1=pod
2
3=head1 NAME
4
5OPENSSL_INIT_new, OPENSSL_INIT_set_config_filename,
6OPENSSL_INIT_set_config_appname, OPENSSL_INIT_set_config_file_flags,
7OPENSSL_INIT_free, OPENSSL_init_crypto, OPENSSL_cleanup, OPENSSL_atexit,
8OPENSSL_thread_stop - OpenSSL initialisation
9and deinitialisation functions
10
11=head1 SYNOPSIS
12
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
29=head1 DESCRIPTION
30
31During normal operation OpenSSL (libcrypto) will allocate various resources at
32start up that must, subsequently, be freed on close down of the library.
33Additionally some resources are allocated on a per thread basis (if the
34application is multi-threaded), and these resources must be freed prior to the
35thread closing.
36
37As of version 1.1.0 OpenSSL will automatically allocate all resources that it
38needs so no explicit initialisation is required. Similarly it will also
39automatically deinitialise as required.
40
41However, there may be situations when explicit initialisation is desirable or
42needed, for example when some nondefault initialisation is required. The
43function OPENSSL_init_crypto() can be used for this purpose for
44libcrypto (see also L<OPENSSL_init_ssl(3)> for the libssl
45equivalent).
46
47Numerous internal OpenSSL functions call OPENSSL_init_crypto().
48Therefore, in order to perform nondefault initialisation,
49OPENSSL_init_crypto() MUST be called by application code prior to
50any other OpenSSL function calls.
51
52The B<opts> parameter specifies which aspects of libcrypto should be
53initialised. Valid options are:
54
55=over 4
56
57=item OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS
58
59Suppress automatic loading of the libcrypto error strings. This option is
60not a default option. Once selected subsequent calls to
61OPENSSL_init_crypto() with the option
62B<OPENSSL_INIT_LOAD_CRYPTO_STRINGS> will be ignored.
63
64=item OPENSSL_INIT_LOAD_CRYPTO_STRINGS
65
66Automatic loading of the libcrypto error strings. With this option the
67library will automatically load the libcrypto error strings.
68This option is a default option. Once selected subsequent calls to
69OPENSSL_init_crypto() with the option
70B<OPENSSL_INIT_NO_LOAD_CRYPTO_STRINGS> will be ignored.
71
72=item OPENSSL_INIT_ADD_ALL_CIPHERS
73
74With this option the library will automatically load and make available all
75libcrypto ciphers. This option is a default option. Once selected subsequent
76calls to OPENSSL_init_crypto() with the option
77B<OPENSSL_INIT_NO_ADD_ALL_CIPHERS> will be ignored.
78
79=item OPENSSL_INIT_ADD_ALL_DIGESTS
80
81With this option the library will automatically load and make available all
82libcrypto digests. This option is a default option. Once selected subsequent
83calls to OPENSSL_init_crypto() with the option
84B<OPENSSL_INIT_NO_ADD_ALL_CIPHERS> will be ignored.
85
86=item OPENSSL_INIT_NO_ADD_ALL_CIPHERS
87
88With this option the library will suppress automatic loading of libcrypto
89ciphers. This option is not a default option. Once selected subsequent
90calls to OPENSSL_init_crypto() with the option
91B<OPENSSL_INIT_ADD_ALL_CIPHERS> will be ignored.
92
93=item OPENSSL_INIT_NO_ADD_ALL_DIGESTS
94
95With this option the library will suppress automatic loading of libcrypto
96digests. This option is not a default option. Once selected subsequent
97calls to OPENSSL_init_crypto() with the option
98B<OPENSSL_INIT_ADD_ALL_DIGESTS> will be ignored.
99
100=item OPENSSL_INIT_LOAD_CONFIG
101
102With this option an OpenSSL configuration file will be automatically loaded and
103used by calling OPENSSL_config(). This is not a default option for libcrypto.
