depending on platform.  See <literal>POLLIN</literal>
       and <literal>POLLOUT</literal> from <function>poll(2)</function>,
       or <parameter>readfds</parameter> and
       <parameter>writefds</parameter> from <function>select(2)</function>,
       for more information.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry id="libpq-PQconndefaults">
     <term><function>PQconndefaults</function><indexterm><primary>PQconndefaults</primary></indexterm></term>
     <listitem>
      <para>
       Returns the default connection options.
<synopsis>
PQconninfoOption *PQconndefaults(void);

typedef struct
{
    char   *keyword;   /* The keyword of the option */
    char   *envvar;    /* Fallback environment variable name */
    char   *compiled;  /* Fallback compiled in default value */
    char   *val;       /* Option's current value, or NULL */
    char   *label;     /* Label for field in connect dialog */
    char   *dispchar;  /* Indicates how to display this field
                          in a connect dialog. Values are:
                          ""        Display entered value as is
                          "*"       Password field - hide value
                          "D"       Debug option - don't show by default */
    int     dispsize;  /* Field size in characters for dialog */
} PQconninfoOption;
</synopsis>
      </para>

      <para>
       Returns a connection options array.  This can be used to determine
       all possible <xref linkend="libpq-PQconnectdb"/> options and their
       current default values.  The return value points to an array of
       <structname>PQconninfoOption</structname> structures, which ends
       with an entry having a null <structfield>keyword</structfield> pointer.  The
       null pointer is returned if memory could not be allocated. Note that
       the current default values (<structfield>val</structfield> fields)
       will depend on environment variables and other context.  A
       missing or invalid service file will be silently ignored.  Callers
       must treat the connection options data as read-only.
      </para>

      <para>
       After processing the options array, free it by passing it to
       <xref linkend="libpq-PQconninfoFree"/>.  If this is not done, a small amount of memory
       is leaked for each call to <xref linkend="libpq-PQconndefaults"/>.
      </para>

     </listitem>
    </varlistentry>

    <varlistentry id="libpq-PQconninfo">
     <term><function>PQconninfo</function><indexterm><primary>PQconninfo</primary></indexterm></term>
     <listitem>
      <para>
       Returns the connection options used by a live connection.
<synopsis>
PQconninfoOption *PQconninfo(PGconn *conn);
</synopsis>
      </para>

      <para>
       Returns a connection options array.  This can be used to determine
       all possible <xref linkend="libpq-PQconnectdb"/> options and the
       values that were used to connect to the server. The return
       value points to an array of <structname>PQconninfoOption</structname>
       structures, which ends with an entry having a null <structfield>keyword</structfield>
       pointer. All notes above for <xref linkend="libpq-PQconndefaults"/> also
       apply to the result of <xref linkend="libpq-PQconninfo"/>.
      </para>

     </listitem>
    </varlistentry>


    <varlistentry id="libpq-PQconninfoParse">
     <term><function>PQconninfoParse</function><indexterm><primary>PQconninfoParse</primary></indexterm></term>
     <listitem>
      <para>
       Returns parsed connection options from the provided connection string.

<synopsis>
PQconninfoOption *PQconninfoParse(const char *conninfo, char **errmsg);
</synopsis>
      </para>

      <para>
       Parses a connection string and returns the resulting options as an
       array; or returns <symbol>NULL</symbol> if there is a problem with the connection
       string.  This function can be used to extract
       the <xref linkend="libpq-PQconnectdb"/> options