v2api/reverse: implement Lookup & Getattr
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18b3bdb158
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@ -1,7 +1,15 @@
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package fusefrontend_reverse
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package fusefrontend_reverse
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import (
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import (
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"context"
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"syscall"
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"golang.org/x/sys/unix"
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"github.com/hanwen/go-fuse/v2/fs"
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"github.com/hanwen/go-fuse/v2/fs"
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"github.com/hanwen/go-fuse/v2/fuse"
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"github.com/rfjakob/gocryptfs/internal/syscallcompat"
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)
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)
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// Node is a file or directory in the filesystem tree
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// Node is a file or directory in the filesystem tree
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@ -9,3 +17,61 @@ import (
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type Node struct {
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type Node struct {
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fs.Inode
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fs.Inode
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}
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}
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// Lookup - FUSE call for discovering a file.
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// TODO handle virtual files
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func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (ch *fs.Inode, errno syscall.Errno) {
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dirfd, cName, errno := n.prepareAtSyscall(name)
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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// Get device number and inode number into `st`
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st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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return nil, fs.ToErrno(err)
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}
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// Create new inode and fill `out`
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ch = n.newChild(ctx, st, out)
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// Translate ciphertext size in `out.Attr.Size` to plaintext size
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n.translateSize(dirfd, cName, &out.Attr)
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return ch, 0
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}
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// GetAttr - FUSE call for stat()ing a file.
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//
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// GetAttr is symlink-safe through use of openBackingDir() and Fstatat().
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func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut) (errno syscall.Errno) {
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// If the kernel gives us a file handle, use it.
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if f != nil {
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return f.(fs.FileGetattrer).Getattr(ctx, out)
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}
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dirfd, cName, errno := n.prepareAtSyscall("")
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if errno != 0 {
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return
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}
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defer syscall.Close(dirfd)
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st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
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if err != nil {
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return fs.ToErrno(err)
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}
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// Fix inode number
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rn := n.rootNode()
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rn.inoMap.TranslateStat(st)
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out.Attr.FromStat(st)
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// Translate ciphertext size in `out.Attr.Size` to plaintext size
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n.translateSize(dirfd, cName, &out.Attr)
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if rn.args.ForceOwner != nil {
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out.Owner = *rn.args.ForceOwner
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}
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return 0
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}
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67
internal/fusefrontend_reverse/node_helpers.go
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67
internal/fusefrontend_reverse/node_helpers.go
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@ -0,0 +1,67 @@
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package fusefrontend_reverse
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import (
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"context"
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"path/filepath"
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"syscall"
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"github.com/hanwen/go-fuse/v2/fs"
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"github.com/hanwen/go-fuse/v2/fuse"
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)
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// translateSize translates the ciphertext size in `out` into plaintext size.
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func (n *Node) translateSize(dirfd int, cName string, out *fuse.Attr) {
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if out.IsRegular() {
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rn := n.rootNode()
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out.Size = rn.contentEnc.PlainSizeToCipherSize(out.Size)
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} else if out.IsSymlink() {
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panic("todo: call readlink once it is implemented")
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}
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}
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// Path returns the relative plaintext path of this node
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func (n *Node) Path() string {
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return n.Inode.Path(n.Root())
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}
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// rootNode returns the Root Node of the filesystem.
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func (n *Node) rootNode() *RootNode {
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return n.Root().Operations().(*RootNode)
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}
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// prepareAtSyscall returns a (dirfd, cName) pair that can be used
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// with the "___at" family of system calls (openat, fstatat, unlinkat...) to
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// access the backing encrypted directory.
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//
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// If you pass a `child` file name, the (dirfd, cName) pair will refer to
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// a child of this node.
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// If `child` is empty, the (dirfd, cName) pair refers to this node itself.
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func (n *Node) prepareAtSyscall(child string) (dirfd int, cName string, errno syscall.Errno) {
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p := n.Path()
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if child != "" {
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p = filepath.Join(p, child)
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}
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rn := n.rootNode()
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dirfd, cName, err := rn.openBackingDir(p)
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if err != nil {
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errno = fs.ToErrno(err)
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}
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return
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}
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// newChild attaches a new child inode to n.
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// The passed-in `st` will be modified to get a unique inode number.
