.

go/wcsrv/t/t.go

@@ -2,8 +2,10 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"log"
 	"os"
+	"time"
 
 	"github.com/hanwen/go-fuse/fuse"
 	"github.com/hanwen/go-fuse/fuse/nodefs"
@@ -21,11 +23,14 @@ type file struct {
 
 // fileHandle represents opened file.
 type fileHandle struct {
+	nodefs.File
+
+	content []byte
 }
 
 
 
-func (d *dir) Lookup(out *fuse.Attr, name string, ctx *fuse.Context) (*nodefs.Inode, fuse.Status) {
+func (d *dir) Lookup(out *fuse.Attr, name string, _ *fuse.Context) (*nodefs.Inode, fuse.Status) {
 	ientry := d.Inode().GetChild(name)
 	if ientry == nil {
 		return nil, fuse.ENOENT
@@ -34,6 +39,39 @@ func (d *dir) Lookup(out *fuse.Attr, name string, ctx *fuse.Context) (*nodefs.In
 	return ientry, fuse.OK
 }
 
+var nopen = 0
+
+func (f *file) Open(flags uint32, _ *fuse.Context) (nodefs.File, fuse.Status) {
+	_, name := f.Inode().Parent()
+	nopen++ // XXX -> atomic
+	data := fmt.Sprintf("%04d %s\n", nopen, name)
+	h := &fileHandle{File: nodefs.NewDefaultFile(), content: []byte(data)}
+	// force direct-io to disable pagecache: we alway return different data
+	// and st_size=0 (like in /proc).
+	return &nodefs.WithFlags{
+		File:		h,
+		FuseFlags:	fuse.FOPEN_DIRECT_IO,
+	}, fuse.OK
+}
+
+func (fh *fileHandle) Read(dest []byte, off int64) (fuse.ReadResult, fuse.Status) {
+	l := int64(len(dest))
+
+	// XXX demonstrate we can indeed serve different content to different openings.
+	if l >= 1 {
+		l = 1
+		time.Sleep(1*time.Second)
+	}
+
+	end := off + l
+	if ldata := int64(len(fh.content)); end > ldata {
+		end = ldata
+	}
+
+	res := fh.content[off:end]
+	fmt.Printf("read [%d:%d] -> %q\n", off, end, res)
+	return fuse.ReadResultData(res), fuse.OK
+}
 
 
 func (d *dir) mkdir(name string) *dir {
@@ -57,9 +95,6 @@ func main() {
 	}
 	mntpt := flag.Args()[0]
 	root  := &dir{Node: nodefs.NewDefaultNode()}
-	//nodefs.NewInode(true, root)
-	//println(root.Inode())
-
 	opts := nodefs.NewOptions()
 	if *debug {
 		opts.Debug = true
@@ -69,6 +104,8 @@ func main() {
 		log.Fatal(err)	// XXX err ctx?
 	}
 
+	// NOTE cannot make entries before mount because Inode.AddChild does
+	// not work before that (panics on nil deref to mountRootXXX)
 	root.mkdir("aaa")
 	root.mkfile("hello.txt")