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 (consult the correspond-
       ing 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 argu-
       ment 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 Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (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.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003						POSIX_TRACE_GET_FILTER(3P)