Refactor tryLock

simplify `locked` at the expenso of adding a boolean arg to tryLock.

Signed-off-by: Natanael Copa <ncopa@mirantis.com>

pkg/config/flock_unix.go

@@ -19,23 +19,35 @@ limitations under the License.
 package config
 
 import (
+	"errors"
 	"golang.org/x/sys/unix"
 	"os"
 	"path/filepath"
 )
 
 // tryLock attempts to acquire the lock. Returns *os.File if successful, nil otherwise.
-func tryLock(path string) (*os.File, error) {
+func tryLock(path string, exclusive bool) (*os.File, error) {
 	fullPath, err := filepath.Abs(path)
 	if err != nil {
 		return nil, err
 	}
-	file, err := os.OpenFile(fullPath, os.O_CREATE|os.O_RDWR, 0600)
+	mode := os.O_RDWR
+	if exclusive {
+		mode |= os.O_CREATE
+	}
+	file, err := os.OpenFile(fullPath, mode, 0600)
 	if err != nil {
 		return nil, err
 	}
 
-	if err := unix.Flock(int(file.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
+	flockMode := unix.LOCK_NB
+	if exclusive {
+		flockMode |= unix.LOCK_EX
+	} else {
+		flockMode |= unix.LOCK_SH
+	}
+
+	if err := unix.Flock(int(file.Fd()), flockMode); err != nil {
 		_ = file.Close()
 		if err == unix.EWOULDBLOCK {
 			return nil, ErrK0sAlreadyRunning // Lock is already held by another process
@@ -47,19 +59,10 @@ func tryLock(path string) (*os.File, error) {
 
 // locked checks if the lock is currently held by another process.
 func locked(path string) bool {
-	file, err := os.OpenFile(path, os.O_RDWR, 0600)
+	f, err := tryLock(path, false)
 	if err != nil {
-		return false
-	}
-	defer file.Close()
-
-	// Attempt a non-blocking shared lock to test the lock state
-	if err := unix.Flock(int(file.Fd()), unix.LOCK_SH|unix.LOCK_NB); err != nil {
-		if err == unix.EWOULDBLOCK {
-			return true
-		}
-		return false
+		return errors.Is(err, ErrK0sAlreadyRunning)
 	}
-
+	f.Close()
 	return false
 }

pkg/config/runtime.go

@@ -115,7 +115,7 @@ func NewRuntimeConfig(k0sVars *CfgVars) (*RuntimeConfig, error) {
 	//
 	// It works similar on Windows, but with LockFileEx
 
-	lockFile, err := tryLock(k0sVars.RuntimeConfigPath + ".lock")
+	lockFile, err := tryLock(k0sVars.RuntimeConfigPath+".lock", true)
 	if err != nil {
 		return nil, err
 	}