NAME

BUF_MEM_new, BUF_MEM_free, BUF_MEM_grow, BUF_strdup — 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); char *
BUF_strdup(const char *str);

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. 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_strdup() copies a NUL terminated string into a block of allocated memory and returns a pointer to the allocated block. Unlike the system strdup(3) function, BUF_strdup() will accept a NULL argument and will return NULL in that case. Its use in new programs is discouraged. The memory allocated from BUF_strdup() should be freed up using the free(3) function.

RETURN VALUES

BUF_MEM_new() returns the buffer or NULL on error. BUF_MEM_free() returns no value. BUF_MEM_grow() returns zero on error or the new size (i.e. len).

SEE ALSO

bio(3)

HISTORY

BUF_MEM_new(), BUF_MEM_free() and BUF_MEM_grow() are available in all versions of SSLeay and OpenSSL. BUF_strdup() was added in SSLeay 0.8.