=pod

=head1 NAME

ossl_algorithm_do_all - generic algorithm implementation iterator

=head1 SYNOPSIS

 void ossl_algorithm_do_all(OSSL_LIB_CTX *libctx, int operation_id,
                            OSSL_PROVIDER *provider,
                            void (*fn)(OSSL_PROVIDER *provider,
                                       const OSSL_ALGORITHM *algo,
                                       int no_store, void *data),
                            void *data);

=head1 DESCRIPTION

ossl_algorithm_do_all() looks up every algorithm it can find, given a
library context I<libctx>, an operation identity I<operation_id> and a
provider I<provider>.
I<libctx> may be NULL to signify that the default library context should
be used.
I<operation_id> may be zero to signify that all kinds of operations
will be looked up.
I<provider> may be NULL to signify that all loaded providers will be
queried.

For each implementation found, the function I<fn> is called with the
I<provider> for the implementation, the algorithm descriptor I<algo>,
the flag I<no_store> indicating whether the algorithm descriptor may
be remembered or not, and the caller I<data> that was passed to
ossl_algorithm_do_all().

=head1 RETURN VALUES

ossl_algorithm_do_all() doesn't return any value.

=head1 NOTES

The function described here are mainly useful for discovery, and
possibly display of what has been discovered, for example an
application that wants to display the loaded providers and what they
may offer, but also for constructors, such as
L<ossl_method_construct(3)>.

=head1 SEE ALSO

L<ossl_method_construct(3)>, L<EVP_MAC_do_all_provided(3)>

=head1 HISTORY

This functionality was added to OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2019-2020 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>.

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