1OPENSSL_INIT_CRYPTO(3)              OpenSSL             OPENSSL_INIT_CRYPTO(3)
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NAME

6       OPENSSL_INIT_new, OPENSSL_INIT_set_config_filename,
7       OPENSSL_INIT_set_config_appname, OPENSSL_INIT_set_config_file_flags,
8       OPENSSL_INIT_free, OPENSSL_init_crypto, OPENSSL_cleanup,
9       OPENSSL_atexit, OPENSSL_thread_stop - OpenSSL initialisation and
10       deinitialisation functions
11

SYNOPSIS

13        #include <openssl/crypto.h>
14
15        void OPENSSL_cleanup(void);
16        int OPENSSL_init_crypto(uint64_t opts, const OPENSSL_INIT_SETTINGS *settings);
17        int OPENSSL_atexit(void (*handler)(void));
18        void OPENSSL_thread_stop(void);
19
20        OPENSSL_INIT_SETTINGS *OPENSSL_INIT_new(void);
21        int OPENSSL_INIT_set_config_filename(OPENSSL_INIT_SETTINGS *init,
22                                             const char* filename);
23        int OPENSSL_INIT_set_config_file_flags(OPENSSL_INIT_SETTINGS *init,
24                                               unsigned long flags);
25        int OPENSSL_INIT_set_config_appname(OPENSSL_INIT_SETTINGS *init,
26                                            const char* name);
27        void OPENSSL_INIT_free(OPENSSL_INIT_SETTINGS *init);
28

