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package fusefrontend
import (
"context"
"os"
"path/filepath"
"syscall"
"golang.org/x/sys/unix"
"github.com/hanwen/go-fuse/v2/fs"
"github.com/hanwen/go-fuse/v2/fuse"
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// Node is a file or directory in the filesystem tree
// in a gocryptfs mount.
type Node struct {
fs.Inode
}
// path returns the relative plaintext path of this node
func (n *Node) path() string {
return n.Path(n.Root())
}
func (n *Node) rootNode() *RootNode {
return n.Root().Operations().(*RootNode)
}
// Lookup - FUSE call for discovering a file.
func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (*fs.Inode, syscall.Errno) {
rn := n.rootNode()
p := filepath.Join(n.path(), name)
if rn.isFiltered(p) {
return nil, syscall.EPERM
}
dirfd, cName, err := rn.openBackingDir(p)
if err != nil {
return nil, fs.ToErrno(err)
}
defer syscall.Close(dirfd)
// Get device number and inode number into `st`
st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
return nil, fs.ToErrno(err)
}
// Get unique inode number
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{}
ch := n.NewInode(ctx, node, id)
return ch, 0
}
// GetAttr - FUSE call for stat()ing a file.
//
// GetAttr is symlink-safe through use of openBackingDir() and Fstatat().
func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut) syscall.Errno {
rn := n.rootNode()
dirfd, cName, err := rn.openBackingDir(n.path())
if err != nil {
return fs.ToErrno(err)
}
defer syscall.Close(dirfd)
st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
return fs.ToErrno(err)
}
rn.inoMap.TranslateStat(st)
out.Attr.FromStat(st)
return 0
}
// Create - FUSE call. Creates a new file.
//
// Symlink-safe through the use of Openat().
func (n *Node) Create(ctx context.Context, name string, flags uint32, mode uint32, out *fuse.EntryOut) (inode *fs.Inode, fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
rn := n.rootNode()
path := filepath.Join(n.path(), name)
if rn.isFiltered(path) {
return nil, nil, 0, syscall.EPERM
}
dirfd, cName, err := rn.openBackingDir(path)
if err != nil {
return nil, nil, 0, fs.ToErrno(err)
}
defer syscall.Close(dirfd)
fd := -1
// Make sure context is nil if we don't want to preserve the owner
if !rn.args.PreserveOwner {
ctx = nil
}
newFlags := rn.mangleOpenFlags(flags)
// Handle long file name
if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
// Create ".name"
err = rn.nameTransform.WriteLongNameAt(dirfd, cName, path)
if err != nil {
return nil, nil, 0, fs.ToErrno(err)
}
// Create content
fd, err = syscallcompat.OpenatUserCtx(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx)
if err != nil {
nametransform.DeleteLongNameAt(dirfd, cName)
}
} else {
// Create content, normal (short) file name
fd, err = syscallcompat.OpenatUserCtx(dirfd, cName, newFlags|syscall.O_CREAT|syscall.O_EXCL, mode, ctx)
}
if err != nil {
// xfstests generic/488 triggers this
if err == syscall.EMFILE {
var lim syscall.Rlimit
syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim)
tlog.Warn.Printf("Create %q: too many open files. Current \"ulimit -n\": %d", cName, lim.Cur)
}
return nil, nil, 0, fs.ToErrno(err)
}
// Get device number and inode number into `st`
st, err := syscallcompat.Fstatat2(dirfd, cName, unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
return nil, nil, 0, fs.ToErrno(err)
}
// Get unique inode number
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{}
ch := n.NewInode(ctx, node, id)
f := os.NewFile(uintptr(fd), cName)
return ch, NewFile2(f, rn, st), 0, 0
}
// Unlink - FUSE call. Delete a file.
//
// Symlink-safe through use of Unlinkat().
func (n *Node) Unlink(ctx context.Context, name string) syscall.Errno {
rn := n.rootNode()
p := filepath.Join(n.path(), name)
if rn.isFiltered(p) {
return syscall.EPERM
}
dirfd, cName, err := rn.openBackingDir(p)
if err != nil {
return fs.ToErrno(err)
}
defer syscall.Close(dirfd)
// Delete content
err = syscallcompat.Unlinkat(dirfd, cName, 0)
if err != nil {
return fs.ToErrno(err)
}
// Delete ".name" file
if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
err = nametransform.DeleteLongNameAt(dirfd, cName)
if err != nil {
tlog.Warn.Printf("Unlink: could not delete .name file: %v", err)
}
}
return fs.ToErrno(err)
}
// Readlink - FUSE call.
//
// Symlink-safe through openBackingDir() + Readlinkat().
func (n *Node) Readlink(ctx context.Context) ([]byte, syscall.Errno) {
rn := n.rootNode()
p := n.path()
if rn.isFiltered(p) {
return nil, syscall.EPERM
}
dirfd, cName, err := rn.openBackingDir(p)
if err != nil {
return nil, fs.ToErrno(err)
}
defer syscall.Close(dirfd)
cTarget, err := syscallcompat.Readlinkat(dirfd, cName)
if err != nil {
return nil, fs.ToErrno(err)
}
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
}
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