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authorJakob Unterwurzacher2015-11-25 22:17:42 +0100
committerJakob Unterwurzacher2015-11-25 22:17:42 +0100
commitfe2fcf6c162a8370670fd1262b90925bf321f199 (patch)
treef6b7c3d5d45d5328f9eeb9fc36ca271b3eb4d7ed /pathfs_frontend/fs.go
parentb5bf59a31d78527171d6d6109b51e8dee7f024c8 (diff)
diriv: Transactionally delete gocryptfs.diriv in Rmdir
Diffstat (limited to 'pathfs_frontend/fs.go')
-rw-r--r--pathfs_frontend/fs.go62
1 files changed, 59 insertions, 3 deletions
diff --git a/pathfs_frontend/fs.go b/pathfs_frontend/fs.go
index 3d6d79c..9c809df 100644
--- a/pathfs_frontend/fs.go
+++ b/pathfs_frontend/fs.go
@@ -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) {