6cac308bcd
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>
99 lines
2.5 KiB
Go
99 lines
2.5 KiB
Go
// Copyright (C) 2022 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package fs
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import (
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"strconv"
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"sync"
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"time"
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"github.com/syncthing/syncthing/lib/protocol"
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)
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// unixPlatformData is used on all platforms, because apart from being the
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// implementation for BasicFilesystem on Unixes it's also the implementation
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// in fakeFS.
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func unixPlatformData(fs Filesystem, name string, userCache *userCache, groupCache *groupCache, scanOwnership, scanXattrs bool, xattrFilter XattrFilter) (protocol.PlatformData, error) {
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var pd protocol.PlatformData
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if scanOwnership {
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var ud protocol.UnixData
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stat, err := fs.Lstat(name)
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if err != nil {
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return protocol.PlatformData{}, err
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}
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ud.UID = stat.Owner()
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if user := userCache.lookup(strconv.Itoa(ud.UID)); user != nil {
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ud.OwnerName = user.Username
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} else if ud.UID == 0 {
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// We couldn't look up a name, but UID zero should be "root". This
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// fixup works around the (unlikely) situation where the ownership
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// is 0:0 but we can't look up a name for either uid zero or gid
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// zero. If that were the case we'd return a zero PlatformData which
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// wouldn't get serialized over the wire and the other side would
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// assume a lack of ownership info...
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ud.OwnerName = "root"
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}
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ud.GID = stat.Group()
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if group := groupCache.lookup(strconv.Itoa(ud.GID)); group != nil {
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ud.GroupName = group.Name
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} else if ud.GID == 0 {
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ud.GroupName = "root"
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}
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pd.Unix = &ud
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}
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if scanXattrs {
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xattrs, err := fs.GetXattr(name, xattrFilter)
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if err != nil {
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return protocol.PlatformData{}, err
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}
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pd.SetXattrs(xattrs)
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}
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return pd, nil
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}
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type valueCache[K comparable, V any] struct {
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validity time.Duration
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fill func(K) (V, error)
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mut sync.Mutex
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cache map[K]cacheEntry[V]
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}
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type cacheEntry[V any] struct {
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value V
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when time.Time
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}
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func newValueCache[K comparable, V any](validity time.Duration, fill func(K) (V, error)) *valueCache[K, V] {
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return &valueCache[K, V]{
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validity: validity,
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fill: fill,
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cache: make(map[K]cacheEntry[V]),
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}
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}
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func (c *valueCache[K, V]) lookup(key K) V {
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c.mut.Lock()
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defer c.mut.Unlock()
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if e, ok := c.cache[key]; ok && time.Since(e.when) < c.validity {
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return e.value
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}
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var e cacheEntry[V]
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if val, err := c.fill(key); err == nil {
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e.value = val
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}
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e.when = time.Now()
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c.cache[key] = e
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return e.value
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}
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