I found out how file_has_acl is meant to be called by looking at the coreutils
source code.
2011-10-03 Bruno Haible <br...@clisp.org>
acl: Fix specification.
* lib/file-has-acl.c (file_has_acl): Fix specification.
--- lib/file-has-acl.c.orig Mon Oct 3 15:47:44 2011
+++ lib/file-has-acl.c Mon Oct 3 15:47:12 2011
@@ -439,7 +439,8 @@
/* Return 1 if NAME has a nontrivial access control list, 0 if NAME
only has no or a base access control list, and -1 (setting errno)
- on error. SB must be set to the stat buffer of FILE. */
+ on error. SB must be set to the stat buffer of NAME, obtained
+ through stat() or lstat(). */
int
file_has_acl (char const *name, struct stat const *sb)
