344 lines
8.1 KiB
Go
344 lines
8.1 KiB
Go
// Copyright 2018 Google Inc.
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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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// Binary local_server provides a local 9P2000.L server for the p9 package.
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//
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// To use, first start the server:
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// local_server /tmp/my_bind_addr
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//
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// Then, connect using the Linux 9P filesystem:
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// mount -t 9p -o trans=unix /tmp/my_bind_addr /mnt
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//
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// This package also serves as an examplar.
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package main
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import (
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"os"
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"path"
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"syscall"
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"gvisor.googlesource.com/gvisor/pkg/fd"
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"gvisor.googlesource.com/gvisor/pkg/log"
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"gvisor.googlesource.com/gvisor/pkg/p9"
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"gvisor.googlesource.com/gvisor/pkg/unet"
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)
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// local wraps a local file.
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type local struct {
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p9.DefaultWalkGetAttr
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path string
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file *os.File
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}
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// info constructs a QID for this file.
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func (l *local) info() (p9.QID, os.FileInfo, error) {
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var (
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qid p9.QID
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fi os.FileInfo
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err error
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)
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// Stat the file.
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if l.file != nil {
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fi, err = l.file.Stat()
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} else {
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fi, err = os.Lstat(l.path)
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}
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if err != nil {
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log.Warningf("error stating %#v: %v", l, err)
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return qid, nil, err
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}
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// Construct the QID type.
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qid.Type = p9.ModeFromOS(fi.Mode()).QIDType()
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// Save the path from the Ino.
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qid.Path = fi.Sys().(*syscall.Stat_t).Ino
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return qid, fi, nil
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}
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// Attach implements p9.Attacher.Attach.
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func (l *local) Attach(name string) (p9.File, error) {
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return &local{path: path.Clean(name)}, nil
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}
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// Walk implements p9.File.Walk.
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func (l *local) Walk(names []string) ([]p9.QID, p9.File, error) {
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var qids []p9.QID
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last := &local{path: l.path}
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for _, name := range names {
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c := &local{path: path.Join(last.path, name)}
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qid, _, err := c.info()
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if err != nil {
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return nil, nil, err
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}
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qids = append(qids, qid)
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last = c
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}
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return qids, last, nil
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}
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// StatFS implements p9.File.StatFS.
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//
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// Not implemented.
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func (l *local) StatFS() (p9.FSStat, error) {
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return p9.FSStat{}, syscall.ENOSYS
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}
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// FSync implements p9.File.FSync.
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func (l *local) FSync() error {
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return l.file.Sync()
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}
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// GetAttr implements p9.File.GetAttr.
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//
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// Not fully implemented.
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func (l *local) GetAttr(req p9.AttrMask) (p9.QID, p9.AttrMask, p9.Attr, error) {
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qid, fi, err := l.info()
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if err != nil {
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return qid, p9.AttrMask{}, p9.Attr{}, err
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}
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stat := fi.Sys().(*syscall.Stat_t)
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attr := p9.Attr{
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Mode: p9.FileMode(stat.Mode),
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UID: p9.UID(stat.Uid),
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GID: p9.GID(stat.Gid),
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NLink: stat.Nlink,
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RDev: stat.Rdev,
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Size: uint64(stat.Size),
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BlockSize: uint64(stat.Blksize),
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Blocks: uint64(stat.Blocks),
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ATimeSeconds: uint64(stat.Atim.Sec),
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ATimeNanoSeconds: uint64(stat.Atim.Nsec),
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MTimeSeconds: uint64(stat.Mtim.Sec),
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MTimeNanoSeconds: uint64(stat.Mtim.Nsec),
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CTimeSeconds: uint64(stat.Ctim.Sec),
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CTimeNanoSeconds: uint64(stat.Ctim.Nsec),
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}
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valid := p9.AttrMask{
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Mode: true,
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UID: true,
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GID: true,
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NLink: true,
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RDev: true,
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Size: true,
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Blocks: true,
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ATime: true,
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MTime: true,
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CTime: true,
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}
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return qid, valid, attr, nil
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}
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// SetAttr implements p9.File.SetAttr.
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//
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// Not implemented.
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func (l *local) SetAttr(valid p9.SetAttrMask, attr p9.SetAttr) error {
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return syscall.ENOSYS
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}
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// Remove implements p9.File.Remove.
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//
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// Not implemented.
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func (l *local) Remove() error {
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return syscall.ENOSYS
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}
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// Rename implements p9.File.Rename.
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//
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// Not implemented.
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func (l *local) Rename(directory p9.File, name string) error {
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return syscall.ENOSYS
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}
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// Close implements p9.File.Close.
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func (l *local) Close() error {
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if l.file != nil {
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return l.file.Close()
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}
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return nil
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}
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// Open implements p9.File.Open.
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func (l *local) Open(mode p9.OpenFlags) (*fd.FD, p9.QID, uint32, error) {
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qid, _, err := l.info()
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if err != nil {
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return nil, qid, 0, err
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}
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// Do the actual open.
