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POSIX_TRACE_CREATE(3P)     POSIX Programmer's Manual    POSIX_TRACE_CREATE(3P)

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_create,   posix_trace_create_withlog,    posix_trace_flush,
       posix_trace_shutdown - trace stream initialization, flush, and shutdown
       from a process (TRACING)
SYNOPSIS
       #include <sys/types.h>
       #include <trace.h>
       int posix_trace_create(pid_t pid,
              const trace_attr_t *restrict attr,
              trace_id_t *restrict trid);

       int posix_trace_create_withlog(pid_t pid,
              const trace_attr_t *restrict attr, int file_desc,
              trace_id_t *restrict trid);
       int posix_trace_flush(trace_id_t trid);

       int posix_trace_shutdown(trace_id_t trid);

DESCRIPTION
       The posix_trace_create() function shall create an active trace  stream.
       It allocates all the resources needed by the trace stream being created
       for tracing the process specified by pid in accordance  with  the  attr
       argument.  The  attr  argument represents the initial attributes of the
       trace  stream  and  shall  have  been  initialized  by   the   function
       posix_trace_attr_init()  prior to the posix_trace_create() call. If the
       argument attr is NULL, the default attributes shall be used.  The  attr
       attributes  object  shall  be  manipulated  through  a set of functions
       described  in  the  posix_trace_attr  family  of  functions.   If   the
       attributes  of  the  object  pointed to by attr are modified later, the
       attributes of the trace stream shall not be affected. The creation-time
       attribute  of  the newly created trace stream shall be set to the value
       of the system clock, if the Timers option is not supported, or  to  the
       value of the CLOCK_REALTIME clock, if the Timers option is supported.
       The  pid  argument  represents the target process to be traced.  If the
       process executing this function does not have appropriate privileges to
       trace the process identified by pid, an error shall be returned. If the
       pid argument is zero, the calling process shall be traced.
       The posix_trace_create() function shall store the trace stream  identi-
       fier of the new trace stream in the object pointed to by the trid argu-
       ment. This trace stream identifier shall be used in subsequent calls to
       control  tracing.  The  trid argument may only be used by the following
       functions:



  posix_trace_clear()                       posix_trace_getnext_event()
  posix_trace_eventid_equal()               posix_trace_shutdown()
  posix_trace_eventid_get_name()            posix_trace_start()
  posix_trace_eventtypelist_getnext_id()    posix_trace_stop()
  posix_trace_eventtypelist_rewind()        posix_trace_timedgetnext_event()
  posix_trace_get_attr()                    posix_trace_trid_eventid_open()
  posix_trace_get_status()                  posix_trace_trygetnext_event()

       If the Trace Event Filter option is supported, the following additional
       functions may use the trid argument:
               posix_trace_get_filter()    posix_trace_set_filter()
       In particular, notice that the operations normally used by a trace ana-
       lyzer process, such  as  posix_trace_rewind()  or  posix_trace_close(),
       cannot  be  invoked  using  the trace stream identifier returned by the
       posix_trace_create() function.
       A trace stream shall be created in a suspended  state.   If  the  Trace
       Event  Filter option is supported, its trace event type filter shall be
       empty.
       The posix_trace_create() function may be called multiple times from the
       same  or  different  processes, with the system-wide limit indicated by
       the runtime invariant value  {TRACE_SYS_MAX},  which  has  the  minimum
       value {_POSIX_TRACE_SYS_MAX}.
       The  trace stream identifier returned by the posix_trace_create() func-
       tion in the argument pointed to by trid is valid only  in  the  process
       that  made  the function call. If it is used from another process, that
       is a child process, in functions defined in IEEE Std 1003.1-2001, these
       functions shall return with the error [EINVAL].
       The   posix_trace_create_withlog()  function  shall  be  equivalent  to
       posix_trace_create(), except that it associates a trace log  with  this
       stream. The file_desc argument shall be the file descriptor designating
       the trace log  destination.  The  function  shall  fail  if  this  file
       descriptor  refers  to  a  file with a file type that is not compatible
       with the log policy associated with the trace  log.  The  list  of  the
       appropriate  file  types  that  are  compatible with each log policy is
       implementation-defined.
       The posix_trace_create_withlog() function shall return in the parameter
       pointed  to by trid the trace stream identifier, which uniquely identi-
       fies the newly created trace stream, and shall be  used  in  subsequent
       calls  to  control  tracing.  The trid argument may only be used by the
       following functions:
  posix_trace_clear()                       posix_trace_getnext_event()
  posix_trace_eventid_equal()               posix_trace_shutdown()
  posix_trace_eventid_get_name()            posix_trace_start()
  posix_trace_eventtypelist_getnext_id()    posix_trace_stop()
  posix_trace_eventtypelist_rewind()        posix_trace_timedgetnext_event()
  posix_trace_flush()                       posix_trace_trid_eventid_open()
  posix_trace_get_attr()                    posix_trace_trygetnext_event()
  posix_trace_get_status()

