- NAME
- DESCRIPTION
  - The macros
- COPYRIGHT

# NAME

openssl_user_macros, OPENSSL_API_COMPAT, OPENSSL_NO_DEPRECATED - User defined macros

# DESCRIPTION

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

NOTE: to be effective, a user defined macro must be defined before including any header file that depends on it, either in the compilation command (`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.

## The macros

OPENSSL_API_COMPAT

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

  `0xMNNFF000L`

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

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

    `0x00908000L` (version 0.9.8)
    `0x10000000L` (version 1.0.0)
    `0x10100000L` (version 1.1.0)

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

  `mmnnpp`

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

    major * 10000 + minor * 100 + patch

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

    30000 corresponds to version 3.0.0
    10002 corresponds to version 1.0.2
    420101 corresponds to version 42.1.1

  If OPENSSL_API_COMPAT is undefined, this default value is used in its place: `40000`

OPENSSL_NO_DEPRECATED

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

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 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 OPENSSL_API_COMPAT define is used.

# 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 https://www.openssl.org/source/license.html.