vendor: upgrade containers/storage

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

vendor/github.com/containers/storage/lockfile.go

@@ -0,0 +1,139 @@
+package storage
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/containers/storage/pkg/stringid"
+)
+
+// A Locker represents a file lock where the file is used to cache an
+// identifier of the last party that made changes to whatever's being protected
+// by the lock.
+type Locker interface {
+	sync.Locker
+
+	// Touch records, for others sharing the lock, that the caller was the
+	// last writer.  It should only be called with the lock held.
+	Touch() error
+
+	// Modified() checks if the most recent writer was a party other than the
+	// last recorded writer.  It should only be called with the lock held.
+	Modified() (bool, error)
+
+	// TouchedSince() checks if the most recent writer modified the file (likely using Touch()) after the specified time.
+	TouchedSince(when time.Time) bool
+}
+
+type lockfile struct {
+	mu   sync.Mutex
+	file string
+	fd   uintptr
+	lw   string
+}
+
+var (
+	lockfiles     map[string]*lockfile
+	lockfilesLock sync.Mutex
+)
+
+// GetLockfile opens a lock file, creating it if necessary.  The Locker object
+// return will be returned unlocked.
+func GetLockfile(path string) (Locker, error) {
+	lockfilesLock.Lock()
+	defer lockfilesLock.Unlock()
+	if lockfiles == nil {
+		lockfiles = make(map[string]*lockfile)
+	}
+	if locker, ok := lockfiles[filepath.Clean(path)]; ok {
+		return locker, nil
+	}
+	fd, err := unix.Open(filepath.Clean(path), os.O_RDWR|os.O_CREATE, unix.S_IRUSR|unix.S_IWUSR)
+	if err != nil {
+		return nil, err
+	}
+	locker := &lockfile{file: path, fd: uintptr(fd), lw: stringid.GenerateRandomID()}
+	lockfiles[filepath.Clean(path)] = locker
+	return locker, nil
+}
+
+func (l *lockfile) Lock() {
+	lk := unix.Flock_t{
+		Type:   unix.F_WRLCK,
+		Whence: int16(os.SEEK_SET),
+		Start:  0,
+		Len:    0,
+		Pid:    int32(os.Getpid()),
+	}
+	l.mu.Lock()
+	for unix.FcntlFlock(l.fd, unix.F_SETLKW, &lk) != nil {
+		time.Sleep(10 * time.Millisecond)
+	}
+}
+
+func (l *lockfile) Unlock() {
+	lk := unix.Flock_t{
+		Type:   unix.F_UNLCK,
+		Whence: int16(os.SEEK_SET),
+		Start:  0,
+		Len:    0,
+		Pid:    int32(os.Getpid()),
+	}
+	for unix.FcntlFlock(l.fd, unix.F_SETLKW, &lk) != nil {
+		time.Sleep(10 * time.Millisecond)
+	}
+	l.mu.Unlock()
+}
+
+func (l *lockfile) Touch() error {
+	l.lw = stringid.GenerateRandomID()
+	id := []byte(l.lw)
+	_, err := unix.Seek(int(l.fd), 0, os.SEEK_SET)
+	if err != nil {
+		return err
+	}
+	n, err := unix.Write(int(l.fd), id)
+	if err != nil {
+		return err
+	}
+	if n != len(id) {
+		return unix.ENOSPC
+	}
+	err = unix.Fsync(int(l.fd))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (l *lockfile) Modified() (bool, error) {
+	id := []byte(l.lw)
+	_, err := unix.Seek(int(l.fd), 0, os.SEEK_SET)
+	if err != nil {
+		return true, err
+	}
+	n, err := unix.Read(int(l.fd), id)
+	if err != nil {
+		return true, err
+	}
+	if n != len(id) {
+		return true, unix.ENOSPC
+	}
+	lw := l.lw
+	l.lw = string(id)
+	return l.lw != lw, nil
+}
+
+func (l *lockfile) TouchedSince(when time.Time) bool {
+	st := unix.Stat_t{}
+	err := unix.Fstat(int(l.fd), &st)
+	if err != nil {
+		return true
+	}
+	touched := time.Unix(statTMtimeUnix(st))
+	return when.Before(touched)
+}