+ <para>The four calls return 0 on success or a negative
+ errno-style error code. The
+ <citerefentry><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ variable itself is not altered.</para>
+
+ <para>If
+ <citerefentry><refentrytitle>systemd-journald</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ is not running (the socket is not present), those
+ functions do nothing, and also return 0.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Async signal safety</title>
+ <para><function>sd_journal_sendv()</function> is "async signal
+ safe" in the meaning of <citerefentry><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
+ </para>
+
+ <para><function>sd_journal_print</function>,
+ <function>sd_journal_printv</function>,
+ <function>sd_journal_send</function>, and
+ <function>sd_journal_perror</function> are
+ not async signal safe.</para>