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package fusefrontend_reverse
import (
"context"
"fmt"
"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/contentenc"
"github.com/rfjakob/gocryptfs/internal/pathiv"
"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 -reverse` mount.
type Node struct {
fs.Inode
}
// Lookup - FUSE call for discovering a file.
func (n *Node) Lookup(ctx context.Context, cName string, out *fuse.EntryOut) (ch *fs.Inode, errno syscall.Errno) {
dirfd := int(-1)
pName := ""
t := n.lookupFileType(cName)
if t == typeDiriv {
// gocryptfs.diriv
return n.lookupDiriv(ctx, out)
} else if t == typeName {
// gocryptfs.longname.*.name
return n.lookupLongnameName(ctx, cName, out)
} else if t == typeConfig {
// gocryptfs.conf
return n.lookupConf(ctx, out)
} else if t == typeReal {
// real file
dirfd, pName, errno = n.prepareAtSyscall(cName)
if errno != 0 {
return
}
defer syscall.Close(dirfd)
}
// Get device number and inode number into `st`
st, err := syscallcompat.Fstatat2(dirfd, pName, unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
return nil, fs.ToErrno(err)
}
// Create new inode and fill `out`
ch = n.newChild(ctx, st, out)
// Translate ciphertext size in `out.Attr.Size` to plaintext size
if t == typeReal {
n.translateSize(dirfd, cName, pName, &out.Attr)
}
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) (errno syscall.Errno) {
// If the kernel gives us a file handle, use it.
if f != nil {
return f.(fs.FileGetattrer).Getattr(ctx, out)
}
dirfd, pName, errno := n.prepareAtSyscall("")
if errno != 0 {
return
}
defer syscall.Close(dirfd)
st, err := syscallcompat.Fstatat2(dirfd, pName, unix.AT_SYMLINK_NOFOLLOW)
if err != nil {
return fs.ToErrno(err)
}
// Fix inode number
rn := n.rootNode()
rn.inoMap.TranslateStat(st)
out.Attr.FromStat(st)
// Translate ciphertext size in `out.Attr.Size` to plaintext size
cName := filepath.Base(n.Path())
n.translateSize(dirfd, cName, pName, &out.Attr)
if rn.args.ForceOwner != nil {
out.Owner = *rn.args.ForceOwner
}
return 0
}
// Readlink - FUSE call.
//
// Symlink-safe through openBackingDir() + Readlinkat().
func (n *Node) Readlink(ctx context.Context) (out []byte, errno syscall.Errno) {
dirfd, pName, errno := n.prepareAtSyscall("")
if errno != 0 {
return
}
defer syscall.Close(dirfd)
cName := filepath.Base(n.Path())
return n.readlink(dirfd, cName, pName)
}
// Open - FUSE call. Open already-existing file.
//
// Symlink-safe through Openat().
func (n *Node) Open(ctx context.Context, flags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
dirfd, pName, errno := n.prepareAtSyscall("")
if errno != 0 {
return
}
defer syscall.Close(dirfd)
fd, err := syscallcompat.Openat(dirfd, pName, syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)
if err != nil {
errno = fs.ToErrno(err)
return
}
// Reject access if the file descriptor does not refer to a regular file.
var st syscall.Stat_t
err = syscall.Fstat(fd, &st)
if err != nil {
tlog.Warn.Printf("Open: Fstat error: %v", err)
syscall.Close(fd)
errno = fs.ToErrno(err)
return
}
var a fuse.Attr
a.FromStat(&st)
if !a.IsRegular() {
tlog.Warn.Printf("ino%d: newFile: not a regular file", st.Ino)
syscall.Close(fd)
errno = syscall.EACCES
return
}
// See if we have that inode number already in the table
// (even if Nlink has dropped to 1)
var derivedIVs pathiv.FileIVs
v, found := inodeTable.Load(st.Ino)
if found {
tlog.Debug.Printf("ino%d: newFile: found in the inode table", st.Ino)
derivedIVs = v.(pathiv.FileIVs)
} else {
p := n.Path()
derivedIVs = pathiv.DeriveFile(p)
// Nlink > 1 means there is more than one path to this file.
// Store the derived values so we always return the same data,
// regardless of the path that is used to access the file.
// This means that the first path wins.
if st.Nlink > 1 {
v, found = inodeTable.LoadOrStore(st.Ino, derivedIVs)
if found {
// Another thread has stored a different value before we could.
derivedIVs = v.(pathiv.FileIVs)
} else {
tlog.Debug.Printf("ino%d: newFile: Nlink=%d, stored in the inode table", st.Ino, st.Nlink)
}
}
}
header := contentenc.FileHeader{
Version: contentenc.CurrentVersion,
ID: derivedIVs.ID,
}
fh = &File{
fd: os.NewFile(uintptr(fd), fmt.Sprintf("fd%d", fd)),
header: header,
block0IV: derivedIVs.Block0IV,
contentEnc: n.rootNode().contentEnc,
}
return
}
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