DragonFly On-Line Manual Pages
BIO(3) DragonFly Library Functions Manual BIO(3)
NAME
BIO -- I/O abstraction
SYNOPSIS
#include <openssl/bio.h>
DESCRIPTION
A BIO is an I/O abstraction, it hides many of the underlying I/O details
from an application. If an application uses a BIO for its I/O, it can
transparently handle SSL connections, unencrypted network connections and
file I/O.
There are two types of BIO, a source/sink BIO and a filter BIO.
As its name implies, a source/sink BIO is a source and/or sink of data,
examples include a socket BIO and a file BIO.
A filter BIO takes data from one BIO and passes it through to another, or
to the application. The data may be left unmodified (for example a mes-
sage digest BIO) or translated (for example an encryption BIO). The
effect of a filter BIO may change according to the I/O operation it is
performing: for example an encryption BIO will encrypt data if it is
being written to and decrypt data if it is being read from.
BIOs can be joined together to form a chain (a single BIO is a chain with
one component). A chain normally consist of one source/sink BIO and one
or more filter BIOs. Data read from or written to the first BIO then
traverses the chain to the end (normally a source/sink BIO).
SEE ALSO
BIO_ctrl(3), BIO_f_base64(3), BIO_f_buffer(3), BIO_f_cipher(3),
BIO_f_md(3), BIO_f_null(3), BIO_f_ssl(3), BIO_find_type(3), BIO_new(3),
BIO_new_bio_pair(3), BIO_push(3), BIO_read(3), BIO_s_accept(3),
BIO_s_bio(3), BIO_s_connect(3), BIO_s_fd(3), BIO_s_file(3), BIO_s_mem(3),
BIO_s_null(3), BIO_s_socket(3), BIO_set_callback(3), BIO_should_retry(3)
DragonFly 4.7 July 17, 2014 DragonFly 4.7
BIO_new(3) OpenSSL BIO_new(3)
NAME
BIO_new, BIO_set, BIO_free, BIO_vfree, BIO_free_all - BIO allocation
and freeing functions
SYNOPSIS
#include <openssl/bio.h>
BIO * BIO_new(BIO_METHOD *type);
int BIO_set(BIO *a,BIO_METHOD *type);
int BIO_free(BIO *a);
void BIO_vfree(BIO *a);
void BIO_free_all(BIO *a);
DESCRIPTION
The BIO_new() function returns a new BIO using method type.
BIO_set() sets the method of an already existing BIO.
BIO_free() frees up a single BIO, BIO_vfree() also frees up a single
BIO but it does not return a value. Calling BIO_free() may also have
some effect on the underlying I/O structure, for example it may close
the file being referred to under certain circumstances. For more
details see the individual BIO_METHOD descriptions.
BIO_free_all() frees up an entire BIO chain, it does not halt if an
error occurs freeing up an individual BIO in the chain.
RETURN VALUES
BIO_new() returns a newly created BIO or NULL if the call fails.
BIO_set(), BIO_free() return 1 for success and 0 for failure.
BIO_free_all() and BIO_vfree() do not return values.
NOTES
Some BIOs (such as memory BIOs) can be used immediately after calling
BIO_new(). Others (such as file BIOs) need some additional
initialization, and frequently a utility function exists to create and
initialize such BIOs.
If BIO_free() is called on a BIO chain it will only free one BIO
resulting in a memory leak.
Calling BIO_free_all() a single BIO has the same effect as calling
BIO_free() on it other than the discarded return value.
Normally the type argument is supplied by a function which returns a
pointer to a BIO_METHOD. There is a naming convention for such
functions: a source/sink BIO is normally called BIO_s_*() and a filter
BIO BIO_f_*();
EXAMPLE
Create a memory BIO:
BIO *mem = BIO_new(BIO_s_mem());
SEE ALSO
TBA
1.0.2h 2016-05-03 BIO_new(3)