LIBTRACEFS(3)

💅 LIBTRACEFS(3) — the libtracefs manual, bestie edition ✨

okay so this is the libtracefs manual page, and today we're talking about the binary-writing girlies 🎀 (and yes, the manual name is literally libtracefs in case you were wondering 💖)

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✨ NAME ✨

tracefs_binary_init, tracefs_binary_close, tracefs_binary_write — the trio that opens, closes, and writes binary data into the trace buffer. no cap, that's the whole vibe. 🦋

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🌸 SYNOPSIS 🌸

#include <tracefs.h>

int tracefs_binary_init(struct tracefs_instance *instance);
int tracefs_binary_write(struct tracefs_instance *instance, void *data, int len);
void tracefs_binary_close(struct tracefs_instance *instance);

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💜 DESCRIPTION 💜

so this is a little set of functions that write binary data into the trace buffer. if you want the deep lore, go read Documentation/trace/ftrace.rst from the Linux kernel tree — that's where all the writing-from-user-space-into-the-trace-buffer info lives. 📖

all of these APIs take instance as their first argument. and if you pass NULL as instance? the top trace instance gets used. easy. 😌

• tracefs_binary_init() — initializes the library for writing into the trace buffer of whichever instance you picked. and listen — it is not mandatory to call this before writing data, because tracefs_binary_write() will call it automatically if the library isn't initialized yet. but calling tracefs_binary_init() in advance will speed up the writing. so like… technically optional, but iconically efficient. 🔥
• tracefs_binary_write() — writes a binary blob into the trace buffer of the selected instance. data points to the data, and its length is len — that's what's going into the trace buffer. 💫
• tracefs_binary_close() — closes the resources the library used for writing into the trace buffer of the selected instance. cleanup era, we love to see it. 🧹✨

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⭐ RETURN VALUE ⭐

tracefs_binary_init() and tracefs_binary_write() both return 0 if the operation is successful, or -1 if something went wrong. that's it, that's the check. 💀

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🦋 EXAMPLE 🦋

#include <tracefs.h>

if (tracefs_binary_init(NULL) < 0) {
 /* Failed to initialize the library for writing in the trace buffer of the top trace instance */
}

unsigned int data = 0xdeadbeef;

        if (tracefs_binary_write(NULL, &data, sizeof(data)) < 0) {
                /* Failed to write in the trace buffer */
        }

tracefs_binary_close();

she's writing 0xdeadbeef and closing up shop. main character energy honestly. 👑

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🎀 FILES 🎀

• tracefs.h — the header file you include to get access to the library APIs. manifesting those declarations for you. 🙏
• -ltracefs — the linker switch you add when building a program that uses the library. don't forget her, fr fr. 💅

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🌈 SEE ALSO 🌈

libtracefs(3), libtraceevent(3), trace-cmd(1), and Documentation/trace/ftrace.rst from the Linux kernel tree — the whole friend group 🫶

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💖 AUTHOR 💖

• Steven Rostedt <rostedt@goodmis.org[1]>
• Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>

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🙈 REPORTING BUGS 🙈

found a bug? report it to <linux-trace-devel@vger.kernel.org[3]> — they wanna know, bestie. 😭

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👑 LICENSE 👑

libtracefs is Free Software licensed under the GNU LGPL 2.1 💜

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🔥 RESOURCES 🔥

https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ — go look, it's giving open source excellence ✨

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🌸 COPYING 🌸

Copyright (C) 2021 VMware, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).

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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 libtracefs version 1.8.4, dated 10/21/2026 — write it down, screenshot it, put it in the group chat, whatever you gotta do. love u, go write some binary data into that trace buffer 💅✨🫶