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-rw-r--r--runsc/fsgofer/fsgofer.go937
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diff --git a/runsc/fsgofer/fsgofer.go b/runsc/fsgofer/fsgofer.go
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index 000000000..5ddc75a9d
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+++ b/runsc/fsgofer/fsgofer.go
@@ -0,0 +1,937 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package fsgofer implements p9.File giving access to local files using
+// a simple mapping from a path prefix that is added to the path requested
+// by the sandbox. Ex:
+//
+// prefix: "/docker/imgs/alpine"
+// app path: /bin/ls => /docker/imgs/alpine/bin/ls
+package fsgofer
+
+import (
+ "fmt"
+ "io"
+ "math"
+ "os"
+ "path"
+ "path/filepath"
+ "strings"
+ "sync"
+ "syscall"
+
+ "golang.org/x/sys/unix"
+ "gvisor.googlesource.com/gvisor/pkg/abi/linux"
+ "gvisor.googlesource.com/gvisor/pkg/fd"
+ "gvisor.googlesource.com/gvisor/pkg/log"
+ "gvisor.googlesource.com/gvisor/pkg/p9"
+)
+
+const (
+ // invalidMode is set to a value that doesn't match any other valid
+ // modes to ensure an unopened/closed file fails all mode checks.
+ invalidMode = p9.OpenFlags(math.MaxUint32)
+
+ openFlags = syscall.O_NOFOLLOW | syscall.O_CLOEXEC
+)
+
+type fileType int
+
+const (
+ regular fileType = iota
+ directory
+ symlink
+)
+
+// String implements fmt.Stringer.
+func (f fileType) String() string {
+ switch f {
+ case regular:
+ return "regular"
+ case directory:
+ return "directory"
+ case symlink:
+ return "symlink"
+ }
+ return "unknown"
+}
+
+// Config sets configuration options for each attach point.
+type Config struct {
+ // ROMount is set to true if this is a readonly mount.
+ ROMount bool
+
+ // LazyOpenForWrite makes the underlying file to be opened in RDONLY
+ // mode initially and be reopened in case write access is desired.
+ // This is done to workaround the behavior in 'overlay2' that
+ // copies the entire file up eagerly when it's opened in write mode
+ // even if the file is never actually written to.
+ LazyOpenForWrite bool
+}
+
+type attachPoint struct {
+ prefix string
+ conf Config
+}
+
+// NewAttachPoint creates a new attacher that gives local file
+// access to all files under 'prefix'.
+func NewAttachPoint(prefix string, c Config) p9.Attacher {
+ return &attachPoint{prefix: prefix, conf: c}
+}
+
+// Attach implements p9.Attacher.
+func (a *attachPoint) Attach(appPath string) (p9.File, error) {
+ if !path.IsAbs(appPath) {
+ return nil, fmt.Errorf("invalid path %q", appPath)
+ }
+
+ root := filepath.Join(a.prefix, appPath)
+ f, err := os.OpenFile(root, openFlags|syscall.O_RDONLY, 0)
+ if err != nil {
+ return nil, fmt.Errorf("unable to open file %q, err: %v", root, err)
+ }
+ stat, err := stat(int(f.Fd()))
+ if err != nil {
+ return nil, fmt.Errorf("failed to stat file %q, err: %v", root, err)
+ }
+ return newLocalFile(a.conf, f, root, stat)
+}
+
+func makeQID(stat syscall.Stat_t) p9.QID {
+ return p9.QID{
+ Type: p9.FileMode(stat.Mode).QIDType(),
+ Path: stat.Ino,
+ }
+}
+
+func isNameValid(name string) bool {
+ if name == "" || name == "." || name == ".." {
+ log.Warningf("Invalid name: %s", name)
+ return false
+ }
+ if strings.IndexByte(name, '/') >= 0 {
+ log.Warningf("Invalid name: %s", name)
+ return false
+ }
+ return true
+}
+
+// localFile implements p9.File wrapping a local file. The underlying file
+// is opened during Walk() and stored in 'controlFile' to be used with other
+// operations. The mode in which the file is opened varies depending on the
+// configuration (see below). 'controlFile' is dup'ed when Walk(nil) is called
+// to clone the file.
