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 .