Handle EOF when splicing.

fuse/loopback_test.go

@@ -139,7 +139,8 @@ func TestReadLarge(t *testing.T) {
 	ts := NewTestCase(t)
 	defer ts.Cleanup()
 
-	content := make([]byte, 1024*1024)
+	// Add a bit more to test the splicing at the end.
+	content := make([]byte, 1024*1024 + 43)
 	for i := range content {
 		content[i] = byte(i)
 	}

fuse/mountstate.go

@@ -3,6 +3,7 @@ package fuse
 import (
 	"fmt"
 	"log"
+	"io"
 	"os"
 	"strings"
 	"sync"
@@ -364,6 +365,7 @@ func (ms *MountState) write(req *request) Status {
 		if err := ms.TrySplice(header, req); err == nil {
 			return OK
 		} else {
+			log.Println("Splice error", err)
 			buf := ms.AllocOut(req, uint32(req.flatData.FdSize))
 			req.flatData.Read(buf)
 			header = req.serializeHeader()
@@ -391,19 +393,39 @@ func (ms *MountState) TrySplice(header []byte, req *request) error {
 		return err
 	}
 
-	n, err := finalSplice.LoadFromAt(req.flatData.Fd, req.flatData.FdSize, req.flatData.FdOff)
+	var n int
+	if req.flatData.FdOff < 0 {
+		n, err = finalSplice.LoadFrom(req.flatData.Fd, req.flatData.FdSize)
+	} else {
+		n, err = finalSplice.LoadFromAt(req.flatData.Fd, req.flatData.FdSize, req.flatData.FdOff)
+	}
+	if err == io.EOF || (err == nil && n < req.flatData.FdSize && n > 0) {
+		discard := make([]byte, len(header))
+		_, err = finalSplice.Read(discard)
+		if err != nil {
+			return err
+		}
+
+		// TODO - fix debug output.
+		req.flatData.FdSize = n
+		req.flatData.Fd = finalSplice.ReadFd()
+		req.flatData.FdOff = -1
+		header = req.serializeHeader()
+		return ms.TrySplice(header, req)
+	}
+
 	if err != nil {
-		// TODO - handle EOF.
 		// TODO - extract the data from splice.
 		return err
 	}
+
 	if n != req.flatData.FdSize {
-		return fmt.Errorf("Size mismatch %d %d", n, req.flatData.FdSize)		
+		return fmt.Errorf("splice: wrote %d, want %d", n, req.flatData.FdSize)
 	}
 
 	_, err = finalSplice.WriteTo(ms.mountFile.Fd(), total)
 	if err != nil {
-		return fmt.Errorf("Splice write %v", err)
+		return fmt.Errorf("splice write: %v", err)
 	}
 	return nil
 }

fuse/read.go

@@ -12,6 +12,8 @@ type ReadResult struct {
 	// If Data is nil and Status OK, splice from the following
 	// file.
 	Fd   uintptr
+
+	// Offset within Fd, or -1 to use current offset.
 	FdOff  int64
 	FdSize int
 }

splice/pair.go

@@ -52,6 +52,14 @@ func (p *Pair) Read(d []byte) (n int, err error) {
 	return p.r.Read(d)
 }
 
+func (p *Pair) ReadFd() uintptr {
+	return p.r.Fd()
+}
+
+func (p *Pair) WriteFd() uintptr {
+	return p.w.Fd()
+}
+
 func (p *Pair) Write(d []byte) (n int, err error) {
 	return p.w.Write(d)
 }