DESCRIPTION

30       During normal operation OpenSSL (libcrypto) will allocate various
31       resources at start up that must, subsequently, be freed on close down
32       of the library.  Additionally some resources are allocated on a per
33       thread basis (if the application is multi-threaded), and these
34       resources must be freed prior to the thread closing.
35
36       As of version 1.1.0 OpenSSL will automatically allocate all resources
37       that it needs so no explicit initialisation is required. Similarly it
38       will also automatically deinitialise as required.
39
40       However, there may be situations when explicit initialisation is
41       desirable or needed, for example when some nondefault initialisation is
42       required. The function OPENSSL_init_crypto() can be used for this
43       purpose for libcrypto (see also OPENSSL_init_ssl(3) for the libssl
44       equivalent).
45
46       Numerous internal OpenSSL functions call OPENSSL_init_crypto().
47       Therefore, in order to perform nondefault initialisation,
48       OPENSSL_init_crypto() MUST be called by application code prior to any
49       other OpenSSL function calls.
50
51       The opts parameter specifies which aspects of libcrypto should be
52       initialised. Valid options are:
53
54       OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS
55           Suppress automatic loading of the libcrypto error strings. This
56           option is not a default option. Once selected subsequent calls to
57           OPENSSL_init_crypto() with the option
58           OPENSSL_INIT_LOAD_CRYPTO_STRINGS will be ignored.
59
60       OPENSSL_INIT_LOAD_CRYPTO_STRINGS
61           Automatic loading of the libcrypto error strings. With this option
62           the library will automatically load the libcrypto error strings.
63           This option is a default option. Once selected subsequent calls to
64           OPENSSL_init_crypto() with the option
65           OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS will be ignored.
66
67       OPENSSL_INIT_ADD_ALL_CIPHERS
68           With this option the library will automatically load and make
69           available all libcrypto ciphers. This option is a default option.
70           Once selected subsequent calls to OPENSSL_init_crypto() with the
71           option OPENSSL_INIT_NO_ADD_ALL_CIPHERS will be ignored.
72
73       OPENSSL_INIT_ADD_ALL_DIGESTS
74           With this option the library will automatically load and make
75           available all libcrypto digests. This option is a default option.
76           Once selected subsequent calls to OPENSSL_init_crypto() with the
77           option OPENSSL_INIT_NO_ADD_ALL_CIPHERS will be ignored.
78
79       OPENSSL_INIT_NO_ADD_ALL_CIPHERS
80           With this option the library will suppress automatic loading of
81           libcrypto ciphers. This option is not a default option. Once
82           selected subsequent calls to OPENSSL_init_crypto() with the option
83           OPENSSL_INIT_ADD_ALL_CIPHERS will be ignored.
84
85       OPENSSL_INIT_NO_ADD_ALL_DIGESTS
86           With this option the library will suppress automatic loading of
87           libcrypto digests. This option is not a default option. Once
88           selected subsequent calls to OPENSSL_init_crypto() with the option
89           OPENSSL_INIT_ADD_ALL_DIGESTS will be ignored.
90
91       OPENSSL_INIT_LOAD_CONFIG
92           With this option an OpenSSL configuration file will be
93           automatically loaded and used by calling OPENSSL_config(). This is
94           not a default option for libcrypto.  As of OpenSSL 1.1.1 this is a
95           default option for libssl (see OPENSSL_init_ssl(3) for further
96           details about libssl initialisation). See the description of
97           OPENSSL_INIT_new(), below.
98
99       OPENSSL_INIT_NO_LOAD_CONFIG
100           With this option the loading of OpenSSL configuration files will be
101           suppressed.  It is the equivalent of calling OPENSSL_no_config().
102           This is not a default option.
103
104       OPENSSL_INIT_ASYNC
105           With this option the library with automatically initialise the
106           libcrypto async sub-library (see ASYNC_start_job(3)). This is a
107           default option.
108
109       OPENSSL_INIT_ENGINE_RDRAND
110           With this option the library will automatically load and initialise
111           the RDRAND engine (if available). This not a default option.
112
113       OPENSSL_INIT_ENGINE_DYNAMIC
114           With this option the library will automatically load and initialise
115           the dynamic engine. This not a default option.
116
117       OPENSSL_INIT_ENGINE_OPENSSL
118           With this option the library will automatically load and initialise
119           the openssl engine. This not a default option.
120
121       OPENSSL_INIT_ENGINE_CRYPTODEV
122           With this option the library will automatically load and initialise
123           the cryptodev engine (if available). This not a default option.
124
125       OPENSSL_INIT_ENGINE_CAPI
126           With this option the library will automatically load and initialise
127           the CAPI engine (if available). This not a default option.
128
129       OPENSSL_INIT_ENGINE_PADLOCK
130           With this option the library will automatically load and initialise
131           the padlock engine (if available). This not a default option.
132
133       OPENSSL_INIT_ENGINE_AFALG
134           With this option the library will automatically load and initialise
135           the AFALG engine. This not a default option.
136
137       OPENSSL_INIT_ENGINE_ALL_BUILTIN
138           With this option the library will automatically load and initialise
139           all the built in engines listed above with the exception of the
140           openssl and afalg engines. This not a default option.
141
142       OPENSSL_INIT_ATFORK
143           With this option the library will register its fork handlers.  See
144           OPENSSL_fork_prepare(3) for details.
145
146       OPENSSL_INIT_NO_ATEXIT
147           By default OpenSSL will attempt to clean itself up when the process
148           exits via an "atexit" handler. Using this option suppresses that
149           behaviour. This means that the application will have to clean up
150           OpenSSL explicitly using OPENSSL_cleanup().
151
152       Multiple options may be combined together in a single call to
153       OPENSSL_init_crypto(). For example:
154
155        OPENSSL_init_crypto(OPENSSL_INIT_NO_ADD_ALL_CIPHERS
156                            | OPENSSL_INIT_NO_ADD_ALL_DIGESTS, NULL);
157
158       The OPENSSL_cleanup() function deinitialises OpenSSL (both libcrypto
159       and libssl). All resources allocated by OpenSSL are freed. Typically
160       there should be no need to call this function directly as it is
161       initiated automatically on application exit. This is done via the
162       standard C library atexit() function. In the event that the application
163       will close in a manner that will not call the registered atexit()
164       handlers then the application should call OPENSSL_cleanup() directly.
165       Developers of libraries using OpenSSL are discouraged from calling this
166       function and should instead, typically, rely on auto-deinitialisation.
167       This is to avoid error conditions where both an application and a
168       library it depends on both use OpenSSL, and the library deinitialises
169       it before the application has finished using it.
170
171       Once OPENSSL_cleanup() has been called the library cannot be
172       reinitialised.  Attempts to call OPENSSL_init_crypto() will fail and an
173       ERR_R_INIT_FAIL error will be added to the error stack. Note that
174       because initialisation has failed OpenSSL error strings will not be
175       available, only an error code. This code can be put through the openssl
176       errstr command line application to produce a human readable error (see
177       errstr(1)).
178
179       The OPENSSL_atexit() function enables the registration of a function to
180       be called during OPENSSL_cleanup(). Stop handlers are called after
181       deinitialisation of resources local to a thread, but before other
182       process wide resources are freed. In the event that multiple stop
183       handlers are registered, no guarantees are made about the order of
184       execution.
185
186       The OPENSSL_thread_stop() function deallocates resources associated
187       with the current thread. Typically this function will be called
188       automatically by the library when the thread exits. This should only be
189       called directly if resources should be freed at an earlier time, or
190       under the circumstances described in the NOTES section below.
191
192       The OPENSSL_INIT_LOAD_CONFIG flag will load a configuration file, as
193       with CONF_modules_load_file(3) with NULL filename and application name
194       and the CONF_MFLAGS_IGNORE_MISSING_FILE,
195       CONF_MFLAGS_IGNORE_RETURN_CODES  and CONF_MFLAGS_DEFAULT_SECTION flags.
196       The filename, application name, and flags can be customized by
197       providing a non-null OPENSSL_INIT_SETTINGS object.  The object can be
198       allocated via OPENSSL_init_new().  The
199       OPENSSL_INIT_set_config_filename() function can be used to specify a
200       nondefault filename, which is copied and need not refer to persistent
201       storage.  Similarly, OPENSSL_INIT_set_config_appname() can be used to
202       specify a nondefault application name.  Finally,
203       OPENSSL_INIT_set_file_flags can be used to specify nondefault flags.
204       If the CONF_MFLAGS_IGNORE_RETURN_CODES flag is not included, any errors
205       in the configuration file will cause an error return from
206       OPENSSL_init_crypto or indirectly OPENSSL_init_ssl(3).  The object can
207       be released with OPENSSL_INIT_free() when done.
208

