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262 lines
4.9 KiB
Go
262 lines
4.9 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package hellofs
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import (
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"context"
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"io"
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"os"
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"strings"
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"github.com/jacobsa/fuse"
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"github.com/jacobsa/fuse/fuseops"
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"github.com/jacobsa/fuse/fuseutil"
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"github.com/jacobsa/timeutil"
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)
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// Create a file system with a fixed structure that looks like this:
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//
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// hello
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// dir/
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// world
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//
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// Each file contains the string "Hello, world!".
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func NewHelloFS(clock timeutil.Clock) (fuse.Server, error) {
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fs := &helloFS{
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Clock: clock,
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}
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return fuseutil.NewFileSystemServer(fs), nil
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}
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type helloFS struct {
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fuseutil.NotImplementedFileSystem
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Clock timeutil.Clock
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}
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const (
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rootInode fuseops.InodeID = fuseops.RootInodeID + iota
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helloInode
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dirInode
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worldInode
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)
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type inodeInfo struct {
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attributes fuseops.InodeAttributes
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// File or directory?
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dir bool
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// For directories, children.
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children []fuseutil.Dirent
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}
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// We have a fixed directory structure.
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var gInodeInfo = map[fuseops.InodeID]inodeInfo{
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// root
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rootInode: inodeInfo{
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attributes: fuseops.InodeAttributes{
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Nlink: 1,
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Mode: 0555 | os.ModeDir,
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},
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dir: true,
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children: []fuseutil.Dirent{
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fuseutil.Dirent{
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Offset: 1,
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Inode: helloInode,
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Name: "hello",
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Type: fuseutil.DT_File,
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},
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fuseutil.Dirent{
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Offset: 2,
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Inode: dirInode,
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Name: "dir",
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Type: fuseutil.DT_Directory,
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},
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},
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},
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// hello
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helloInode: inodeInfo{
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attributes: fuseops.InodeAttributes{
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Nlink: 1,
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Mode: 0444,
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Size: uint64(len("Hello, world!")),
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},
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},
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// dir
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dirInode: inodeInfo{
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attributes: fuseops.InodeAttributes{
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Nlink: 1,
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Mode: 0555 | os.ModeDir,
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},
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dir: true,
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children: []fuseutil.Dirent{
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fuseutil.Dirent{
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Offset: 1,
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Inode: worldInode,
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Name: "world",
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Type: fuseutil.DT_File,
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},
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},
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},
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// world
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worldInode: inodeInfo{
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attributes: fuseops.InodeAttributes{
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Nlink: 1,
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Mode: 0444,
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Size: uint64(len("Hello, world!")),
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},
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},
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}
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func findChildInode(
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name string,
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children []fuseutil.Dirent) (fuseops.InodeID, error) {
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for _, e := range children {
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if e.Name == name {
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return e.Inode, nil
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}
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}
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return 0, fuse.ENOENT
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}
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func (fs *helloFS) patchAttributes(
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attr *fuseops.InodeAttributes) {
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now := fs.Clock.Now()
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attr.Atime = now
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attr.Mtime = now
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attr.Crtime = now
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}
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func (fs *helloFS) StatFS(
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ctx context.Context,
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op *fuseops.StatFSOp) error {
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return nil
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}
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func (fs *helloFS) LookUpInode(
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ctx context.Context,
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op *fuseops.LookUpInodeOp) error {
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// Find the info for the parent.
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parentInfo, ok := gInodeInfo[op.Parent]
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if !ok {
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return fuse.ENOENT
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}
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// Find the child within the parent.
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childInode, err := findChildInode(op.Name, parentInfo.children)
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if err != nil {
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return err
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}
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// Copy over information.
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op.Entry.Child = childInode
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op.Entry.Attributes = gInodeInfo[childInode].attributes
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// Patch attributes.
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fs.patchAttributes(&op.Entry.Attributes)
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return nil
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}
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func (fs *helloFS) GetInodeAttributes(
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ctx context.Context,
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op *fuseops.GetInodeAttributesOp) error {
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// Find the info for this inode.
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info, ok := gInodeInfo[op.Inode]
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if !ok {
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return fuse.ENOENT
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}
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// Copy over its attributes.
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op.Attributes = info.attributes
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// Patch attributes.
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fs.patchAttributes(&op.Attributes)
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return nil
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}
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func (fs *helloFS) OpenDir(
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ctx context.Context,
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op *fuseops.OpenDirOp) error {
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// Allow opening any directory.
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return nil
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}
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func (fs *helloFS) ReadDir(
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ctx context.Context,
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op *fuseops.ReadDirOp) error {
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// Find the info for this inode.
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info, ok := gInodeInfo[op.Inode]
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if !ok {
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return fuse.ENOENT
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}
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if !info.dir {
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return fuse.EIO
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}
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entries := info.children
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// Grab the range of interest.
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if op.Offset > fuseops.DirOffset(len(entries)) {
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return fuse.EIO
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}
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entries = entries[op.Offset:]
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// Resume at the specified offset into the array.
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for _, e := range entries {
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n := fuseutil.WriteDirent(op.Dst[op.BytesRead:], e)
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if n == 0 {
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break
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}
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op.BytesRead += n
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}
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return nil
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}
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func (fs *helloFS) OpenFile(
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ctx context.Context,
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op *fuseops.OpenFileOp) error {
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// Allow opening any file.
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return nil
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}
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func (fs *helloFS) ReadFile(
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ctx context.Context,
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op *fuseops.ReadFileOp) error {
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// Let io.ReaderAt deal with the semantics.
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reader := strings.NewReader("Hello, world!")
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var err error
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op.BytesRead, err = reader.ReadAt(op.Dst, op.Offset)
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// Special case: FUSE doesn't expect us to return io.EOF.
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if err == io.EOF {
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return nil
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}
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return err
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}
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