+int symlink_idempotent(const char *from, const char *to) {
+ _cleanup_free_ char *p = NULL;
+ int r;
+
+ assert(from);
+ assert(to);
+
+ if (symlink(from, to) < 0) {
+ if (errno != EEXIST)
+ return -errno;
+
+ r = readlink_malloc(to, &p);
+ if (r < 0)
+ return r;
+
+ if (!streq(p, from))
+ return -EINVAL;
+ }
+
+ return 0;
+}
+