nbd_can_meta_context(3)

📦
version 1.25.8 · 18 versions
, in centos-stream 10

✨ nbd_can_meta_context(3) 💅

okay so bestie, this is a LIBNBD manual page — specifically for nbd_can_meta_context(3) — and it is literally about checking whether the server supports one specific meta context. no cap, that is the whole vibe.

🎀 NAME 🎀

nbd_can_meta_context — does the server support a specific meta context?

🌸 SYNOPSIS 🌸

        #include <libnbd.h>

        int nbd_can_meta_context (
              struct nbd_handle *h, const char *metacontext
            );

🦋 DESCRIPTION 🦋

So this returns true if the server supports the meta context you passed in (peep nbd_add_meta_context(3)), and false if the server does not. It is possible for this command to fail if meta contexts were requested but there is a missing or failed attempt at NBD_OPT_SET_META_CONTEXT during option negotiation. Like, it tried and it did not slay.

If the server supports block status filtering (see nbd_can_block_status_payload(3)), this function must return true for any filter name passed to nbd_block_status_filter(3). That is a must, bestie, not a suggestion.

The single parameter is the name of the metadata context — for example, "LIBNBD_CONTEXT_BASE_ALLOCATION". <libnbd.h> includes defined constants for well-known namespace contexts beginning with "LIBNBD_CONTEXT_", but you are free to pass in other contexts. your call, main character 💅.

💖 RETURN VALUE 💖

This call returns a boolean value. true/false, yes/no, slay/not slay.

🔥 ERRORS 🔥

On error -1 is returned.

For how to get further details of the error, refer to "ERROR HANDLING" in libnbd(3).

The following parameters must not be NULL: "h", "metacontext". For more information see "Non-NULL parameters" in libnbd(3). do not be out here passing NULL, bestie — the manual is very clear about this.

🧚 NOTES 🧚

Non-blocking call

This call does not block, because it returns data that is saved in the handle from the NBD protocol handshake. so it is giving instant, already-there energy ✨.

👑 HANDLE STATE 👑

You can call nbd_can_meta_context when the handle is in the following states:

  • Handle created, before connecting — ❌ error
  • Connecting — ❌ error
  • Connecting & handshaking (opt_mode) — ✅ allowed
  • Connected to the server — ✅ allowed
  • Connection shut down — ✅ allowed
  • Handle dead — ❌ error

🌈 VERSION 🌈

This function first appeared in libnbd 1.0.

If you need to test if this function is available at compile time, check if the following macro is defined:

#define LIBNBD_HAVE_NBD_CAN_META_CONTEXT 1

⭐ SEE ALSO ⭐

💜 AUTHORS 💜

  • Eric Blake
  • Richard W.M. Jones

Copyright Red Hat

💀 LICENSE 💀

okay legal bestie moment, here is the license exactly as it comes:

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

mwah 💋 this page is from libnbd-1.25.8, dated 2026-10-13, and it is literally nbd_can_meta_context(3) — periodt.

📦 where this page comes from