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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | NOTES | COLOPHON |
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LIBTRACEEVENT(3) libtraceevent Manual LIBTRACEEVENT(3)
tep_get_any_field_val, tep_get_common_field_val,
tep_get_field_val, tep_get_field_raw - Get value of a field.
#include <event-parse.h>
#include <trace-seq.h>
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_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_field_val(struct trace_seq *s, struct tep_event *event, const char *name, struct tep_record *record, unsigned long long *val, int err);
void *tep_get_field_raw(struct trace_seq *s, struct tep_event *event, const char *name, struct tep_record *record, int *len, int err);
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.
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.
#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 *event;
unsigned long long val;
event = tep_find_event_by_record(tep, 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 */
}
}
}
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.
libtraceevent(3), trace-cmd(1)
Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
libtraceevent is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
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
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 2023-12-22. (At that time, the date of the most recent commit
that was found in the repository was 2023-06-07.) 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)
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HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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