syncthing/lib/protocol/bep_extensions.go
Jakob Borg 6cac308bcd
all: Support syncing extended attributes (fixes #2698) (#8513)
This adds support for syncing extended attributes on supported
filesystem on Linux, macOS, FreeBSD and NetBSD. Windows is currently
excluded because the APIs seem onerous and annoying and frankly the uses
cases seem few and far between. On Unixes this also covers ACLs as those
are stored as extended attributes.

Similar to ownership syncing this will optional & opt-in, which two
settings controlling the main behavior: one to "sync" xattrs (read &
write) and another one to "scan" xattrs (only read them so other devices
can "sync" them, but not apply any locally).

Co-authored-by: Tomasz Wilczyński <twilczynski@naver.com>
2022-09-14 09:50:55 +02:00

563 lines
14 KiB
Go

// Copyright (C) 2014 The Protocol Authors.
package protocol
import (
"bytes"
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"time"
"github.com/syncthing/syncthing/lib/build"
"github.com/syncthing/syncthing/lib/rand"
"github.com/syncthing/syncthing/lib/sha256"
)
const (
SyntheticDirectorySize = 128
HelloMessageMagic uint32 = 0x2EA7D90B
Version13HelloMagic uint32 = 0x9F79BC40 // old
)
// FileIntf is the set of methods implemented by both FileInfo and
// db.FileInfoTruncated.
type FileIntf interface {
FileSize() int64
FileName() string
FileLocalFlags() uint32
IsDeleted() bool
IsInvalid() bool
IsIgnored() bool
IsUnsupported() bool
MustRescan() bool
IsReceiveOnlyChanged() bool
IsDirectory() bool
IsSymlink() bool
ShouldConflict() bool
HasPermissionBits() bool
SequenceNo() int64
BlockSize() int
FileVersion() Vector
FileType() FileInfoType
FilePermissions() uint32
FileModifiedBy() ShortID
ModTime() time.Time
PlatformData() PlatformData
InodeChangeTime() time.Time
}
func (Hello) Magic() uint32 {
return HelloMessageMagic
}
func (f FileInfo) String() string {
switch f.Type {
case FileInfoTypeDirectory:
return fmt.Sprintf("Directory{Name:%q, Sequence:%d, Permissions:0%o, ModTime:%v, Version:%v, VersionHash:%x, Deleted:%v, Invalid:%v, LocalFlags:0x%x, NoPermissions:%v, Platform:%v}",
f.Name, f.Sequence, f.Permissions, f.ModTime(), f.Version, f.VersionHash, f.Deleted, f.RawInvalid, f.LocalFlags, f.NoPermissions, f.Platform)
case FileInfoTypeFile:
return fmt.Sprintf("File{Name:%q, Sequence:%d, Permissions:0%o, ModTime:%v, Version:%v, VersionHash:%x, Length:%d, Deleted:%v, Invalid:%v, LocalFlags:0x%x, NoPermissions:%v, BlockSize:%d, Blocks:%v, BlocksHash:%x, Platform:%v}",
f.Name, f.Sequence, f.Permissions, f.ModTime(), f.Version, f.VersionHash, f.Size, f.Deleted, f.RawInvalid, f.LocalFlags, f.NoPermissions, f.RawBlockSize, f.Blocks, f.BlocksHash, f.Platform)
case FileInfoTypeSymlink, FileInfoTypeSymlinkDirectory, FileInfoTypeSymlinkFile:
return fmt.Sprintf("Symlink{Name:%q, Type:%v, Sequence:%d, Version:%v, VersionHash:%x, Deleted:%v, Invalid:%v, LocalFlags:0x%x, NoPermissions:%v, SymlinkTarget:%q, Platform:%v}",
f.Name, f.Type, f.Sequence, f.Version, f.VersionHash, f.Deleted, f.RawInvalid, f.LocalFlags, f.NoPermissions, f.SymlinkTarget, f.Platform)
default:
panic("mystery file type detected")
}
}
func (f FileInfo) IsDeleted() bool {
return f.Deleted
}
func (f FileInfo) IsInvalid() bool {
return f.RawInvalid || f.LocalFlags&LocalInvalidFlags != 0
}
func (f FileInfo) IsUnsupported() bool {
return f.LocalFlags&FlagLocalUnsupported != 0
}
func (f FileInfo) IsIgnored() bool {
return f.LocalFlags&FlagLocalIgnored != 0
}
func (f FileInfo) MustRescan() bool {
return f.LocalFlags&FlagLocalMustRescan != 0
}
func (f FileInfo) IsReceiveOnlyChanged() bool {
return f.LocalFlags&FlagLocalReceiveOnly != 0
}
func (f FileInfo) IsDirectory() bool {
return f.Type == FileInfoTypeDirectory
}
func (f FileInfo) ShouldConflict() bool {
return f.LocalFlags&LocalConflictFlags != 0
}
func (f FileInfo) IsSymlink() bool {
switch f.Type {
case FileInfoTypeSymlink, FileInfoTypeSymlinkDirectory, FileInfoTypeSymlinkFile:
