github.com/hugh712/snapd@v0.0.0-20200910133618-1a99902bd583/cmd/snaplock/lock.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2017 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  // Package snaplock offers per-snap locking also used by snap-confine.
    21  // The corresponding C code is in libsnap-confine-private/locking.c
    22  package snaplock
    23  
    24  import (
    25  	"fmt"
    26  	"os"
    27  	"path/filepath"
    28  
    29  	"github.com/snapcore/snapd/dirs"
    30  	"github.com/snapcore/snapd/osutil"
    31  )
    32  
    33  // lockFileName returns the name of the lock file for the given snap.
    34  func lockFileName(snapName string) string {
    35  	return filepath.Join(dirs.SnapRunLockDir, fmt.Sprintf("%s.lock", snapName))
    36  }
    37  
    38  // OpenLock creates and opens a lock file associated with a particular snap.
    39  func OpenLock(snapName string) (*osutil.FileLock, error) {
    40  	if err := os.MkdirAll(dirs.SnapRunLockDir, 0700); err != nil {
    41  		return nil, fmt.Errorf("cannot create lock directory: %s", err)
    42  	}
    43  	flock, err := osutil.NewFileLock(lockFileName(snapName))
    44  	if err != nil {
    45  		return nil, err
    46  	}
    47  	return flock, nil
    48  }