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https://github.com/systemd/systemd.git
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man: set constant tag to NUL or NULL
This commit is contained in:
parent
725d9713a9
commit
6b44ad0bf8
@ -433,7 +433,7 @@
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<listitem><para>The maximum line length to permit when converting stream logs into record logs. When a systemd
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unit's standard output/error are connected to the journal via a stream socket, the data read is split into
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individual log records at newline (<literal>\n</literal>, ASCII 10) and NUL characters. If no such delimiter is
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individual log records at newline (<literal>\n</literal>, ASCII 10) and <constant>NUL</constant> characters. If no such delimiter is
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read for the specified number of bytes a hard log record boundary is artificially inserted, breaking up overly
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long lines into multiple log records. Selecting overly large values increases the possible memory usage of the
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Journal daemon for each stream client, as in the worst case the journal daemon needs to buffer the specified
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@ -244,7 +244,7 @@
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<title>Session limits</title>
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<para>PAM modules earlier in the stack, that is those that come before <command>pam_systemd.so</command>,
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can set session scope limits using the PAM context objects. The data for these objects is provided as NUL-terminated C strings
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can set session scope limits using the PAM context objects. The data for these objects is provided as <constant>NUL</constant>-terminated C strings
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and maps directly to the respective unit resource control directives. Note that these limits apply to individual sessions of the user,
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they do not apply to all user processes as a combined whole. In particular, the per-user <command>user@.service</command> unit instance,
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which runs the <command>systemd --user</command> manager process and its children, and is tracked outside of any session, being shared
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@ -85,8 +85,8 @@
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<programlisting>#define SD_MESSAGE_COREDUMP SD_ID128_MAKE(fc,2e,22,bc,6e,e6,47,b6,b9,07,29,ab,34,a2,50,b1)</programlisting>
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<para><constant>SD_ID128_NULL</constant> may be used to refer to the 128bit ID consisting of only NUL
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bytes.</para>
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<para><constant>SD_ID128_NULL</constant> may be used to refer to the 128bit ID consisting of only
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<constant>NUL</constant> bytes.</para>
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<para><function>SD_ID128_MAKE_STR()</function> is similar to <function>SD_ID128_MAKE()</function>, but creates a
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<type>const char*</type> expression that can be conveniently used in message formats and such:</para>
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@ -136,7 +136,8 @@ int main(int argc, char **argv) {
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return 0;
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}</programlisting>
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<para>Use <function>sd_id128_is_null()</function> to check if an 128bit ID consists of only NUL bytes:</para>
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<para>Use <function>sd_id128_is_null()</function> to check if an 128bit ID consists of only
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<constant>NUL</constant> bytes:</para>
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<programlisting>int main(int argc, char *argv[]) {
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assert(sd_id128_is_null(SD_ID128_NULL));
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@ -439,14 +439,14 @@
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<para>All functions that take a <parameter>const
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char**</parameter> parameter will store the answer there as an
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address of a NUL-terminated string. It will be valid as long as
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address of a <constant>NUL</constant>-terminated string. It will be valid as long as
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<parameter>c</parameter> remains valid, and should not be freed or
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modified by the caller.</para>
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<para>All functions that take a <parameter>char***</parameter>
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parameter will store the answer there as an address of an array
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of strings. Each individual string is NUL-terminated, and the
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array is NULL-terminated as a whole. It will be valid as long as
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of strings. Each individual string is <constant>NUL</constant>-terminated, and the
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array is <constant>NULL</constant>-terminated as a whole. It will be valid as long as
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<parameter>c</parameter> remains valid, and should not be freed or
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modified by the caller.</para>
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</refsect1>
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@ -160,10 +160,10 @@
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but additional domain-specific errors may be defined by
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applications. The <structfield>message</structfield> field usually
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contains a human-readable string describing the details, but might
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be NULL. An unset <structname>sd_bus_error</structname> structure
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should have both fields initialized to NULL. Set an error
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be <constant>NULL</constant>. An unset <structname>sd_bus_error</structname> structure
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should have both fields initialized to <constant>NULL</constant>. Set an error
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structure to <constant>SD_BUS_ERROR_NULL</constant> in order to
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reset both fields to NULL. When no longer necessary, resources
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reset both fields to <constant>NULL</constant>. When no longer necessary, resources
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held by the <structname>sd_bus_error</structname> structure should
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be destroyed with <function>sd_bus_error_free()</function>.</para>
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@ -181,14 +181,14 @@
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for a list of well-known error names. Additional error mappings
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may be defined with
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<citerefentry><refentrytitle>sd_bus_error_add_map</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If
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<parameter>e</parameter> is NULL, no error structure is initialized,
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<parameter>e</parameter> is <constant>NULL</constant>, no error structure is initialized,
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but the error is still converted into an
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<varname>errno</varname>-style error. If
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<parameter>name</parameter> is <constant>NULL</constant>, it is
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assumed that no error occurred, and 0 is returned. This means that
