NAME

       X509_new, X509_new_ex, X509_free, X509_up_ref, X509_chain_up_ref - X509 certificate ASN1
       allocation functions

SYNOPSIS

        #include <openssl/x509.h>

        X509 *X509_new(void);
        X509 *X509_new_ex(OSSL_LIB_CTX *libctx, const char *propq);
        void X509_free(X509 *a);
        int X509_up_ref(X509 *a);
        STACK_OF(X509) *X509_chain_up_ref(STACK_OF(X509) *x);

DESCRIPTION

       The X509 ASN1 allocation routines, allocate and free an X509 structure, which represents
       an X509 certificate.

       X509_new_ex() allocates and initializes a X509 structure with a library context of libctx,
       property query of propq and a reference count of 1. Many X509 functions such as
       X509_check_purpose(), and X509_verify() use this library context to select which providers
       supply the fetched algorithms (SHA1 is used internally). This created X509 object can then
       be used when loading binary data using d2i_X509().

       X509_new() is similar to X509_new_ex() but sets the library context and property query to
       NULL. This results in the default (NULL) library context being used for any X509
       operations requiring algorithm fetches.

       X509_free() decrements the reference count of X509 structure a and frees it up if the
       reference count is zero. If a is NULL nothing is done.

       X509_up_ref() increments the reference count of a.

       X509_chain_up_ref() increases the reference count of all certificates in chain x and
       returns a copy of the stack, or an empty stack if a is NULL.

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.

RETURN VALUES

       If the allocation fails, X509_new() returns NULL and sets an error code that can be
       obtained by 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 NULL if an error occurred.

SEE ALSO

       d2i_X509(3), ERR_get_error(3), X509_CRL_get0_by_serial(3), X509_get0_signature(3),
       X509_get_ext_d2i(3), X509_get_extension_flags(3), X509_get_pubkey(3),
       X509_get_subject_name(3), X509_get_version(3), X509_NAME_add_entry_by_txt(3),
       X509_NAME_ENTRY_get_object(3), X509_NAME_get_index_by_NID(3), X509_NAME_print_ex(3),
       X509_sign(3), X509V3_get_d2i(3), X509_verify_cert(3)

HISTORY

       The function X509_new_ex() was added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2002-2021 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 <https://www.openssl.org/source/license.html>.