POSIX_TRACE_ATTR_GETINHERITED(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_attr_getinherited, posix_trace_attr_getlogfullpolicy, posix_trace_attr_getstreamfullpolicy, posix_trace_attr_setinherited, posix_trace_attr_setlogfullpolicy, posix_trace_attr_setstreamfullpolicy — retrieve and set the behavior of a trace stream (TRACING)

SYNOPSIS

#include <trace.h>

int posix_trace_attr_getinherited(const trace_attr_t *restrict attr,
    int *restrict inheritancepolicy);
int posix_trace_attr_getlogfullpolicy(const trace_attr_t *restrict attr,
    int *restrict logpolicy);
int posix_trace_attr_getstreamfullpolicy(const trace_attr_t *restrict
    attr, int *restrict streampolicy);
int posix_trace_attr_setinherited(trace_attr_t *attr,
    int inheritancepolicy);
int posix_trace_attr_setlogfullpolicy(trace_attr_t *attr,
    int logpolicy);
int posix_trace_attr_setstreamfullpolicy(trace_attr_t *attr,
    int streampolicy);

DESCRIPTION
The posix_trace_attr_getinherited() and posix_trace_attr_setinherited() functions, respectively, shall get and set the inheritance policy stored in the inheritance attribute for traced processes across the fork() and spawn() operations. The inheritance attribute of the attributes object pointed to by the attr argument shall be set to one of the following values defined by manifest constants in the <trace.h> header:

POSIX_TRACE_CLOSE_FOR_CHILD
    After a fork() or spawn() operation, the child shall not be traced, and tracing of the parent shall continue.

POSIX_TRACE_INHERITED
    After a fork() or spawn() operation, if the parent is being traced, its child shall be concurrently traced using the same trace stream.

The default value for the inheritance attribute is POSIX_TRACE_CLOSE_FOR_CHILD.

The posix_trace_attr_getlogfullpolicy() and posix_trace_attr_setlogfullpolicy() functions, respectively, shall get and set the trace log full policy stored in the log-full-policy attribute of the attributes object pointed to by the attr argument.

The log-full-policy attribute shall be set to one of the following values defined by manifest constants in the <trace.h> header:

POSIX_TRACE_LOOP
    The trace log shall loop until the associated trace stream is stopped. This policy means that when the trace log gets full, the file system shall reuse the resources allocated to the oldest trace events that were recorded. In this way, the trace log will always contain the most recent trace events flushed.

POSIX_TRACE_UNTIL_FULL
    The trace stream shall be flushed to the trace log until the trace log is full. This condition can be deduced from the posix_log_full_status member status (see the posix_trace_status_info structure defined in <trace.h>). The last recorded trace event shall be the POSIX_TRACE_STOP trace event.

POSIX_TRACE_APPEND
    The associated trace stream shall be flushed to the trace log without log size limitation. If the application specifies POSIX_TRACE_APPEND, the implementation shall ignore the log-max-size attribute.

The default value for the log-full-policy attribute is POSIX_TRACE_LOOP.

The posix_trace_attr_getstreamfullpolicy() and posix_trace_attr_setstreamfullpolicy() functions, respectively, shall get and set the trace stream full policy stored in the stream-full-policy attribute of the attributes object pointed to by the attr argument.

The stream-full-policy attribute shall be set to one of the following values defined by manifest constants in the <trace.h> header:

POSIX_TRACE_LOOP
    The trace stream shall loop until explicitly stopped by the posix_trace_stop() function. This policy means that when the trace stream is full, the trace system shall reuse the resources allocated to the oldest trace events recorded. In this way, the trace stream will always contain the most recent trace events recorded.

POSIX_TRACE_UNTIL_FULL
    The trace stream will run until the trace stream resources are exhausted. Then the trace stream will stop. This condition can be deduced from posix_stream_status and posix_stream_full_status (see the posix_trace_status_info structure defined in <trace.h>). When this trace stream is read, a POSIX_TRACE_STOP trace event shall be reported after reporting the last recorded trace event. The trace system shall reuse the resources allocated to any trace events already reported—see the posix_trace_getnext_event(), posix_trace_trygetnext_event(), and posix_trace_timedgetnext_event() functions—or already flushed for an active trace stream with log if the Trace Log option is supported; see the posix_trace_flush() function. The trace system shall restart the trace stream when it is empty and may restart it sooner. A POSIX_TRACE_START trace event shall be reported before reporting the next recorded trace event.

POSIX_TRACE_FLUSH
    If the Trace Log option is supported, this policy is identical to the POSIX_TRACE_UNTIL_FULL trace stream full policy except that the trace stream shall be flushed regularly as if posix_trace_flush() had been explicitly called. Defining this policy for an active trace stream without log shall be invalid.

The default value for the stream-full-policy attribute shall be POSIX_TRACE_LOOP for an active trace stream without log.

If the Trace Log option is supported, the default value for the stream-full-policy attribute shall be POSIX_TRACE_FLUSH for an active trace stream with log.

RETURN VALUE
Upon successful completion, these functions shall return a value of zero. Otherwise, they shall return the corresponding error number.

If successful, the posix_trace_attr_getinherited() function shall store the inheritance attribute value in the object pointed to by inheritancepolicy. Otherwise, the content of this object is undefined.

If successful, the posix_trace_attr_getlogfullpolicy() function shall store the log-full-policy attribute value in the object pointed to by logpolicy. Otherwise, the content of this object is undefined.

If successful, the posix_trace_attr_getstreamfullpolicy() function shall store the stream-full-policy attribute value in the object pointed to by streampolicy. Otherwise, the content of this object is undefined.

ERRORS
These functions may fail if:

EINVAL
    The value specified by at least one of the arguments is invalid.

The following sections are informative.

EXAMPLES
None.

APPLICATION USAGE
None.

RATIONALE
None.

FUTURE DIRECTIONS
The following functions:

    posix_trace_attr_getinherited()
    posix_trace_attr_getlogfullpolicy()
    posix_trace_attr_getstreamfullpolicy()
    posix_trace_attr_setinherited()
    posix_trace_attr_setlogfullpolicy()
    posix_trace_attr_setstreamfullpolicy()

may be removed in a future version.

SEE ALSO
fork(), posix_trace_attr_destroy(), posix_trace_create(), posix_trace_get_attr(), posix_trace_getnext_event(), posix_trace_start()

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 .