tailscale/util/groupmember/groupmember_cgo.go

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// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build cgo && !osusergo
// +build cgo,!osusergo
package groupmember
import (
"os/user"
"sync"
)
func isMemberOfGroup(group, name string) (bool, error) {
u, err := user.Lookup(name)
if err != nil {
return false, err
}
ugids, err := u.GroupIds()
if err != nil {
return false, err
}
gid, err := getGroupID(group)
if err != nil {
return false, err
}
for _, ugid := range ugids {
if gid == ugid {
return true, nil
}
}
return false, nil
}
var groupIDCache sync.Map // of string
func getGroupID(groupName string) (string, error) {
s, ok := groupIDCache.Load(groupName)
if ok {
return s.(string), nil
}
g, err := user.LookupGroup(groupName)
if err != nil {
return "", err
}
groupIDCache.Store(groupName, g.Gid)
return g.Gid, nil
}