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 .