mirror of
https://github.com/openssl/openssl.git
synced 2024-12-09 05:51:54 +08:00
4746f25ac6
[skip ci] Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7829)
58 lines
1.6 KiB
Plaintext
58 lines
1.6 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
BN_CTX_start, BN_CTX_get, BN_CTX_end - use temporary BIGNUM variables
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/bn.h>
|
|
|
|
void BN_CTX_start(BN_CTX *ctx);
|
|
|
|
BIGNUM *BN_CTX_get(BN_CTX *ctx);
|
|
|
|
void BN_CTX_end(BN_CTX *ctx);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
These functions are used to obtain temporary B<BIGNUM> variables from
|
|
a B<BN_CTX> (which can been created by using L<BN_CTX_new(3)>)
|
|
in order to save the overhead of repeatedly creating and
|
|
freeing B<BIGNUM>s in functions that are called from inside a loop.
|
|
|
|
A function must call BN_CTX_start() first. Then, BN_CTX_get() may be
|
|
called repeatedly to obtain temporary B<BIGNUM>s. All BN_CTX_get()
|
|
calls must be made before calling any other functions that use the
|
|
B<ctx> as an argument.
|
|
|
|
Finally, BN_CTX_end() must be called before returning from the function.
|
|
When BN_CTX_end() is called, the B<BIGNUM> pointers obtained from
|
|
BN_CTX_get() become invalid.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
BN_CTX_start() and BN_CTX_end() return no values.
|
|
|
|
BN_CTX_get() returns a pointer to the B<BIGNUM>, or B<NULL> on error.
|
|
Once BN_CTX_get() has failed, the subsequent calls will return B<NULL>
|
|
as well, so it is sufficient to check the return value of the last
|
|
BN_CTX_get() call. In case of an error, an error code is set, which
|
|
can be obtained by L<ERR_get_error(3)>.
|
|
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<BN_CTX_new(3)>
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
|
|
|
|
Licensed under the Apache License 2.0 (the "License"). You may not use
|
|
this file except in compliance with the License. You can obtain a copy
|
|
in the file LICENSE in the source distribution or at
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|