// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"errors"
)

var (
	errLockConflict       = errors.New("lock conflict")
	errLockNotInitialized = errors.New("lock not initialized")
	errLockNotFound       = errors.New("lock not found")

```sh
aws s3api put-object --bucket testbucket --key lockme --object-lock-mode GOVERNANCE --object-lock-retain-until-date "2019-11-20"  --body /etc/issue
```

		ilm       lifecycle.Lifecycle
		retention lock.Retention
		obj       ObjectInfo
		want      lifecycle.Action
	}{
		{
			// with object locking
			ilm:       *deleteAllLc,
			retention: lock.Retention{LockEnabled: true},
			obj:       obj,
			want:      lifecycle.NoneAction,
		},
		{
			// without object locking
			ilm:       *deleteAllLc,
			retention: lock.Retention{},
			obj:       obj,

	r  io.Reader
	mu sync.Mutex
}

func (d *disconnectReader) Read(p []byte) (n int, err error) {
	d.mu.Lock()
	defer d.mu.Unlock()
	if d.r != nil {
		return d.r.Read(p)
	}
	return 0, errors.New("reader closed")
}

func (d *disconnectReader) Close() error {
	d.mu.Lock()
	d.r = nil
	d.mu.Unlock()
	return nil
}

// if it is not successful yet.
func (l *Init) Do(f func() error) error {
	if atomic.LoadUint32(&l.done) == 0 {
		return l.do(f)
	}
	return nil
}

func (l *Init) do(f func() error) error {
	l.m.Lock()
	defer l.m.Unlock()
	if atomic.LoadUint32(&l.done) == 0 {
		if err := f(); err != nil {
			return err
		}
		// Mark as done only when f() is successful
		atomic.StoreUint32(&l.done, 1)
	}
	return nil
}

// AddSystemTarget adds a new logger target to the
// list of enabled loggers
func AddSystemTarget(ctx context.Context, t Target) error {
	if err := t.Init(ctx); err != nil {
		return err
	}

	swapSystemMuRW.Lock()
	defer swapSystemMuRW.Unlock()

	if consoleTgt == nil {
		if t.Type() == types.TargetConsole {
			consoleTgt = t
		}
	}
	updated := append(make([]Target, 0, len(systemTargets)+1), systemTargets...)

	go func() {
		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		// Leader node (that successfully acquires the lock inside licenceUpdaterLoop)
		// will keep performing the license update. If the leader goes down for some
		// reason, the lock will be released and another node will acquire it and
		// take over because of this loop.
		for {
			licenceUpdaterLoop(ctx, objAPI)

func (srv *Server) Shutdown() error {
	srv.listenerMutex.Lock()
	if srv.listener == nil {
		srv.listenerMutex.Unlock()
		return http.ErrServerClosed
	}
	srv.listenerMutex.Unlock()

	if atomic.AddUint32(&srv.inShutdown, 1) > 1 {
		// shutdown in progress
		return http.ErrServerClosed
	}

	// Close underneath HTTP listener.
	srv.listenerMutex.Lock()
	err := srv.listener.Close()
	srv.listenerMutex.Unlock()

type TargetList struct {
	sync.RWMutex
	targets map[TargetID]Target
}

// Add - adds unique target to target list.
func (list *TargetList) Add(targets ...Target) error {
	list.Lock()
	defer list.Unlock()

	for _, target := range targets {
		if _, ok := list.targets[target.ID()]; ok {
			return fmt.Errorf("target %v already exists", target.ID())
		}
		list.targets[target.ID()] = target
	}

		config.KV{
			Key:   browserHSTSPreload,
			Value: config.EnableOff,
		},
		config.KV{
			Key:   browserReferrerPolicy,
			Value: "strict-origin-when-cross-origin",
		},
	}
)

// configLock is a global lock for browser config
var configLock sync.RWMutex

// Config storage class configuration
type Config struct {
	CSPPolicy             string `json:"csp_policy"`
	HSTSSeconds           int    `json:"hsts_seconds"`