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=head1 NAME

X509_chain_up_ref,

X509_new, X509_free, X509_up_ref - X509 certificate ASN1 allocation functions

=head1 SYNOPSIS

 #include <openssl/x509.h>

 X509 *X509_new(void);

 void X509_free(X509 *a);

 int X509_up_ref(X509 *a);

 STACK_OF(X509) *X509_chain_up_ref(STACK_OF(X509) *x);

=head1 DESCRIPTION

The X509 ASN1 allocation routines, allocate and free an

X509 structure, which represents an X509 certificate.

X509_new() allocates and initializes a X509 structure with reference count

B<1>.

X509_free() decrements the reference count of B<X509> structure B and

frees it up if the reference count is zero. If B is NULL nothing is done.

X509_up_ref() increments the reference count of B.

X509_chain_up_ref() increases the reference count of all certificates in

chain B<x> and returns a copy of the stack.

=head1 NOTES

The function X509_up_ref() if useful if a certificate structure is being

used by several different operations each of which will free it up after

use: this avoids the need to duplicate the entire certificate structure.

The function X509_chain_up_ref() doesn't just up the reference count of

each certificate it also returns a copy of the stack, using sk_X509_dup(),

but it serves a similar purpose: the returned chain persists after the

original has been freed.

=head1 RETURN VALUES

If the allocation fails, X509_new() returns B<NULL> and sets an error

code that can be obtained by L<ERR_get_error(3)>.

Otherwise it returns a pointer to the newly allocated structure.

X509_up_ref() returns 1 for success and 0 for failure.

X509_chain_up_ref() returns a copy of the stack or B<NULL> if an error

occurred.

=head1 SEE ALSO

L<d2i_X509(3)>,

L<ERR_get_error(3)>,

L<X509_CRL_get0_by_serial(3)>,

L<X509_get0_signature(3)>,

L<X509_get_ext_d2i(3)>,

L<X509_get_extension_flags(3)>,

L<X509_get_pubkey(3)>,

L<X509_get_subject_name(3)>,

L<X509_get_version(3)>,

L<X509_NAME_add_entry_by_txt(3)>,

L<X509_NAME_ENTRY_get_object(3)>,

L<X509_NAME_get_index_by_NID(3)>,

L<X509_NAME_print_ex(3)>,

L<X509_sign(3)>,

L<X509V3_get_d2i(3)>,

L<X509_verify_cert(3)>

=head1 COPYRIGHT

Copyright 2002-2016 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>.

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