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POSIX_TRACE_EVENT(P)		    POSIX Programmer's Manual		     POSIX_TRACE_EVENT(P)

NAME
       posix_trace_event,  posix_trace_eventid_open  - trace functions for instrumenting applica-
       tion code (TRACING)

SYNOPSIS
       #include <sys/types.h>
       #include <trace.h>

       void posix_trace_event(trace_event_id_t event_id,
	      const void *restrictdata_ptr, size_t data_len);
       int posix_trace_eventid_open(const char *restrict event_name,
	      trace_event_id_t *restrict event_id);

DESCRIPTION
       The posix_trace_event() function shall record the event_id and the user data pointed to by
       data_ptr  in  the trace stream into which the calling process is being traced and in which
       event_id is not filtered out. If the total size of the user trace event	data  represented
       by  data_len is not greater than the declared maximum size for user trace event data, then
       the truncation-status attribute of the trace event recorded is  POSIX_TRACE_NOT_TRUNCATED.
       Otherwise,  the	user  trace event data is truncated to this declared maximum size and the
       truncation-status attribute of the trace event recorded is POSIX_TRACE_TRUNCATED_RECORD.

       If there is no trace stream created for the process or if the created trace stream is  not
       running,  or if the trace event specified by event_id is filtered out in the trace stream,
       the posix_trace_event() function shall have no effect.

       The posix_trace_eventid_open() function shall associate a user trace  event  name  with	a
       trace  event  type  identifier for the calling process. The trace event name is the string
       pointed to by the argument event_name. It shall have a maximum  of  {TRACE_EVENT_NAME_MAX}
       characters  (which  has	the  minimum value {_POSIX_TRACE_EVENT_NAME_MAX}).  The number of
       user trace event type identifiers that can be defined for any given process is limited  by
       the    maximum	 value	  {TRACE_USER_EVENT_MAX},    which    has   the   minimum   value
       {POSIX_TRACE_USER_EVENT_MAX}.

       If the Trace Inherit option is  not  supported,	the  posix_trace_eventid_open()  function
       shall  associate  the  user  trace event name pointed to by the event_name argument with a
       trace event type identifier that is unique for the traced process, and is returned in  the
       variable  pointed  to  by the event_id argument.  If the user trace event name has already
       been mapped for the traced process, then the previously assigned trace event type  identi-
       fier  shall  be	returned.  If  the per-process user trace event name limit represented by
       {TRACE_USER_EVENT_MAX} has been	reached,  the  pre-defined  POSIX_TRACE_UNNAMED_USEREVENT
       (see Trace Option: User Trace Event ) user trace event shall be returned.

       If  the	Trace  Inherit option is supported, the posix_trace_eventid_open() function shall
       associate the user trace event name pointed to by the event_name  argument  with  a  trace
       event type identifier that is unique for all the processes being traced in this same trace
       stream, and is returned in the variable pointed to by the event_id argument. If	the  user
       trace  event  name  has	already been mapped for the traced processes, then the previously
       assigned trace event type identifier shall be returned.	If  the  per-process  user  trace
       event  name  limit represented by {TRACE_USER_EVENT_MAX} has been reached, the pre-defined
       POSIX_TRACE_UNNAMED_USEREVENT ( Trace Option: User Trace Event ) user trace event shall be
       returned.

       Note:  The  above  procedure,  together	with the fact that multiple processes can only be
	      traced into the same trace stream by inheritance, ensure	that  all  the	processes
	      that  are  traced into a trace stream have the same mapping of trace event names to
	      trace event type identifiers.

       If there is no trace stream created, the posix_trace_eventid_open() function  shall  store
       this information for future trace streams created for this process.

RETURN VALUE
       No return value is defined for the posix_trace_event() function.

       Upon  successful  completion, the posix_trace_eventid_open() function shall return a value
       of zero. Otherwise, it shall return the corresponding error number. The	posix_trace_even-
       tid_open()  function stores the trace event type identifier value in the object pointed to
       by event_id, if successful.

ERRORS
       The posix_trace_eventid_open() function shall fail if:

       ENAMETOOLONG
	      The size of the name pointed to by the event_name  argument  was	longer	than  the
	      implementation-defined value {TRACE_EVENT_NAME_MAX}.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Trace  Option:  User Trace Event , posix_trace_start() , posix_trace_trid_eventid_open() ,
       the Base Definitions volume of IEEE Std 1003.1-2001, <sys/types.h>, <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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003			     POSIX_TRACE_EVENT(P)
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