []byte) (Object, error) {
switch ty {
case ObjBlob:
return parseBlob(id, body)
case ObjTree:
return parseTree(id, body)
case ObjCommit:
return parseCommit(id, body)
case ObjTag:
return parseTag(id, body)
case ObjInvalid, ObjFuture, ObjOfsDelta, ObjRefDelta:
return nil, fmt.Errorf("furgit: object: unsupported type %d", ty)
default:
return nil, fmt.Errorf("furgit: object: unknown type %d", ty)
}
}
// ReadObject resolves an ID by consulting loose then packed storage.
func (repo *Repository) ReadObject(id Hash) (Object, error) {
obj, err := repo.looseRead(id)
if err == nil {
return obj, nil
}
if !errors.Is(err, ErrNotFound) {
return nil, err
}
obj, err = repo.packRead(id)
if errors.Is(err, ErrNotFound) {
return nil, ErrInvalidObject
}
return obj, err
}
// ReadObjectTypeSize reports the object type and size without inflating the body.
func (repo *Repository) ReadObjectTypeSize(id Hash) (ObjType, int64, error) {
ty, size, err := repo.looseTypeSize(id)
if err == nil {
return ty, size, nil
}
if !errors.Is(err, ErrNotFound) {
return ObjInvalid, 0, err
}
loc, err := repo.packIndexFind(id)
if err != nil {
if errors.Is(err, ErrNotFound) {
return ObjInvalid, 0, ErrInvalidObject
}
return ObjInvalid, 0, err
}
return repo.packTypeSizeAtLocation(loc, nil)
}
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