+//
+// 'openedFile' is assigned when Open() is called. If requested open mode is
+// a subset of controlFile's mode, it's possible to use the same file. If mode
+// is not a subset, then another file is opened. Consequently, 'openedFile'
+// could have a mode wider than requested and must be verified before read/write
+// operations. Before the file is opened and after it's closed, 'mode' is set to
+// an invalid value to prevent an unopened file from being used.
+//
+// localFile has 2 modes of operation based on the configuration:
+//
+// ** conf.lazyRWOpen == false **
+// This is the preferred mode. 'controlFile' is opened in RW mode in Walk()
+// and used across all functions. The file is never reopened as the mode will
+// always be a super set of the requested open mode. This reduces the number of
+// syscalls required per operation and makes it resilient to renames anywhere
+// in the path to the file.
+//
+// ** conf.lazyRWOpen == true **
+// This mode is used for better performance with 'overlay2' storage driver.
+// overlay2 eagerly copies the entire file up when it's opened in write mode
+// which makes the mode above perform badly when serveral of files are opened
+// for read (esp. startup). In this mode, 'controlFile' is opened as readonly
+// (or O_PATH for symlinks). Reopening the file is required if write mode
+// is requested in Open().
+type localFile struct {
+ p9.DefaultWalkGetAttr
+
+ // mu protects 'hostPath' when file is renamed.
+ mu sync.Mutex
+
+ // TODO: hostPath is not safe to use as path needs to be walked
+ // everytime (and can change underneath us). Remove all usages.
+ hostPath string
+
+ // controlFile is opened when localFile is created and it's never nil.
+ controlFile *os.File
+
+ // openedFile is nil until localFile is opened. It may point to controlFile
+ // or be a new file struct. See struct comment for more details.
+ openedFile *os.File
+
+ // mode is the mode in which the file was opened. Set to invalidMode
+ // if localFile isn't opened.
+ mode p9.OpenFlags
+
+ ft fileType
+
+ conf Config
+
+ // readDirMu protects against concurrent Readdir calls.
+ readDirMu sync.Mutex
+}
+
+func openAnyFile(parent *localFile, name string) (*os.File, string, error) {
+ // Attempt to open file in the following mode in order:
+ // 1. RDWR: for files with rw mounts and LazyOpenForWrite disabled
+ // 2. RDONLY: for directories, ro mounts or LazyOpenForWrite enabled
+ // 3. PATH: for symlinks
+ modes := []int{syscall.O_RDWR, syscall.O_RDONLY, unix.O_PATH}
+ symlinkIdx := len(modes) - 1
+
+ startIdx := 0
+ if parent.conf.ROMount || parent.conf.LazyOpenForWrite {
+ // Skip attempt to open in RDWR based on configuration.
+ startIdx = 1
+ }
+
+ var err error
+ var fd int
+ for i := startIdx; i < len(modes); i++ {
+ fd, err = syscall.Openat(parent.controlFD(), name, openFlags|modes[i], 0)
+ if err == nil {
+ // openat succeeded, we're done.
+ break
+ }
+ switch e := extractErrno(err); e {
+ case syscall.ENOENT:
+ // File doesn't exist, no point in retrying.
+ return nil, "", e
+ case syscall.ELOOP:
+ if i < symlinkIdx {
+ // File was opened with O_NOFOLLOW, so this error can only happen when
+ // trying ot open a symlink. Jump straight to flags compatible with symlink.
+ i = symlinkIdx - 1
+ }
+ }
+ // openat failed. Try again with next mode, preserving 'err' in
+ // case this was the last attempt.
+ log.Debugf("Attempt %d to open file failed, mode: %#x, path: %s/%s, err: %v", i, openFlags|modes[i], parent.controlFile.Name(), name, err)
+ }
+ if err != nil {
+ // All attempts to open file have failed, return the last error.
