tep_print_field_content(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | NOTES | COLOPHON

LIBTRACEEVENT(3)          libtraceevent Manual          LIBTRACEEVENT(3)

NAME         top

       tep_print_field_content, tep_print_fields, tep_print_num_field,
       tep_print_func_field, tep_record_print_fields,
       tep_record_print_selected_fields - Print the field content.

SYNOPSIS         top

       #include <event-parse.h>
       #include <trace-seq.h>

       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);

DESCRIPTION         top

       These functions print recorded field’s data, according to the
       field’s type.

       The tep_print_field_content() function extracts from the recorded
       raw data value of the field and prints it into s, according to
       the field type.

       The tep_print_fields() prints each field name followed by the
       record’s field value according to the field’s type:

           "field1_name=field1_value field2_name=field2_value ..."

       It iterates all fields of the event, and calls
       tep_print_field_content() for each of them.

       The tep_print_num_field() function prints a numeric field with
       given format string. A search is performed in the event for a
       field with name. If such field is found, its value is extracted
       from the record and is printed in the s, according to the given
       format string fmt. If the argument err is non-zero, and an error
       occures - it is printed in the s.

       The tep_print_func_field() function prints a function field with
       given format string. A search is performed in the event for a
       field with name. If such field is found, its value is extracted
       from the record. The value is assumed to be a function address,
       and a search is perform to find the name of this function. The
       function name (if found) and its address are printed in the s,
       according to the given format string fmt. If the argument err is
       non-zero, and an error occures - it is printed in s.

       The tep_record_print_fields() prints the field’s name followed by
       its value for all record’s field.

       The tep_record_print_selected_fields() prints the field’s name
       followed by its value for selected subset of record field. The
       fields to be printed are defined by the select_mask bit mask.

RETURN VALUE         top

       The tep_print_num_field() and tep_print_func_field() functions
       return 1 on success, -1 in case of an error or 0 if the print
       buffer s is full.

EXAMPLE         top

           #include <event-parse.h>
           #include <trace-seq.h>
           ...
           struct tep_handle *tep = tep_alloc();
           ...
           struct trace_seq seq;
           trace_seq_init(&seq);
           struct tep_event *event = tep_find_event_by_name(tep, "timer", "hrtimer_start");
           ...
           void process_record(struct tep_record *record)
           {
                   struct tep_format_field *field_pid = tep_find_common_field(event, "common_pid");

                   trace_seq_reset(&seq);

                   /* Print the value of "common_pid" */
                   tep_print_field_content(&seq, record->data, record->size, field_pid);

                   /* Print all fields of the "hrtimer_start" event */
                   tep_print_fields(&seq, record->data, record->size, event);

                   /* Print the value of "expires" field with custom format string */
                   tep_print_num_field(&seq, " timer expires in %llu ", event, "expires", record, 0);

                   /* Print the address and the name of "function" field with custom format string */
                   tep_print_func_field(&seq, " timer function is %s ", event, "function", record, 0);
            }
            ...

FILES         top

           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         top

       libtraceevent(3), trace-cmd(1)

AUTHOR         top

           Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
           Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.

REPORTING BUGS         top

       Report bugs to <linux-trace-devel@vger.kernel.org[3]>

LICENSE         top

       libtraceevent is Free Software licensed under the GNU LGPL 2.1

RESOURCES         top

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

NOTES         top

        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

COLOPHON         top

       This page is part of the libtraceevent (Linux kernel trace event
       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/libtraceevent.git⟩
       on 2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-05-17.)  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

libtraceevent 1.7.3            09/24/2023               LIBTRACEEVENT(3)