package fuse import ( "sync" "github.com/restic/restic" "github.com/restic/restic/backend" "github.com/restic/restic/pack" "bazil.org/fuse" "bazil.org/fuse/fs" "golang.org/x/net/context" ) // Statically ensure that *file implements the given interface var _ = fs.HandleReader(&file{}) var _ = fs.HandleReleaser(&file{}) // BlobLoader is an abstracted repository with a reduced set of methods used // for fuse operations. type BlobLoader interface { LookupBlobSize(backend.ID) (uint, error) LoadBlob(pack.BlobType, backend.ID, []byte) ([]byte, error) } type file struct { repo BlobLoader node *restic.Node sizes []uint blobs [][]byte } const defaultBlobSize = 128 * 1024 var blobPool = sync.Pool{ New: func() interface{} { return make([]byte, defaultBlobSize) }, } func newFile(repo BlobLoader, node *restic.Node) (*file, error) { sizes := make([]uint, len(node.Content)) for i, id := range node.Content { size, err := repo.LookupBlobSize(id) if err != nil { return nil, err } sizes[i] = size } return &file{ repo: repo, node: node, sizes: sizes, blobs: make([][]byte, len(node.Content)), }, nil } func (f *file) Attr(ctx context.Context, a *fuse.Attr) error { a.Inode = f.node.Inode a.Mode = f.node.Mode a.Size = f.node.Size return nil } func (f *file) getBlobAt(i int) (blob []byte, err error) { if f.blobs[i] != nil { return f.blobs[i], nil } buf := blobPool.Get().([]byte) buf = buf[:cap(buf)] if uint(len(buf)) < f.sizes[i] { if len(buf) > defaultBlobSize { blobPool.Put(buf) } buf = make([]byte, f.sizes[i]) } blob, err = f.repo.LoadBlob(pack.Data, f.node.Content[i], buf) if err != nil { return nil, err } f.blobs[i] = blob return blob, nil } func (f *file) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error { offset := req.Offset // Skip blobs before the offset startContent := 0 for offset > int64(f.sizes[startContent]) { offset -= int64(f.sizes[startContent]) startContent++ } dst := resp.Data[0:req.Size] readBytes := 0 remainingBytes := req.Size for i := startContent; remainingBytes > 0 && i < len(f.sizes); i++ { blob, err := f.getBlobAt(i) if err != nil { return err } if offset > 0 { blob = blob[offset:len(blob)] offset = 0 } copied := copy(dst, blob) remainingBytes -= copied readBytes += copied dst = dst[copied:] } resp.Data = resp.Data[:readBytes] return nil } func (f *file) Release(ctx context.Context, req *fuse.ReleaseRequest) error { for i := range f.blobs { if f.blobs[i] != nil { blobPool.Put(f.blobs[i]) f.blobs[i] = nil } } return nil }