104As of OpenSSL 1.1.1 this is a default option for libssl (see
105L<OPENSSL_init_ssl(3)> for further details about libssl initialisation). See the
106description of OPENSSL_INIT_new(), below.
107
108=item OPENSSL_INIT_NO_LOAD_CONFIG
109
110With this option the loading of OpenSSL configuration files will be suppressed.
111It is the equivalent of calling OPENSSL_no_config(). This is not a default
112option.
113
114=item OPENSSL_INIT_ASYNC
115
116With this option the library with automatically initialise the libcrypto async
117sub-library (see L<ASYNC_start_job(3)>). This is a default option.
118
119=item OPENSSL_INIT_ENGINE_RDRAND
120
121With this option the library will automatically load and initialise the
122RDRAND engine (if available). This not a default option.
123
124=item OPENSSL_INIT_ENGINE_DYNAMIC
125
126With this option the library will automatically load and initialise the
127dynamic engine. This not a default option.
128
129=item OPENSSL_INIT_ENGINE_OPENSSL
130
131With this option the library will automatically load and initialise the
132openssl engine. This not a default option.
133
134=item OPENSSL_INIT_ENGINE_CRYPTODEV
135
136With this option the library will automatically load and initialise the
137cryptodev engine (if available). This not a default option.
138
139=item OPENSSL_INIT_ENGINE_CAPI
140
141With this option the library will automatically load and initialise the
142CAPI engine (if available). This not a default option.
143
144=item OPENSSL_INIT_ENGINE_PADLOCK
145
146With this option the library will automatically load and initialise the
147padlock engine (if available). This not a default option.
148
149=item OPENSSL_INIT_ENGINE_AFALG
150
151With this option the library will automatically load and initialise the
152AFALG engine. This not a default option.
153
154=item OPENSSL_INIT_ENGINE_ALL_BUILTIN
155
156With this option the library will automatically load and initialise all the
157built in engines listed above with the exception of the openssl and afalg
158engines. This not a default option.
159
160=item OPENSSL_INIT_ATFORK
161
162With this option the library will register its fork handlers.
163See OPENSSL_fork_prepare(3) for details.
164
165=item OPENSSL_INIT_NO_ATEXIT
166
167By default OpenSSL will attempt to clean itself up when the process exits via an
168"atexit" handler. Using this option suppresses that behaviour. This means that
169the application will have to clean up OpenSSL explicitly using
170OPENSSL_cleanup().
171
172=back
173
174Multiple options may be combined together in a single call to
175OPENSSL_init_crypto(). For example:
176
177 OPENSSL_init_crypto(OPENSSL_INIT_NO_ADD_ALL_CIPHERS
178                     | OPENSSL_INIT_NO_ADD_ALL_DIGESTS, NULL);
179
180The OPENSSL_cleanup() function deinitialises OpenSSL (both libcrypto
181and libssl). All resources allocated by OpenSSL are freed. Typically there
182should be no need to call this function directly as it is initiated
183automatically on application exit. This is done via the standard C library
184atexit() function. In the event that the application will close in a manner
185that will not call the registered atexit() handlers then the application should
186call OPENSSL_cleanup() directly. Developers of libraries using OpenSSL
187are discouraged from calling this function and should instead, typically, rely
188on auto-deinitialisation. This is to avoid error conditions where both an
189application and a library it depends on both use OpenSSL, and the library
190deinitialises it before the application has finished using it.
191
192Once OPENSSL_cleanup() has been called the library cannot be reinitialised.
193Attempts to call OPENSSL_init_crypto() will fail and an ERR_R_INIT_FAIL error
194will be added to the error stack. Note that because initialisation has failed
195OpenSSL error strings will not be available, only an error code. This code can
196be put through the openssl errstr command line application to produce a human
197readable error (see L<errstr(1)>).
