Fix bpb around end-of-file.

fuse/loopback_test.go

 package fuse
 
 import (
-	"bytes"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -530,18 +529,38 @@ func TestReadLarge(t *testing.T) {
 	ts := NewTestCase(t)
 	defer ts.Cleanup()
 
-	// 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)
+	// Make blocks that are not period on 1024 bytes, so we can
+	// catch errors due to misalignments. 
+	block := make([]byte, 1023)
+	content := make([]byte, 385*1023)
+	for i := range block {
+		block[i] = byte(i)
+	}
+	start := 0
+	for start < len(content) {
+		left := len(content) - start
+		if left < len(block) {
+			block = block[:left]
 		}
+			
+		copy(content[start:], block)
+		start += len(block)
+	}
+	
+	
 	err := ioutil.WriteFile(ts.origFile, []byte(content), 0644)
 	CheckSuccess(err)
 
 	back, err := ioutil.ReadFile(ts.mountFile)
 	CheckSuccess(err)
-	if bytes.Compare(content, back) != 0 {
-		t.Errorf("content comparison failed")
+	if len(back) != len(content) {
+		t.Errorf("content length: got %d want %d", len(back), len(content))
+	}
+	for i := range content {
+		if content[i] != back[i] {
+			t.Errorf("content mismatch byte %d, got %d want %d.", i,  back[i], content[i])
+			break
+		}
 	}
 }
 

fuse/mountstate.go

@@ -364,7 +364,7 @@ func (ms *MountState) write(req *request) Status {
 		if err := ms.TrySplice(header, req, req.flatData.Fd, req.flatData.FdSize, req.flatData.FdOff); err == nil {
 			return OK
 		} else {
-			log.Println("Splice error", err)
+			log.Println("TrySplice:", err)
 			buf := ms.AllocOut(req, uint32(req.flatData.FdSize))
 			req.flatData.Read(buf)
 			header = req.serializeHeader(req.flatData.Size())
@@ -406,9 +406,8 @@ func (ms *MountState) TrySplice(header []byte, req *request,
 			return err
 		}
 
-		// TODO - fix debug output.
 		header = req.serializeHeader(n)
-		return ms.TrySplice(header, req, fd, n, -1)
+		return ms.TrySplice(header, req, finalSplice.ReadFd(), n, -1)
 	}
 
 	if err != nil {
@@ -417,7 +416,7 @@ func (ms *MountState) TrySplice(header []byte, req *request,
 	}
 
 	if n != size {
-		return fmt.Errorf("splice: wrote %d, want %d", n, req.flatData.FdSize)
+		return fmt.Errorf("wrote %d, want %d", n, req.flatData.FdSize)
 	}
 
 	_, err = finalSplice.WriteTo(ms.mountFile.Fd(), total)