github.com/containerd/nerdctl@v1.7.7/pkg/lockutil/lockutil_unix.go (about)

     1  //go:build freebsd || linux
     2  
     3  /*
     4     Copyright The containerd Authors.
     5  
     6     Licensed under the Apache License, Version 2.0 (the "License");
     7     you may not use this file except in compliance with the License.
     8     You may obtain a copy of the License at
     9  
    10         http://www.apache.org/licenses/LICENSE-2.0
    11  
    12     Unless required by applicable law or agreed to in writing, software
    13     distributed under the License is distributed on an "AS IS" BASIS,
    14     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    15     See the License for the specific language governing permissions and
    16     limitations under the License.
    17  */
    18  
    19  package lockutil
    20  
    21  import (
    22  	"fmt"
    23  	"os"
    24  
    25  	"github.com/containerd/log"
    26  	"golang.org/x/sys/unix"
    27  )
    28  
    29  func WithDirLock(dir string, fn func() error) error {
    30  	dirFile, err := os.Open(dir)
    31  	if err != nil {
    32  		return err
    33  	}
    34  	defer dirFile.Close()
    35  	if err := Flock(dirFile, unix.LOCK_EX); err != nil {
    36  		return fmt.Errorf("failed to lock %q: %w", dir, err)
    37  	}
    38  	defer func() {
    39  		if err := Flock(dirFile, unix.LOCK_UN); err != nil {
    40  			log.L.WithError(err).Errorf("failed to unlock %q", dir)
    41  		}
    42  	}()
    43  	return fn()
    44  }
    45  
    46  func Flock(f *os.File, flags int) error {
    47  	fd := int(f.Fd())
    48  	for {
    49  		err := unix.Flock(fd, flags)
    50  		if err == nil || err != unix.EINTR {
    51  			return err
    52  		}
    53  	}
    54  }