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libgocryptfs
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v2api: add prepareAtSyscall helper

This commit is contained in:
Jakob Unterwurzacher 2020-07-04 21:16:20 +02:00
parent 23180794fe
commit d73e4b3f7c
1 changed files with 51 additions and 42 deletions
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93
internal/fusefrontend/node.go
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@ -27,29 +27,50 @@ func (n *Node) path() string {
return n.Path(n.Root())
}
// rootNode returns the Root Node of the filesystem.
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) {
// 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()
p := filepath.Join(n.path(), name)
if rn.isFiltered(p) {
return nil, syscall.EPERM
errno = syscall.EPERM
return
}
dirfd, cName, err := rn.openBackingDir(p)
if err != nil {
return nil, fs.ToErrno(err)
errno = fs.ToErrno(err)
}
return
}
// Lookup - FUSE call for discovering a file.
func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (ch *fs.Inode, errno syscall.Errno) {
dirfd, cName, errno := n.prepareAtSyscall(name)
if errno != 0 {
return
}
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)
n.rootNode().inoMap.TranslateStat(st)
out.Attr.FromStat(st)
// Create child node
id := fs.StableAttr{
@ -58,18 +79,17 @@ func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (*fs
Ino: st.Ino,
}
node := &Node{}
ch := n.NewInode(ctx, node, id)
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)
func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut) (errno syscall.Errno) {
dirfd, cName, errno := n.prepareAtSyscall("")
if errno != 0 {
return
}
defer syscall.Close(dirfd)
@ -77,7 +97,7 @@ func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut)
if err != nil {
return fs.ToErrno(err)
}
rn.inoMap.TranslateStat(st)
n.rootNode().inoMap.TranslateStat(st)
out.Attr.FromStat(st)
return 0
}
@ -86,19 +106,16 @@ func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut)
//
// 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)
dirfd, cName, errno := n.prepareAtSyscall(name)
if errno != 0 {
return
}
defer syscall.Close(dirfd)
var err error
fd := -1
// Make sure context is nil if we don't want to preserve the owner
rn := n.rootNode()
if !rn.args.PreserveOwner {
ctx = nil
}
@ -106,7 +123,7 @@ func (n *Node) Create(ctx context.Context, name string, flags uint32, mode uint3
// Handle long file name
if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
// Create ".name"
err = rn.nameTransform.WriteLongNameAt(dirfd, cName, path)
err = rn.nameTransform.WriteLongNameAt(dirfd, cName, name)
if err != nil {
return nil, nil, 0, fs.ToErrno(err)
}
@ -153,24 +170,20 @@ func (n *Node) Create(ctx context.Context, name string, flags uint32, mode uint3
// 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)
func (n *Node) Unlink(ctx context.Context, name string) (errno syscall.Errno) {
dirfd, cName, errno := n.prepareAtSyscall(name)
if errno != 0 {
return
}
defer syscall.Close(dirfd)
// Delete content
err = syscallcompat.Unlinkat(dirfd, cName, 0)
err := syscallcompat.Unlinkat(dirfd, cName, 0)
if err != nil {
return fs.ToErrno(err)
}
// Delete ".name" file
if !rn.args.PlaintextNames && nametransform.IsLongContent(cName) {
if !n.rootNode().args.PlaintextNames && nametransform.IsLongContent(cName) {
err = nametransform.DeleteLongNameAt(dirfd, cName)
if err != nil {
tlog.Warn.Printf("Unlink: could not delete .name file: %v", err)
@ -182,15 +195,10 @@ func (n *Node) Unlink(ctx context.Context, name string) syscall.Errno {
// 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)
func (n *Node) Readlink(ctx context.Context) (out []byte, errno syscall.Errno) {
dirfd, cName, errno := n.prepareAtSyscall("")
if errno != 0 {
return
}
defer syscall.Close(dirfd)
@ -198,6 +206,7 @@ func (n *Node) Readlink(ctx context.Context) ([]byte, syscall.Errno) {
if err != nil {
return nil, fs.ToErrno(err)
}
rn := n.rootNode()
if rn.args.PlaintextNames {
return []byte(cTarget), 0
}