openssl/doc/crypto/BN_CTX_new.pod
Matt Caswell aafbe1ccd2 Document updates from wiki.
PR#3071

The primary changes made are:
- Updates to the "NAME" section of many pages to correctly reflect the
functions defined on those pages. This section is automatically parsed
by the util/extract-names.pl script, so if it is not correct then
running "man" will not correctly locate the right manual pages.
- Updates to take account of where functions are now deprecated
- Full documentation of the ec sub-library
- A number of other typo corrections and other minor tweaks
2013-06-12 23:42:08 +01:00

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1.5 KiB
Text

=pod
=head1 NAME
BN_CTX_new, BN_CTX_init, BN_CTX_free - allocate and free BN_CTX structures
=head1 SYNOPSIS
#include <openssl/bn.h>
BN_CTX *BN_CTX_new(void);
void BN_CTX_free(BN_CTX *c);
Deprecated:
void BN_CTX_init(BN_CTX *c);
=head1 DESCRIPTION
A B<BN_CTX> is a structure that holds B<BIGNUM> temporary variables used by
library functions. Since dynamic memory allocation to create B<BIGNUM>s
is rather expensive when used in conjunction with repeated subroutine
calls, the B<BN_CTX> structure is used.
BN_CTX_new() allocates and initializes a B<BN_CTX>
structure.
BN_CTX_free() frees the components of the B<BN_CTX>, and if it was
created by BN_CTX_new(), also the structure itself.
If L<BN_CTX_start(3)|BN_CTX_start(3)> has been used on the B<BN_CTX>,
L<BN_CTX_end(3)|BN_CTX_end(3)> must be called before the B<BN_CTX>
may be freed by BN_CTX_free().
BN_CTX_init() (deprecated) initializes an existing uninitialized B<BN_CTX>.
This should not be used for new programs. Use BN_CTX_new() instead.
=head1 RETURN VALUES
BN_CTX_new() returns a pointer to the B<BN_CTX>. If the allocation fails,
it returns B<NULL> and sets an error code that can be obtained by
L<ERR_get_error(3)|ERR_get_error(3)>.
BN_CTX_init() and BN_CTX_free() have no return values.
=head1 SEE ALSO
L<bn(3)|bn(3)>, L<ERR_get_error(3)|ERR_get_error(3)>, L<BN_add(3)|BN_add(3)>,
L<BN_CTX_start(3)|BN_CTX_start(3)>
=head1 HISTORY
BN_CTX_new() and BN_CTX_free() are available in all versions on SSLeay
and OpenSSL. BN_CTX_init() was added in SSLeay 0.9.1b.
=cut