tep_get_any_field_val, tep_get_common_field_val, tep_get_field_val, tep_get_field_raw - Get value of a

StevenRostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
           TzvetomirStoyanov <tz.stoyanov@gmail.com[2]>, author of this man page.

       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.

           #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 is Free Software licensed under the GNU LGPL 2.1

       tep_get_any_field_val, tep_get_common_field_val, tep_get_field_val, tep_get_field_raw - Get value of a
       field.

        1. rostedt@goodmis.orgmailto:rostedt@goodmis.org

        2. tz.stoyanov@gmail.commailto:tz.stoyanov@gmail.com

        3. linux-trace-devel@vger.kernel.orgmailto:linux-trace-devel@vger.kernel.org

libtraceevent 1.8.4                                12/24/2024                                   LIBTRACEEVENT(3)

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

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

       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.

libtraceevent(3), trace-cmd(1)

#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);