# libtraceevent(3) Manual Page

## NAME

libtraceevent - Linux kernel trace event library

## SYNOPSIS

    #include <event-parse.h>

    Management of tep handler data structure and access of its members:
            struct tep_handle *tep_alloc(void);
            void tep_free(struct tep_handle *tep);
            void tep_ref(struct tep_handle *tep);
            void tep_unref(struct tep_handle *tep);
            int tep_get_ref(struct tep_handle *tep);
            void tep_set_flag(struct tep_handle *tep, enum tep_flag flag);
            void tep_clear_flag(struct tep_handle *tep, enum tep_flag flag);
            bool tep_test_flag(struct tep_handle *tep, enum tep_flag flags);
            int tep_get_cpus(struct tep_handle *tep);
            void tep_set_cpus(struct tep_handle *tep, int cpus);
            int tep_get_long_size(strucqt tep_handle *tep);
            void tep_set_long_size(struct tep_handle *tep, int long_size);
            int tep_get_page_size(struct tep_handle *tep);
            void tep_set_page_size(struct tep_handle *tep, int page_size);
            int tep_get_sub_buffer_size(struct tep_handle *tep);
            int tep_get_sub_buffer_data_size(struct tep_handle *tep);
            int tep_get_sub_buffer_commit_offset(struct tep_handle *tep);
            int tep_get_header_page_size(struct tep_handle *tep);
            int tep_get_header_timestamp_size(struct tep_handle *tep);
            bool tep_is_old_format(struct tep_handle *tep);
            int tep_strerror(struct tep_handle *tep, enum tep_errno errnum, char *buf, size_t buflen);
            struct kbuffer *tep_kbuffer(struct tep_handle *tep);

    Register / unregister APIs:
            int tep_register_function(struct tep_handle *tep, char *name, unsigned long long addr, char *mod);
            int tep_register_event_handler(struct tep_handle *tep, int id, const char *sys_name, const char *event_name, tep_event_handler_func func, void *context);
            int tep_unregister_event_handler(struct tep_handle *tep, int id, const char *sys_name, const char *event_name, tep_event_handler_func func, void *context);
            int tep_register_print_string(struct tep_handle *tep, const char *fmt, unsigned long long addr);
            int tep_register_print_function(struct tep_handle *tep, tep_func_handler func, enum tep_func_arg_type ret_type, char *name, …);
            int tep_unregister_print_function(struct tep_handle *tep, tep_func_handler func, char *name);
            int tep_get_function_count(struct tep_handle tep);

    Trace printk parsing:
            void *tep_print_printk(struct tep_handle *tep);
            void tep_print_funcs(struct tep_handle *tep);
            void tep_set_test_filters(struct tep_handle *tep, int test_filters);
            void tep_plugin_print_options(struct trace_seq *s);
            int tep_plugin_add_option(const char *name, const char *val);

    Meta data parsing:
            int tep_parse_saved_cmdlines(struct tep_handle *tep, const char *buf);
            int tep_parse_printk_formats(struct tep_handle *tep, const char *buf);
            int tep_parse_kallsyms(struct tep_handle *tep, const char *buf);

    Plugins management:
            struct tep_plugin_list *tep_load_plugins(struct tep_handle *tep);
            void tep_unload_plugins(struct tep_plugin_list *plugin_list, struct tep_handle *tep);
            char **tep_plugin_list_options(void);
            void tep_plugin_free_options_list(char **list);
            int tep_plugin_add_options(const char *name, struct tep_plugin_option *options);
            void tep_plugin_remove_options(struct tep_plugin_option *options);
            void tep_print_plugins(struct trace_seq *s, const char *prefix, const char *suffix, const struct tep_plugin_list *list);
            void tep_load_plugins_hook(struct tep_handle *tep, const char *suffix,
                               void (*load_plugin)(struct tep_handle *tep,
                                                   const char *path,
                                                   const char *name,
                                                   void *data),
                               void *data);
            int tep_add_plugin_path(struct tep_handle *tep, char *path,
                              enum tep_plugin_load_priority prio);

    Event related APIs:
            struct tep_event *tep_get_event(struct tep_handle *tep, int index);
            struct tep_event *tep_get_first_event(struct tep_handle *tep);
            int tep_get_events_count(struct tep_handle *tep);
            struct tep_event **tep_list_events(struct tep_handle *tep, enum tep_event_sort_type sort_type);
            struct tep_event **tep_list_events_copy(struct tep_handle *tep, enum tep_event_sort_type sort_type);
            void tep_print_event(struct tep_handle *tep, struct trace_seq *s, struct tep_record *record, const char *fmt, …);

