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OPENSSL_init_crypto(3)              OpenSSL             OPENSSL_init_crypto(3)



NAME
       OPENSSL_INIT_new, OPENSSL_INIT_set_config_appname, OPENSSL_INIT_free,
       OPENSSL_init_crypto, OPENSSL_cleanup, OPENSSL_atexit,
       OPENSSL_thread_stop - OpenSSL initialisation and deinitialisation
       functions

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/crypto.h>

        void OPENSSL_cleanup(void);
        int OPENSSL_init_crypto(uint64_t opts, const OPENSSL_INIT_SETTINGS *settings);
        int OPENSSL_atexit(void (*handler)(void));
        void OPENSSL_thread_stop(void);

        OPENSSL_INIT_SETTINGS *OPENSSL_INIT_new(void);
        int OPENSSL_INIT_set_config_appname(OPENSSL_INIT_SETTINGS *init,
                                            const char* name);
        void OPENSSL_INIT_free(OPENSSL_INIT_SETTINGS *init);

DESCRIPTION
       During normal operation OpenSSL (libcrypto) will allocate various
       resources at start up that must, subsequently, be freed on close down
       of the library.  Additionally some resources are allocated on a per
       thread basis (if the application is multi-threaded), and these
       resources must be freed prior to the thread closing.

       As of version 1.1.0 OpenSSL will automatically allocate all resources
       that it needs so no explicit initialisation is required. Similarly it
       will also automatically deinitialise as required.

       However, there way be situations when explicit initialisation is
       desirable or needed, for example when some non-default initialisation
       is required. The function OPENSSL_init_crypto() can be used for this
       purpose for libcrypto (see also OPENSSL_init_ssl(3) for the libssl
       equivalent).

       Numerous internal OpenSSL functions call OPENSSL_init_crypto().
       Therefore, in order to perform non-default initialisation,
       OPENSSL_init_crypto() MUST be called by application code prior to any
       other OpenSSL function calls.

       The opts parameter specifies which aspects of libcrypto should be
       initialised. Valid options are:

       OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS
           Suppress automatic loading of the libcrypto error strings. This
           option is not a default option. Once selected subsequent calls to
           OPENSSL_init_crypto() with the option
           OPENSSL_INIT_LOAD_CRYPTO_STRINGS will be ignored.

       OPENSSL_INIT_LOAD_CRYPTO_STRINGS
           Automatic loading of the libcrypto error strings. With this option
           the library will automatically load the libcrypto error strings.
           This option is a default option. Once selected subsequent calls to
           OPENSSL_init_crypto() with the option
           OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS will be ignored.

       OPENSSL_INIT_ADD_ALL_CIPHERS
           With this option the library will automatically load and make
           available all libcrypto ciphers. This option is a default option.
           Once selected subsequent calls to OPENSSL_init_crypto() with the
           option OPENSSL_INIT_NO_ADD_ALL_CIPHERS will be ignored.

       OPENSSL_INIT_ADD_ALL_DIGESTS
           With this option the library will automatically load and make
           available all libcrypto digests. This option is a default option.
           Once selected subsequent calls to OPENSSL_init_crypto() with the
           option OPENSSL_INIT_NO_ADD_ALL_CIPHERS will be ignored.

       OPENSSL_INIT_NO_ADD_ALL_CIPHERS
           With this option the library will suppress automatic loading of
           libcrypto ciphers. This option is not a default option. Once
           selected subsequent calls to OPENSSL_init_crypto() with the option
           OPENSSL_INIT_ADD_ALL_CIPHERS will be ignored.

       OPENSSL_INIT_NO_ADD_ALL_DIGESTS
           With this option the library will suppress automatic loading of
           libcrypto digests. This option is not a default option. Once
           selected subsequent calls to OPENSSL_init_crypto() with the option
           OPENSSL_INIT_ADD_ALL_DIGESTS will be ignored.

       OPENSSL_INIT_LOAD_CONFIG
           With this option an OpenSSL configuration file will be
           automatically loaded and used by calling OPENSSL_config(). This is
           not a default option for libcrypto.  From OpenSSL 1.1.1 this is a
           default option for libssl (see OPENSSL_init_ssl(3) for further
           details about libssl initialisation). See the description of
           OPENSSL_INIT_new(), below.

       OPENSSL_INIT_NO_LOAD_CONFIG
           With this option the loading of OpenSSL configuration files will be
           suppressed.  It is the equivalent of calling OPENSSL_no_config().
           This is not a default option.

       OPENSSL_INIT_ASYNC
           With this option the library with automatically initialise the
           libcrypto async sub-library (see ASYNC_start_job(3)). This is a
           default option.

       OPENSSL_INIT_ENGINE_RDRAND
           With this option the library will automatically load and initialise
           the RDRAND engine (if available). This not a default option.

       OPENSSL_INIT_ENGINE_DYNAMIC
           With this option the library will automatically load and initialise
           the dynamic engine. This not a default option.

       OPENSSL_INIT_ENGINE_OPENSSL
           With this option the library will automatically load and initialise
           the openssl engine. This not a default option.

