Fix examples to use vectored read

samples/cachingfs/caching_fs.go

@@ -368,6 +368,8 @@ func (fs *cachingFS) ReadFile(
 	ctx context.Context,
 	op *fuseops.ReadFileOp) error {
 	var err error
-	op.BytesRead, err = io.ReadFull(rand.Reader, op.Dst)
+	dst := make([]byte, op.Size)
+	op.BytesRead, err = io.ReadFull(rand.Reader, dst)
+	op.Data = [][]byte{dst}
 	return err
 }

samples/dynamicfs/dynamic_fs.go

@@ -246,7 +246,8 @@ func (fs *dynamicFS) ReadFile(
 	}
 	reader := strings.NewReader(contents)
 	var err error
-	op.BytesRead, err = reader.ReadAt(op.Dst, op.Offset)
+	op.Data = [][]byte{ make([]byte, op.Size) }
+	op.BytesRead, err = reader.ReadAt(op.Data[0], op.Offset)
 	if err == io.EOF {
 		return nil
 	}

samples/errorfs/error_fs.go

@@ -26,7 +26,7 @@ import (
 	"github.com/jacobsa/fuse/fuseutil"
 )
 
-const FooContents = "xxxx"
+var FooContents = []byte("xxxx")
 
 const fooInodeID = fuseops.RootInodeID + 1
 
@@ -171,7 +171,8 @@ func (fs *errorFS) ReadFile(
 		return fmt.Errorf("Unexpected request: %#v", op)
 	}
 
-	op.BytesRead = copy(op.Dst, FooContents)
+	op.Data = [][]byte{FooContents}
+	op.BytesRead = len(FooContents)
 
 	return nil
 }

samples/flushfs/flush_fs.go

@@ -196,7 +196,12 @@ func (fs *flushFS) ReadFile(
 	}
 
 	// Read what we can.
-	op.BytesRead = copy(op.Dst, fs.fooContents[op.Offset:])
+	end := op.Offset+op.Size
+	if end > int64(len(fs.fooContents)) {
+		end = int64(len(fs.fooContents))
+	}
+	op.Data = [][]byte{ fs.fooContents[op.Offset : end] }
+	op.BytesRead = int(end-op.Offset)
 
 	return nil
 }

samples/hellofs/hello_fs.go

@@ -250,7 +250,8 @@ func (fs *helloFS) ReadFile(
 	reader := strings.NewReader("Hello, world!")
 
 	var err error
-	op.BytesRead, err = reader.ReadAt(op.Dst, op.Offset)
+	op.Data = [][]byte{ make([]byte, op.Size) }
+	op.BytesRead, err = reader.ReadAt(op.Data[0], op.Offset)
 
 	// Special case: FUSE doesn't expect us to return io.EOF.
 	if err == io.EOF {

samples/memfs/memfs.go

@@ -692,7 +692,8 @@ func (fs *memFS) ReadFile(
 
 	// Serve the request.
 	var err error
-	op.BytesRead, err = inode.ReadAt(op.Dst, op.Offset)
+	op.Data = [][]byte{ make([]byte, op.Size) }
+	op.BytesRead, err = inode.ReadAt(op.Data[0], op.Offset)
 
 	// Don't return EOF errors; we just indicate EOF to fuse using a short read.
 	if err == io.EOF {

samples/roloopbackfs/roloopbackfs.go

@@ -160,8 +160,13 @@ func (fs *readonlyLoopbackFs) ReadFile(
 		return fuse.EIO
 	}
 
-	contents = contents[op.Offset:]
-	op.BytesRead = copy(op.Dst, contents)
+	end := op.Offset+op.Size
+	if end > int64(len(contents)) {
+		end = int64(len(contents))
+	}
+
+	op.Data = [][]byte{ contents[op.Offset : end] }
+	op.BytesRead = int(end-op.Offset)
 	return nil
 }