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+libtracefs(3)
+=============
+
+NAME
+----
+tracefs_file_exists, tracefs_dir_exists,
+tracefs_instance_get_file, tracefs_instance_get_dir - Work with files directories in tracing instances.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <tracefs.h>*
+
+bool *tracefs_file_exists*(struct tracefs_instance pass:[*]_instance_, char pass:[*]_name_);
+bool *tracefs_dir_exists*(struct tracefs_instance pass:[*]_instance_, char pass:[*]_name_);
+char pass:[*]*tracefs_instance_get_file*(struct tracefs_instance pass:[*]_instance_, const char pass:[*]_file_);
+char pass:[*]*tracefs_instance_get_dir*(struct tracefs_instance pass:[*]_instance_);
+
+--
+
+DESCRIPTION
+-----------
+This set of APIs can be used to work with trace files in all trace instances.
+Each of these APIs take an _instance_ argument, that can be NULL to act
+on the top level instance. Otherwise, it acts on an instance created with
+*tracefs_insance_create*(3)
+
+The *tracefs_file_exists()* function checks if a file with _name_ exists in _instance_.
+
+The *tracefs_dir_exists()* function checks if a directory with _name_ exists in _instance_.
+
+The *tracefs_instance_get_file()* function returns the full path of the file
+with given _name_ in _instance_. Note, it does not check if the file exists in
+the instance.
+
+The *tracefs_instance_get_dir()* function returns the full path of the directory
+with given _name_ in _instance_. Note, it does not check if the directory exists
+in the instance.
+
+RETURN VALUE
+------------
+The *tracefs_file_exists()* and *tracefs_dir_exists()* functions return true if the
+file / directory exist in the given instance or false if it does not exist.
+
+The *tracefs_instance_get_file()* and *tracefs_instance_get_dir()* functions return
+a string or NULL in case of an error. The returned string must be freed with
+*tracefs_put_tracing_file()*.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <tracefs.h>
+
+struct tracefs_instance *inst = tracefs_instance_create("foo");
+ if (!inst) {
+ /* Error creating a new trace instance */
+ ...
+ }
+
+ if (tracefs_file_exists(inst,"trace_clock")) {
+ /* The instance foo supports trace clock */
+ char *path, *clock;
+ int size;
+
+ path = = tracefs_instance_get_file(inst, "trace_clock")
+ if (!path) {
+ /* Error getting the path to trace_clock file in instance foo */
+ ...
+ }
+ ...
+ tracefs_put_tracing_file(path);
+
+ clock = tracefs_instance_file_read(inst, "trace_clock", &size);
+ if (!clock) {
+ /* Failed to read trace_clock file in instance foo */
+ ...
+ }
+ ...
+ free(clock);
+
+ if (tracefs_instance_file_write(inst, "trace_clock", "global") != strlen("global")) {
+ /* Failed to set gloabl trace clock in instance foo */
+ ...
+ }
+ } else {
+ /* The instance foo does not support trace clock */
+ }
+
+ if (tracefs_dir_exists(inst,"options")) {
+ /* The instance foo supports trace options */
+ char *path = tracefs_instance_get_file(inst, "options");
+ if (!path) {
+ /* Error getting the path to options directory in instance foo */
+ ...
+ }
+
+ tracefs_put_tracing_file(path);
+ } else {
+ /* The instance foo does not support trace options */
+ }
+
+ ...
+
+ if (tracefs_instance_is_new(inst))
+ tracefs_instance_destroy(inst);
+ else
+ tracefs_instance_free(inst);
+ ...
+
+ long long int res;
+ if (tracefs_instance_file_read_number(NULL, "tracing_on", &res) == 0) {
+ if (res == 0) {
+ /* tracing is disabled in the top instance */
+ } else if (res == 1) {
+ /* tracing is enabled in the top instance */
+ } else {
+ /* Unknown tracing state of the top instance */
+ }
+ } else {
+ /* Failed to read integer from tracing_on file */
+ }
+
+ ...
+
+ int fd;
+ fd = tracefs_instance_file_open(NULL, "tracing_on", O_WRONLY);
+ if (fd >= 0) {
+ /* Got file descriptor to the tracing_on file from the top instance for writing */
+ ...
+ close(fd);
+ }
+--
+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).