Make FlockFile function private to not expose it for misuse. (#3204)

* Make FlockFile function private to not expose it for misuse.

* Update pr number in changelog

* fix changelog

Co-authored-by: Jörn Friedrich Dreyer <[email protected]>

changelog/unreleased/makeflockfileprivate.md

@@ -0,0 +1,8 @@
+Enhancement: Make the function flockFile private
+
+Having that function exported is tempting people to use the func
+to get the name for calling the lock functions. That is wrong, as
+this function is just a helper to generate the lock file name from
+a given file to lock.
+
+https://github.com/cs3org/reva/pull/3204

pkg/storage/utils/filelocks/filelocks.go

@@ -64,7 +64,7 @@ func acquireLock(file string, write bool) (*flock.Flock, error) {
 	var err error
 
 	// Create a file to carry the log
-	n := FlockFile(file)
+	n := flockFile(file)
 	if len(n) == 0 {
 		return nil, errors.New("lock path is empty")
 	}
@@ -107,9 +107,9 @@ func acquireLock(file string, write bool) (*flock.Flock, error) {
 	return flock, nil
 }
 
-// FlockFile returns the flock filename for a given file name
+// flockFile returns the flock filename for a given file name
 // it returns an empty string if the input is empty
-func FlockFile(file string) string {
+func flockFile(file string) string {
 	var n string
 	if len(file) > 0 {
 		n = file + ".flock"
@@ -119,12 +119,16 @@ func FlockFile(file string) string {
 
 // AcquireReadLock tries to acquire a shared lock to read from the
 // file and returns a lock object or an error accordingly.
+// Call with the file to lock. This function creates .lock file next
+// to it.
 func AcquireReadLock(file string) (*flock.Flock, error) {
 	return acquireLock(file, false)
 }
 
 // AcquireWriteLock tries to acquire a shared lock to write from the
 // file and returns a lock object or an error accordingly.
+// Call with the file to lock. This function creates an extra .lock
+// file next to it.
 func AcquireWriteLock(file string) (*flock.Flock, error) {
 	return acquireLock(file, true)
 }