Handle error conditions in ReadResultFd.

fuse/api.go

@@ -191,7 +191,7 @@ type ReadResult interface {
 	// Returns the raw bytes for the read, possibly using the
 	// passed buffer. The buffer should be larger than the return
 	// value from Size.
-	Bytes(buf []byte) []byte
+	Bytes(buf []byte) ([]byte, Status)
 
 	// Size returns how many bytes this return value takes at most.
 	Size() int

fuse/copy.go

@@ -31,7 +31,10 @@ func CopyFile(srcFs, destFs FileSystem, srcFile, destFile string, context *Conte
 		if !code.Ok() {
 			return code
 		}
-		data := res.Bytes(buf)
+		data, code := res.Bytes(buf)
+		if !code.Ok() {
+			return code
+		}
 
 		if len(data) == 0 {
 			break

fuse/mountstate.go

@@ -363,7 +363,7 @@ func (ms *MountState) write(req *request) Status {
 			log.Println("TrySplice:", err)
 			sz := req.flatDataSize()
 			buf := ms.AllocOut(req, uint32(sz))
-			req.flatData = req.fdData.Bytes(buf)
+			req.flatData, req.status = req.fdData.Bytes(buf)
 			header = req.serializeHeader(len(req.flatData))
 		}
 	}

fuse/opcode.go

@@ -279,7 +279,7 @@ func doRead(state *MountState, req *request) {
 		req.fdData = fd
 		req.flatData = nil
 	} else if r != nil {
-		req.flatData = r.Bytes(buf)
+		req.flatData, req.status = r.Bytes(buf)
 	}
 }
 

fuse/read.go

@@ -15,8 +15,8 @@ func (r *ReadResultData) Size() int {
 	return len(r.Data)
 }
 
-func (r *ReadResultData) Bytes(buf []byte) []byte {
-	return r.Data
+func (r *ReadResultData) Bytes(buf []byte) ([]byte, Status) {
+	return r.Data, OK
 }
 
 // ReadResultFd is the read return for zero-copy file data.
@@ -34,7 +34,7 @@ type ReadResultFd struct {
 
 // Reads raw bytes from file descriptor if necessary, using the passed
 // buffer as storage.
-func (r *ReadResultFd) Bytes(buf []byte) []byte {
+func (r *ReadResultFd) Bytes(buf []byte) ([]byte, Status) {
 	sz := r.Sz
 	if len(buf) < sz {
 		sz = len(buf)
@@ -44,8 +44,12 @@ func (r *ReadResultFd) Bytes(buf []byte) []byte {
 	if err == io.EOF {
 		err = nil
 	}
-	// TODO - error handling?
-	return buf[:n]
+
+	if n < 0 {
+		n = 0
+	}
+
+	return buf[:n], ToStatus(err)
 }
 
 func (r *ReadResultFd) Size() int {