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func (n *Node) newChild(ctx context.Context, st *syscall.Stat_t, out *fuse.EntryOut) *fs.Inode {
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// Get unique inode number
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rn := n.rootNode()
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rn.inoMap.TranslateStat(st)
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out.Attr.FromStat(st)
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// Create child node
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id := fs.StableAttr{
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Mode: uint32(st.Mode),
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Gen: 1,
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Ino: st.Ino,
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}
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node := &Node{}
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return n.NewInode(ctx, node, id)
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}
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102
internal/fusefrontend_reverse/rpath.go
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102
internal/fusefrontend_reverse/rpath.go
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@ -0,0 +1,102 @@
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package fusefrontend_reverse
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import (
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"encoding/base64"
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"path/filepath"
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"strings"
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"syscall"
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"github.com/rfjakob/gocryptfs/internal/nametransform"
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"github.com/rfjakob/gocryptfs/internal/pathiv"
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"github.com/rfjakob/gocryptfs/internal/syscallcompat"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// abs basically returns storage dir + "/" + relPath.
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// It takes an error parameter so it can directly wrap decryptPath like this:
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// a, err := rfs.abs(rfs.decryptPath(relPath))
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// abs never generates an error on its own. In other words, abs(p, nil) never
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// fails.
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func (rfs *RootNode) abs(relPath string, err error) (string, error) {
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if err != nil {
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return "", err
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}
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return filepath.Join(rfs.args.Cipherdir, relPath), nil
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}
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// rDecryptName decrypts the ciphertext name "cName", given the dirIV of the
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// directory "cName" lies in. The relative plaintext path to the directory
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// "pDir" is used if a "gocryptfs.longname.XYZ.name" must be resolved.
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func (rfs *RootNode) rDecryptName(cName string, dirIV []byte, pDir string) (pName string, err error) {
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nameType := nametransform.NameType(cName)
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if nameType == nametransform.LongNameNone {
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pName, err = rfs.nameTransform.DecryptName(cName, dirIV)
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if err != nil {
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// We get lots of decrypt requests for names like ".Trash" that
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// are invalid base64. Convert them to ENOENT so the correct
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// error gets returned to the user.
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if _, ok := err.(base64.CorruptInputError); ok {
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return "", syscall.ENOENT
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}
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// Stat attempts on the link target of encrypted symlinks.
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// These are always valid base64 but the length is not a
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// multiple of 16.
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if err == syscall.EBADMSG {
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return "", syscall.ENOENT
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}
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return "", err
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}
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} else if nameType == nametransform.LongNameContent {
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panic("todo")
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//pName, err = rfs.findLongnameParent(pDir, dirIV, cName)
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if err != nil {
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return "", err
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}
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} else {
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// It makes no sense to decrypt a ".name" file. This is a virtual file
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// that has no representation in the plaintext filesystem. ".name"
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// files should have already been handled in virtualfile.go.
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tlog.Warn.Printf("rDecryptName: cannot decrypt virtual file %q", cName)
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return "", syscall.EINVAL
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}
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return pName, nil
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}
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// decryptPath decrypts a relative ciphertext path to a relative plaintext
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// path.
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func (rn *RootNode) decryptPath(relPath string) (string, error) {
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if rn.args.PlaintextNames || relPath == "" {
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return relPath, nil
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}
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parts := strings.Split(relPath, "/")
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var transformedParts []string
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for i := range parts {
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// Start at the top and recurse
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currentCipherDir := filepath.Join(parts[:i]...)
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currentPlainDir := filepath.Join(transformedParts[:i]...)
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dirIV := pathiv.Derive(currentCipherDir, pathiv.PurposeDirIV)
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transformedPart, err := rn.rDecryptName(parts[i], dirIV, currentPlainDir)
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if err != nil {
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return "", err
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}
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transformedParts = append(transformedParts, transformedPart)
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}
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pRelPath := filepath.Join(transformedParts...)
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return pRelPath, nil
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}
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// openBackingDir receives an already decrypted relative path
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// "pRelPath", opens the directory that contains the target file/dir
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// and returns the fd to the directory and the decrypted name of the
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// target file. The fd/name pair is intended for use with fchownat and
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// friends.
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func (rn *RootNode) openBackingDir(pRelPath string) (dirfd int, pName string, err error) {
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// Open directory, safe against symlink races
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pDir := filepath.Dir(pRelPath)
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dirfd, err = syscallcompat.OpenDirNofollow(rn.args.Cipherdir, pDir)
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if err != nil {
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return -1, "", err
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}
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pName = filepath.Base(pRelPath)
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return dirfd, pName, nil
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}
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