LIBTRACEEVENT(3)

💖 libtraceevent — the pretty-girl guide to LIBTRACEEVENT(3) 💖

okay so bestie, welcome to the manual page for libtraceevent's field-getting era ✨ this is section 3 of the manual, and we're about to be so normal about retrieving field values, i promise 🎀

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✨ NAME ✨

tep_get_any_field_val, tep_get_common_field_val, tep_get_field_val, tep_get_field_raw — the girlies that go get you the value of a field 💅

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✨ SYNOPSIS ✨

#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);

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✨ DESCRIPTION ✨

so these four functions are literally your little search party 🕵️‍♀️ they go find a field and pull out its value, no cap.

tep_get_any_field_val() — she searches through the record for a field with name, part of the event. 👑 if the field is found, its value gets stored in val. and if something goes wrong and err is not zero, then an error string gets written into s. not me exposing the error like that 😭

tep_get_common_field_val() — does the exact same thing as tep_get_any_field_val(), but she only searches the common fields. and this lowkey works for literally any event, because every single event includes the common fields. it's giving universal access, periodt. 🌈

tep_get_field_val() — again, same energy as tep_get_any_field_val(), but she only searches the event specific fields. so niche of her, we stan. 🦋

tep_get_field_raw() — she searches the record for a field with name, part of the event. if the field is found, you get back a pointer to where that field actually lives inside the record's raw data 🔥. the size of the data gets stored in len. and again, if there's an error and err is not zero, an error string gets written into s 🤧

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✨ RETURN VALUE ✨

tep_get_any_field_val(), tep_get_common_field_val() and tep_get_field_val() return 0 on success 💚, or -1 in case of an error 💀.

tep_get_field_raw() returns a pointer to the field's raw data, and places the length of that data in len. in case of an error, NULL is returned 🙈

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✨ EXAMPLE ✨

bestie this is the whole vibe, look:

#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 */
                }
        }
}

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✨ FILES ✨

• event-parse.h — the header file you include to get access to the library APIs 💜
• trace-seq.h — the header file you include to get access to trace sequences related APIs. trace sequences are used to let a function call a bunch of other functions and cook up a string of data to use. chef's kiss 👩‍🍳
• -ltraceevent — the linker switch you add when you're building a program that uses the library 🔗

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✨ SEE ALSO ✨

libtraceevent(3), trace-cmd(1) — go read these too, i'm obsessed 🫶

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✨ AUTHOR ✨

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

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✨ REPORTING BUGS ✨

found something cursed?? report bugs to <linux-trace-devel@vger.kernel.org[3]> 📬

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✨ LICENSE ✨

libtraceevent is Free Software licensed under the GNU LGPL 2.1 ⚖️

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✨ RESOURCES ✨

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

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✨ 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

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~ and that's the whole page, bestie ~ this was libtraceevent 1.9.0, dated 06/15/2026, and you just read LIBTRACEEVENT(3) 💖✨🎀 slay, go get those field values, i'll be right here cheering 🦋💅