• NAME
• SYNOPSIS
• DESCRIPTION
• NOTES
• RETURN VALUES
• SEE ALSO
• HISTORY
• COPYRIGHT

NAME

OPENSSL_INIT_new, OPENSSL_INIT_set_config_filename, OPENSSL_INIT_set_config_appname, OPENSSL_INIT_set_config_file_flags, OPENSSL_INIT_free, OPENSSL_init_crypto, OPENSSL_cleanup, OPENSSL_atexit, OPENSSL_thread_stop_ex, OPENSSL_thread_stop - OpenSSL initialisation and deinitialisation functions

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_ex(OPENSSL_CTX *ctx);
 void OPENSSL_thread_stop(void);
 
 OPENSSL_INIT_SETTINGS *OPENSSL_INIT_new(void);
 int OPENSSL_INIT_set_config_filename(OPENSSL_INIT_SETTINGS *init,
                                      const char* filename);
 int OPENSSL_INIT_set_config_file_flags(OPENSSL_INIT_SETTINGS *init,
                                        unsigned long flags);
 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 may 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_NO_LOAD_CRYPTO_STRINGS

 OPENSSL_init_crypto(OPENSSL_INIT_NO_ADD_ALL_CIPHERS
                     | OPENSSL_INIT_NO_ADD_ALL_DIGESTS, NULL);

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 CONF_modules_load_file(3) with NULL filename and application name and the CONF_MFLAGS_IGNORE_MISSING_FILE, CONF_MFLAGS_IGNORE_RETURN_CODES and CONF_MFLAGS_DEFAULT_SECTION flags. The filename, application name, and flags can be customized by providing a non-null OPENSSL_INIT_SETTINGS object. The object can be allocated via OPENSSL_INIT_new(). The OPENSSL_INIT_set_config_filename() function can be used to specify a non-default filename, which is copied and need not refer to persistent storage. Similarly, OPENSSL_INIT_set_config_appname() can be used to specify a non-default application name. Finally, OPENSSL_INIT_set_file_flags can be used to specify non-default flags. If the CONF_MFLAGS_IGNORE_RETURN_CODES flag is not included, any errors in the configuration file will cause an error return from OPENSSL_init_crypto or indirectly 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.

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.

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.