return true
default:
return false
}
}
func (f FileInfo) HasPermissionBits() bool {
return !f.NoPermissions
}
func (f FileInfo) FileSize() int64 {
if f.Deleted {
return 0
}
if f.IsDirectory() || f.IsSymlink() {
return SyntheticDirectorySize
}
return f.Size
}
func (f FileInfo) BlockSize() int {
if f.RawBlockSize < MinBlockSize {
return MinBlockSize
}
return f.RawBlockSize
}
func (f FileInfo) FileName() string {
return f.Name
}
func (f FileInfo) FileLocalFlags() uint32 {
return f.LocalFlags
}
func (f FileInfo) ModTime() time.Time {
return time.Unix(f.ModifiedS, int64(f.ModifiedNs))
}
func (f FileInfo) SequenceNo() int64 {
return f.Sequence
}
func (f FileInfo) FileVersion() Vector {
return f.Version
}
func (f FileInfo) FileType() FileInfoType {
return f.Type
}
func (f FileInfo) FilePermissions() uint32 {
return f.Permissions
}
func (f FileInfo) FileModifiedBy() ShortID {
return f.ModifiedBy
}
func (f FileInfo) PlatformData() PlatformData {
return f.Platform
}
func (f FileInfo) InodeChangeTime() time.Time {
return time.Unix(0, f.InodeChangeNs)
}
// WinsConflict returns true if "f" is the one to choose when it is in
// conflict with "other".
func WinsConflict(f, other FileIntf) bool {
// If only one of the files is invalid, that one loses.
if f.IsInvalid() != other.IsInvalid() {
return !f.IsInvalid()
}
// If a modification is in conflict with a delete, we pick the
// modification.
if !f.IsDeleted() && other.IsDeleted() {
return true
}
if f.IsDeleted() && !other.IsDeleted() {
return false
}
// The one with the newer modification time wins.
if f.ModTime().After(other.ModTime()) {
return true
}
if f.ModTime().Before(other.ModTime()) {
return false
}
// The modification times were equal. Use the device ID in the version
// vector as tie breaker.
return f.FileVersion().Compare(other.FileVersion()) == ConcurrentGreater
}
type FileInfoComparison struct {
ModTimeWindow time.Duration
IgnorePerms bool
IgnoreBlocks bool
IgnoreFlags uint32
IgnoreOwnership bool
IgnoreXattrs bool
}
func (f FileInfo) IsEquivalent(other FileInfo, modTimeWindow time.Duration) bool {
return f.isEquivalent(other, FileInfoComparison{ModTimeWindow: modTimeWindow})
}
func (f FileInfo) IsEquivalentOptional(other FileInfo, comp FileInfoComparison) bool {
return f.isEquivalent(other, comp)
}
// isEquivalent checks that the two file infos represent the same actual file content,
// i.e. it does purposely not check only selected (see below) struct members.
// Permissions (config) and blocks (scanning) can be excluded from the comparison.
// Any file info is not "equivalent", if it has different
// - type
// - deleted flag
// - invalid flag
// - permissions, unless they are ignored
//
// A file is not "equivalent", if it has different
// - modification time (difference bigger than modTimeWindow)
// - size
// - blocks, unless there are no blocks to compare (scanning)
// - os data
//
// A symlink is not "equivalent", if it has different
// - target
//
// A directory does not have anything specific to check.
func (f FileInfo) isEquivalent(other FileInfo, comp FileInfoComparison) bool {
if f.MustRescan() || other.MustRescan() {
// These are per definition not equivalent because they don't
// represent a valid state, even if both happen to have the
// MustRescan bit set.
return false
}
// If we are recording inode change times and it changed, they are not
// equal.
if f.InodeChangeNs != 0 && other.InodeChangeNs != 0 && f.InodeChangeNs != other.InodeChangeNs {
return false
}
// Mask out the ignored local flags before checking IsInvalid() below
f.LocalFlags &^= comp.IgnoreFlags
other.LocalFlags &^= comp.IgnoreFlags
if f.Name != other.Name || f.Type != other.Type || f.Deleted != other.Deleted || f.IsInvalid() != other.IsInvalid() {
return false
}
// OS data comparison is special: we consider a difference only if an
// entry for the same OS exists on both sides and they are different.
