Man page - tep_record_print_fields(3)

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Manual

LIBTRACEEVENT

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

NAME

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

#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

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

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

#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

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

libtraceevent (3), trace-cmd (1)

AUTHOR

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

REPORTING BUGS

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

LICENSE

libtraceevent is Free Software licensed under the GNU LGPL 2.1

RESOURCES

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

NOTES

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