---
name: "BUF_MEM_new"
section: "3ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/BUF_MEM_new"
---

# BUF\_MEM\_new(3ssl)

simple character array structure

## NAME

BUF\_MEM\_new, BUF\_MEM\_new\_ex, BUF\_MEM\_free, BUF\_MEM\_grow, BUF\_MEM\_grow\_clean, BUF\_reverse - simple character array structure

## SYNOPSIS

```
 #include <openssl/buffer.h>
 BUF_MEM *BUF_MEM_new(void);
 BUF_MEM *BUF_MEM_new_ex(unsigned long flags);
 void BUF_MEM_free(BUF_MEM *a);
 int BUF_MEM_grow(BUF_MEM *str, int len);
 size_t BUF_MEM_grow_clean(BUF_MEM *str, size_t len);
 void BUF_reverse(unsigned char *out, const unsigned char *in, size_t size);
```

## DESCRIPTION

The buffer library handles simple character arrays. Buffers are used for various purposes in the library, most notably memory BIOs.

**BUF\_MEM\_new()** allocates a new buffer of zero size.

**BUF\_MEM\_new\_ex()** allocates a buffer with the specified flags. The flag **BUF\_MEM\_FLAG\_SECURE** specifies that the **data** pointer should be allocated on the secure heap; see **CRYPTO\_secure\_malloc**(3).

**BUF\_MEM\_free()** frees up an already existing buffer. The data is zeroed before freeing up in case the buffer contains sensitive data. If the argument is NULL, nothing is done.

**BUF\_MEM\_grow()** changes the size of an already existing buffer to **len**. Any data already in the buffer is preserved if it increases in size.

**BUF\_MEM\_grow\_clean()** is similar to **BUF\_MEM\_grow()** but it sets any free'd or additionally-allocated memory to zero.

**BUF\_reverse()** reverses **size** bytes at **in** into **out**.  If **in** is NULL, the array is reversed in-place.

## RETURN VALUES

**BUF\_MEM\_new()** returns the buffer or NULL on error.

**BUF\_MEM\_free()** has no return value.

**BUF\_MEM\_grow()** and **BUF\_MEM\_grow\_clean()** return zero on error or the new size (i.e., **len**).

## SEE ALSO

**bio**(7), **CRYPTO\_secure\_malloc**(3).

## HISTORY

The **BUF\_MEM\_new\_ex()** function was added in OpenSSL 1.1.0.

## COPYRIGHT

Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance with the License.  You can obtain a copy in the file LICENSE in the source distribution or at \<https://www.openssl.org/source/license.html\>.