+ log.Debugf("Failed to open file, path: %s/%s, err: %v", parent.controlFile.Name(), name, err)
+ return nil, "", extractErrno(err)
+ }
+
+ parent.mu.Lock()
+ defer parent.mu.Unlock()
+ newPath := path.Join(parent.hostPath, name)
+
+ return os.NewFile(uintptr(fd), newPath), newPath, nil
+}
+
+func newLocalFile(conf Config, file *os.File, path string, stat syscall.Stat_t) (*localFile, error) {
+ var ft fileType
+ switch stat.Mode & syscall.S_IFMT {
+ case syscall.S_IFREG:
+ ft = regular
+ case syscall.S_IFDIR:
+ ft = directory
+ case syscall.S_IFLNK:
+ ft = symlink
+ default:
+ return nil, syscall.EINVAL
+ }
+ return &localFile{
+ hostPath: path,
+ controlFile: file,
+ conf: conf,
+ mode: invalidMode,
+ ft: ft,
+ }, nil
+}
+
+// newFDMaybe creates a fd.FD from a file, dup'ing the FD and setting it as
+// non-blocking. If anything fails, returns nil. It's better to have a file
+// without host FD, than to fail the operation.
+func newFDMaybe(file *os.File) *fd.FD {
+ fd, err := fd.NewFromFile(file)
+ if err != nil {
+ return nil
+ }
+
+ // fd is blocking; non-blocking is required.
+ if err := syscall.SetNonblock(fd.FD(), true); err != nil {
+ fd.Close()
+ return nil
+ }
+ return fd
+}
+
+func stat(fd int) (syscall.Stat_t, error) {
+ var stat syscall.Stat_t
+ if err := syscall.Fstat(fd, &stat); err != nil {
+ return syscall.Stat_t{}, err
+ }
+ return stat, nil
+}
+
+func fchown(fd int, uid p9.UID, gid p9.GID) error {
+ return syscall.Fchownat(fd, "", int(uid), int(gid), linux.AT_EMPTY_PATH|unix.AT_SYMLINK_NOFOLLOW)
+}
+
+func (l *localFile) controlFD() int {
+ return int(l.controlFile.Fd())
+}
+
+func (l *localFile) openedFD() int {
+ if l.openedFile == nil {
+ panic(fmt.Sprintf("trying to use an unopened file: %q", l.controlFile.Name()))
+ }
+ return int(l.openedFile.Fd())
+}
+
+// Open implements p9.File.
+func (l *localFile) Open(mode p9.OpenFlags) (*fd.FD, p9.QID, uint32, error) {
+ if l.openedFile != nil {
+ panic(fmt.Sprintf("attempting to open already opened file: %q", l.controlFile.Name()))
+ }
+
+ // Check if control file can be used or if a new open must be created.
+ var newFile *os.File
+ if mode == p9.ReadOnly || !l.conf.LazyOpenForWrite {
+ log.Debugf("Open reusing control file, mode: %v, %q", mode, l.controlFile.Name())
+ newFile = l.controlFile
+ } else {
+ // Ideally reopen would call name_to_handle_at (with empty name) and open_by_handle_at
+ // to reopen the file without using 'hostPath'. However, name_to_handle_at and
+ // open_by_handle_at aren't supported by overlay2.
+ log.Debugf("Open reopening file, mode: %v, %q", mode, l.controlFile.Name())
+ var err error
+
+ l.mu.Lock()
+ newFile, err = os.OpenFile(l.hostPath, openFlags|mode.OSFlags(), 0)
+ if err != nil {
+ l.mu.Unlock()
+ return nil, p9.QID{}, 0, extractErrno(err)
+ }
+ l.mu.Unlock()
+ }
+
+ stat, err := stat(int(newFile.Fd()))
+ if err != nil {
+ newFile.Close()
+ return nil, p9.QID{}, 0, extractErrno(err)
+ }
+
+ var fd *fd.FD
+ if stat.Mode&syscall.S_IFMT == syscall.S_IFREG {
+ // Donate FD for regular files only.
