PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult 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 Table 2-4, Trace and Trace Event Filter Options:
       System Trace Events and Table 2-6, 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

       The  posix_trace_get_filter()  and  posix_trace_set_filter() functions may be removed in a
       future version.

SEE ALSO

       Table 2-4, Trace and Trace Event Filter Options: System Trace Events, Table 2-6, Trace,
       Trace Log, and Trace Event Filter Options: System Trace Events, posix_trace_eventset_add()

       The Base Definitions volume of POSIX.1‐2017, <trace.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .