+int log_format_iovec(
+ struct iovec *iovec,
+ unsigned iovec_len,
+ unsigned *n,
+ bool newline_separator,
+ int error,
+ const char *format,
+ va_list ap) {
+
+ static const char nl = '\n';
+
+ while (format && *n + 1 < iovec_len) {
+ va_list aq;
+ char *m;
+ int r;
+
+ /* We need to copy the va_list structure,
+ * since vasprintf() leaves it afterwards at
+ * an undefined location */
+
+ if (error != 0)
+ errno = error;
+
+ va_copy(aq, ap);
+ r = vasprintf(&m, format, aq);
+ va_end(aq);
+ if (r < 0)
+ return -EINVAL;
+
+ /* Now, jump enough ahead, so that we point to
+ * the next format string */
+ VA_FORMAT_ADVANCE(format, ap);
+
+ IOVEC_SET_STRING(iovec[(*n)++], m);
+
+ if (newline_separator) {
+ iovec[*n].iov_base = (char*) &nl;
+ iovec[*n].iov_len = 1;
+ (*n)++;
+ }
+
+ format = va_arg(ap, char *);
+ }
+ return 0;
+}
+