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.