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// Copyright 2019 the Go-FUSE Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package fs_test
import (
"context"
"fmt"
"log"
"syscall"
"time"
"github.com/hanwen/go-fuse/v2/fs"
"github.com/hanwen/go-fuse/v2/fuse"
)
// bytesFileHandle is a file handle that carries separate content for
// each Open call
type bytesFileHandle struct {
content []byte
}
// bytesFileHandle allows reads
var _ = (fs.FileReader)((*bytesFileHandle)(nil))
func (fh *bytesFileHandle) Read(ctx context.Context, dest []byte, off int64) (fuse.ReadResult, syscall.Errno) {
end := off + int64(len(dest))
if end > int64(len(fh.content)) {
end = int64(len(fh.content))
}
// We could copy to the `dest` buffer, but since we have a
// []byte already, return that.
return fuse.ReadResultData(fh.content[off:end]), 0
}
// timeFile is a file that contains the wall clock time as ASCII.
type timeFile struct {
fs.Inode
}
// timeFile implements Open
var _ = (fs.NodeOpener)((*timeFile)(nil))
func (f *timeFile) Open(ctx context.Context, openFlags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
// disallow writes
if fuseFlags&(syscall.O_RDWR|syscall.O_WRONLY) != 0 {
return nil, 0, syscall.EROFS
}
// capture open time
now := time.Now().Format(time.StampNano) + "\n"
fh = &bytesFileHandle{
content: []byte(now),
}
// Return FOPEN_DIRECT_IO so content is not cached.
return fh, fuse.FOPEN_DIRECT_IO, 0
}
// ExampleDirectIO shows how to create a file whose contents change on
// every read.
func Example_directIO() {
mntDir := "/tmp/x"
root := &fs.Inode{}
// Mount the file system
server, err := fs.Mount(mntDir, root, &fs.Options{
MountOptions: fuse.MountOptions{Debug: false},
// Setup the clock file.
OnAdd: func(ctx context.Context) {
ch := root.NewPersistentInode(
ctx,
&timeFile{},
fs.StableAttr{Mode: syscall.S_IFREG})
root.AddChild("clock", ch, true)
},
})
if err != nil {
log.Fatal(err)
}
fmt.Printf("cat %s/clock to see the time\n", mntDir)
fmt.Printf("Unmount by calling 'fusermount -u %s'\n", mntDir)
// Serve the file system, until unmounted by calling fusermount -u
server.Wait()
}
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