BUF_MEM_new, BUF_MEM_new_ex, BUF_MEM_free, BUF_MEM_grow, BUF_MEM_grow_clean, BUF_reverse - simple

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       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>.

3.5.0                                              2025-06-04                                  BUF_MEM_NEW(3SSL)

       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.

       The BUF_MEM_new_ex() function was added in OpenSSL 1.1.0.

       BUF_MEM_new, BUF_MEM_new_ex, BUF_MEM_free, BUF_MEM_grow, BUF_MEM_grow_clean, BUF_reverse - simple
       character array structure

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).

bio(7), CRYPTO_secure_malloc(3).

        #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);