// Otherwise a file would become different as soon as it's synced from
// Windows to Linux, as Linux would add a new POSIX entry for the file.
if !comp.IgnoreOwnership && f.Platform != other.Platform {
if f.Platform.Unix != nil && other.Platform.Unix != nil {
if *f.Platform.Unix != *other.Platform.Unix {
return false
}
}
if f.Platform.Windows != nil && other.Platform.Windows != nil {
if f.Platform.Windows.OwnerName != other.Platform.Windows.OwnerName ||
f.Platform.Windows.OwnerIsGroup != other.Platform.Windows.OwnerIsGroup {
return false
}
}
}
if !comp.IgnoreXattrs && f.Platform != other.Platform {
if !xattrsEqual(f.Platform.Linux, other.Platform.Linux) {
return false
}
if !xattrsEqual(f.Platform.Darwin, other.Platform.Darwin) {
return false
}
if !xattrsEqual(f.Platform.FreeBSD, other.Platform.FreeBSD) {
return false
}
if !xattrsEqual(f.Platform.NetBSD, other.Platform.NetBSD) {
return false
}
}
if !comp.IgnorePerms && !f.NoPermissions && !other.NoPermissions && !PermsEqual(f.Permissions, other.Permissions) {
return false
}
switch f.Type {
case FileInfoTypeFile:
return f.Size == other.Size && ModTimeEqual(f.ModTime(), other.ModTime(), comp.ModTimeWindow) && (comp.IgnoreBlocks || f.BlocksEqual(other))
case FileInfoTypeSymlink:
return f.SymlinkTarget == other.SymlinkTarget
case FileInfoTypeDirectory:
return true
}
return false
}
func ModTimeEqual(a, b time.Time, modTimeWindow time.Duration) bool {
if a.Equal(b) {
return true
}
diff := a.Sub(b)
if diff < 0 {
diff *= -1
}
return diff < modTimeWindow
}
func PermsEqual(a, b uint32) bool {
if build.IsWindows {
// There is only writeable and read only, represented for user, group
// and other equally. We only compare against user.
return a&0600 == b&0600
}
// All bits count
return a&0777 == b&0777
}
// BlocksEqual returns true when the two files have identical block lists.
func (f FileInfo) BlocksEqual(other FileInfo) bool {
// If both sides have blocks hashes and they match, we are good. If they
// don't match still check individual block hashes to catch differences
// in weak hashes only (e.g. after switching weak hash algo).
if len(f.BlocksHash) > 0 && len(other.BlocksHash) > 0 && bytes.Equal(f.BlocksHash, other.BlocksHash) {
return true
}
// Actually compare the block lists in full.
return blocksEqual(f.Blocks, other.Blocks)
}
// Xattrs is a convenience method to return the extended attributes of the
// file for the current platform.
func (f *PlatformData) Xattrs() []Xattr {
switch {
case build.IsLinux && f.Linux != nil:
return f.Linux.Xattrs
case build.IsDarwin && f.Darwin != nil:
return f.Darwin.Xattrs
case build.IsFreeBSD && f.FreeBSD != nil:
return f.FreeBSD.Xattrs
case build.IsNetBSD && f.NetBSD != nil:
return f.NetBSD.Xattrs
default:
return nil
}
}
// SetXattrs is a convenience method to set the extended attributes of the
// file for the current platform.
func (p *PlatformData) SetXattrs(xattrs []Xattr) {
switch {
case build.IsLinux:
if p.Linux == nil {
p.Linux = &XattrData{}
}
p.Linux.Xattrs = xattrs
case build.IsDarwin:
if p.Darwin == nil {
p.Darwin = &XattrData{}
}
p.Darwin.Xattrs = xattrs
case build.IsFreeBSD:
if p.FreeBSD == nil {
p.FreeBSD = &XattrData{}
}
p.FreeBSD.Xattrs = xattrs
case build.IsNetBSD:
if p.NetBSD == nil {
p.NetBSD = &XattrData{}
}
p.NetBSD.Xattrs = xattrs
}
}
// MergeWith copies platform data from other, for platforms where it's not
// already set on p.
