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-rw-r--r--pathfs_frontend/file.go235
1 files changed, 235 insertions, 0 deletions
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)
+}