+
+int take_password_lock(const char *root) {
+
+ struct flock flock = {
+ .l_type = F_WRLCK,
+ .l_whence = SEEK_SET,
+ .l_start = 0,
+ .l_len = 0,
+ };
+
+ const char *path;
+ int fd, r;
+
+ /* This is roughly the same as lckpwdf(), but not as awful. We
+ * don't want to use alarm() and signals, hence we implement
+ * our own trivial version of this.
+ *
+ * Note that shadow-utils also takes per-database locks in
+ * addition to lckpwdf(). However, we don't given that they
+ * are redundant as they they invoke lckpwdf() first and keep
+ * it during everything they do. The per-database locks are
+ * awfully racy, and thus we just won't do them. */
+
+ if (root)
+ path = strappenda(root, "/etc/.pwd.lock");
+ else
+ path = "/etc/.pwd.lock";
+
+ fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, 0600);
+ if (fd < 0)
+ return -errno;
+
+ r = fcntl(fd, F_SETLKW, &flock);
+ if (r < 0) {
+ safe_close(fd);
+ return -errno;
+ }
+
+ return fd;
+}
+
+int is_symlink(const char *path) {
+ struct stat info;
+
+ if (lstat(path, &info) < 0)
+ return -errno;
+
+ if (S_ISLNK(info.st_mode))
+ return 1;
+
+ return 0;
+}