int posix_trace_get_filter(trace_id_t trid, trace_event_set_t
int posix_trace_set_filter(trace_id_t trid,
const trace_event_set_t *set, int how);
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:
The resulting set of trace event types to be filtered shall be the trace event type set pointed to by the argument set.
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.
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.
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.
These functions shall fail if:
The following sections are informative.
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>