    Event finding:
            struct tep_event *tep_find_event(struct tep_handle *tep, int id);
            struct tep_event *tep_find_event_by_name(struct tep_handle *tep, const char *sys, const char *name);
            struct tep_event *tep_find_event_by_record(struct tep_handle *tep, struct tep_record *record);
            bool tep_record_is_event(struct tep_record *record, struct tep_event *event);

    Parsing of event files:
            int tep_parse_header_page(struct tep_handle *tep, char *buf, unsigned long size, int long_size);
            enum tep_errno tep_parse_event(struct tep_handle *tep, const char *buf, unsigned long size, const char *sys);
            enum tep_errno tep_parse_format(struct tep_handle *tep, struct tep_event **eventp, const char *buf, unsigned long size, const char *sys);

    APIs related to fields from event’s format files:
            struct tep_format_field **tep_event_common_fields(struct tep_event *event);
            struct tep_format_field **tep_event_fields(struct tep_event *event);
            void *tep_get_field_raw(struct trace_seq *s, struct tep_event *event, const char *name, struct tep_record *record, int *len, int err);
            int tep_get_field_val(struct trace_seq *s, struct tep_event *event, const char *name, struct tep_record *record, unsigned long long *val, int err);
            int tep_get_common_field_val(struct trace_seq *s, struct tep_event *event, const char *name, struct tep_record *record, unsigned long long *val, int err);
            int tep_get_any_field_val(struct trace_seq *s, struct tep_event *event, const char *name, struct tep_record *record, unsigned long long *val, int err);
            int tep_read_number_field(struct tep_format_field *field, const void *data, unsigned long long *value);

    Event fields printing:
            void tep_print_field_content(struct trace_seq *s, void *data, int size, struct tep_format_field *field);
            void tep_print_fields(struct trace_seq *s, void *data, int size, struct tep_event *event);
            int tep_print_num_field(struct trace_seq *s, const char *fmt, struct tep_event *event, const char *name, struct tep_record *record, int err);
            int tep_print_func_field(struct trace_seq *s, const char *fmt, struct tep_event *event, const char *name, struct tep_record *record, int err);
            void tep_record_print_fields(struct trace_seq *s, struct tep_record *record, struct tep_event *event);
            void tep_record_print_selected_fields(struct trace_seq *s, struct tep_record *record, struct tep_event *event, int select_mask);

    Event fields finding:
            struct tep_format_field *tep_find_common_field(struct tep_event *event, const char *name);
            struct tep_format_field *tep_find_field(struct tep_event_ormat *event, const char *name);
            struct tep_format_field *tep_find_any_field(struct tep_event *event, const char *name);

    Functions resolver:
            int tep_set_function_resolver(struct tep_handle *tep, tep_func_resolver_t *func, void *priv);
            void tep_reset_function_resolver(struct tep_handle *tep);
            const char *tep_find_function(struct tep_handle *tep, unsigned long long addr);
            unsigned long long tep_find_function_address(struct tep_handle *tep, unsigned long long addr);
            int tep_find_function_info(struct tep_handle *tep, unsigned long long addr, const char **name,
                               unsigned long long *start, unsigned long *size);

    Filter management:
            struct tep_event_filter *tep_filter_alloc(struct tep_handle *tep);
            enum tep_errno tep_filter_add_filter_str(struct tep_event_filter *filter, const char *filter_str);
            enum tep_errno tep_filter_match(struct tep_event_filter *filter, struct tep_record *record);
            int tep_filter_strerror(struct tep_event_filter *filter, enum tep_errno err, char *buf, size_t buflen);
            int tep_event_filtered(struct tep_event_filter *filter, int event_id);
            void tep_filter_reset(struct tep_event_filter *filter);
            void tep_filter_free(struct tep_event_filter *filter);
            char *tep_filter_make_string(struct tep_event_filter *filter, int event_id);
            int tep_filter_remove_event(struct tep_event_filter *filter, int event_id);
            int tep_filter_copy(struct tep_event_filter *dest, struct tep_event_filter *source);
            int tep_filter_compare(struct tep_event_filter *filter1, struct tep_event_filter *filter2);

    Parsing various data from the records:
            int tep_data_type(struct tep_handle *tep, struct tep_record *rec);
            int tep_data_pid(struct tep_handle *tep, struct tep_record *rec);
            int tep_data_preempt_count(struct tep_handle *tep, struct tep_record *rec);
            int tep_data_flags(struct tep_handle *tep, struct tep_record *rec);