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f, err := os.OpenFile(l.path, int(mode), 0)
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if err != nil {
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return nil, qid, 0, err
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}
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l.file = f
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// Note: we don't send the local file for this server.
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return nil, qid, 4096, nil
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}
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// Read implements p9.File.Read.
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func (l *local) ReadAt(p []byte, offset uint64) (int, error) {
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return l.file.ReadAt(p, int64(offset))
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}
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// Write implements p9.File.Write.
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func (l *local) WriteAt(p []byte, offset uint64) (int, error) {
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return l.file.WriteAt(p, int64(offset))
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}
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// Create implements p9.File.Create.
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func (l *local) Create(name string, mode p9.OpenFlags, permissions p9.FileMode, _ p9.UID, _ p9.GID) (*fd.FD, p9.File, p9.QID, uint32, error) {
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f, err := os.OpenFile(l.path, int(mode)|syscall.O_CREAT|syscall.O_EXCL, os.FileMode(permissions))
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if err != nil {
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return nil, nil, p9.QID{}, 0, err
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}
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l2 := &local{path: path.Join(l.path, name), file: f}
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qid, _, err := l2.info()
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if err != nil {
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l2.Close()
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return nil, nil, p9.QID{}, 0, err
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}
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return nil, l2, qid, 4096, nil
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}
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// Mkdir implements p9.File.Mkdir.
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//
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// Not properly implemented.
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func (l *local) Mkdir(name string, permissions p9.FileMode, _ p9.UID, _ p9.GID) (p9.QID, error) {
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if err := os.Mkdir(path.Join(l.path, name), os.FileMode(permissions)); err != nil {
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return p9.QID{}, err
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}
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// Blank QID.
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return p9.QID{}, nil
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}
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// Symlink implements p9.File.Symlink.
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//
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// Not properly implemented.
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func (l *local) Symlink(oldname string, newname string, _ p9.UID, _ p9.GID) (p9.QID, error) {
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if err := os.Symlink(oldname, path.Join(l.path, newname)); err != nil {
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return p9.QID{}, err
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}
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// Blank QID.
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return p9.QID{}, nil
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}
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// Link implements p9.File.Link.
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//
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// Not properly implemented.
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func (l *local) Link(target p9.File, newname string) error {
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return os.Link(target.(*local).path, path.Join(l.path, newname))
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}
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// Mknod implements p9.File.Mknod.
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//
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// Not implemented.
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func (l *local) Mknod(name string, permissions p9.FileMode, major uint32, minor uint32, _ p9.UID, _ p9.GID) (p9.QID, error) {
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return p9.QID{}, syscall.ENOSYS
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}
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// RenameAt implements p9.File.RenameAt.
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//
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// Not implemented.
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func (l *local) RenameAt(oldname string, newdir p9.File, newname string) error {
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return syscall.ENOSYS
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}
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// UnlinkAt implements p9.File.UnlinkAt.
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//
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// Not implemented.
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func (l *local) UnlinkAt(name string, flags uint32) error {
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return syscall.ENOSYS
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}
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// Readdir implements p9.File.Readdir.
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func (l *local) Readdir(offset uint64, count uint32) ([]p9.Dirent, error) {
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// We only do *all* dirents in single shot.
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const maxDirentBuffer = 1024 * 1024
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buf := make([]byte, maxDirentBuffer)
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n, err := syscall.ReadDirent(int(l.file.Fd()), buf)
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if err != nil {
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// Return zero entries.
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return nil, nil
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}
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// Parse the entries; note that we read up to offset+count here.
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_, newCount, newNames := syscall.ParseDirent(buf[:n], int(offset)+int(count), nil)
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var dirents []p9.Dirent
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for i := int(offset); i >= 0 && i < newCount; i++ {
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entry := local{path: path.Join(l.path, newNames[i])}
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qid, _, err := entry.info()
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if err != nil {
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continue
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}
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dirents = append(dirents, p9.Dirent{
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QID: qid,
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Type: qid.Type,
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Name: newNames[i],
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Offset: uint64(i + 1),
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})
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}
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return dirents, nil
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}
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// Readlink implements p9.File.Readlink.
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//
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// Not properly implemented.
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func (l *local) Readlink() (string, error) {
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return os.Readlink(l.path)
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}
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// Flush implements p9.File.Flush.
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func (l *local) Flush() error {
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return nil
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}
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// Connect implements p9.File.Connect.
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func (l *local) Connect(p9.ConnectFlags) (*fd.FD, error) {
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return nil, syscall.ECONNREFUSED
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}
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func main() {
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log.SetLevel(log.Debug)
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if len(os.Args) != 2 {
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log.Warningf("usage: %s <bind-addr>", os.Args[0])
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os.Exit(1)
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}
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// Bind and listen on the socket.
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serverSocket, err := unet.BindAndListen(os.Args[1], false)
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if err != nil {
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log.Warningf("err binding: %v", err)
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os.Exit(1)
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}
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// Run the server.
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s := p9.NewServer(&local{})
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s.Serve(serverSocket)
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}
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var (
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_ p9.File = &local{}
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)
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