libtracefs(3)

# libtracefs(3) Manual Page

## NAME

libtracefs - Linux kernel trace file system library

## SYNOPSIS

    #include <tracefs.h>

    Locations of tracing files and directories:
            char *tracefs_get_tracing_file(const char *name);
            void tracefs_put_tracing_file(char *name);
            const char *tracefs_tracing_dir(void);

    Trace instances:
            struct tracefs_instance *tracefs_instance_create(const char *name);
            int tracefs_instance_destroy(struct tracefs_instance *instance);
            void tracefs_instance_free(struct tracefs_instance *instance);
            bool tracefs_instance_is_new(struct tracefs_instance *instance);
            bool tracefs_file_exists(struct tracefs_instance *instance, char *name);
            bool tracefs_dir_exists(struct tracefs_instance *instance, char *name);
            char *tracefs_instance_get_file(struct tracefs_instance *instance, const char *file);
            char *tracefs_instance_get_dir(struct tracefs_instance *instance);
            int tracefs_instance_file_open(struct tracefs_instance *instance, const char *file, int mode);
            int tracefs_instance_file_write(struct tracefs_instance *instance, const char *file, const char *str);
            char *tracefs_instance_file_read(struct tracefs_instance *instance, const char *file, int *psize);
            int tracefs_instance_file_read_number(struct tracefs_instance *instance, const char *file, long long int *res);
            const char *tracefs_instance_get_name(struct tracefs_instance *instance);
            int tracefs_instances_walk(int (*callback)(const char *, void *), void *context);
            bool tracefs_instance_exists(const char *name);

    Trace events:
            char **tracefs_event_systems(const char *tracing_dir);
            char **tracefs_system_events(const char *tracing_dir, const char *system);
            int tracefs_iterate_raw_events(struct tep_handle *tep, struct tracefs_instance *instance, cpu_set_t *cpus, int cpu_size, int (*callback)(struct tep_event *, struct tep_record *, int, void *), void *callback_context);
            struct tep_handle *tracefs_local_events(const char *tracing_dir);
            struct tep_handle *tracefs_local_events_system(const char *tracing_dir, const char * const *sys_names);
            int tracefs_fill_local_events(const char *tracing_dir, struct tep_handle *tep, int *parsing_failures);

    Trace helper functions:
            void tracefs_list_free(char **list);
            char **tracefs_tracers(const char *tracing_dir);
            char *tracefs_get_clock(struct tracefs_instance *instance);
            int tracefs_trace_is_on(struct tracefs_instance *instance);
            int tracefs_trace_on(struct tracefs_instance *instance);
            int tracefs_trace_off(struct tracefs_instance *instance);
            int tracefs_trace_on_get_fd(struct tracefs_instance *instance);
            int tracefs_trace_on_fd(int fd);
            int tracefs_trace_off_fd(int fd);

    Writing data in the trace buffer:
            int tracefs_print_init(struct tracefs_instance *instance);
            int tracefs_printf(struct tracefs_instance *instance, const char *fmt, …);
            int tracefs_vprintf(struct tracefs_instance *instance, const char *fmt, va_list ap);
            void tracefs_print_close(struct tracefs_instance *instance);
            int tracefs_binary_init(struct tracefs_instance *instance);
            int tracefs_binary_write(struct tracefs_instance *instance, void *data, int len);
            void tracefs_binary_close(struct tracefs_instance *instance);

    Control library logs:
            int tracefs_set_loglevel(enum tep_loglevel level);

## DESCRIPTION

The libtracefs(3) library provides APIs to access kernel trace file system.

## FILES

    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

libtraceevent(3) trace-cmd(1)

## AUTHOR

    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).