Merge pull request #957 from saschagrunert/panic-fix

Fix runtime panic for opening lockfile if parent dir got removed

pkg/lockfile/lockfile_unix.go

@@ -5,6 +5,7 @@ package lockfile
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 	"sync"
 	"time"
 
@@ -33,11 +34,30 @@ type lockfile struct {
 // descriptor.  Note that the path is opened read-only when ro is set.  If ro
 // is unset, openLock will open the path read-write and create the file if
 // necessary.
-func openLock(path string, ro bool) (int, error) {
+func openLock(path string, ro bool) (fd int, err error) {
 	if ro {
-		return unix.Open(path, os.O_RDONLY|unix.O_CLOEXEC, 0)
+		fd, err = unix.Open(path, os.O_RDONLY|unix.O_CLOEXEC, 0)
+	} else {
+		fd, err = unix.Open(path,
+			os.O_RDWR|unix.O_CLOEXEC|os.O_CREATE,
+			unix.S_IRUSR|unix.S_IWUSR|unix.S_IRGRP|unix.S_IROTH,
+		)
 	}
-	return unix.Open(path, os.O_RDWR|unix.O_CLOEXEC|os.O_CREATE, unix.S_IRUSR|unix.S_IWUSR|unix.S_IRGRP|unix.S_IROTH)
+
+	if err == nil {
+		return
+	}
+
+	// the directory of the lockfile seems to be removed, try to create it
+	if os.IsNotExist(err) {
+		if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
+			return fd, errors.Wrap(err, "creating locker directory")
+		}
+
+		return openLock(path, ro)
+	}
+
+	return
 }
 
 // createLockerForPath returns a Locker object, possibly (depending on the platform)

pkg/lockfile/lockfile_unix_test.go

@@ -0,0 +1,65 @@
+// +build linux solaris darwin freebsd
+
+package lockfile
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestOpenLock(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name    string
+		prepare func() (path string, readOnly bool)
+	}{
+		{
+			name: "file exists (read/write)",
+			prepare: func() (string, bool) {
+				tempFile, err := ioutil.TempFile("", "lock-")
+				require.NoError(t, err)
+				return tempFile.Name(), false
+			},
+		},
+		{
+			name: "file exists readonly (readonly)",
+			prepare: func() (string, bool) {
+				tempFile, err := ioutil.TempFile("", "lock-")
+				require.NoError(t, err)
+				return tempFile.Name(), true
+			},
+		},
+		{
+			name: "base dir exists (read/write)",
+			prepare: func() (string, bool) {
+				tempDir := os.TempDir()
+				require.DirExists(t, tempDir)
+				return filepath.Join(tempDir, "test-1.lock"), false
+			},
+		},
+		{
+			name: "base dir not exists (read/write)",
+			prepare: func() (string, bool) {
+				tempDir, err := ioutil.TempDir("", "lock-")
+				require.NoError(t, err)
+				return filepath.Join(tempDir, "subdir", "test-1.lock"), false
+			},
+		},
+	} {
+		path, readOnly := tc.prepare()
+
+		_, err := openLock(path, readOnly)
+
+		require.NoError(t, err, tc.name)
+
+		_, err = openLock(path, readOnly)
+		require.NoError(t, err)
+
+		require.Nil(t, os.RemoveAll(path))
+	}
+}