v2api/reverse: implement Lookup & Getattr

1 files changed, 67 insertions, 0 deletions

diff --git a/internal/fusefrontend_reverse/node_helpers.go b/internal/fusefrontend_reverse/node_helpers.go
new file mode 100644
index 0000000..a26ee81
--- /dev/null
+++ b/internal/fusefrontend_reverse/node_helpers.go
@@ -0,0 +1,67 @@
+package fusefrontend_reverse
+
+import (
+	"context"
+	"path/filepath"
+	"syscall"
+
+	"github.com/hanwen/go-fuse/v2/fs"
+	"github.com/hanwen/go-fuse/v2/fuse"
+)
+
+// translateSize translates the ciphertext size in `out` into plaintext size.
+func (n *Node) translateSize(dirfd int, cName string, out *fuse.Attr) {
+	if out.IsRegular() {
+		rn := n.rootNode()
+		out.Size = rn.contentEnc.PlainSizeToCipherSize(out.Size)
+	} else if out.IsSymlink() {
+		panic("todo: call readlink once it is implemented")
+	}
+}
+
+// Path returns the relative plaintext path of this node
+func (n *Node) Path() string {
+	return n.Inode.Path(n.Root())
+}
+
+// rootNode returns the Root Node of the filesystem.
+func (n *Node) rootNode() *RootNode {
+	return n.Root().Operations().(*RootNode)
+}
+
+// prepareAtSyscall returns a (dirfd, cName) pair that can be used
+// with the "___at" family of system calls (openat, fstatat, unlinkat...) to
+// access the backing encrypted directory.
+//
+// If you pass a `child` file name, the (dirfd, cName) pair will refer to
+// a child of this node.
+// If `child` is empty, the (dirfd, cName) pair refers to this node itself.
+func (n *Node) prepareAtSyscall(child string) (dirfd int, cName string, errno syscall.Errno) {
+	p := n.Path()
+	if child != "" {
+		p = filepath.Join(p, child)
+	}
+	rn := n.rootNode()
+	dirfd, cName, err := rn.openBackingDir(p)
+	if err != nil {
+		errno = fs.ToErrno(err)
+	}
+	return
+}
+
+// newChild attaches a new child inode to n.
+// The passed-in `st` will be modified to get a unique inode number.
+func (n *Node) newChild(ctx context.Context, st *syscall.Stat_t, out *fuse.EntryOut) *fs.Inode {
+	// Get unique inode number
+	rn := n.rootNode()
+	rn.inoMap.TranslateStat(st)
+	out.Attr.FromStat(st)
+	// Create child node
+	id := fs.StableAttr{
+		Mode: uint32(st.Mode),
+		Gen:  1,
+		Ino:  st.Ino,
+	}
+	node := &Node{}
+	return n.NewInode(ctx, node, id)
+}