+ fd = newFDMaybe(newFile)
+ }
+
+ // Set fields on success
+ l.openedFile = newFile
+ l.mode = mode
+ return fd, makeQID(stat), 0, nil
+}
+
+// Create implements p9.File.
+func (l *localFile) Create(name string, mode p9.OpenFlags, perm p9.FileMode, uid p9.UID, gid p9.GID) (*fd.FD, p9.File, p9.QID, uint32, error) {
+ if l.conf.ROMount {
+ return nil, nil, p9.QID{}, 0, syscall.EBADF
+ }
+ if !isNameValid(name) {
+ return nil, nil, p9.QID{}, 0, syscall.EINVAL
+ }
+
+ // Use a single file for both 'controlFile' and 'openedFile'. Mode must include read for control
+ // and whichever else was requested by caller. Note that resulting file might have a wider mode
+ // than needed for each particular case.
+ flags := openFlags | syscall.O_CREAT | syscall.O_EXCL
+ if mode == p9.WriteOnly {
+ flags |= syscall.O_RDWR
+ } else {
+ flags |= mode.OSFlags()
+ }
+
+ fd, err := syscall.Openat(l.controlFD(), name, flags, uint32(perm.Permissions()))
+ if err != nil {
+ return nil, nil, p9.QID{}, 0, extractErrno(err)
+ }
+ if err := fchown(fd, uid, gid); err != nil {
+ syscall.Close(fd)
+ return nil, nil, p9.QID{}, 0, extractErrno(err)
+ }
+ stat, err := stat(fd)
+ if err != nil {
+ syscall.Close(fd)
+ return nil, nil, p9.QID{}, 0, extractErrno(err)
+ }
+
+ l.mu.Lock()
+ defer l.mu.Unlock()
+
+ cPath := path.Join(l.hostPath, name)
+ f := os.NewFile(uintptr(fd), cPath)
+ c := &localFile{
+ hostPath: cPath,
+ controlFile: f,
+ openedFile: f,
+ mode: mode,
+ conf: l.conf,
+ }
+ return newFDMaybe(c.openedFile), c, makeQID(stat), 0, nil
+}
+
+// Mkdir implements p9.File.
+func (l *localFile) Mkdir(name string, perm p9.FileMode, uid p9.UID, gid p9.GID) (p9.QID, error) {
+ if l.conf.ROMount {
+ return p9.QID{}, syscall.EBADF
+ }
+
+ if !isNameValid(name) {
+ return p9.QID{}, syscall.EINVAL
+ }
+
+ if err := syscall.Mkdirat(l.controlFD(), name, uint32(perm.Permissions())); err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+
+ // Open directory to change ownership and stat it.
+ flags := syscall.O_DIRECTORY | syscall.O_RDONLY | openFlags
+ fd, err := syscall.Openat(l.controlFD(), name, flags, 0)
+ if err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+ defer syscall.Close(fd)
+
+ if err := fchown(fd, uid, gid); err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+ stat, err := stat(fd)
+ if err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+ return makeQID(stat), nil
+}
+
+// Walk implements p9.File.
+func (l *localFile) Walk(names []string) ([]p9.QID, p9.File, error) {
+ // Duplicate current file if 'names' is empty.
+ if len(names) == 0 {
+ newFd, err := syscall.Dup(l.controlFD())
+ if err != nil {
+ return nil, nil, extractErrno(err)
+ }
+ stat, err := stat(newFd)
+ if err != nil {
+ syscall.Close(newFd)
+ return nil, nil, extractErrno(err)
+ }
+
+ l.mu.Lock()
+ defer l.mu.Unlock()
+
+ c := &localFile{
+ hostPath: l.hostPath,
+ controlFile: os.NewFile(uintptr(newFd), l.hostPath),
+ mode: invalidMode,
+ conf: l.conf,
+ }
+ return []p9.QID{makeQID(stat)}, c, nil
+ }
+
+ var qids []p9.QID
+ last := l
+ for _, name := range names {
+ if !isNameValid(name) {
+ return nil, nil, syscall.EINVAL
+ }
+
+ f, path, err := openAnyFile(last, name)
+ if err != nil {
+ return nil, nil, extractErrno(err)
+ }
+ stat, err := stat(int(f.Fd()))
+ if err != nil {
+ return nil, nil, extractErrno(err)
+ }
+ c, err := newLocalFile(last.conf, f, path, stat)
+ if err != nil {
+ return nil, nil, extractErrno(err)
+ }
+
+ qids = append(qids, makeQID(stat))
+ last = c
+ }
+ return qids, last, nil
+}
+
+// StatFS implements p9.File.
