mirror of
https://github.com/restic/restic.git
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186 lines
4.6 KiB
Go
186 lines
4.6 KiB
Go
//go:build darwin || freebsd || linux
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// +build darwin freebsd linux
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package fuse
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import (
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"context"
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"sort"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/restic"
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"github.com/anacrolix/fuse"
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"github.com/anacrolix/fuse/fs"
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)
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// The default block size to report in stat
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const blockSize = 512
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// Statically ensure that *file and *openFile implement the given interfaces
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var _ = fs.HandleReader(&openFile{})
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var _ = fs.NodeListxattrer(&file{})
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var _ = fs.NodeGetxattrer(&file{})
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var _ = fs.NodeOpener(&file{})
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type file struct {
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root *Root
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node *restic.Node
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inode uint64
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}
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type openFile struct {
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file
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// cumsize[i] holds the cumulative size of blobs[:i].
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cumsize []uint64
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}
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func newFile(root *Root, inode uint64, node *restic.Node) (fusefile *file, err error) {
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debug.Log("create new file for %v with %d blobs", node.Name, len(node.Content))
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return &file{
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inode: inode,
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root: root,
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node: node,
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}, nil
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}
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func (f *file) Attr(ctx context.Context, a *fuse.Attr) error {
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debug.Log("Attr(%v)", f.node.Name)
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a.Inode = f.inode
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a.Mode = f.node.Mode
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a.Size = f.node.Size
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a.Blocks = (f.node.Size + blockSize - 1) / blockSize
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a.BlockSize = blockSize
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a.Nlink = uint32(f.node.Links)
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if !f.root.cfg.OwnerIsRoot {
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a.Uid = f.node.UID
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a.Gid = f.node.GID
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}
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a.Atime = f.node.AccessTime
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a.Ctime = f.node.ChangeTime
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a.Mtime = f.node.ModTime
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return nil
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}
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func (f *file) Open(ctx context.Context, req *fuse.OpenRequest, resp *fuse.OpenResponse) (fs.Handle, error) {
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debug.Log("open file %v with %d blobs", f.node.Name, len(f.node.Content))
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var bytes uint64
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cumsize := make([]uint64, 1+len(f.node.Content))
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for i, id := range f.node.Content {
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size, found := f.root.repo.LookupBlobSize(id, restic.DataBlob)
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if !found {
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return nil, errors.Errorf("id %v not found in repository", id)
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}
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bytes += uint64(size)
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cumsize[i+1] = bytes
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}
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var of = openFile{file: *f}
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if bytes != f.node.Size {
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debug.Log("sizes do not match: node.Size %v != size %v, using real size", f.node.Size, bytes)
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// Make a copy of the node with correct size
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nodenew := *f.node
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nodenew.Size = bytes
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of.file.node = &nodenew
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}
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of.cumsize = cumsize
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return &of, nil
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}
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func (f *openFile) getBlobAt(ctx context.Context, i int) (blob []byte, err error) {
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blob, ok := f.root.blobCache.Get(f.node.Content[i])
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if ok {
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return blob, nil
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}
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blob, err = f.root.repo.LoadBlob(ctx, restic.DataBlob, f.node.Content[i], nil)
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if err != nil {
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debug.Log("LoadBlob(%v, %v) failed: %v", f.node.Name, f.node.Content[i], err)
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return nil, unwrapCtxCanceled(err)
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}
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f.root.blobCache.Add(f.node.Content[i], blob)
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return blob, nil
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}
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func (f *openFile) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
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debug.Log("Read(%v, %v, %v), file size %v", f.node.Name, req.Size, req.Offset, f.node.Size)
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offset := uint64(req.Offset)
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// as stated in https://godoc.org/bazil.org/fuse/fs#HandleReader there
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// is no need to check if offset > size
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// handle special case: file is empty
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if f.node.Size == 0 {
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resp.Data = resp.Data[:0]
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return nil
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}
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// Skip blobs before the offset
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startContent := -1 + sort.Search(len(f.cumsize), func(i int) bool {
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return f.cumsize[i] > offset
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})
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offset -= f.cumsize[startContent]
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dst := resp.Data[0:req.Size]
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readBytes := 0
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remainingBytes := req.Size
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// The documentation of bazil/fuse actually says that synchronization is
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// required (see https://godoc.org/bazil.org/fuse#hdr-Service_Methods):
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//
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// Multiple goroutines may call service methods simultaneously;
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// the methods being called are responsible for appropriate synchronization.
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//
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// However, no lock needed here as getBlobAt can be called conurrently
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// (blobCache has it's own locking)
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for i := startContent; remainingBytes > 0 && i < len(f.cumsize)-1; i++ {
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blob, err := f.getBlobAt(ctx, i)
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if err != nil {
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return err
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}
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if offset > 0 {
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blob = blob[offset:]
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offset = 0
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}
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copied := copy(dst, blob)
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remainingBytes -= copied
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readBytes += copied
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dst = dst[copied:]
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}
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resp.Data = resp.Data[:readBytes]
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return nil
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}
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func (f *file) Listxattr(ctx context.Context, req *fuse.ListxattrRequest, resp *fuse.ListxattrResponse) error {
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debug.Log("Listxattr(%v, %v)", f.node.Name, req.Size)
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for _, attr := range f.node.ExtendedAttributes {
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resp.Append(attr.Name)
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}
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return nil
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}
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func (f *file) Getxattr(ctx context.Context, req *fuse.GetxattrRequest, resp *fuse.GetxattrResponse) error {
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debug.Log("Getxattr(%v, %v, %v)", f.node.Name, req.Name, req.Size)
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attrval := f.node.GetExtendedAttribute(req.Name)
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if attrval != nil {
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resp.Xattr = attrval
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return nil
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}
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return fuse.ErrNoXattr
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}
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