       OPENSSL_INIT_ENGINE_CRYPTODEV
           With this option the library will automatically load and initialise
           the cryptodev engine (if available). This not a default option.

       OPENSSL_INIT_ENGINE_CAPI
           With this option the library will automatically load and initialise
           the CAPI engine (if available). This not a default option.

       OPENSSL_INIT_ENGINE_PADLOCK
           With this option the library will automatically load and initialise
           the padlock engine (if available). This not a default option.

       OPENSSL_INIT_ENGINE_AFALG
           With this option the library will automatically load and initialise
           the AFALG engine. This not a default option.

       OPENSSL_INIT_ENGINE_ALL_BUILTIN
           With this option the library will automatically load and initialise
           all the built in engines listed above with the exception of the
           openssl and afalg engines. This not a default option.

       OPENSSL_INIT_ATFORK
           With this option the library will register its fork handlers.  See
           OPENSSL_fork_prepare(3) for details.

       Multiple options may be combined together in a single call to
       OPENSSL_init_crypto(). For example:

        OPENSSL_init_crypto(OPENSSL_INIT_NO_ADD_ALL_CIPHERS
                            | OPENSSL_INIT_NO_ADD_ALL_DIGESTS, NULL);

       The OPENSSL_cleanup() function deinitialises OpenSSL (both libcrypto
       and libssl). All resources allocated by OpenSSL are freed. Typically
       there should be no need to call this function directly as it is
       initiated automatically on application exit. This is done via the
       standard C library atexit() function. In the event that the application
       will close in a manner that will not call the registered atexit()
       handlers then the application should call OPENSSL_cleanup() directly.
       Developers of libraries using OpenSSL are discouraged from calling this
       function and should instead, typically, rely on auto-deinitialisation.
       This is to avoid error conditions where both an application and a
       library it depends on both use OpenSSL, and the library deinitialises
       it before the application has finished using it.

       Once OPENSSL_cleanup() has been called the library cannot be
       reinitialised.  Attempts to call OPENSSL_init_crypto() will fail and an
       ERR_R_INIT_FAIL error will be added to the error stack. Note that
       because initialisation has failed OpenSSL error strings will not be
       available, only an error code. This code can be put through the openssl
       errstr command line application to produce a human readable error (see
       errstr(1)).

       The OPENSSL_atexit() function enables the registration of a function to
       be called during OPENSSL_cleanup(). Stop handlers are called after
       deinitialisation of resources local to a thread, but before other
       process wide resources are freed. In the event that multiple stop
       handlers are registered, no guarantees are made about the order of
       execution.

       The OPENSSL_thread_stop() function deallocates resources associated
       with the current thread. Typically this function will be called
       automatically by the library when the thread exits. This should only be
       called directly if resources should be freed at an earlier time, or
       under the circumstances described in the NOTES section below.

       The OPENSSL_INIT_LOAD_CONFIG flag will load a default configuration
       file. For optional configuration file settings, an
       OPENSSL_INIT_SETTINGS must be created and used.  The routines
       OPENSSL_init_new() and OPENSSL_INIT_set_config_appname() can be used to
       allocate the object and set the application name, and then the object
       can be released with OPENSSL_INIT_free() when done.

NOTES
       Resources local to a thread are deallocated automatically when the
       thread exits (e.g. in a pthreads environment, when pthread_exit() is
       called). On Windows platforms this is done in response to a
       DLL_THREAD_DETACH message being sent to the libcrypto32.dll entry
       point. Some windows functions may cause threads to exit without sending
       this message (for example ExitProcess()). If the application uses such
       functions, then the application must free up OpenSSL resources directly
       via a call to OPENSSL_thread_stop() on each thread. Similarly this
       message will also not be sent if OpenSSL is linked statically, and
       therefore applications using static linking should also call
       OPENSSL_thread_stop() on each thread. Additionally if OpenSSL is loaded
       dynamically via LoadLibrary() and the threads are not destroyed until
       after FreeLibrary() is called then each thread should call
       OPENSSL_thread_stop() prior to the FreeLibrary() call.

       On Linux/Unix where OpenSSL has been loaded via dlopen() and the
       application is multi-threaded and if dlclose() is subsequently called
       prior to the threads being destroyed then OpenSSL will not be able to
       deallocate resources associated with those threads. The application
       should either call OPENSSL_thread_stop() on each thread prior to the
       dlclose() call, or alternatively the original dlopen() call should use
       the RTLD_NODELETE flag (where available on the platform).

RETURN VALUES
       The functions OPENSSL_init_crypto, OPENSSL_atexit() and
       OPENSSL_INIT_set_config_appname() return 1 on success or 0 on error.

SEE ALSO
       OPENSSL_init_ssl(3)

HISTORY
       The OPENSSL_init_crypto(), OPENSSL_cleanup(), OPENSSL_atexit(),
       OPENSSL_thread_stop(), OPENSSL_INIT_new(),
       OPENSSL_INIT_set_config_appname() and OPENSSL_INIT_free() functions
       were added in OpenSSL 1.1.0.

COPYRIGHT
       Copyright 2016-2018 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
       <https://www.openssl.org/source/license.html>.



1.1.1                             2018-09-17            OPENSSL_init_crypto(3)