.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "POSIX_TRACE_CREATE" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" posix_trace_create 
.SH NAME
posix_trace_create, posix_trace_create_withlog, posix_trace_flush,
posix_trace_shutdown \- trace stream initialization,
flush, and shutdown from a process (\fBTRACING\fP)
.SH SYNOPSIS
.LP
\fB#include <sys/types.h>
.br
#include <trace.h>
.br
.sp
int posix_trace_create(pid_t\fP \fIpid\fP\fB,
.br
\ \ \ \ \ \  const trace_attr_t *restrict\fP \fIattr\fP\fB,
.br
\ \ \ \ \ \  trace_id_t *restrict\fP \fItrid\fP\fB);
.br
\fP
.LP
\fBint posix_trace_create_withlog(pid_t\fP \fIpid\fP\fB,
.br
\ \ \ \ \ \  const trace_attr_t *restrict\fP \fIattr\fP\fB, int\fP
\fIfile_desc\fP\fB,
.br
\ \ \ \ \ \  trace_id_t *restrict\fP \fItrid\fP\fB);
.br
int posix_trace_flush(trace_id_t\fP \fItrid\fP\fB);
.br
\fP
.LP
\fBint posix_trace_shutdown(trace_id_t\fP \fItrid\fP\fB); \fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
The \fIposix_trace_create\fP() 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 \fIpid\fP
in accordance with the \fIattr\fP argument. The \fIattr\fP
argument represents the initial attributes of the trace stream and
shall have been initialized by the function \fIposix_trace_attr_init\fP()
prior to the \fIposix_trace_create\fP() call. If the
argument \fIattr\fP is NULL, the default attributes shall be used.
The \fIattr\fP attributes object shall be manipulated through
a set of functions described in the \fIposix_trace_attr\fP family
of functions. If the attributes of the object pointed to by
\fIattr\fP are modified later, the attributes of the trace stream
shall not be affected. The \fIcreation-time\fP 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.
.LP
The \fIpid\fP 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 \fIpid\fP,
an error shall be returned. If the \fIpid\fP argument is
zero, the calling process shall be traced.
.LP
The \fIposix_trace_create\fP() function shall store the trace stream
identifier of the new trace stream in the object pointed
to by the \fItrid\fP argument. This trace stream identifier shall
be used in subsequent calls to control tracing. The \fItrid\fP
argument may only be used by the following functions:
.TS C
center; lw(39) lw(39).
T{
.br
\fIposix_trace_clear\fP()
.br
\fIposix_trace_eventid_equal\fP()
.br
\fIposix_trace_eventid_get_name\fP()
.br
\fIposix_trace_eventtypelist_getnext_id\fP()
.br
\fIposix_trace_eventtypelist_rewind\fP()
.br
\fIposix_trace_get_attr\fP()
.br
\fIposix_trace_get_status\fP()
.br
\ 
T}	T{
.br
\fIposix_trace_getnext_event\fP()
.br
\fIposix_trace_shutdown\fP()
.br
\fIposix_trace_start\fP()
.br
\fIposix_trace_stop\fP()
.br
\fIposix_trace_timedgetnext_event\fP()
.br
\fIposix_trace_trid_eventid_open\fP()
.br
\fIposix_trace_trygetnext_event\fP()
.br
\ 
T}
.TE
.LP
If the Trace Event Filter option is supported, the following additional
functions may use the \fItrid\fP argument:
.TS C
center; l2 l.
\fIposix_trace_get_filter\fP() \ 	\fIposix_trace_set_filter\fP() \ 
.TE
.LP
In particular, notice that the operations normally used by a trace
analyzer process, such as \fIposix_trace_rewind\fP() or \fIposix_trace_close\fP(),
cannot be invoked using the trace stream identifier returned
by the \fIposix_trace_create\fP() function.
.LP
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. 
.LP
The \fIposix_trace_create\fP() 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}.
.LP
The trace stream identifier returned by the \fIposix_trace_create\fP()
function in the argument pointed to by \fItrid\fP 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].
.LP
The \fIposix_trace_create_withlog\fP() function shall be equivalent
to \fIposix_trace_create\fP(), except that it associates a
trace log with this stream. The \fIfile_desc\fP 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.
.LP
The \fIposix_trace_create_withlog\fP() function shall return in the
parameter pointed to by \fItrid\fP the trace stream
identifier, which uniquely identifies the newly created trace stream,
and shall be used in subsequent calls to control tracing. The
\fItrid\fP argument may only be used by the following functions:
.TS C
center; lw(39) lw(39).
T{
.br
\fIposix_trace_clear\fP()
.br
\fIposix_trace_eventid_equal\fP()
.br
\fIposix_trace_eventid_get_name\fP()
.br
\fIposix_trace_eventtypelist_getnext_id\fP()
.br
\fIposix_trace_eventtypelist_rewind\fP()
.br
\fIposix_trace_flush\fP()
.br
\fIposix_trace_get_attr\fP()
.br
\fIposix_trace_get_status\fP()
.br
\ 
T}	T{
.br
\fIposix_trace_getnext_event\fP()
.br
\fIposix_trace_shutdown\fP()
.br
\fIposix_trace_start\fP()
.br
\fIposix_trace_stop\fP()
.br
\fIposix_trace_timedgetnext_event\fP()
.br
\fIposix_trace_trid_eventid_open\fP()
.br
\fIposix_trace_trygetnext_event\fP()
.br
\ 
T}
.TE
.LP
If the Trace Event Filter option is supported, the following additional
functions may use the \fItrid\fP argument:
.TS C
center; l2 l.
