STRUCT XZ_BUF(9)

💖 struct xz_buf(9) 💖

okay bestie, so this is from the Kernel API Manual and honestly it's giving "the little struct that could" — it's literally just the carrier bag that XZ code uses to pass input and output buffers around. no cap.

✨ NAME ✨

struct xz_buf — passing input and output buffers to XZ code 🎀

🦋 SYNOPSIS 🦋

struct xz_buf {
    const uint8_t *in;
    size_t in_pos;
    size_t in_size;
    uint8_t *out;
    size_t out_pos;
    size_t out_size;
 };

like, look at her. six fields. iconic. 👑

🌸 Members 🌸

• in — the very beginning of the input buffer. she may be NULL if and only if in_pos is equal to in_size — that's the whole rule, no wiggle room, fr.
• in_pos — where we're currently at in the input buffer. must not exceed in_size. periodt.
• in_size — the size of the input buffer. that's it, that's the vibe check.
• out — beginning of the output buffer. this one may be NULL if and only if out_pos is equal to out_size. same energy as in, matching set 🫶.
• out_pos — current position in the output buffer. must not exceed out_size. don't test her.
• out_size — size of the output buffer. standard.

💅 Description 💅

okay so here's the thing that makes her special: the XZ code only ever touches the contents of the output buffer from out[out_pos] onward, and the variables in_pos and out_pos. that's it. everything else stays exactly where you left it. she's respectful like that 💜.

bestie pls note — the "may be NULL if and only if" thing on in and out is not a suggestion. it's an if-and-only-if. slay responsibly ✨.

🔥 SEE ALSO 🔥

kernel file ./include/linux/xz.h, and her whole friend group:

• enum xz_mode(9)
• enum xz_ret(9)
• xz_dec_init(9)
• xz_dec_run(9)
• xz_dec_reset(9)
• xz_dec_end(9)
• MicroLZMA decompressor(9)
• xz_dec_microlzma_alloc(9)
• xz_dec_microlzma_reset(9)
• xz_dec_microlzma_run(9)
• xz_dec_microlzma_end(9)

and that's the whole page, no notes 💖 shoutout to ./include/linux, dated October 2026 — keep her in your kernel and she'll keep your buffers in check. mwah 🎀🧚💫