LIBTRACECMD(3) libtracefs Manual LIBTRACECMD(3)
NAME
tracecmd_buffer_instances, tracecmd_buffer_instance_name,
tracecmd_buffer_instance_handle - Read tracing instances from a trace
file.
SYNOPSIS
#include <trace-cmd.h>
int tracecmd_buffer_instances(struct tracecmd_input *handle);
const char *tracecmd_buffer_instance_name(struct tracecmd_input *handle, int indx);
struct tracecmd_input *tracecmd_buffer_instance_handle(struct tracecmd_input *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
#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
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
Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
REPORTING BUGS
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
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).
NOTES
1. rostedt@goodmis.org
mailto:rostedt@goodmis.org
2. tz.stoyanov@gmail.com
mailto:tz.stoyanov@gmail.com
3. linux-trace-devel@vger.kernel.org
mailto:linux-trace-devel@vger.kernel.org
libtracefs 04/08/2024 LIBTRACECMD(3)
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