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package nametransform
import (
"crypto/sha256"
"encoding/base64"
"io/ioutil"
"path/filepath"
"strings"
"syscall"
"github.com/rfjakob/gocryptfs/internal/toggledlog"
)
// Files with long names are stored in two files:
// gocryptfs.longname.[sha256] <--- File content
// gocryptfs.longname.[sha256].name <--- File name
const longNamePrefix = "gocryptfs.longname."
const longNameSuffix = ".name"
// HashLongName - take the hash of a long string "name" and return
// "gocryptfs.longname.[sha256]"
func HashLongName(name string) string {
hashBin := sha256.Sum256([]byte(name))
hashBase64 := base64.URLEncoding.EncodeToString(hashBin[:])
return longNamePrefix + hashBase64
}
// Values returned by IsLongName
const (
LongNameContent = iota
LongNameFilename = iota
LongNameNone = iota
)
// IsLongName - detect if cName is
// gocryptfs.longname.[sha256] ........ LongNameContent (content of a long name file)
// gocryptfs.longname.[sha256].name .... LongNameFilename (full file name of a long name file)
// else ................................ LongNameNone (normal file)
func IsLongName(cName string) int {
if !strings.HasPrefix(cName, longNamePrefix) {
return LongNameNone
}
if strings.HasSuffix(cName, longNameSuffix) {
return LongNameFilename
}
return LongNameContent
}
// ReadLongName - read path.name
func ReadLongName(path string) (string, error) {
content, err := ioutil.ReadFile(path + longNameSuffix)
if err != nil {
toggledlog.Warn.Printf("ReadLongName: %v", err)
}
return string(content), err
}
// DeleteLongName - if cPath ends in "gocryptfs.longname.[sha256]",
// delete the "gocryptfs.longname.[sha256].name" file
func DeleteLongName(cPath string) error {
if IsLongName(filepath.Base(cPath)) == LongNameContent {
err := syscall.Unlink(cPath + longNameSuffix)
if err != nil {
toggledlog.Warn.Printf("DeleteLongName: %v", err)
}
return err
}
return nil
}
// WriteLongName - if cPath ends in "gocryptfs.longname.[sha256]", write the
// "gocryptfs.longname.[sha256].name" file
func (n *NameTransform) WriteLongName(cPath string, plainPath string) (err error) {
cHashedName := filepath.Base(cPath)
if IsLongName(cHashedName) != LongNameContent {
// This is not a hashed file name, nothing to do
return nil
}
// Encrypt (but do not hash) the plaintext name
cDir := filepath.Dir(cPath)
dirIV, err := ReadDirIV(cDir)
if err != nil {
toggledlog.Warn.Printf("WriteLongName: %v", err)
return err
}
plainName := filepath.Base(plainPath)
cName := n.EncryptName(plainName, dirIV)
// Write the encrypted name into gocryptfs.longname.[sha256].name
err = ioutil.WriteFile(filepath.Join(cDir, cHashedName+longNameSuffix), []byte(cName), 0600)
if err != nil {
toggledlog.Warn.Printf("WriteLongName: %v", err)
}
return err
}
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