    Command and task related APIs:
            const char *tep_data_comm_from_pid(struct tep_handle *tep, int pid);
            struct cmdline *tep_data_pid_from_comm(struct tep_handle *tep, const char *comm, struct cmdline *next);
            int tep_register_comm(struct tep_handle *tep, const char *comm, int pid);
            int tep_override_comm(struct tep_handle *tep, const char *comm, int pid);
            bool tep_is_pid_registered(struct tep_handle *tep, int pid);
            int tep_cmdline_pid(struct tep_handle *tep, struct cmdline *cmdline);

    Endian related APIs:
            int tep_is_bigendian(void);
            unsigned long long tep_read_number(struct tep_handle *tep, const void *ptr, int size);
            bool tep_is_file_bigendian(struct tep_handle *tep);
            void tep_set_file_bigendian(struct tep_handle *tep, enum tep_endian endian);
            bool tep_is_local_bigendian(struct tep_handle *tep);
            void tep_set_local_bigendian(struct tep_handle *tep, enum tep_endian endian);

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

    KVM plugin calllbacks: (Defined by the application and complied with -rdynamic)
            const char *tep_plugin_kvm_get_func(struct tep_event *event,
                                        struct tep_record *record,
                                        unsigned long long *paddr);
            void tep_plugin_kvm_put_func(const char *func);

    Trace sequences:
    #include <trace-seq.h>
            void trace_seq_init(struct trace_seq *s);
            void trace_seq_reset(struct trace_seq *s);
            void trace_seq_destroy(struct trace_seq *s);
            int trace_seq_printf(struct trace_seq *s, const char *fmt, …);
            int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
            int trace_seq_puts(struct trace_seq *s, const char *str);
            int trace_seq_putc(struct trace_seq *s, unsigned char c);
            void trace_seq_terminate(struct trace_seq *s);
            int trace_seq_do_fprintf(struct trace_seq *s, FILE *fp);
            int trace_seq_do_printf(struct trace_seq *s);

    kbuffer parsing:
    #include <kbuffer.h>
            struct kbuffer *kbuffer_alloc(enum kbuffer_long_size size, enum kbuffer_endian endian);
            struct kbuffer *kbuffer_dup(struct kbuffer *kbuf);
            void kbuffer_free(struct kbuffer *kbuf);
            int kbuffer_load_subbuffer(struct kbuffer *kbuf, void *subbuffer);
            int kbuffer_subbuffer_size(struct kbuffer *kbuf);
            void *kbuffer_subbuffer(struct kbuffer *_kbuf);
            int kbuffer_refresh(struct kbuffer *_kbuf);
            int kbuffer_start_of_data(struct kbuffer *kbuf);
            unsigned long long kbuffer_timestamp(struct kbuffer *kbuf);
            unsigned long long kbuffer_subbuf_timestamp(struct kbuffer *kbuf, void *subbuf);
            void *kbuffer_read_event(struct kbuffer *kbuf, unsigned long long *ts);
            void *kbuffer_next_event(struct kbuffer *kbuf, unsigned long long *ts);
            void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset, unsigned long long *ts);
            int kbuffer_missed_events(struct kbuffer *kbuf);
            int kbuffer_event_size(struct kbuffer *kbuf);
            int kbuffer_curr_size(struct kbuffer *kbuf);
            int kbuffer_curr_offset(struct kbuffer *kbuf);
            int kbuffer_curr_index(struct kbuffer *kbuf);
            int kbuffer_read_buffer(struct kbuffer *kbuf, void *buffer, int start, int len);

## DESCRIPTION

The libtraceevent(3) library provides APIs to access kernel tracepoint events, located in the tracefs file system under the events directory.

## ENVIRONMENT

    TRACEEVENT_PLUGIN_DIR
            Additional plugin directory. All shared object files, located in this directory will be loaded as traceevent plugins.

## FILES

    event-parse.h
            Header file to include in order to have access to the library APIs.
    trace-seq.h
            Header file to include in order to have access to trace sequences related APIs.
            Trace sequences are used to allow a function to call several other functions
            to create a string of data to use.
    -ltraceevent
            Linker switch to add when building a program that uses the library.

## SEE ALSO

trace-cmd(1)

## AUTHOR

    Steven Rostedt <rostedt@goodmis.org>, author of libtraceevent.
    Tzvetomir Stoyanov <tz.stoyanov@gmail.com>, author of this man page.

## REPORTING BUGS

Report bugs to <linux-trace-devel@vger.kernel.org>

## LICENSE

libtraceevent is Free Software licensed under the GNU LGPL 2.1

## RESOURCES

https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/