restic/internal/fuse/file.go

185 lines
4.6 KiB
Go

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