func (p *PlatformData) MergeWith(other *PlatformData) {
if p.Unix == nil {
p.Unix = other.Unix
}
if p.Windows == nil {
p.Windows = other.Windows
}
if p.Linux == nil {
p.Linux = other.Linux
}
if p.Darwin == nil {
p.Darwin = other.Darwin
}
if p.FreeBSD == nil {
p.FreeBSD = other.FreeBSD
}
if p.NetBSD == nil {
p.NetBSD = other.NetBSD
}
}
// blocksEqual returns whether two slices of blocks are exactly the same hash
// and index pair wise.
func blocksEqual(a, b []BlockInfo) bool {
if len(b) != len(a) {
return false
}
for i, sblk := range a {
if !bytes.Equal(sblk.Hash, b[i].Hash) {
return false
}
}
return true
}
func (f *FileInfo) SetMustRescan() {
f.setLocalFlags(FlagLocalMustRescan)
}
func (f *FileInfo) SetIgnored() {
f.setLocalFlags(FlagLocalIgnored)
}
func (f *FileInfo) SetUnsupported() {
f.setLocalFlags(FlagLocalUnsupported)
}
func (f *FileInfo) SetDeleted(by ShortID) {
f.ModifiedBy = by
f.Deleted = true
f.Version = f.Version.Update(by)
f.ModifiedS = time.Now().Unix()
f.setNoContent()
}
func (f *FileInfo) setLocalFlags(flags uint32) {
f.RawInvalid = false
f.LocalFlags = flags
f.setNoContent()
}
func (f *FileInfo) setNoContent() {
f.Blocks = nil
f.BlocksHash = nil
f.Size = 0
}
func (b BlockInfo) String() string {
return fmt.Sprintf("Block{%d/%d/%d/%x}", b.Offset, b.Size, b.WeakHash, b.Hash)
}
// IsEmpty returns true if the block is a full block of zeroes.
func (b BlockInfo) IsEmpty() bool {
if v, ok := sha256OfEmptyBlock[int(b.Size)]; ok {
return bytes.Equal(b.Hash, v[:])
}
return false
}
type IndexID uint64
func (i IndexID) String() string {
return fmt.Sprintf("0x%016X", uint64(i))
}
func (i IndexID) Marshal() ([]byte, error) {
bs := make([]byte, 8)
binary.BigEndian.PutUint64(bs, uint64(i))
return bs, nil
}
func (i *IndexID) Unmarshal(bs []byte) error {
if len(bs) != 8 {
return errors.New("incorrect IndexID length")
}
*i = IndexID(binary.BigEndian.Uint64(bs))
return nil
}
func NewIndexID() IndexID {
return IndexID(rand.Uint64())
}
func (f Folder) Description() string {
// used by logging stuff
if f.Label == "" {
return f.ID
}
return fmt.Sprintf("%q (%s)", f.Label, f.ID)
}
func BlocksHash(bs []BlockInfo) []byte {
h := sha256.New()
for _, b := range bs {
_, _ = h.Write(b.Hash)
_ = binary.Write(h, binary.BigEndian, b.WeakHash)
}
return h.Sum(nil)
}
func VectorHash(v Vector) []byte {
h := sha256.New()
for _, c := range v.Counters {
if err := binary.Write(h, binary.BigEndian, c.ID); err != nil {
panic("impossible: failed to write c.ID to hash function: " + err.Error())
}
if err := binary.Write(h, binary.BigEndian, c.Value); err != nil {
panic("impossible: failed to write c.Value to hash function: " + err.Error())
}
}
return h.Sum(nil)
}
func (x *FileInfoType) MarshalJSON() ([]byte, error) {
return json.Marshal(x.String())
}
func (x *FileInfoType) UnmarshalJSON(data []byte) error {
var s string
if err := json.Unmarshal(data, &s); err != nil {
return err
}
n, ok := FileInfoType_value[s]
if !ok {
return errors.New("invalid value: " + s)
}
*x = FileInfoType(n)
return nil
}
func xattrsEqual(a, b *XattrData) bool {
if a == nil || b == nil {
// Having no data on either side means we have nothing to compare
// to, and we consider that equal.
return true
}
if len(a.Xattrs) != len(b.Xattrs) {
return false
}
for i := range a.Xattrs {
if a.Xattrs[i].Name != b.Xattrs[i].Name {
return false
}
if !bytes.Equal(a.Xattrs[i].Value, b.Xattrs[i].Value) {
return false
}
}
return true
}