198
199The OPENSSL_atexit() function enables the registration of a
200function to be called during OPENSSL_cleanup(). Stop handlers are
201called after deinitialisation of resources local to a thread, but before other
202process wide resources are freed. In the event that multiple stop handlers are
203registered, no guarantees are made about the order of execution.
204
205The OPENSSL_thread_stop() function deallocates resources associated
206with the current thread. Typically this function will be called automatically by
207the library when the thread exits. This should only be called directly if
208resources should be freed at an earlier time, or under the circumstances
209described in the NOTES section below.
210
211The B<OPENSSL_INIT_LOAD_CONFIG> flag will load a configuration file, as with
212L<CONF_modules_load_file(3)> with NULL filename and application name and the
213B<CONF_MFLAGS_IGNORE_MISSING_FILE>, B<CONF_MFLAGS_IGNORE_RETURN_CODES>  and
214B<CONF_MFLAGS_DEFAULT_SECTION> flags.
215The filename, application name, and flags can be customized by providing a
216non-null B<OPENSSL_INIT_SETTINGS> object.
217The object can be allocated via B<OPENSSL_init_new()>.
218The B<OPENSSL_INIT_set_config_filename()> function can be used to specify a
219nondefault filename, which is copied and need not refer to persistent storage.
220Similarly, OPENSSL_INIT_set_config_appname() can be used to specify a
221nondefault application name.
222Finally, OPENSSL_INIT_set_file_flags can be used to specify nondefault flags.
223If the B<CONF_MFLAGS_IGNORE_RETURN_CODES> flag is not included, any errors in
224the configuration file will cause an error return from B<OPENSSL_init_crypto>
225or indirectly L<OPENSSL_init_ssl(3)>.
226The object can be released with OPENSSL_INIT_free() when done.
227
228=head1 NOTES
229
230Resources local to a thread are deallocated automatically when the thread exits
231(e.g. in a pthreads environment, when pthread_exit() is called). On Windows
232platforms this is done in response to a DLL_THREAD_DETACH message being sent to
233the libcrypto32.dll entry point. Some windows functions may cause threads to exit
234without sending this message (for example ExitProcess()). If the application
235uses such functions, then the application must free up OpenSSL resources
236directly via a call to OPENSSL_thread_stop() on each thread. Similarly this
237message will also not be sent if OpenSSL is linked statically, and therefore
238applications using static linking should also call OPENSSL_thread_stop() on each
239thread. Additionally if OpenSSL is loaded dynamically via LoadLibrary() and the
240threads are not destroyed until after FreeLibrary() is called then each thread
241should call OPENSSL_thread_stop() prior to the FreeLibrary() call.
242
243On Linux/Unix where OpenSSL has been loaded via dlopen() and the application is
244multi-threaded and if dlclose() is subsequently called prior to the threads
245being destroyed then OpenSSL will not be able to deallocate resources associated
246with those threads. The application should either call OPENSSL_thread_stop() on
247each thread prior to the dlclose() call, or alternatively the original dlopen()
248call should use the RTLD_NODELETE flag (where available on the platform).
249
250=head1 RETURN VALUES
251
252The functions OPENSSL_init_crypto, OPENSSL_atexit() and
253OPENSSL_INIT_set_config_appname() return 1 on success or 0 on error.
254
255=head1 SEE ALSO
256
257L<OPENSSL_init_ssl(3)>
258
259=head1 HISTORY
260
261The OPENSSL_init_crypto(), OPENSSL_cleanup(), OPENSSL_atexit(),
262OPENSSL_thread_stop(), OPENSSL_INIT_new(), OPENSSL_INIT_set_config_appname()
263and OPENSSL_INIT_free() functions were added in OpenSSL 1.1.0.
264
265=head1 COPYRIGHT
266
267Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.
268
269Licensed under the OpenSSL license (the "License").  You may not use
270this file except in compliance with the License.  You can obtain a copy
271in the file LICENSE in the source distribution or at
272L<https://www.openssl.org/source/license.html>.
273
274=cut
275