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libtracecmd(3)
=============
NAME
----
tracecmd_buffer_instances, tracecmd_buffer_instance_name, tracecmd_buffer_instance_handle
- Read tracing instances from a trace file.
SYNOPSIS
--------
[verse]
--
*#include <trace-cmd.h>*
int *tracecmd_buffer_instances*(struct tracecmd_input pass:[*]_handle_);
const char pass:[*]*tracecmd_buffer_instance_name*(struct tracecmd_input pass:[*]_handle_, int _indx_);
struct tracecmd_input pass:[*]*tracecmd_buffer_instance_handle*(struct tracecmd_input pass:[*]_handle_, int _indx_);
--
DESCRIPTION
-----------
This set of APIs can be used to get information and read tracing data
from tracing instances stored in a trace file.
The *tracecmd_buffer_instances()* function gets the number of tracing
instances recorded in a trace file. The top instance is not counted.
The _handle_ is a tracecmd_input handler returned by
*tracecmd_open_head()*.
The *tracecmd_buffer_instance_name()* function gets the name of the
tracing instance with given index _indx_, recorded in a trace file.
The _indx_ is a number in the interval [0 .. count-1], where count
is the number returned by *tracecmd_buffer_instances()*. The _handle_
is a tracecmd_input handler returned by *tracecmd_open_head()*.
The *tracecmd_buffer_instance_handle()* allocates and initializes a
tracecmd_input handle, associated with trace instance with index
_indx_ from a trace file. The _handle_ is a tracecmd_input handler
returned by *tracecmd_open_head()*. The _indx_ is a number in the
interval [0 .. count-1], where count is the number returned by
*tracecmd_buffer_instances()*.
RETURN VALUE
------------
The *tracecmd_buffer_instances()* function returns the number of tracing
instances recorded in a trace file.
The *tracecmd_buffer_instance_name()* function returns a string, the name
of a tracing instance, or NULL in case of an error The string must *not*
be freed.
The *tracecmd_buffer_instance_handle()* function returns a pointer to
newly allocated tracecmd_input handler or NULL in case if an error. The
returned handler must be closed by *tracecmd_close()(3)*
EXAMPLE
-------
[source,c]
--
#include <trace-cmd.h>
...
struct tracecmd_input *handle = tracecmd_open_head("trace.dat");
if (!handle) {
/* Failed to open trace.dat file */
}
...
int num = tracecmd_buffer_instances(handle);
while(num) {
struct tracecmd_input *h;
char *name;
name = tracecmd_buffer_instance_name(handle, num);
if (!name) {
/* Failed to get name of instance num */
}
h = tracecmd_buffer_instance_handle(handle, num);
if (!h) {
/* Failed to initialize handler for instance num */
}
...
tracecmd_close(h);
num--;
}
...
tracecmd_close(handle);
--
FILES
-----
[verse]
--
*trace-cmd.h*
Header file to include in order to have access to the library APIs.
*-ltracecmd*
Linker switch to add when building a program that uses the library.
--
SEE ALSO
--------
*libtracefs(3)*,
*libtraceevent(3)*,
*trace-cmd(1)*
*trace-cmd.dat(5)*
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
-------
libtracecmd is Free Software licensed under the GNU LGPL 2.1
RESOURCES
---------
https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git/
COPYING
-------
Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under
the terms of the GNU Public License (GPL).
|
