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package fusefrontend
import (
"context"
"syscall"
"github.com/hanwen/go-fuse/v2/fs"
"github.com/hanwen/go-fuse/v2/fuse"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// toFuseCtx tries to extract a fuse.Context from a generic context.Context.
func toFuseCtx(ctx context.Context) (ctx2 *fuse.Context) {
if ctx == nil {
return nil
}
if caller, ok := fuse.FromContext(ctx); ok {
ctx2 = &fuse.Context{
Caller: *caller,
}
}
return ctx2
}
// toNode casts a generic fs.InodeEmbedder into *Node. Also handles *RootNode
// by return rn.Node.
func toNode(op fs.InodeEmbedder) *Node {
if r, ok := op.(*RootNode); ok {
return &r.Node
}
return op.(*Node)
}
// readlink reads and decrypts a symlink. Used by Readlink, Getattr, Lookup.
func (n *Node) readlink(dirfd int, cName string) (out []byte, errno syscall.Errno) {
cTarget, err := syscallcompat.Readlinkat(dirfd, cName)
if err != nil {
return nil, fs.ToErrno(err)
}
rn := n.rootNode()
if rn.args.PlaintextNames {
return []byte(cTarget), 0
}
// Symlinks are encrypted like file contents (GCM) and base64-encoded
target, err := rn.decryptSymlinkTarget(cTarget)
if err != nil {
tlog.Warn.Printf("Readlink %q: decrypting target failed: %v", cName, err)
return nil, syscall.EIO
}
return []byte(target), 0
}
// 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.CipherSizeToPlainSize(out.Size)
} else if out.IsSymlink() {
target, _ := n.readlink(dirfd, cName)
out.Size = uint64(len(target))
}
}
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