\fIposix_trace_get_filter\fP() \ 	\fIposix_trace_set_filter\fP() \ 
.TE
.LP
In particular, notice that the operations normally used by a trace
analyzer process, such as \fIposix_trace_rewind\fP() or \fIposix_trace_close\fP(),
cannot be invoked using the trace stream identifier returned
by the \fIposix_trace_create_withlog\fP() function.
.LP
The \fIposix_trace_flush\fP() function shall initiate a flush operation
which copies the contents of the trace stream
identified by the argument \fItrid\fP 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 \fItrid\fP,
this function shall return an error. The termination of the
flush operation can be polled by the \fIposix_trace_get_status\fP()
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 flushing is completed, the space used by the flushed trace
events shall be available for tracing new trace events.
.LP
If flushing the trace stream causes the resulting trace log to become
full, the trace log full policy shall be applied. If the
trace \fIlog-full-policy\fP attribute is set, the following occurs:
.TP 7
POSIX_TRACE_UNTIL_FULL
.sp
The trace events that have not yet been flushed shall be discarded.
.TP 7
POSIX_TRACE_LOOP
.sp
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.
.TP 7
POSIX_TRACE_APPEND
.sp
The trace events that have not yet been flushed shall be appended
to the trace log.
.sp
.LP
The \fIposix_trace_shutdown\fP() function shall stop the tracing of
trace events in the trace stream identified by \fItrid\fP,
as if \fIposix_trace_stop\fP() had been invoked. The
\fIposix_trace_shutdown\fP() function shall free all the resources
associated with the trace stream.
.LP
The \fIposix_trace_shutdown\fP() function shall not return until all
the resources associated with the trace stream have been
freed. When the \fIposix_trace_shutdown\fP() function returns, the
\fItrid\fP argument becomes an invalid trace stream
identifier. A call to this function shall unconditionally deallocate
the resources regardless of whether all trace events have been
retrieved by the analyzer process. Any thread blocked on one of the
\fItrace_getnext_event\fP() functions (which specified this
\fItrid\fP) before this call is unblocked with the error [EINVAL].
.LP
If the process exits, invokes a member of the \fIexec\fP 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 \fIposix_trace_shutdown\fP()
function.
.LP
For an active trace stream with log, when the \fIposix_trace_shutdown\fP()
function is called, all trace events that have not yet
been flushed to the trace log shall be flushed, as in the \fIposix_trace_flush\fP()
function, and the trace log shall be
closed.
.LP
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 status.
.LP
In addition, unspecified information shall be written to the trace
log to allow detection of a valid trace log during the \fIposix_trace_open\fP()
operation.
.LP
The \fIposix_trace_shutdown\fP() function shall not return until all
trace events have been flushed. 
.SH RETURN VALUE
.LP
Upon successful completion, these functions shall return a value of
zero. Otherwise, they shall return the corresponding error
number.
.LP
The \fIposix_trace_create\fP() and   \fIposix_trace_create_withlog\fP()
\ functions store the trace stream identifier value in the object
pointed to by \fItrid\fP, if
successful.
.SH ERRORS
.LP
The \fIposix_trace_create\fP() and   \fIposix_trace_create_withlog\fP()
\ functions shall fail if:
.TP 7
.B EAGAIN
No more trace streams can be started now. {TRACE_SYS_MAX} has been
exceeded.
.TP 7
.B EINTR
The operation was interrupted by a signal. No trace stream was created.
.TP 7
.B EINVAL
One or more of the trace parameters specified by the \fIattr\fP parameter
is invalid.
.TP 7
.B ENOMEM
The implementation does not currently have sufficient memory to create
the trace stream with the specified parameters.
.TP 7
.B EPERM
The caller does not have appropriate privilege to trace the process
specified by \fIpid\fP.
.TP 7
.B ESRCH
The \fIpid\fP argument does not refer to an existing process.
.sp
.LP
The \fIposix_trace_create_withlog\fP() function shall fail if:
.TP 7
.B EBADF
The \fIfile_desc\fP argument is not a valid file descriptor open for
writing.
.TP 7
.B EINVAL
The \fIfile_desc\fP argument refers to a file with a file type that
does not support the log policy associated with the trace
log.
.TP 7
.B ENOSPC
No space left on device. The device corresponding to the argument
\fIfile_desc\fP does not contain the space required to
create this trace log.
.sp
.LP
The   \fIposix_trace_flush\fP()  \ and
\fIposix_trace_shutdown\fP() functions shall fail if:
.TP 7
.B EINVAL
The value of the \fItrid\fP argument does not correspond to an active
trace stream with log.
.TP 7
.B EFBIG
The trace log file has attempted to exceed an implementation-defined
maximum file size.
.TP 7
.B ENOSPC
No space left on device.
.sp
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
None.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIclock_getres\fP() , \fIexec\fP() , \fIposix_trace_attr_init\fP()
, \fIposix_trace_clear\fP() , \fIposix_trace_close\fP() , \fIposix_trace_eventid_equal\fP()
, \fIposix_trace_eventtypelist_getnext_id\fP() , \fIposix_trace_flush\fP()
, \fIposix_trace_get_attr\fP() ,
\fIposix_trace_get_filter\fP() , \fIposix_trace_get_status\fP() ,
\fIposix_trace_getnext_event\fP() , \fIposix_trace_open\fP() , \fIposix_trace_set_filter\fP()
,
\fIposix_trace_shutdown\fP() , \fIposix_trace_start\fP() , \fIposix_trace_timedgetnext_event\fP()
, \fIposix_trace_trid_eventid_open\fP() , \fIposix_trace_start\fP()
, \fItime\fP() , the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<sys/types.h>\fP, \fI<trace.h>\fP
.SH 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 .