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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | COPYING | NOTES | COLOPHON |
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LIBTRACEFS(3) libtracefs Manual LIBTRACEFS(3)
tracefs_tracers, tracefs_tracer_available, tracefs_get_clock,
tracefs_list_free, tracefs_list_add, tracefs_list_size - Helper
functions for working with trace file system.
#include <tracefs.h>
char **tracefs_tracers(const char *tracing_dir);
bool tracefs_tracer_available(const char *tracing_dir, const char *tracer);
char *tracefs_get_clock(struct tracefs_instance *instance);
void tracefs_list_free(char **list);
char **tracefs_list_add(char *list, const char *string);
int *tracefs_list_size(char **list);
Various useful functions for working with trace file system.
The tracefs_tracers() function returns array of strings with the
names of supported tracer plugins, located in the given
tracing_dir directory. This could be NULL or the location of the
tracefs mount point for the trace systems of the local machine,
or it may be a path to a copy of the tracefs directory from
another machine. The last entry in the array as a NULL pointer.
The array must be freed with tracefs_list_free() API.
The tracefs_tracer_available() returns true if the tracer is
available in the given tracing_dir_director, and false otherwise.
The tracefs_get_clock() function returns name of the current
trace clock, used in the given instance. If instance is NULL, the
clock of the main trace instance is returned. The returned string
must be freed with free().
The tracefs_list_free() function frees an array of strings,
returned by tracefs_event_systems(), tracefs_system_events() and
tracefs_tracers() APIs.
The tracefs_list_add() function adds string to the string list.
If list is NULL, then a new list is created with the first
element a copy of string, and the second element will be a NULL
pointer. If list is not NULL, then it is reallocated to include a
new element and a NULL terminator, and the new allocated array is
returned. The list passed in should be ignored, as it wil be
freed if a new one was allocated.
The tracefs_list_size() is a fast way to find out the number of
elements in a string array that is to be freed with
tracefs_list_free(). Note, this depends on meta data that is
created for these lists and will not work on normal string arrays
like argv.
The tracefs_tracers() returns array of strings. The last element
in that array is a NULL pointer. The array must be freed with
tracefs_list_free() API. In case of an error, NULL is returned.
The tracefs_tracer_available() returns true if the tracer is
available, and false otherwise.
The tracefs_get_clock() returns string, that must be freed with
free(), or NULL in case of an error.
The tracefs_list_add() returns an allocated string array that
must be freed with tracefs_list_free() on success or NULL on
error. If NULL is returned, then the passed in list is untouched.
Thus, tracefs_list_add() should be treated similarly to
realloc(3).
The tracefs_list_size() returns the number of strings in the
list. The passed in list must be one that is to be freed with
tracefs_list_free() as the list has meta data that is used to
determine the size and this does not work on any normal string
array like argv.
#include <tracefs.h>
char **tracers = tracefs_tracers(NULL);
if (tracers) {
/* Got tracer plugins from the top trace instance */
...
tracefs_list_free(tracers);
}
....
char *clock = tracefs_get_clock(NULL);
if (clock) {
/* Got current trace clock of the top trace instance */
...
free(clock);
}
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.
libtracefs(3), libtraceevent(3), trace-cmd(1)
Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
libtracefs is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Copyright (C) 2020 VMware, Inc. Free use of this software is
granted under the terms of the GNU Public License (GPL).
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
This page is part of the libtracefs (Linux kernel trace file
system library) project. Information about the project can be
found at ⟨https://www.trace-cmd.org/⟩. If you have a bug report
for this manual page, see ⟨https://www.trace-cmd.org/⟩. This
page was obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git⟩ on
2023-12-22. (At that time, the date of the most recent commit
that was found in the repository was 2023-07-05.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
libtracefs 1.7.0 12/22/2023 LIBTRACEFS(3)
Pages that refer to this page: tracefs_instance_create(3)
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HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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