Fix File.GettAttr() size reporting

The too-large reported value broke mmap
(applications saw appended zero bytes)

Also
* Add locking for all fd operations
* Add "--debug" command line switch

cryptfs/log.go

@@ -2,18 +2,28 @@ package cryptfs
 
 import (
 	"fmt"
+	"strings"
 )
 
 type logChannel struct {
 	enabled bool
 }
 
-func (l logChannel) Printf(format string, args ...interface{}) {
+func (l *logChannel) Printf(format string, args ...interface{}) {
 	if l.enabled == true {
 		fmt.Printf(format, args...)
 	}
 }
 
+func (l *logChannel) Dump(d []byte) {
+	s := string(d)
+	fmt.Println(strings.Replace(s, "\000", "\\0", -1))
+}
+
+func (l *logChannel) Enable() {
+	l.enabled = true
+}
+
 
 var Debug = logChannel{false}
 var Warn = logChannel{true}

main.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/rfjakob/gocryptfs/cluefs_frontend"
 	"github.com/rfjakob/gocryptfs/pathfs_frontend"
+	"github.com/rfjakob/gocryptfs/cryptfs"
 
 	bazilfuse "bazil.org/fuse"
 	bazilfusefs "bazil.org/fuse/fs"
@@ -31,11 +32,18 @@ const (
 	ERREXIT_MOUNT  = 3
 	ERREXIT_SERVE  = 4
 	ERREXIT_MOUNT2 = 5
+	ERREXIT_CIPHERDIR = 6
 )
 
 func main() {
 	// Parse command line arguments
+	var debug bool
+	flag.BoolVar(&debug, "debug", false, "Enable debug output")
 	flag.Parse()
+	if debug {
+		cryptfs.Debug.Enable()
+		cryptfs.Debug.Printf("Debug output enabled\n")
+	}
 	if flag.NArg() < 2 {
 		fmt.Printf("NArg=%d\n", flag.NArg())
 		fmt.Printf("usage: %s CIPHERDIR MOUNTPOINT\n", PROGRAM_NAME)
@@ -43,13 +51,20 @@ func main() {
 	}
 	cipherdir, _ := filepath.Abs(flag.Arg(0))
 	mountpoint, _ := filepath.Abs(flag.Arg(1))
+	cryptfs.Debug.Printf("cipherdir=%s\nmountpoint=%s\n", cipherdir, mountpoint)
+
+	_, err := os.Stat(cipherdir)
+	if err != nil {
+		fmt.Printf("Cipherdir: %s\n", err.Error())
+		os.Exit(ERREXIT_CIPHERDIR)
+	}
 
 	var key [16]byte
 
 	if USE_CLUEFS {
 		cluefsFrontend(key, cipherdir, mountpoint)
 	} else {
-		pathfsFrontend(key, cipherdir, mountpoint)
+		pathfsFrontend(key, cipherdir, mountpoint, debug)
 	}
 }
 
@@ -92,7 +107,7 @@ func cluefsFrontend(key [16]byte, cipherdir string, mountpoint string) {
 	os.Exit(0)
 }
 
-func pathfsFrontend(key [16]byte, cipherdir string, mountpoint string){
+func pathfsFrontend(key [16]byte, cipherdir string, mountpoint string, debug bool){
 
 	finalFs := pathfs_frontend.NewFS(key, cipherdir, USE_OPENSSL)
 
@@ -113,7 +128,7 @@ func pathfsFrontend(key [16]byte, cipherdir string, mountpoint string){
 		fmt.Printf("Mount fail: %v\n", err)
 		os.Exit(1)
 	}
-	state.SetDebug(PATHFS_DEBUG)
+	state.SetDebug(debug)
 
 	fmt.Println("Mounted!")
 	state.Serve()

pathfs_frontend/file.go

@@ -58,7 +58,9 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
 	alignedOffset, alignedLength, skip := f.cfs.CiphertextRange(off, length)
 	cryptfs.Debug.Printf("CiphertextRange(%d, %d) -> %d, %d, %d\n", off, length, alignedOffset, alignedLength, skip)
 	ciphertext := make([]byte, int(alignedLength))
+	f.lock.Lock()
 	n, err := f.fd.ReadAt(ciphertext, int64(alignedOffset))
+	f.lock.Unlock()
 	ciphertext = ciphertext[0:n]
 	if err != nil && err != io.EOF {
 		cryptfs.Warn.Printf("read: ReadAt: %s\n", err.Error())
@@ -131,11 +133,14 @@ func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
 			blockData = f.cfs.MergeBlocks(oldData, blockData, int(b.Offset))
 			cryptfs.Debug.Printf("len(oldData)=%d len(blockData)=%d\n", len(oldData), len(blockData))
 		}
+
 		// Write
 		blockOffset, _ := b.CiphertextRange()
 		blockData = f.cfs.EncryptBlock(blockData)
 		cryptfs.Debug.Printf("WriteAt offset=%d length=%d\n", blockOffset, len(blockData))
+		f.lock.Lock()
 		_, err := f.fd.WriteAt(blockData, int64(blockOffset))
+		f.lock.Unlock()
 
 		if err != nil {
 			cryptfs.Warn.Printf("Write failed: %s\n", err.Error())
@@ -213,6 +218,7 @@ func (f *file) GetAttr(a *fuse.Attr) fuse.Status {
 		return fuse.ToStatus(err)
 	}
 	a.FromStat(&st)
+	a.Size = f.cfs.PlainSize(a.Size)
 
 	return fuse.OK
 }

pathfs_frontend/fs.go

@@ -112,8 +112,17 @@ func (fs *FS) Utimens(path string, Atime *time.Time, Mtime *time.Time, context *
 	return fs.FileSystem.Utimens(fs.EncryptPath(path), Atime, Mtime, context)
 }
 
-func (fs *FS) Readlink(name string, context *fuse.Context) (out string, code fuse.Status) {
+func (fs *FS) Readlink(name string, context *fuse.Context) (out string, status fuse.Status) {
-	return fs.FileSystem.Readlink(fs.EncryptPath(name), context)
+	dst, status := fs.FileSystem.Readlink(fs.EncryptPath(name), context)
+	if status != fuse.OK {
+		return "", status
+	}
+	dstPlain, err := fs.DecryptPath(dst)
+	if err != nil {
+		cryptfs.Warn.Printf("Failed decrypting symlink: %s\n", err.Error())
+		return "", fuse.EIO
+	}
+	return dstPlain, status
 }
 
 func (fs *FS) Mknod(name string, mode uint32, dev uint32, context *fuse.Context) (code fuse.Status) {