<para><function>sd_is_fifo()</function> may be called
to check whether the specified file descriptor refers
to a FIFO or pipe. If the <parameter>path</parameter>
- parameter is not NULL, it is checked whether the FIFO
- is bound to the specified file system path.</para>
+ parameter is not <constant>NULL</constant>, it is
+ checked whether the FIFO is bound to the specified
+ file system path.</para>
<para><function>sd_is_socket()</function> may be
called to check whether the specified file descriptor
<para><function>sd_is_mq()</function> may be called to
check whether the specified file descriptor refers to
a POSIX message queue. If the
- <parameter>path</parameter> parameter is not NULL, it
- is checked whether the message queue is bound to the
- specified name.</para>
+ <parameter>path</parameter> parameter is not
+ <constant>NULL</constant>, it is checked whether the
+ message queue is bound to the specified name.</para>
</refsect1>
<refsect1>
<para>On failure, these calls return a negative
errno-style error code. If the file descriptor is of
- the specified type and bound to the specified address
+ the specified type and bound to the specified address,
a positive return value is returned, otherwise
zero.</para>
</refsect1>