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Diffstat (limited to 'doc/man3/BN_CTX_start.pod')
-rw-r--r-- | doc/man3/BN_CTX_start.pod | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/doc/man3/BN_CTX_start.pod b/doc/man3/BN_CTX_start.pod new file mode 100644 index 0000000000..372da506d9 --- /dev/null +++ b/doc/man3/BN_CTX_start.pod @@ -0,0 +1,57 @@ +=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 OpenSSL license (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 |