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

2 files changed, 17 insertions, 2 deletions

diff --git a/pathfs_frontend/file.go b/pathfs_frontend/file.go
index 8fdd4b2..493a223 100644
--- a/pathfs_frontend/file.go
+++ b/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
 }
diff --git a/pathfs_frontend/fs.go b/pathfs_frontend/fs.go
index 0c1d879..1e4a1f3 100644
--- a/pathfs_frontend/fs.go
+++ b/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) {
-	return fs.FileSystem.Readlink(fs.EncryptPath(name), context)
+func (fs *FS) Readlink(name string, context *fuse.Context) (out string, status fuse.Status) {
+	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) {