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this function may be conveniently used in a
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<function>return</function> statement. If
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<parameter>message</parameter> is NULL, no message is set. This
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<parameter>message</parameter> is <constant>NULL</constant>, no message is set. This
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call can fail if no memory may be allocated for the name and
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message strings, in which case an
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<constant>SD_BUS_ERROR_NO_MEMORY</constant> error might be set
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@ -291,10 +291,10 @@
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will not be deallocated, and must be <citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>d
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by the caller if necessary. The function may also be called safely
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on unset errors (error structures with both fields set to NULL),
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on unset errors (error structures with both fields set to <constant>NULL</constant>),
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in which case it performs no operation. This call will reset the
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error structure after freeing the data, so that all fields are set
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to NULL. The structure may be reused afterwards.</para>
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to <constant>NULL</constant>. The structure may be reused afterwards.</para>
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</refsect1>
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<refsect1>
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@ -65,7 +65,7 @@
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<title>Return Value</title>
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<para>Those functions return 1 if the argument is a valid interface / service / member name or object
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path, and 0 if it is not. If the argument is NULL, an error is returned.</para>
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path, and 0 if it is not. If the argument is <constant>NULL</constant>, an error is returned.</para>
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<refsect2>
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<title>Errors</title>
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@ -118,7 +118,7 @@
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will be stored there. Each <literal>%</literal> character will
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only match the current label. It will never match across labels.
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Furthermore, only a single directive is allowed per label.
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If <literal>NULL</literal> is passed as output storage, the
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If <constant>NULL</constant> is passed as output storage, the
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label is verified but not returned to the caller.</para>
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</refsect1>
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@ -130,7 +130,7 @@
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argument. On success, <function>sd_bus_path_decode()</function>
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returns a positive value if the prefixed matched, or 0 if it
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did not. If the prefix matched, the external identifier is returned
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in the return parameter. If it did not match, NULL is returned in
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in the return parameter. If it did not match, <constant>NULL</constant> is returned in
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the return parameter. On failure, a negative errno-style error
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number is returned by either function. The returned strings must
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be
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@ -56,7 +56,7 @@
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<parameter>ret</parameter> is not <constant>NULL</constant> and the call processed a message,
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<parameter>*ret</parameter> is set to this message. The caller owns a reference to this message and should call
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<citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> when the
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message is no longer needed. If <parameter>ret</parameter> is not NULL, progress was made, but no message was
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message is no longer needed. If <parameter>ret</parameter> is not <constant>NULL</constant>, progress was made, but no message was
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processed, <parameter>*ret</parameter> is set to <constant>NULL</constant>.</para>
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<para>If a the bus object is connected to an
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@ -101,11 +101,11 @@
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<function>sd_bus_track_add_sender()</function>. They may be dropped again via
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<function>sd_bus_track_remove_name()</function> and
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<function>sd_bus_track_remove_sender()</function>. Alternatively, references on peers are removed automatically
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when they disconnect from the bus. If non-NULL the <parameter>handler</parameter> may specify a function that is
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invoked whenever the last reference is dropped, regardless whether the reference is dropped explicitly via
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<function>sd_bus_track_remove_name()</function> or implicitly because the peer disconnected from the bus. The final
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argument <parameter>userdata</parameter> may be used to attach a generic user data pointer to the object. This
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pointer is passed to the handler callback when it is invoked.</para>
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when they disconnect from the bus. If non-<constant>NULL</constant> the <parameter>handler</parameter> may specify
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a function that is invoked whenever the last reference is dropped, regardless whether the reference is dropped
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explicitly via <function>sd_bus_track_remove_name()</function> or implicitly because the peer disconnected from the
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bus. The final argument <parameter>userdata</parameter> may be used to attach a generic user data pointer to the
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object. This pointer is passed to the handler callback when it is invoked.</para>
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<para><function>sd_bus_track_ref()</function> creates a new reference to a bus peer tracking object. This object
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will not be destroyed until <function>sd_bus_track_unref()</function> has been called as many times plus once
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@ -51,7 +51,7 @@
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<para>On success, <function>sd_event_source_get_event()</function>
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returns the associated event loop object. On failure, it returns
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NULL.</para>
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<constant>NULL</constant>.</para>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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@ -52,7 +52,7 @@
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when the event source was created. The event source will be disabled
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if the callback function returns a negative error code. The callback
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function may be used to reconfigure the precise events to wait for.
