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package loose
import (
"compress/zlib"
"crypto/rand"
"errors"
"fmt"
"io/fs"
"os"
"path/filepath"
"codeberg.org/lindenii/furgit/objectheader"
"codeberg.org/lindenii/furgit/objectid"
"codeberg.org/lindenii/furgit/objecttype"
)
const tempObjectFilePrefix = "tmp_obj_"
// WriteBytesFull writes a full serialized object as "type size\\x00content".
func (store *Store) WriteBytesFull(raw []byte) (objectid.ObjectID, error) {
var zero objectid.ObjectID
if _, _, err := parseRaw(raw); err != nil {
return zero, err
}
id := store.algo.Sum(raw)
relPath, err := store.objectPath(id)
if err != nil {
return zero, err
}
if err := store.writeCompressedAtomic(relPath, raw); err != nil {
return zero, err
}
return id, nil
}
// WriteBytesContent writes typed content bytes as a loose object.
func (store *Store) WriteBytesContent(ty objecttype.Type, content []byte) (objectid.ObjectID, error) {
var zero objectid.ObjectID
header, ok := objectheader.Encode(ty, int64(len(content)))
if !ok {
return zero, fmt.Errorf("objectstore/loose: failed to encode object header for type %d", ty)
}
raw := make([]byte, len(header)+len(content))
copy(raw, header)
copy(raw[len(header):], content)
return store.WriteBytesFull(raw)
}
// writeCompressedAtomic compresses raw and writes it to relPath atomically.
func (store *Store) writeCompressedAtomic(relPath string, raw []byte) error {
if _, err := store.root.Stat(relPath); err == nil {
return nil
} else if !errors.Is(err, fs.ErrNotExist) {
return err
}
dir := filepath.Dir(relPath)
if err := store.root.MkdirAll(dir, 0o755); err != nil {
return err
}
tmpRelPath, tmpFile, err := store.createTempObjectFile(dir)
if err != nil {
return err
}
cleanup := true
defer func() {
if tmpFile != nil {
_ = tmpFile.Close()
}
if cleanup {
_ = store.root.Remove(tmpRelPath)
}
}()
zw := zlib.NewWriter(tmpFile)
if _, err := zw.Write(raw); err != nil {
_ = zw.Close()
return err
}
if err := zw.Close(); err != nil {
return err
}
if err := tmpFile.Sync(); err != nil {
return err
}
if err := tmpFile.Close(); err != nil {
return err
}
tmpFile = nil
if err := store.root.Rename(tmpRelPath, relPath); err != nil {
if errors.Is(err, fs.ErrExist) {
return nil
}
return err
}
cleanup = false
return nil
}
// createTempObjectFile creates a unique temporary object file within dir.
func (store *Store) createTempObjectFile(dir string) (string, *os.File, error) {
for range 16 {
relPath := filepath.Join(dir, tempObjectFilePrefix+rand.Text())
file, err := store.root.OpenFile(relPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o644)
if err == nil {
return relPath, file, nil
}
if errors.Is(err, fs.ErrExist) {
continue
}
return "", nil, err
}
return "", nil, errors.New("objectstore/loose: failed to create temporary object file")
}
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