+func (l *localFile) StatFS() (p9.FSStat, error) {
+ var s syscall.Statfs_t
+ if err := syscall.Fstatfs(l.controlFD(), &s); err != nil {
+ return p9.FSStat{}, extractErrno(err)
+ }
+
+ // Populate with what's available.
+ return p9.FSStat{
+ Type: uint32(s.Type),
+ BlockSize: uint32(s.Bsize),
+ Blocks: s.Blocks,
+ BlocksFree: s.Bfree,
+ BlocksAvailable: s.Bavail,
+ Files: s.Files,
+ FilesFree: s.Ffree,
+ NameLength: uint32(s.Namelen),
+ }, nil
+}
+
+// FSync implements p9.File.
+func (l *localFile) FSync() error {
+ if l.openedFile == nil {
+ return syscall.EBADF
+ }
+ if err := l.openedFile.Sync(); err != nil {
+ return extractErrno(err)
+ }
+ return nil
+}
+
+// GetAttr implements p9.File.
+func (l *localFile) GetAttr(_ p9.AttrMask) (p9.QID, p9.AttrMask, p9.Attr, error) {
+ stat, err := stat(l.controlFD())
+ if err != nil {
+ return p9.QID{}, p9.AttrMask{}, p9.Attr{}, extractErrno(err)
+ }
+
+ attr := p9.Attr{
+ Mode: p9.FileMode(stat.Mode),
+ UID: p9.UID(stat.Uid),
+ GID: p9.GID(stat.Gid),
+ NLink: stat.Nlink,
+ RDev: stat.Rdev,
+ Size: uint64(stat.Size),
+ BlockSize: uint64(stat.Blksize),
+ Blocks: uint64(stat.Blocks),
+ ATimeSeconds: uint64(stat.Atim.Sec),
+ ATimeNanoSeconds: uint64(stat.Atim.Nsec),
+ MTimeSeconds: uint64(stat.Mtim.Sec),
+ MTimeNanoSeconds: uint64(stat.Mtim.Nsec),
+ CTimeSeconds: uint64(stat.Ctim.Sec),
+ CTimeNanoSeconds: uint64(stat.Ctim.Nsec),
+ }
+ valid := p9.AttrMask{
+ Mode: true,
+ UID: true,
+ GID: true,
+ NLink: true,
+ RDev: true,
+ Size: true,
+ Blocks: true,
+ ATime: true,
+ MTime: true,
+ CTime: true,
+ }
+
+ return makeQID(stat), valid, attr, nil
+}
+
+// SetAttr implements p9.File. Due to mismatch in file API, options
+// cannot be changed atomicaly and user may see partial changes when
+// an error happens.
+func (l *localFile) SetAttr(valid p9.SetAttrMask, attr p9.SetAttr) error {
+ if l.conf.ROMount {
+ return syscall.EBADF
+ }
+
+ allowed := p9.SetAttrMask{
+ Permissions: true,
+ UID: true,
+ GID: true,
+ Size: true,
+ ATime: true,
+ MTime: true,
+ ATimeNotSystemTime: true,
+ MTimeNotSystemTime: true,
+ }
+
+ if valid.Empty() {
+ // Nothing to do.
+ return nil
+ }
+
+ // Handle all the sanity checks up front so that the client gets a
+ // consistent result that is not attribute dependent.
+ if !valid.IsSubsetOf(allowed) {
+ log.Warningf("SetAttr() failed for %q, mask: %v", l.controlFile.Name(), valid)
+ return syscall.EPERM
+ }
+
+ fd := l.controlFD()
+ if l.conf.LazyOpenForWrite && l.ft == regular {
+ // Regular files are opened in RO mode when lazy open is set.
