=pod

=head1 NAME

BIO_new, BIO_set, BIO_up_ref, BIO_free, BIO_vfree, BIO_free_all - BIO allocation and freeing functions

=head1 SYNOPSIS

 #include <openssl/bio.h>

 BIO *	BIO_new(const BIO_METHOD *type);
 int	BIO_set(BIO *a,const BIO_METHOD *type);
 int	BIO_up_ref(BIO *a);
 int	BIO_free(BIO *a);
 void	BIO_vfree(BIO *a);
 void	BIO_free_all(BIO *a);

=head1 DESCRIPTION

The BIO_new() function returns a new BIO using method B<type>.

BIO_set() sets the method of an already existing BIO.

BIO_up_ref() increments the reference count associated with the BIO object.

BIO_free() frees up a single BIO, BIO_vfree() also frees up a single BIO
but it does not return a value.
If B<a> is NULL nothing is done.
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.
If B<a> is NULL nothing is done.

=head1 RETURN VALUES

BIO_new() returns a newly created BIO or NULL if the call fails.

BIO_set(), BIO_up_ref() and BIO_free() return 1 for success and 0 for failure.

BIO_free_all() and BIO_vfree() do not return values.

=head1 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 B<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_*();

=head1 EXAMPLE

Create a memory BIO:

 BIO *mem = BIO_new(BIO_s_mem());

=head1 SEE ALSO

TBA