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If the <parameter>callback</parameter> parameter is passed as NULL
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If the <parameter>callback</parameter> parameter is passed as <constant>NULL</constant>
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the callback function is reset. </para>
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<para>Event source objects have no preparation callback associated
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@ -70,7 +70,7 @@
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<function>sd_event_source_set_userdata()</function> and
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<function>sd_event_source_get_userdata()</function> return the
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previously set user data pointer. On failure, they return
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NULL.</para>
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<constant>NULL</constant>.</para>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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@ -56,7 +56,7 @@
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<para><function>sd_get_seats()</function> may be used to determine
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all currently available local seats. Returns the number of seat
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identifiers and if the input pointer is non-NULL, a
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identifiers and if the input pointer is non-<constant>NULL</constant>, a
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<constant>NULL</constant>-terminated array of seat identifiers
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is stored at the address.
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The returned array and all strings it references need to be freed
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@ -50,8 +50,9 @@
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<para><function>sd_id128_from_string()</function> implements the reverse operation: it takes a 33 character string
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with 32 hexadecimal digits (either lowercase or uppercase, terminated by <constant>NUL</constant>) and parses them
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back into a 128-bit ID returned in <parameter>ret</parameter>. Alternatively, this call can also parse a
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37-character string with a 128-bit ID formatted as RFC UUID. If <parameter>ret</parameter> is passed as NULL the
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function will validate the passed ID string, but not actually return it in parsed form.</para>
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37-character string with a 128-bit ID formatted as RFC UUID. If <parameter>ret</parameter> is passed as
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<constant>NULL</constant> the function will validate the passed ID string, but not actually return it in parsed
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form.</para>
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<para>For more information about the <literal>sd_id128_t</literal>
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type see
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<title>Return value</title>
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<para>Both <function>sd_journal_has_runtime_files()</function>
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and <function>sd_journal_has_persistent_files()</function> return -EINVAL
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if their argument is NULL.
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if their argument is <constant>NULL</constant>.
