123 lines
4.0 KiB
Plaintext
123 lines
4.0 KiB
Plaintext
libtraceevent(3)
|
|
================
|
|
|
|
NAME
|
|
----
|
|
tep_get_any_field_val, tep_get_common_field_val, tep_get_field_val,
|
|
tep_get_field_raw - Get value of a field.
|
|
|
|
SYNOPSIS
|
|
--------
|
|
[verse]
|
|
--
|
|
*#include <event-parse.h>*
|
|
*#include <trace-seq.h>*
|
|
|
|
int *tep_get_any_field_val*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, unsigned long long pass:[*]_val_, int _err_);
|
|
int *tep_get_common_field_val*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, unsigned long long pass:[*]_val_, int _err_);
|
|
int *tep_get_field_val*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, unsigned long long pass:[*]_val_, int _err_);
|
|
void pass:[*]*tep_get_field_raw*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int pass:[*]_len_, int _err_);
|
|
--
|
|
|
|
DESCRIPTION
|
|
-----------
|
|
These functions can be used to find a field and retrieve its value.
|
|
|
|
The _tep_get_any_field_val()_ function searches in the _record_ for a field
|
|
with _name_, part of the _event_. If the field is found, its value is stored in
|
|
_val_. If there is an error and _err_ is not zero, then an error string is
|
|
written into _s_.
|
|
|
|
The _tep_get_common_field_val()_ function does the same as
|
|
_tep_get_any_field_val()_, but searches only in the common fields. This works
|
|
for any event as all events include the common fields.
|
|
|
|
The _tep_get_field_val()_ function does the same as _tep_get_any_field_val()_,
|
|
but searches only in the event specific fields.
|
|
|
|
The _tep_get_field_raw()_ function searches in the _record_ for a field with
|
|
_name_, part of the _event_. If the field is found, a pointer to where the field
|
|
exists in the record's raw data is returned. The size of the data is stored in
|
|
_len_. If there is an error and _err_ is not zero, then an error string is
|
|
written into _s_.
|
|
|
|
RETURN VALUE
|
|
------------
|
|
The _tep_get_any_field_val()_, _tep_get_common_field_val()_ and
|
|
_tep_get_field_val()_ functions return 0 on success, or -1 in case of an error.
|
|
|
|
The _tep_get_field_raw()_ function returns a pointer to field's raw data, and
|
|
places the length of this data in _len_. In case of an error NULL is returned.
|
|
|
|
EXAMPLE
|
|
-------
|
|
[source,c]
|
|
--
|
|
#include <event-parse.h>
|
|
#include <trace-seq.h>
|
|
...
|
|
struct tep_handle *tep = tep_alloc();
|
|
...
|
|
struct tep_event *event = tep_find_event_by_name(tep, "kvm", "kvm_exit");
|
|
...
|
|
void process_record(struct tep_record *record)
|
|
{
|
|
int len;
|
|
char *comm;
|
|
struct tep_event_format *event;
|
|
unsigned long long val;
|
|
|
|
event = tep_find_event_by_record(pevent, record);
|
|
if (event != NULL) {
|
|
if (tep_get_common_field_val(NULL, event, "common_type",
|
|
record, &val, 0) == 0) {
|
|
/* Got the value of common type field */
|
|
}
|
|
if (tep_get_field_val(NULL, event, "pid", record, &val, 0) == 0) {
|
|
/* Got the value of pid specific field */
|
|
}
|
|
comm = tep_get_field_raw(NULL, event, "comm", record, &len, 0);
|
|
if (comm != NULL) {
|
|
/* Got a pointer to the comm event specific field */
|
|
}
|
|
}
|
|
}
|
|
--
|
|
|
|
FILES
|
|
-----
|
|
[verse]
|
|
--
|
|
*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
|
|
------
|
|
[verse]
|
|
--
|
|
*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/linux/kernel/git/torvalds/linux.git
|