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a667ddf132
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e2b40db616
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@ -146,8 +146,10 @@
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</tgroup>
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</table>
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<para>For types "s" and "g" (unicode string or signature), the pointer may be
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<constant>NULL</constant>, which is equivalent to an empty string. See
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<para>For types <literal>s</literal> and <literal>g</literal> (unicode string or signature), the pointer
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may be <constant>NULL</constant>, which is equivalent to an empty string. For <literal>h</literal> (UNIX
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file descriptor), the descriptor is duplicated by this call and the passed descriptor stays in possession
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of the caller. See
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<citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for the precise interpretation of those and other types.</para>
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</refsect1>
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@ -73,7 +73,10 @@
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should be read. See the table below for a complete list of allowed arguments and their types. Note that,
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if the basic type is a pointer (e.g., <type>const char *</type> in the case of a string), the argument is
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a pointer to a pointer, and also the pointer value that is written is only borrowed and the contents must
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be copied if they are to be used after the end of the messages lifetime.</para>
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be copied if they are to be used after the end of the messages lifetime. If the type is
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<literal>h</literal> (UNIX file descriptor), the descriptor is not duplicated by this call and the
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returned descriptor remains in possession of the message object, and needs to be duplicated by the caller
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in order to keep an open reference to it after the message object is freed.</para>
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<para>Each argument may also be <constant>NULL</constant>, in which case the value is read and ignored.
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</para>
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@ -228,6 +231,15 @@ const char *s, *t, *u;
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sd_bus_message_read(m, "a{is}", 3, &i, &s, &j, &t, &k, &u);
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</programlisting>
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<para>Read a single file descriptor, and duplicate it in order to keep it open after the message is
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freed.</para>
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<programlisting>sd_bus_message *m;
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int fd, fd_copy;
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sd_bus_message_read(m, "h", &fd);
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fd_copy = fcntl(fd, FD_DUPFD_CLOEXEC, 3);</programlisting>
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</refsect1>
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<refsect1>
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@ -52,17 +52,19 @@
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</para>
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<para>
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If <parameter>p</parameter> is not <constant>NULL</constant>, it should contain
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a pointer to an appropriate object. For example, if <parameter>type</parameter>
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is <constant>'y'</constant>, the object passed in <parameter>p</parameter>
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should have type <type>uint8_t *</type>. If <parameter>type</parameter> is
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<constant>'s'</constant>, the object passed in <parameter>p</parameter> should
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have type <type>const char **</type>. Note that, if the basic type is a pointer
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(e.g., <type>const char *</type> in the case of a string), the pointer is only
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borrowed and the contents must be copied if they are to be used after the end
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of the messages lifetime. Similarly, during the lifetime of such a pointer, the
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message must not be modified. See the table below for a complete list of allowed
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types.
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If <parameter>p</parameter> is not <constant>NULL</constant>, it should contain a pointer to an
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appropriate object. For example, if <parameter>type</parameter> is <constant>'y'</constant>, the object
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passed in <parameter>p</parameter> should have type <type>uint8_t *</type>. If
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<parameter>type</parameter> is <constant>'s'</constant>, the object passed in <parameter>p</parameter>
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should have type <type>const char **</type>. Note that, if the basic type is a pointer (e.g.,
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<type>const char *</type> in the case of a string), the pointer is only borrowed and the contents must
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be copied if they are to be used after the end of the messages lifetime. Similarly, during the lifetime
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of such a pointer, the message must not be modified. If <parameter>type</parameter> is
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<constant>'h'</constant> (UNIX file descriptor), the descriptor is not duplicated by this call and the
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returned descriptor remains in possession of the message object, and needs to be duplicated by the caller
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in order to keep an open reference to it after the message object is freed (for example by calling
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<literal>fcntl(fd, FD_DUPFD_CLOEXEC, 3)</literal>). See the table below for a complete list of
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allowed types.
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</para>
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<table id='format-specifiers'>
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