POSIX_TRACE_GET_FILTER(3P)                          POSIX Programmer's Manual                         POSIX_TRACE_GET_FILTER(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       posix_trace_get_filter, posix_trace_set_filter - retrieve and set the filter of an initialized trace stream (TRACING)

SYNOPSIS
       #include <trace.h>

       int posix_trace_get_filter(trace_id_t trid, trace_event_set_t *set);
       int posix_trace_set_filter(trace_id_t trid,
              const trace_event_set_t *set, int how);


DESCRIPTION
       The  posix_trace_get_filter() function shall retrieve, into the argument pointed to by set, the actual trace event filter
       from the trace stream specified by trid.

       The posix_trace_set_filter() function shall change the set of filtered trace event types after a trace stream  identified
       by  the  trid  argument  is  created.  This function may be called prior to starting the trace stream, or while the trace
       stream is active. By default, if no call is made to posix_trace_set_filter(), all trace events shall  be  recorded  (that
       is, none of the trace event types are filtered out).

       If  this  function  is  called while the trace is in progress, a special system trace event, POSIX_TRACE_FILTER, shall be
       recorded in the trace indicating both the old and the new sets of filtered trace event types (see Trace and  Trace  Event
       Filter Options: System Trace Events and Trace, Trace Log, and Trace Event Filter Options: System Trace Events ).

       If  the posix_trace_set_filter() function is interrupted by a signal, an error shall be returned and the filter shall not
       be changed. In this case, the state of the trace stream shall not be changed.

       The value of the argument how indicates the manner in which the set is to be changed and shall have one of the  following
       values, as defined in the <trace.h> header:

       POSIX_TRACE_SET_EVENTSET

              The resulting set of trace event types to be filtered shall be the trace event type set pointed to by the argument
              set.

       POSIX_TRACE_ADD_EVENTSET

              The resulting set of trace event types to be filtered shall be the union of the current set and  the  trace  event
              type set pointed to by the argument set.

       POSIX_TRACE_SUB_EVENTSET

              The  resulting  set of trace event types to be filtered shall be all trace event types in the current set that are
              not in the set pointed to by the argument set; that is, remove each element of the specified set from the  current
              filter.


RETURN VALUE
       Upon  successful completion, these functions shall return a value of zero. Otherwise, they shall return the corresponding
       error number.

       The posix_trace_get_filter() function stores the set of filtered trace event types in set, if successful.

ERRORS
       These functions shall fail if:

       EINVAL The value of the trid argument does not correspond to an active trace stream or the value of the argument  pointed
              to by set is invalid.

       EINTR  The operation was interrupted by a signal.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Trace and Trace Event Filter Options: System Trace Events, Trace, Trace Log, and Trace Event Filter Options: System Trace
       Events, posix_trace_eventset_add(), the Base Definitions volume of IEEE Std 1003.1-2001, <trace.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                    POSIX_TRACE_GET_FILTER(3P)