=pod

=head1 NAME

openssl_user_macros, OPENSSL_API_COMPAT, OPENSSL_NO_DEPRECATED
- User defined macros

=head1 DESCRIPTION

User defined macros allow the programmer to control certain aspects of
what is exposed by the OpenSSL headers.

B<NOTE:> to be effective, a user defined macro I<must be defined
before including any header file that depends on it>, either in the
compilation command (C<cc -DMACRO=value>) or by defining the macro in
source before including any headers.

Other manual pages may refer to this page when declarations depend on
user defined macros.

=head2 The macros

=over 4

=item B<OPENSSL_API_COMPAT>

The value is a version number, given in one of the following two forms:

=over 4

=item C<0xMNNFF000L>

This is the form supported for all versions up to 1.1.x, where C<M>
represents the major number, C<NN> represents the minor number, and
C<FF> represents the fix number, as a hexadecimal number.  For version
1.1.0, that's C<0x10100000L>.

Any version number may be given, but these numbers are
the current known major deprecation points, making them the most
meaningful:

=over 4

=item C<0x00908000L> (version 0.9.8)

=item C<0x10000000L> (version 1.0.0)

=item C<0x10100000L> (version 1.1.0)

=back

For convenience, higher numbers are accepted as well, as long as
feasible.  For example, C<0x60000000L> will work as expected.
However, it is recommended to start using the second form instead:

=item C<mmnnpp>

This form is a simple decimal number calculated with this formula:

I<major> * 10000 + I<minor> * 100 + I<patch>

where I<major>, I<minor> and I<patch> are the desired major,
minor and patch components of the version number.  For example:

=over 4

=item 30000 corresponds to version 3.0.0

=item 10002 corresponds to version 1.0.2

=item 420101 corresponds to version 42.1.1

=back

=back

If B<OPENSSL_API_COMPAT> is undefined, this default value is used in its
place:
C<{- join('', map { my @x = split /=/,$_; $x[1] }
              grep /^OPENSSL_CONFIGURED_API=/, @{$config{openssl_api_defines} // []})
     || '0x00000000L'
  -}>

=item B<OPENSSL_NO_DEPRECATED>

If this macro is defined, all deprecated public symbols in all OpenSSL
versions up to and including the version given by B<OPENSSL_API_COMPAT>
(or the default value given above, when B<OPENSSL_API_COMPAT> isn't defined)
will be hidden.

=item B<OPENSSL_ENGINE_STUBS>

ENGINE API, as defined in openssl/engine.h, was permanently removed in OpenSSL 4.0.

The user application can use the define B<OPENSSL_ENGINE_STUBS> to enable stub macros
for API ENGINE functions. It should temporarily help the easy transition of applications
without source code modifications.

Note that all stub macros emulate API function failures; they will not restore
the removed API even if the B<OPENSSL_API_COMPAT> define is used.

=back

=head1 COPYRIGHT

Copyright 2018-2021 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
L<https://www.openssl.org/source/license.html>.

=cut
