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, 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(P)