---
name: "nbd_set_pread_initialize"
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_set_pread_initialize"
---

# nbd\_set\_pread\_initialize(3)

control whether libnbd pre-initializes read buffers

## NAME

nbd\_set\_pread\_initialize - control whether libnbd pre-initializes read buffers

## SYNOPSIS

```
 #include <libnbd.h>
 int nbd_set_pread_initialize (
       struct nbd_handle *h, bool request
     );
```

## DESCRIPTION

By default, libnbd will pre-initialize the contents of a buffer passed to calls such as [**nbd\_pread**(3)](/nbd_pread/3.md) to all zeroes prior to checking for any other errors, so that even if a client application passed in an uninitialized buffer but fails to check for errors, it will not result in a potential security risk caused by an accidental leak of prior heap contents (see CVE-2022-0485 in [**libnbd-security**(3)](/libnbd-security/3.md) for an example of a security hole in an application built against an earlier version of libnbd that lacked consistent pre-initialization).  However, for a client application that has audited that an uninitialized buffer is never dereferenced, or which performs its own pre-initialization, libnbd's sanitization efforts merely pessimize performance (although the time spent in pre-initialization may pale in comparison to time spent waiting on network packets).

Calling this function with `"request"` set to false tells libnbd to skip the buffer initialization step in read commands.

## RETURN VALUE

If the call is successful the function returns `0`.

## 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"`. For more information see "Non-NULL parameters" in [**libnbd**(3)](/libnbd/3.md).

## VERSION

This function first appeared in libnbd 1.12.

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

```
 #define LIBNBD_HAVE_NBD_SET_PREAD_INITIALIZE 1
```

## SEE ALSO

[**nbd\_aio\_pread**(3)](/nbd_aio_pread/3.md), [**nbd\_aio\_pread\_structured**(3)](/nbd_aio_pread_structured/3.md), [**nbd\_create**(3)](/nbd_create/3.md), [**nbd\_get\_pread\_initialize**(3)](/nbd_get_pread_initialize/3.md), [**nbd\_pread**(3)](/nbd_pread/3.md), [**nbd\_pread\_structured**(3)](/nbd_pread_structured/3.md), [**nbd\_set\_strict\_mode**(3)](/nbd_set_strict_mode/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