BUF_MEM_NEW(3)

NAME
BUF_MEM_new, BUF_MEM_free, BUF_MEM_grow, BUF_MEM_grow_clean - simple character arrays structure

SYNOPSIS
#include <openssl/buffer.h>
BUF_MEM *
BUF_MEM_new(void);
void
BUF_MEM_free(BUF_MEM *a);
int
BUF_MEM_grow(BUF_MEM *str, size_t len);
int
BUF_MEM_grow_clean(BUF_MEM *str, size_t len);

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

The library uses the BUF_MEM structure defined in buffer.h:

    typedef struct buf_mem_st {
    	size_t length;	/* current number of bytes */
    	char *data;
    	size_t max;	/* size of buffer */
    } BUF_MEM;

length is the current size of the buffer in bytes; max is the amount of memory allocated to the buffer. There are three functions which handle these and one miscellaneous function.

BUF_MEM_new() allocates a new buffer of zero size.

BUF_MEM_free() frees up an already existing buffer. The data is zeroed before freeing up in case the buffer contains sensitive data. If a is a NULL pointer, no action occurs.

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 freed or additionally allocated memory to zero.

RETURN VALUES
BUF_MEM_new() returns the buffer or NULL on error.

BUF_MEM_grow() and BUF_MEM_grow_clean() return zero on error or the new size (i.e. len).

SEE ALSO
BIO_new(3), BIO_s_mem(3)

HISTORY
BUF_MEM_new(), BUF_MEM_free(), and BUF_MEM_grow() first appeared in SSLeay 0.6.0. All these functions have been available since OpenBSD 2.4.

BUF_MEM_grow_clean() first appeared in OpenSSL 0.9.7 and has been available since OpenBSD 3.2.