---
name: "nbd_can_meta_context"
section: "3"
platform: "linux"
package: "libnbd"
version: "1.24.4-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/nbd_can_meta_context"
---

# nbd\_can\_meta\_context(3)

does the server support a specific meta context?

## 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

Returns true if the server supports the given meta context (see [**nbd\_add\_meta\_context**(3)](/nbd_add_meta_context/3.md)).  Returns 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.

If the server supports block status filtering (see [**nbd\_can\_block\_status\_payload**(3)](/nbd_can_block_status_payload/3.md), this function must return true for any filter name passed to [**nbd\_block\_status\_filter**(3)](/nbd_block_status_filter/3.md).

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.

This call does not block, because it returns data that is saved in the handle from the NBD protocol handshake.

## RETURN VALUE

This call returns a boolean value.

## ERRORS

On error `-1` is returned.

Refer to "ERROR HANDLING" in [**libnbd**(3)](/libnbd/3.md) for how to get further details of the error.

The following parameters must not be NULL: `"h"`, `"metacontext"`. For more information see "Non-NULL parameters" in [**libnbd**(3)](/libnbd/3.md).

## HANDLE STATE

nbd\_can\_meta\_context can be called 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

[**nbd\_add\_meta\_context**(3)](/nbd_add_meta_context/3.md), [**nbd\_aio\_block\_status\_64**(3)](/nbd_aio_block_status_64/3.md), [**nbd\_block\_status\_64**(3)](/nbd_block_status_64/3.md), [**nbd\_block\_status\_filter**(3)](/nbd_block_status_filter/3.md), [**nbd\_can\_block\_status\_payload**(3)](/nbd_can_block_status_payload/3.md), [**nbd\_create**(3)](/nbd_create/3.md), [**nbd\_opt\_info**(3)](/nbd_opt_info/3.md), [**nbd\_opt\_set\_meta\_context**(3)](/nbd_opt_set_meta_context/3.md), [**nbd\_set\_request\_meta\_context**(3)](/nbd_set_request_meta_context/3.md), "Flag calls" in [**libnbd**(3)](/libnbd/3.md), [**libnbd**(3)](/libnbd/3.md).

## AUTHORS

Eric Blake

Richard W.M. Jones

## COPYRIGHT

Copyright Red Hat

## LICENSE

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