+ // Thus it needs to be reopened here for write.
+ f, err := os.OpenFile(l.hostPath, openFlags|os.O_WRONLY, 0)
+ if err != nil {
+ return extractErrno(err)
+ }
+ defer f.Close()
+ fd = int(f.Fd())
+ }
+
+ // The semantics are to either return an error if no changes were made,
+ // or no error if *all* changes were made. Well, this can be impossible
+ // if the filesystem rejects at least one of the changes, especially
+ // since some operations are not easy to undo atomically.
+ //
+ // This could be made better if SetAttr actually returned the changes
+ // it did make, so the client can at least know what has changed. So
+ // we at least attempt to make all of the changes and return a generic
+ // error if any of them fails, which at least doesn't bias any change
+ // over another.
+ var err error
+ if valid.Permissions {
+ if cerr := syscall.Fchmod(fd, uint32(attr.Permissions)); cerr != nil {
+ log.Debugf("SetAttr fchmod failed %q, err: %v", l.hostPath, cerr)
+ err = extractErrno(cerr)
+ }
+ }
+
+ if valid.Size {
+ if terr := syscall.Ftruncate(fd, int64(attr.Size)); terr != nil {
+ log.Debugf("SetAttr ftruncate failed %q, err: %v", l.hostPath, terr)
+ err = extractErrno(terr)
+ }
+ }
+
+ if valid.ATime || valid.MTime {
+ utimes := [2]syscall.Timespec{
+ syscall.Timespec{Sec: 0, Nsec: linux.UTIME_OMIT},
+ syscall.Timespec{Sec: 0, Nsec: linux.UTIME_OMIT},
+ }
+ if valid.ATime {
+ if valid.ATimeNotSystemTime {
+ utimes[0].Sec = int64(attr.ATimeSeconds)
+ utimes[0].Nsec = int64(attr.ATimeNanoSeconds)
+ } else {
+ utimes[0].Nsec = linux.UTIME_NOW
+ }
+ }
+ if valid.MTime {
+ if valid.MTimeNotSystemTime {
+ utimes[1].Sec = int64(attr.MTimeSeconds)
+ utimes[1].Nsec = int64(attr.MTimeNanoSeconds)
+ } else {
+ utimes[1].Nsec = linux.UTIME_NOW
+ }
+ }
+
+ if l.ft == symlink {
+ // utimensat operates different that other syscalls. To operate on a
+ // symlink it *requires* AT_SYMLINK_NOFOLLOW with dirFD and a non-empty
+ // name.
+ f, err := os.OpenFile(path.Dir(l.hostPath), openFlags|unix.O_PATH, 0)
+ if err != nil {
+ return extractErrno(err)
+ }
+ defer f.Close()
+
+ if terr := utimensat(int(f.Fd()), path.Base(l.hostPath), utimes, linux.AT_SYMLINK_NOFOLLOW); terr != nil {
+ log.Debugf("SetAttr utimens failed %q, err: %v", l.hostPath, terr)
+ err = extractErrno(terr)
+ }
+ } else {
+ // Directories and regular files can operate directly on the fd
+ // using empty name.
+ if terr := utimensat(fd, "", utimes, 0); terr != nil {
+ log.Debugf("SetAttr utimens failed %q, err: %v", l.hostPath, terr)
+ err = extractErrno(terr)
+ }
+ }
+ }
+
+ if valid.UID || valid.GID {
+ uid := -1
+ if valid.UID {
+ uid = int(attr.UID)
+ }
+ gid := -1
+ if valid.GID {
+ gid = int(attr.GID)
+ }
+ if oerr := syscall.Fchownat(fd, "", uid, gid, linux.AT_EMPTY_PATH|linux.AT_SYMLINK_NOFOLLOW); oerr != nil {
+ log.Debugf("SetAttr fchownat failed %q, err: %v", l.hostPath, oerr)
+ err = extractErrno(oerr)
+ }
+ }
+
+ return err
+}
+
+// Remove implements p9.File.