NOTES

210       Resources local to a thread are deallocated automatically when the
211       thread exits (e.g. in a pthreads environment, when pthread_exit() is
212       called). On Windows platforms this is done in response to a
213       DLL_THREAD_DETACH message being sent to the libcrypto32.dll entry
214       point. Some windows functions may cause threads to exit without sending
215       this message (for example ExitProcess()). If the application uses such
216       functions, then the application must free up OpenSSL resources directly
217       via a call to OPENSSL_thread_stop() on each thread. Similarly this
218       message will also not be sent if OpenSSL is linked statically, and
219       therefore applications using static linking should also call
220       OPENSSL_thread_stop() on each thread. Additionally if OpenSSL is loaded
221       dynamically via LoadLibrary() and the threads are not destroyed until
222       after FreeLibrary() is called then each thread should call
223       OPENSSL_thread_stop() prior to the FreeLibrary() call.
224
225       On Linux/Unix where OpenSSL has been loaded via dlopen() and the
226       application is multi-threaded and if dlclose() is subsequently called
227       prior to the threads being destroyed then OpenSSL will not be able to
228       deallocate resources associated with those threads. The application
229       should either call OPENSSL_thread_stop() on each thread prior to the
230       dlclose() call, or alternatively the original dlopen() call should use
231       the RTLD_NODELETE flag (where available on the platform).
232

RETURN VALUES

234       The functions OPENSSL_init_crypto, OPENSSL_atexit() and
235       OPENSSL_INIT_set_config_appname() return 1 on success or 0 on error.
236

SEE ALSO

238       OPENSSL_init_ssl(3)
239

HISTORY

241       The OPENSSL_init_crypto(), OPENSSL_cleanup(), OPENSSL_atexit(),
242       OPENSSL_thread_stop(), OPENSSL_INIT_new(),
243       OPENSSL_INIT_set_config_appname() and OPENSSL_INIT_free() functions
244       were added in OpenSSL 1.1.0.
245
247       Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.
248
249       Licensed under the OpenSSL license (the "License").  You may not use
250       this file except in compliance with the License.  You can obtain a copy
251       in the file LICENSE in the source distribution or at
252       <https://www.openssl.org/source/license.html>.
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2561.1.1l                            2021-09-15            OPENSSL_INIT_CRYPTO(3)
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