       If the Trace Event Filter option is supported, the following additional
       functions may use the trid argument:
               posix_trace_get_filter()    posix_trace_set_filter()
       In particular, notice that the operations normally used by a trace ana-
       lyzer process, such  as  posix_trace_rewind()  or  posix_trace_close(),
       cannot  be  invoked  using  the trace stream identifier returned by the
       posix_trace_create_withlog() function.
       The posix_trace_flush() function shall initiate a flush operation which
       copies the contents of the trace stream identified by the argument trid
       into the trace log associated with the trace  stream  at  the  creation
       time. If no trace log has been associated with the trace stream pointed
       to by trid, this function shall return an error. The termination of the
       flush operation can be polled by the posix_trace_get_status() function.
       During the flush operation, it shall be possible  to  trace  new  trace
       events up to the point when the trace stream becomes full. After flush-
       ing is completed, the space used by the flushed trace events  shall  be
       available for tracing new trace events.
       If  flushing  the trace stream causes the resulting trace log to become
       full, the trace log full policy shall be applied.  If  the  trace  log-
       full-policy attribute is set, the following occurs:
       POSIX_TRACE_UNTIL_FULL
              The  trace  events  that have not yet been flushed shall be dis-
              carded.
       POSIX_TRACE_LOOP
              The trace events that have not yet been flushed shall be written
              to  the  beginning  of the trace log, overwriting previous trace
              events stored there.
       POSIX_TRACE_APPEND
              The trace events  that  have  not  yet  been  flushed  shall  be
              appended to the trace log.

       The  posix_trace_shutdown()  function  shall  stop the tracing of trace
       events in the trace stream identified by trid, as if posix_trace_stop()
       had  been  invoked.  The posix_trace_shutdown() function shall free all
       the resources associated with the trace stream.
       The posix_trace_shutdown() function shall  not  return  until  all  the
       resources  associated  with  the trace stream have been freed. When the
       posix_trace_shutdown() function returns, the trid argument  becomes  an
       invalid trace stream identifier. A call to this function shall uncondi-
       tionally deallocate the  resources  regardless  of  whether  all  trace
       events  have been retrieved by the analyzer process. Any thread blocked
       on one of the trace_getnext_event()  functions  (which  specified  this
       trid) before this call is unblocked with the error [EINVAL].
       If the process exits, invokes a member of the exec family of functions,
       or is terminated, the trace streams that the process  had  created  and
       that  have  not yet been shut down, shall be automatically shut down as
       if an explicit call were made to the posix_trace_shutdown() function.
       For an active trace stream with log,  when  the  posix_trace_shutdown()
       function  is called, all trace events that have not yet been flushed to
       the trace log shall be flushed, as in the posix_trace_flush() function,
       and the trace log shall be closed.
       When  a  trace log is closed, all the information that may be retrieved
       later from the trace log through the trace interface  shall  have  been
       written   to  the  trace  log.  This  information  includes  the  trace
       attributes, the list of trace event types  (with  the  mapping  between
       trace event names and trace event type identifiers), and the trace sta-
       tus.
       In addition, unspecified information shall be written to the trace  log
       to  allow  detection of a valid trace log during the posix_trace_open()
       operation.
       The posix_trace_shutdown() function shall not return  until  all  trace
       events have been flushed.
RETURN VALUE
       Upon  successful  completion,  these  functions shall return a value of
       zero. Otherwise, they shall return the corresponding error number.
       The posix_trace_create() and   posix_trace_create_withlog()   functions
       store  the  trace  stream  identifier value in the object pointed to by
       trid, if successful.
ERRORS
       The posix_trace_create() and   posix_trace_create_withlog()   functions
       shall fail if:
       EAGAIN No  more  trace  streams can be started now. {TRACE_SYS_MAX} has
              been exceeded.
       EINTR  The operation was interrupted by a signal. No trace  stream  was
              created.
       EINVAL One or more of the trace parameters specified by the attr param-
              eter is invalid.
       ENOMEM The implementation does not currently have sufficient memory  to
              create the trace stream with the specified parameters.
       EPERM  The  caller  does  not  have  appropriate privilege to trace the
              process specified by pid.
       ESRCH  The pid argument does not refer to an existing process.

       The posix_trace_create_withlog() function shall fail if:
       EBADF  The file_desc argument is not a valid file descriptor  open  for
              writing.
       EINVAL The  file_desc  argument  refers to a file with a file type that
              does not support the log policy associated with the trace log.
       ENOSPC No space left on device. The device corresponding to  the  argu-
              ment  file_desc  does  not  contain the space required to create
              this trace log.

       The   posix_trace_flush() and  posix_trace_shutdown()  functions  shall
       fail if:
       EINVAL The  value of the trid argument does not correspond to an active
              trace stream with log.
       EFBIG  The trace log file has attempted to  exceed  an  implementation-
              defined maximum file size.
       ENOSPC No space left on device.

       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       clock_getres(),  exec(),  posix_trace_attr_init(), posix_trace_clear(),
       posix_trace_close(),  posix_trace_eventid_equal(),   posix_trace_event-
       typelist_getnext_id(),   posix_trace_flush(),   posix_trace_get_attr(),
       posix_trace_get_filter(),  posix_trace_get_status(),   posix_trace_get-
       next_event(),     posix_trace_open(),     posix_trace_set_filter()    ,
       posix_trace_shutdown(),   posix_trace_start(),    posix_trace_timedget-
       next_event(),   posix_trace_trid_eventid_open(),   posix_trace_start(),
       time(),  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 original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003               POSIX_TRACE_CREATE(3P)