xcb_shm_attach(3)

📦
version 1.17.0 · 5 versions
, in alpine 3.22, alpine 3.23, alpine 3.24, arch rolling, centos-stream 10, debian trixie, fedora 43, fedora 44, nixpkgs unstable, opensuse-leap 16.0, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 xcb_shm_attach — the xcb_shm_attach(3) page, but make it make sense

okay bestie, so this is a page from the XCB Requests corner of the libxcb universe, and today we're attaching System V shared memory segments. yes really. it's giving very "low-level but make it fashion" 💅

✨ NAME ✨

xcb_shm_attach — attach a System V shared memory segment. that's it, that's the whole job 🫶

🌸 SYNOPSIS 🌸

first things first, you gotta let the compiler know what's up:

#include <xcb/shm.h>

🎀 Request function 🎀

xcb_void_cookie_t xcb_shm_attach(xcb_connection_t *conn,
       xcb_shm_seg_t shmseg, uint32_t shmid, uint8_t read_only);

look at her. four args, one cookie, zero drama (allegedly) ✨

🦋 REQUEST ARGUMENTS 🦋

here's who's who in this little friend group:

  • conn — the XCB connection to X11. your whole link to the server, your main character, your ride or die.
  • shmseg — a shared memory segment ID that you made with xcb_generate_id(). you gotta make it yourself, bestie, it's not gonna appear out of thin air.
  • shmid — the System V shared memory segment that the server should map. yes, the server maps it. that's the whole point.
  • read_only — True if the segment shall be mapped read only by the X11 server, otherwise false. so like, do you trust them with write access or not? 👀

💜 DESCRIPTION 💜

okay so the vibe here is: you're attaching a System V shared memory segment to the server. that's the whole plot.

heads up though — this will fail unless the server has permission to map the segment. no permission, no segment, no service. periodt. 😭

the cute part? the client may destroy the segment as soon as it receives a XCB_SHM_COMPLETION event with the shmseg value from this request and with the appropriate serial number. so you don't have to hover over it forever — once that event lands with the right serial, you're free to yeet the segment. ✨

🌈 RETURN VALUE 🌈

she returns an xcb_void_cookie_t. errors, if any, have to be handled in the event loop. that's the deal, no takebacks.

if you'd rather handle errors directly with xcb_request_check instead, use xcb_shm_attach_checked. see xcb-requests(3) for the details, iykyk.

💀 ERRORS 💀

this request does never generate any errors. not one. zero. the cleanest girl in the function table, no cap. 👑

🔥 SEE ALSO 🔥

🧚 AUTHOR 🧚

Generated from shm.xml. Contact xcb@lists.freedesktop.org for corrections and improvements. (not me writing this at 2am, it's literally the manpage, go tell the mailing list bestie 🫶)

and that's the tea ☕ — brought to you by X Version 11, libxcb 1.17.0, and the xcb_shm_attach(3) page itself. go map something. slay 💅✨

📦 where this page comes from