+//
+// This is deprecated in favor of UnlinkAt.
+func (*localFile) Remove() error {
+ return syscall.ENOSYS
+}
+
+// Rename implements p9.File.
+func (l *localFile) Rename(directory p9.File, name string) error {
+ if l.conf.ROMount {
+ return syscall.EBADF
+ }
+ if !isNameValid(name) {
+ return syscall.EINVAL
+ }
+
+ l.mu.Lock()
+ defer l.mu.Unlock()
+
+ // TODO: change to renameat(2)
+ parent := directory.(*localFile)
+ newPath := path.Join(parent.hostPath, name)
+ if err := os.Rename(l.hostPath, newPath); err != nil {
+ return extractErrno(err)
+ }
+
+ // Update path on success.
+ // TODO: this doesn't cover cases where any of the
+ // parents have been renamed.
+ l.hostPath = newPath
+ return nil
+}
+
+// RenameAt implements p9.File.RenameAt.
+//
+// Code still uses [deprecated] Rename().
+func (*localFile) RenameAt(_ string, _ p9.File, _ string) error {
+ return syscall.ENOSYS
+}
+
+// ReadAt implements p9.File.
+func (l *localFile) ReadAt(p []byte, offset uint64) (int, error) {
+ if l.mode != p9.ReadOnly && l.mode != p9.ReadWrite {
+ return 0, syscall.EBADF
+ }
+ if l.openedFile == nil {
+ return 0, syscall.EBADF
+ }
+
+ r, err := l.openedFile.ReadAt(p, int64(offset))
+ switch err {
+ case nil, io.EOF:
+ return r, nil
+ default:
+ return r, extractErrno(err)
+ }
+}
+
+// WriteAt implements p9.File.
+func (l *localFile) WriteAt(p []byte, offset uint64) (int, error) {
+ if l.mode != p9.WriteOnly && l.mode != p9.ReadWrite {
+ return 0, syscall.EBADF
+ }
+ if l.openedFile == nil {
+ return 0, syscall.EBADF
+ }
+
+ w, err := l.openedFile.WriteAt(p, int64(offset))
+ if err != nil {
+ return w, extractErrno(err)
+ }
+ return w, nil
+}
+
+// Symlink implements p9.File.
+func (l *localFile) Symlink(target, newName string, uid p9.UID, gid p9.GID) (p9.QID, error) {
+ if l.conf.ROMount {
+ return p9.QID{}, syscall.EBADF
+ }
+ if !isNameValid(newName) {
+ return p9.QID{}, syscall.EINVAL
+ }
+
+ if err := unix.Symlinkat(target, l.controlFD(), newName); err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+
+ // Open symlink to change ownership and stat it.
+ fd, err := syscall.Openat(l.controlFD(), newName, unix.O_PATH|openFlags, 0)
+ if err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+ defer syscall.Close(fd)
+
+ if err := fchown(fd, uid, gid); err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+ stat, err := stat(fd)
+ if err != nil {
+ return p9.QID{}, extractErrno(err)
+ }
+ return makeQID(stat), nil
+}
+
+// Link implements p9.File.
+func (l *localFile) Link(target p9.File, newName string) error {
+ if l.conf.ROMount {
+ return syscall.EBADF
+ }
+ if !isNameValid(newName) {
+ return syscall.EINVAL
+ }
+
+ targetFile := target.(*localFile)
+ if err := unix.Linkat(targetFile.controlFD(), "", l.controlFD(), newName, linux.AT_EMPTY_PATH); err != nil {
+ return extractErrno(err)
+ }
+ return nil
+}
+
+// Mknod implements p9.File.
+//
+// Not implemented.
+func (*localFile) Mknod(_ string, _ p9.FileMode, _ uint32, _ uint32, _ p9.UID, _ p9.GID) (p9.QID, error) {
+ return p9.QID{}, syscall.ENOSYS
+}
+
+// UnlinkAt implements p9.File.
