From 889ae900814aac1c17c38a76882b1aafa5744be6 Mon Sep 17 00:00:00 2001 From: Jakob Unterwurzacher Date: Tue, 8 Sep 2015 00:54:24 +0200 Subject: Add pathfs frontend (uses go-fuse instead of bazil-fuse), part I Currently fails main_test.go, will be fixed in part II --- pathfs_frontend/file.go | 235 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 235 insertions(+) create mode 100644 pathfs_frontend/file.go (limited to 'pathfs_frontend/file.go') diff --git a/pathfs_frontend/file.go b/pathfs_frontend/file.go new file mode 100644 index 0000000..8b6d61d --- /dev/null +++ b/pathfs_frontend/file.go @@ -0,0 +1,235 @@ +package pathfs_frontend + +import ( + "io" + "bytes" + "fmt" + "os" + "sync" + "syscall" + "time" + + "github.com/hanwen/go-fuse/fuse" + "github.com/hanwen/go-fuse/fuse/nodefs" + "github.com/rfjakob/gocryptfs/cryptfs" +) + +// File - based on loopbackFile in go-fuse/fuse/nodefs/files.go +type file struct { + fd *os.File + + // os.File is not threadsafe. Although fd themselves are + // constant during the lifetime of an open file, the OS may + // reuse the fd number after it is closed. When open races + // with another close, they may lead to confusion as which + // file gets written in the end. + lock sync.Mutex + + // Was the file opened O_WRONLY? + writeOnly bool + + // Parent CryptFS + cfs *cryptfs.CryptFS +} + +func NewFile(fd *os.File, writeOnly bool, cfs *cryptfs.CryptFS) nodefs.File { + return &file{ + fd: fd, + writeOnly: writeOnly, + cfs: cfs, + } +} + +func (f *file) InnerFile() nodefs.File { + return nil +} + +func (f *file) SetInode(n *nodefs.Inode) { +} + +func (f *file) String() string { + return fmt.Sprintf("cryptFile(%s)", f.fd.Name()) +} + +// Read - FUSE call +func (f *file) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fuse.Status) { + cryptfs.Debug.Printf("\n\nGot read request: len=%d off=%d\n", len(buf), off) + + if f.writeOnly { + return nil, fuse.EBADF + } + + // Read the backing ciphertext in one go + alignedOffset, alignedLength, skip := f.cfs.CiphertextRange(uint64(off), uint64(len(buf))) + ciphertext := make([]byte, int(alignedLength)) + _, err := f.fd.ReadAt(ciphertext, int64(alignedOffset)) + if err != nil && err != io.EOF { + cryptfs.Warn.Printf("Read error: %s\n", err.Error()) + return nil, fuse.ToStatus(err) + } + + // Decrypt it + plaintext, err := f.cfs.DecryptBlocks(ciphertext) + if err != nil { + cryptfs.Warn.Printf("Decryption error: %s\n", err.Error()) + return nil, fuse.EIO + } + + // Crop down to the relevant part + var out []byte + lenHave := len(plaintext) + lenWant := skip + len(buf) + if lenHave > lenWant { + out = plaintext[skip:skip + len(buf)] + } else if lenHave > skip { + out = plaintext[skip:lenHave] + } + // else: out stays empty + + fmt.Printf("Read: returning %d bytes\n", len(plaintext)) + + return fuse.ReadResultData(out), fuse.OK +} + +// Write - FUSE call +func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) { + var written uint32 + var status fuse.Status + dataBuf := bytes.NewBuffer(data) + blocks := f.cfs.SplitRange(uint64(off), uint64(len(data))) + for _, b := range(blocks) { + + blockData := dataBuf.Next(int(b.Length)) + + // Incomplete block -> Read-Modify-Write + if b.IsPartial() { + // Read + oldData := make([]byte, f.cfs.PlainBS()) + o, _ := b.PlaintextRange() + res, status := f.Read(oldData, int64(o)) + oldData, _ = res.Bytes(oldData) + if status != fuse.OK { + return written, status + } + // Modify + blockData = f.cfs.MergeBlocks(oldData, blockData, int(b.Offset)) + } + // Write + blockOffset, _ := b.CiphertextRange() + blockData = f.cfs.EncryptBlock(blockData) + _, err := f.fd.WriteAt(blockData, int64(blockOffset)) + + if err != nil { + cryptfs.Warn.Printf("Write failed: %s\n", err.Error()) + status = fuse.ToStatus(err) + break + } + written += uint32(b.Length) + } + + return written, status +} + +// Release - FUSE call, forget file +func (f *file) Release() { + f.lock.Lock() + f.fd.Close() + f.lock.Unlock() +} + +// Flush - FUSE call +func (f *file) Flush() fuse.Status { + f.lock.Lock() + + // Since Flush() may be called for each dup'd fd, we don't + // want to really close the file, we just want to flush. This + // is achieved by closing a dup'd fd. + newFd, err := syscall.Dup(int(f.fd.Fd())) + f.lock.Unlock() + + if err != nil { + return fuse.ToStatus(err) + } + err = syscall.Close(newFd) + return fuse.ToStatus(err) +} + +func (f *file) Fsync(flags int) (code fuse.Status) { + f.lock.Lock() + r := fuse.ToStatus(syscall.Fsync(int(f.fd.Fd()))) + f.lock.Unlock() + + return r +} + +func (f *file) Truncate(size uint64) fuse.Status { + f.lock.Lock() + r := fuse.ToStatus(syscall.Ftruncate(int(f.fd.Fd()), int64(size))) + f.lock.Unlock() + + return r +} + +func (f *file) Chmod(mode uint32) fuse.Status { + f.lock.Lock() + r := fuse.ToStatus(f.fd.Chmod(os.FileMode(mode))) + f.lock.Unlock() + + return r +} + +func (f *file) Chown(uid uint32, gid uint32) fuse.Status { + f.lock.Lock() + r := fuse.ToStatus(f.fd.Chown(int(uid), int(gid))) + f.lock.Unlock() + + return r +} + +func (f *file) GetAttr(a *fuse.Attr) fuse.Status { + st := syscall.Stat_t{} + f.lock.Lock() + err := syscall.Fstat(int(f.fd.Fd()), &st) + f.lock.Unlock() + if err != nil { + return fuse.ToStatus(err) + } + a.FromStat(&st) + + return fuse.OK +} + +func (f *file) Allocate(off uint64, sz uint64, mode uint32) fuse.Status { + f.lock.Lock() + err := syscall.Fallocate(int(f.fd.Fd()), mode, int64(off), int64(sz)) + f.lock.Unlock() + if err != nil { + return fuse.ToStatus(err) + } + return fuse.OK +} + +const _UTIME_NOW = ((1 << 30) - 1) +const _UTIME_OMIT = ((1 << 30) - 2) + +func (f *file) Utimens(a *time.Time, m *time.Time) fuse.Status { + tv := make([]syscall.Timeval, 2) + if a == nil { + tv[0].Usec = _UTIME_OMIT + } else { + n := a.UnixNano() + tv[0] = syscall.NsecToTimeval(n) + } + + if m == nil { + tv[1].Usec = _UTIME_OMIT + } else { + n := a.UnixNano() + tv[1] = syscall.NsecToTimeval(n) + } + + f.lock.Lock() + err := syscall.Futimes(int(f.fd.Fd()), tv) + f.lock.Unlock() + return fuse.ToStatus(err) +} -- cgit v1.2.3