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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