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.\" ========================================================================
.\"
.IX Title "X509_NEW 3SSL"
.TH X509_NEW 3SSL 2024-04-11 3.3.0 OpenSSL
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH NAME
X509_new, X509_new_ex,
X509_free, X509_up_ref,
X509_chain_up_ref,
OSSL_STACK_OF_X509_free
\&\- X509 certificate ASN1 allocation and deallocation functions
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #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);
\& void OSSL_STACK_OF_X509_free(STACK_OF(X509) *certs);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
The X509 ASN1 allocation routines, allocate and free an
X509 structure, which represents an X509 certificate.
.PP
\&\fBX509_new_ex()\fR allocates and initializes a X509 structure with a
library context of \fIlibctx\fR, property query of \fIpropq\fR and a reference
count of \fB1\fR. Many X509 functions such as \fBX509_check_purpose()\fR, and
\&\fBX509_verify()\fR 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 \fBd2i_X509()\fR.
.PP
\&\fBX509_new()\fR is similar to \fBX509_new_ex()\fR 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.
.PP
\&\fBX509_free()\fR decrements the reference count of \fBX509\fR structure \fBa\fR and
frees it up if the reference count is zero. If \fBa\fR is NULL nothing is done.
.PP
\&\fBX509_up_ref()\fR increments the reference count of \fBa\fR.
.PP
\&\fBX509_chain_up_ref()\fR increases the reference count of all certificates in
chain \fBx\fR and returns a copy of the stack, or an empty stack if \fBa\fR is NULL.
.PP
\&\fBOSSL_STACK_OF_X509_free()\fR deallocates the given list of pointers to
certificates after calling \fBX509_free()\fR on all its elements.
.SH NOTES
.IX Header "NOTES"
The function \fBX509_up_ref()\fR 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.
.PP
The function \fBX509_chain_up_ref()\fR doesn't just up the reference count of
each certificate. It also returns a copy of the stack, using \fBsk_X509_dup()\fR,
but it serves a similar purpose: the returned chain persists after the
original has been freed.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
If the allocation fails, \fBX509_new()\fR returns NULL and sets an error
code that can be obtained by \fBERR_get_error\fR\|(3).
Otherwise it returns a pointer to the newly allocated structure.
.PP
\&\fBX509_up_ref()\fR returns 1 for success and 0 for failure.
.PP
\&\fBX509_chain_up_ref()\fR returns a copy of the stack or NULL if an error occurred.
.PP
\&\fBOSSL_STACK_OF_X509_free()\fR has no return value.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBd2i_X509\fR\|(3),
\&\fBERR_get_error\fR\|(3),
\&\fBX509_CRL_get0_by_serial\fR\|(3),
\&\fBX509_get0_signature\fR\|(3),
\&\fBX509_get_ext_d2i\fR\|(3),
\&\fBX509_get_extension_flags\fR\|(3),
\&\fBX509_get_pubkey\fR\|(3),
\&\fBX509_get_subject_name\fR\|(3),
\&\fBX509_get_version\fR\|(3),
\&\fBX509_NAME_add_entry_by_txt\fR\|(3),
\&\fBX509_NAME_ENTRY_get_object\fR\|(3),
\&\fBX509_NAME_get_index_by_NID\fR\|(3),
\&\fBX509_NAME_print_ex\fR\|(3),
\&\fBX509_sign\fR\|(3),
\&\fBX509V3_get_d2i\fR\|(3),
\&\fBX509_verify_cert\fR\|(3)
.SH HISTORY
.IX Header "HISTORY"
\&\fBX509_new_ex()\fR was added in OpenSSL 3.0.
.PP
\&\fBOSSL_STACK_OF_X509_free()\fR was added in OpenSSL 3.2.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2002\-2021 The OpenSSL Project Authors. All Rights Reserved.
.PP
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>.