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libgocryptfs
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diriv: Transactionally delete gocryptfs.diriv in Rmdir

This commit is contained in:
Jakob Unterwurzacher 2015-11-25 22:17:42 +01:00
parent b5bf59a31d
commit fe2fcf6c16
1 changed files with 59 additions and 3 deletions
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62
pathfs_frontend/fs.go
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@ -1,6 +1,8 @@
package pathfs_frontend
import (
"fmt"
"sync"
"syscall"
"io/ioutil"
"os"
@ -17,6 +19,7 @@ type FS struct {
*cryptfs.CryptFS
pathfs.FileSystem // loopbackFileSystem, see go-fuse/fuse/pathfs/loopback.go
backing string // Backing directory
dirivLock sync.RWMutex // Global lock that is taken if any "gocryptfs.diriv" file is modified
}
// Encrypted FUSE overlay filesystem
@ -182,10 +185,11 @@ func (fs *FS) Mkdir(relPath string, mode uint32, context *fuse.Context) (code fu
// 0444 permissions: the file is not secret but should not be written to
err = ioutil.WriteFile(dirivPath, diriv, 0444)
if err != nil {
// This should not happen
cryptfs.Warn.Printf("Creating %s in dir %s failed: %v\n", cryptfs.DIRIV_FILENAME, encPath, err)
err2 := syscall.Rmdir(encPath)
if err2 != nil {
cryptfs.Warn.Printf("Removing broken directory failed: %v\n", err2)
cryptfs.Warn.Printf("Mkdir: Rollback failed: %v\n", err2)
}
return fuse.ToStatus(err)
}
@ -199,13 +203,65 @@ func (fs *FS) Unlink(name string, context *fuse.Context) (code fuse.Status) {
cName := fs.EncryptPath(name)
code = fs.FileSystem.Unlink(cName, context)
if code != fuse.OK {
cryptfs.Warn.Printf("Unlink failed on %s [%s], code=%s\n", name, cName, code.String())
cryptfs.Debug.Printf("Unlink failed on %s [%s], code=%s\n", name, cName, code.String())
}
return code
}
func (fs *FS) Rmdir(name string, context *fuse.Context) (code fuse.Status) {
return fs.FileSystem.Rmdir(fs.EncryptPath(name), context)
encPath := fs.GetPath(name)
// If the directory is not empty besides gocryptfs.diriv, do not even
// attempt the dance around gocryptfs.diriv.
fd, err := os.Open(encPath)
if err != nil {
return fuse.ToStatus(err)
}
defer fd.Close()
list, err := fd.Readdirnames(10)
if err != nil {
return fuse.ToStatus(err)
}
if len(list) > 1 {
return fuse.ToStatus(syscall.ENOTEMPTY)
}
// Move "gocryptfs.diriv" to the parent dir under name "gocryptfs.diriv.rmdir.INODENUMBER"
var st syscall.Stat_t
err = syscall.Fstat(int(fd.Fd()), &st)
if err != nil {
return fuse.ToStatus(err)
}
dirivPath := filepath.Join(encPath, cryptfs.DIRIV_FILENAME)
parentDir := filepath.Dir(encPath)
tmpName := fmt.Sprintf("gocryptfs.diriv.rmdir.%d", st.Ino)
tmpDirivPath := filepath.Join(parentDir, tmpName)
cryptfs.Debug.Printf("Rmdir: Renaming %s to %s\n", cryptfs.DIRIV_FILENAME, tmpDirivPath)
fs.dirivLock.Lock() // directory will be in an inconsistent state after the rename
defer fs.dirivLock.Unlock()
err = os.Rename(dirivPath, tmpDirivPath)
if err != nil {
cryptfs.Warn.Printf("Rmdir: Renaming %s to %s failed: %v\n", cryptfs.DIRIV_FILENAME, tmpDirivPath, err)
return fuse.ToStatus(err)
}
// Actual Rmdir
err = syscall.Rmdir(encPath)
if err != nil {
// This can happen if another file in the directory was created in the
// meantime, undo the rename
err2 := os.Rename(tmpDirivPath, dirivPath)
if err2 != nil {
cryptfs.Warn.Printf("Rmdir: Rollback failed: %v\n", err2)
}
return fuse.ToStatus(err)
}
// Delete "gocryptfs.diriv.rmdir.INODENUMBER"
err = syscall.Unlink(tmpDirivPath)
if err != nil {
cryptfs.Warn.Printf("Rmdir: Could not clean up %s: %v\n", tmpName, err)
}
return fuse.OK
}
func (fs *FS) Symlink(pointedTo string, linkName string, context *fuse.Context) (code fuse.Status) {