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package fusefrontend_reverse
import (
"os"
"path/filepath"
"sync"
"syscall"
"time"
"github.com/hanwen/go-fuse/fuse"
"github.com/hanwen/go-fuse/fuse/nodefs"
"github.com/rfjakob/gocryptfs/internal/nametransform"
)
const (
shortNameMax = 176
)
type dirIVNameStruct struct {
dirIV [nametransform.DirIVLen]byte
name string
}
var longnameParentCache map[string]string
var longnameCacheLock sync.Mutex
// Very simple cache cleaner: Nuke it every hour
func longnameCacheCleaner() {
for {
time.Sleep(time.Hour)
longnameCacheLock.Lock()
longnameParentCache = map[string]string{}
longnameCacheLock.Unlock()
}
}
func init() {
longnameParentCache = map[string]string{}
go longnameCacheCleaner()
}
// findLongnameParent converts "gocryptfs.longname.XYZ" to the plaintext name
func (rfs *reverseFS) findLongnameParent(dir string, dirIV []byte, longname string) (plaintextName string, err error) {
longnameCacheLock.Lock()
hit := longnameParentCache[longname]
longnameCacheLock.Unlock()
if hit != "" {
return hit, nil
}
absDir := filepath.Join(rfs.args.Cipherdir, dir)
dirfd, err := os.Open(absDir)
if err != nil {
return "", err
}
dirEntries, err := dirfd.Readdirnames(-1)
if err != nil {
return "", err
}
longnameCacheLock.Lock()
defer longnameCacheLock.Unlock()
for _, plaintextName = range dirEntries {
if len(plaintextName) <= shortNameMax {
continue
}
cName := rfs.nameTransform.EncryptName(plaintextName, dirIV)
if len(cName) <= syscall.NAME_MAX {
panic("logic error or wrong shortNameMax constant?")
}
hName := nametransform.HashLongName(cName)
longnameParentCache[hName] = plaintextName
if longname == hName {
hit = plaintextName
}
}
if hit == "" {
return "", syscall.ENOENT
} else {
return hit, nil
}
}
func (rfs *reverseFS) newNameFile(relPath string) (nodefs.File, fuse.Status) {
dotName := filepath.Base(relPath) // gocryptfs.longname.XYZ.name
longname := dotName[:len(dotName)-len(nametransform.LongNameSuffix)] // gocryptfs.longname.XYZ
cDir := saneDir(relPath)
pDir, err := rfs.decryptPath(cDir)
if err != nil {
return nil, fuse.ToStatus(err)
}
dirIV := deriveDirIV(cDir)
e, err := rfs.findLongnameParent(pDir, dirIV, longname)
if err != nil {
return nil, fuse.ToStatus(err)
}
content := []byte(rfs.nameTransform.EncryptName(e, dirIV))
parentFile := filepath.Join(rfs.args.Cipherdir, pDir)
return rfs.NewVirtualFile(content, parentFile)
}
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