fs: Move file Read behaviour onto a new handle type

fs/file_handle.go

@@ -0,0 +1,43 @@
+package torrentfs
+
+import (
+	"context"
+	"fmt"
+
+	"bazil.org/fuse"
+	"bazil.org/fuse/fs"
+)
+
+type fileHandle struct {
+	fn fileNode
+}
+
+var _ fs.HandleReader = fileHandle{}
+
+func (me fileHandle) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
+	torrentfsReadRequests.Add(1)
+	if req.Dir {
+		panic("read on directory")
+	}
+	size := req.Size
+	fileLeft := int64(me.fn.size) - req.Offset
+	if fileLeft < 0 {
+		fileLeft = 0
+	}
+	if fileLeft < int64(size) {
+		size = int(fileLeft)
+	}
+	resp.Data = resp.Data[:size]
+	if len(resp.Data) == 0 {
+		return nil
+	}
+	torrentOff := me.fn.TorrentOffset + req.Offset
+	n, err := readFull(ctx, me.fn.FS, me.fn.t, torrentOff, resp.Data)
+	if err != nil {
+		return err
+	}
+	if n != size {
+		panic(fmt.Sprintf("%d < %d", n, size))
+	}
+	return nil
+}

fs/filenode.go

@@ -1,8 +1,6 @@
 package torrentfs
 
 import (
-	"fmt"
-
 	"bazil.org/fuse"
 	fusefs "bazil.org/fuse/fs"
 	"golang.org/x/net/context"
@@ -14,7 +12,9 @@ type fileNode struct {
 	TorrentOffset int64
 }
 
-var _ fusefs.HandleReader = fileNode{}
+var (
+	_ fusefs.NodeOpener = fileNode{}
+)
 
 func (fn fileNode) Attr(ctx context.Context, attr *fuse.Attr) error {
 	attr.Size = fn.size
@@ -22,30 +22,6 @@ func (fn fileNode) Attr(ctx context.Context, attr *fuse.Attr) error {
 	return nil
 }
 
-func (fn fileNode) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
-	torrentfsReadRequests.Add(1)
-	if req.Dir {
-		panic("read on directory")
-	}
-	size := req.Size
-	fileLeft := int64(fn.size) - req.Offset
-	if fileLeft < 0 {
-		fileLeft = 0
-	}
-	if fileLeft < int64(size) {
-		size = int(fileLeft)
-	}
-	resp.Data = resp.Data[:size]
-	if len(resp.Data) == 0 {
-		return nil
-	}
-	torrentOff := fn.TorrentOffset + req.Offset
-	n, err := readFull(ctx, fn.FS, fn.t, torrentOff, resp.Data)
-	if err != nil {
-		return err
-	}
-	if n != size {
-		panic(fmt.Sprintf("%d < %d", n, size))
-	}
-	return nil
+func (fn fileNode) Open(ctx context.Context, req *fuse.OpenRequest, resp *fuse.OpenResponse) (fusefs.Handle, error) {
+	return fileHandle{fn}, nil
 }

fs/torrentfs_test.go

@@ -210,7 +210,9 @@ func TestDownloadOnDemand(t *testing.T) {
 	resp := &fuse.ReadResponse{
 		Data: make([]byte, size),
 	}
-	node.(fusefs.HandleReader).Read(netContext.Background(), &fuse.ReadRequest{
+	h, err := node.(fusefs.NodeOpener).Open(nil, nil, nil)
+	require.NoError(t, err)
+	h.(fusefs.HandleReader).Read(netContext.Background(), &fuse.ReadRequest{
 		Size: int(size),
 	}, resp)
 	assert.EqualValues(t, testutil.GreetingFileContents, resp.Data)