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</para>
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</refsect1>
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<function>sd_listen_fds()</function>, but optionally also returns
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an array of strings with identification names for the passed file
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descriptors, if that is available and the
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<parameter>names</parameter> parameter is non-NULL. This
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<parameter>names</parameter> parameter is non-<constant>NULL</constant>. This
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information is read from the <varname>$LISTEN_FDNAMES</varname>
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variable, which may contain a colon-separated list of names. For
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socket-activated services, these names may be configured with the
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@ -113,11 +113,11 @@
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<function>sd_is_socket()</function> and related calls is not
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sufficient. Note that the names used are not unique in any
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way. The returned array of strings has as many entries as file
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descriptors have been received, plus a final NULL pointer
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descriptors have been received, plus a final <constant>NULL</constant> pointer
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terminating the array. The caller needs to free the array itself
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and each of its elements with libc's <function>free()</function>
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call after use. If the <parameter>names</parameter> parameter is
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NULL, the call is entirely equivalent to
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<constant>NULL</constant>, the call is entirely equivalent to
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<function>sd_listen_fds()</function>.</para>
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<para>Under specific conditions, the following automatic file
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@ -161,9 +161,10 @@
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>An input parameter was invalid (out of range, or NULL, where that is not
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accepted). This is also returned if the passed user ID is <constant>0xFFFF</constant> or
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<constant>0xFFFFFFFF</constant>, which are undefined on Linux.</para></listitem>
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<listitem><para>An input parameter was invalid (out of range, or <constant>NULL</constant>,
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where that is not accepted). This is also returned if the passed user ID is
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<constant>0xFFFF</constant> or <constant>0xFFFFFFFF</constant>, which are undefined on Linux.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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@ -63,7 +63,7 @@
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<function>sd_watchdog_enabled()</function> will also return with
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zero.</para>
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<para>If the <parameter>usec</parameter> parameter is non-NULL,
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<para>If the <parameter>usec</parameter> parameter is non-<constant>NULL</constant>,
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<function>sd_watchdog_enabled()</function> will write the timeout
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in µs for the watchdog logic to it.</para>
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cached key will have a timeout of 2.5min set, after which it
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will be purged from the kernel keyring. Note that it is
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possible to cache multiple passwords under the same keyname,
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in which case they will be stored as NUL-separated list of
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in which case they will be stored as <constant>NUL</constant>-separated list of
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passwords. Use
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<citerefentry project='die-net'><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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to access the cached key via the kernel keyring
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user IDs, public key material and similar non-sensitive data. For everything else use
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<varname>LoadCredential=</varname>. In order to embed binary data into the credential data use
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C-style escaping (i.e. <literal>\n</literal> to embed a newline, or <literal>\x00</literal> to embed
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a NUL byte).</para>
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a <constant>NUL</constant> byte).</para>
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<para>If a credential of the same ID is listed in both <varname>LoadCredential=</varname> and
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<varname>SetCredential=</varname>, the latter will act as default if the former cannot be
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<para>Only applies to <literal>_TRANSPORT=stdout</literal> records: indicates that the log message
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in the standard output/error stream was not terminated with a normal newline character
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(<literal>\n</literal>, i.e. ASCII 10). Specifically, when set this field is one of
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<option>nul</option> (in case the line was terminated by a NUL byte), <option>line-max</option> (in
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<option>nul</option> (in case the line was terminated by a <constant>NUL</constant> byte), <option>line-max</option> (in
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case the maximum log line length was reached, as configured with <varname>LineMax=</varname> in
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
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<option>eof</option> (if this was the last log record of a stream and the stream ended without a
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<varlistentry>
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<term><varname>AdActorSystem=</varname></term>
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<listitem>
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<para>Specifies the 802.3ad system mac address. This can not be either NULL or Multicast.</para>
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<para>Specifies the 802.3ad system mac address. This can not be either
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<constant>NULL</constant> or <constant>Multicast</constant>.</para>
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</listitem>
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</varlistentry>
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@ -1944,7 +1944,7 @@ IPv6Token=prefixstable:2002:da8:1::</programlisting></para>
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<ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
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escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
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then all options specified earlier are cleared. Takes a whitespace-separated list of strings. Note that
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currently NUL bytes are not allowed.</para>
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currently <constant>NUL</constant> bytes are not allowed.</para>
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</listitem>
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</varlistentry>
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<title>String Escaping for Inclusion in Unit Names</title>
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<para>Sometimes it is useful to convert arbitrary strings into unit names. To facilitate this, a method of string
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escaping is used, in order to map strings containing arbitrary byte values (except NUL) into valid unit names and
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their restricted character set. A common special case are unit names that reflect paths to objects in the file
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system hierarchy. Example: a device unit <filename>dev-sda.device</filename> refers to a device with the device
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node <filename index="false">/dev/sda</filename> in the file system.</para>
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escaping is used, in order to map strings containing arbitrary byte values (except <constant>NUL</constant>) into
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valid unit names and their restricted character set. A common special case are unit names that reflect paths to
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objects in the file system hierarchy. Example: a device unit <filename>dev-sda.device</filename> refers to a device
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with the device node <filename index="false">/dev/sda</filename> in the file system.</para>
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<para>The escaping algorithm operates as follows: given a string, any <literal>/</literal> character is replaced by
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<literal>-</literal>, and all other characters which are not ASCII alphanumerics or <literal>_</literal> are
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