+func (l *localFile) UnlinkAt(name string, flags uint32) error {
+ if l.conf.ROMount {
+ return syscall.EBADF
+ }
+ if !isNameValid(name) {
+ return syscall.EINVAL
+ }
+ if err := unix.Unlinkat(l.controlFD(), name, int(flags)); err != nil {
+ return extractErrno(err)
+ }
+ return nil
+}
+
+// Readdir implements p9.File.
+func (l *localFile) Readdir(offset uint64, count uint32) ([]p9.Dirent, error) {
+ if l.mode != p9.ReadOnly && l.mode != p9.ReadWrite {
+ return nil, syscall.EBADF
+ }
+ if l.openedFile == nil {
+ return nil, syscall.EBADF
+ }
+
+ // Readdirnames is a cursor over directories, so seek back to 0 to ensure it's
+ // reading all directory contents. Take a lock because this operation is stateful.
+ l.readDirMu.Lock()
+ if _, err := l.openedFile.Seek(0, 0); err != nil {
+ l.readDirMu.Unlock()
+ return nil, extractErrno(err)
+ }
+ names, err := l.openedFile.Readdirnames(-1)
+ if err != nil {
+ l.readDirMu.Unlock()
+ return nil, extractErrno(err)
+ }
+ l.readDirMu.Unlock()
+
+ var dirents []p9.Dirent
+ for i := int(offset); i >= 0 && i < len(names); i++ {
+ stat, err := statAt(l.openedFD(), names[i])
+ if err != nil {
+ continue
+ }
+ qid := makeQID(stat)
+ dirents = append(dirents, p9.Dirent{
+ QID: qid,
+ Type: qid.Type,
+ Name: names[i],
+ Offset: uint64(i + 1),
+ })
+ }
+ return dirents, nil
+}
+
+// Readlink implements p9.File.
+func (l *localFile) Readlink() (string, error) {
+ // Shamelessly stolen from os.Readlink (added upper bound limit to buffer).
+ for len := 128; len < 1024*1024; len *= 2 {
+ b := make([]byte, len)
+ n, err := unix.Readlinkat(l.controlFD(), "", b)
+ if err != nil {
+ return "", extractErrno(err)
+ }
+ if n < len {
+ return string(b[:n]), nil
+ }
+ }
+ return "", syscall.ENOMEM
+}
+
+// Flush implements p9.File.
+func (l *localFile) Flush() error {
+ return nil
+}
+
+// Connect implements p9.File.
+func (l *localFile) Connect(p9.ConnectFlags) (*fd.FD, error) {
+ return nil, syscall.ECONNREFUSED
+}
+
+// Close implements p9.File.
+func (l *localFile) Close() error {
+ err := l.controlFile.Close()
+
+ // Close only once in case opened and control files point to
+ // the same os.File struct.
+ if l.openedFile != nil && l.openedFile != l.controlFile {
+ err = l.openedFile.Close()
+ }
+
+ l.openedFile = nil
+ l.controlFile = nil
+ l.mode = invalidMode
+ return err
+}
+
+// extractErrno tries to determine the errno.
+func extractErrno(err error) syscall.Errno {
+ if err == nil {
+ // This should never happen. The likely result will be that
+ // some user gets the frustration "error: SUCCESS" message.
+ log.Warningf("extractErrno called with nil error!")
+ return 0
+ }
+
+ switch err {
+ case os.ErrNotExist:
+ return syscall.ENOENT
+ case os.ErrExist:
+ return syscall.EEXIST
+ case os.ErrPermission:
+ return syscall.EACCES
+ case os.ErrInvalid:
+ return syscall.EINVAL
+ }
+
+ // See if it's an errno or a common wrapped error.
+ switch e := err.(type) {
+ case syscall.Errno:
+ return e
+ case *os.PathError:
+ return extractErrno(e.Err)
+ case *os.LinkError:
+ return extractErrno(e.Err)
+ case *os.SyscallError:
+ return extractErrno(e.Err)
+ }
+
+ // Fall back to EIO.
+ log.Debugf("Unknown error: %v, defaulting to EIO", err)
+ return syscall.EIO
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 12:24:46 +0000