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=head1 NAME

X509_ALGOR_dup, X509_ALGOR_set0, X509_ALGOR_get0, X509_ALGOR_set_md, X509_ALGOR_cmp - AlgorithmIdentifier functions

=head1 SYNOPSIS

 #include <openssl/x509.h>

 X509_ALGOR *X509_ALGOR_dup(X509_ALGOR *alg);
 int X509_ALGOR_set0(X509_ALGOR *alg, ASN1_OBJECT *aobj, int ptype, void *pval);
 void X509_ALGOR_get0(const ASN1_OBJECT **paobj, int *pptype,
                      const void **ppval, const X509_ALGOR *alg);
 void X509_ALGOR_set_md(X509_ALGOR *alg, const EVP_MD *md);
 int X509_ALGOR_cmp(const X509_ALGOR *a, const X509_ALGOR *b);

=head1 DESCRIPTION

X509_ALGOR_dup() returns a copy of B<alg>.

X509_ALGOR_set0() sets the algorithm OID of B<alg> to B<aobj> and the
associated parameter type to B<ptype> with value B<pval>. If B<ptype> is
B<V_ASN1_UNDEF> the parameter is omitted, otherwise B<ptype> and B<pval> have
the same meaning as the B<type> and B<value> parameters to ASN1_TYPE_set().
All the supplied parameters are used internally so must B<NOT> be freed after
this call.

X509_ALGOR_get0() is the inverse of X509_ALGOR_set0(): it returns the
algorithm OID in B<*paobj> and the associated parameter in B<*pptype>
and B<*ppval> from the B<AlgorithmIdentifier> B<alg>.

X509_ALGOR_set_md() sets the B<AlgorithmIdentifier> B<alg> to appropriate
values for the message digest B<md>.

X509_ALGOR_cmp() compares B<a> and B<b> and returns 0 if they have identical
encodings and non-zero otherwise.

=head1 RETURN VALUES

X509_ALGOR_dup() returns a valid B<X509_ALGOR> structure or NULL if an error
occurred.

X509_ALGOR_set0() returns 1 on success or 0 on error.

X509_ALGOR_get0() and X509_ALGOR_set_md() return no values.

X509_ALGOR_cmp() returns 0 if the two parameters have identical encodings and
non-zero otherwise.

=head1 COPYRIGHT

Copyright 2002-2018 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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