libtracefs(3)
=============

NAME
----
tracefs_get_tracing_file, tracefs_put_tracing_file, tracefs_tracing_dir, tracefs_debug_dir -
Find locations of trace directory and files.

SYNOPSIS
--------
[verse]
--
*#include <tracefs.h>*

char pass:[*]*tracefs_get_tracing_file*(const char pass:[*]_name_);
void *tracefs_put_tracing_file*(char pass:[*]_name_);
const char pass:[*]*tracefs_tracing_dir*(void);
const char pass:[*]*tracefs_debug_dir*(void);
--

DESCRIPTION
-----------
This set of APIs can be used to find the full path of the trace file
system mount point and trace files in it.

The *tracefs_get_tracing_file()* function returns the full path of the
file with given _name_ in the trace file system. The function works
only with files in the tracefs main directory, it is not trace instance
aware. It is recommended to use *tracefs_instance_get_file()* and
*tracefs_instance_get_dir()* instead. The returned string must be freed
with *tracefs_put_tracing_file()*.

The *tracefs_put_tracing_file()* function frees trace file name,
returned by *tracefs_get_tracing_file()*.

The *tracefs_tracing_dir()* function returns the full path to the
trace file system. In the first function call, the mount point of the
tracing file system is located, cached and returned. It will mount it,
if it is not mounted. On any subsequent call the cached path is returned.
The return string must _not_ be freed.

The *tracefs_debug_dir()* is similar to *tracefs_tracing_dir()* except
that it will return where the debugfs file system is mounted. If it
is not mounted it will try to mount it. The return string must _not_
be freed.

RETURN VALUE
------------
The *tracefs_get_tracing_file()* function returns a string or NULL in case
of an error. The returned string must be freed with *tracefs_put_tracing_file()*.

The *tracefs_tracing_dir()* function returns a constant string or NULL
in case of an error. The returned string must _not_ be freed.

The *tracefs_debug_dir()* function returns a constant string or NULL
in case of an error. The returned string must _not_ be freed.

EXAMPLE
-------
[source,c]
--
#include <tracefs.h>
...
char *trace_on = tracefs_get_tracing_file("tracing_on");
	if (trace_on) {
		...
		tracefs_put_tracing_file(trace_on);
	}
...
const char *trace_dir = tracefs_tracing_dir();

--
FILES
-----
[verse]
--
*tracefs.h*
	Header file to include in order to have access to the library APIs.
*-ltracefs*
	Linker switch to add when building a program that uses the library.
--

SEE ALSO
--------
*libtracefs*(3),
*libtraceevent*(3),
*trace-cmd*(1)

AUTHOR
------
[verse]
--
*Steven Rostedt* <rostedt@goodmis.org>
*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>
--
REPORTING BUGS
--------------
Report bugs to  <linux-trace-devel@vger.kernel.org>

LICENSE
-------
libtracefs is Free Software licensed under the GNU LGPL 2.1

RESOURCES
---------
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/

COPYING
-------
Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under
the terms of the GNU Public License (GPL).
