[netbsd-mini2440.git] / crypto / external / bsd / openssl / lib / libcrypto / man / openssl_threads.3
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136 .IX Title "threads 3"
137 .TH threads 3 "2008-08-06" "1.1.0-dev" "OpenSSL"
138 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
139 .\" way too many mistakes in technical documents.
140 .if n .ad l
141 .nh
142 .SH "NAME"
143 CRYPTO_THREADID_set_callback, CRYPTO_THREADID_get_callback,
144 CRYPTO_THREADID_current, CRYPTO_THREADID_cmp, CRYPTO_THREADID_cpy,
145 CRYPTO_THREADID_hash, CRYPTO_set_locking_callback, CRYPTO_num_locks,
146 CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback,
147 CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid,
148 CRYPTO_destroy_dynlockid, CRYPTO_lock \- OpenSSL thread support
149 .SH "LIBRARY"
150 libcrypto, -lcrypto
151 .SH "SYNOPSIS"
152 .IX Header "SYNOPSIS"
153 .Vb 1
154 \& #include <openssl/crypto.h>
155 \&
156 \& /* Don\*(Aqt use this structure directly. */
157 \& typedef struct crypto_threadid_st
158 \& {
159 \& void *ptr;
160 \& unsigned long val;
161 \& } CRYPTO_THREADID;
162 \& /* Only use CRYPTO_THREADID_set_[numeric|pointer]() within callbacks */
163 \& void CRYPTO_THREADID_set_numeric(CRYPTO_THREADID *id, unsigned long val);
164 \& void CRYPTO_THREADID_set_pointer(CRYPTO_THREADID *id, void *ptr);
165 \& int CRYPTO_THREADID_set_callback(void (*threadid_func)(CRYPTO_THREADID *));
166 \& void (*CRYPTO_THREADID_get_callback(void))(CRYPTO_THREADID *);
167 \& void CRYPTO_THREADID_current(CRYPTO_THREADID *id);
168 \& int CRYPTO_THREADID_cmp(const CRYPTO_THREADID *a,
169 \& const CRYPTO_THREADID *b);
170 \& void CRYPTO_THREADID_cpy(CRYPTO_THREADID *dest,
171 \& const CRYPTO_THREADID *src);
172 \& unsigned long CRYPTO_THREADID_hash(const CRYPTO_THREADID *id);
173 \&
174 \& int CRYPTO_num_locks(void);
175 \&
176 \& /* struct CRYPTO_dynlock_value needs to be defined by the user */
177 \& struct CRYPTO_dynlock_value;
178 \&
179 \& void CRYPTO_set_dynlock_create_callback(struct CRYPTO_dynlock_value *
180 \& (*dyn_create_function)(char *file, int line));
181 \& void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function)
182 \& (int mode, struct CRYPTO_dynlock_value *l,
183 \& const char *file, int line));
184 \& void CRYPTO_set_dynlock_destroy_callback(void (*dyn_destroy_function)
185 \& (struct CRYPTO_dynlock_value *l, const char *file, int line));
186 \&
187 \& int CRYPTO_get_new_dynlockid(void);
188 \&
189 \& void CRYPTO_destroy_dynlockid(int i);
190 \&
191 \& void CRYPTO_lock(int mode, int n, const char *file, int line);
192 \&
193 \& #define CRYPTO_w_lock(type) \e
194 \& CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE,type,_\|_FILE_\|_,_\|_LINE_\|_)
195 \& #define CRYPTO_w_unlock(type) \e
196 \& CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE,type,_\|_FILE_\|_,_\|_LINE_\|_)
197 \& #define CRYPTO_r_lock(type) \e
198 \& CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ,type,_\|_FILE_\|_,_\|_LINE_\|_)
199 \& #define CRYPTO_r_unlock(type) \e
200 \& CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ,type,_\|_FILE_\|_,_\|_LINE_\|_)
201 \& #define CRYPTO_add(addr,amount,type) \e
202 \& CRYPTO_add_lock(addr,amount,type,_\|_FILE_\|_,_\|_LINE_\|_)
203 .Ve
204 .SH "DESCRIPTION"
205 .IX Header "DESCRIPTION"
206 OpenSSL can safely be used in multi-threaded applications provided
207 that at least two callback functions are set, locking_function and
208 threadid_func.
209 .PP
210 locking_function(int mode, int n, const char *file, int line) is
211 needed to perform locking on shared data structures.
212 (Note that OpenSSL uses a number of global data structures that
213 will be implicitly shared whenever multiple threads use OpenSSL.)
214 Multi-threaded applications will crash at random if it is not set.
215 .PP
216 \&\fIlocking_function()\fR must be able to handle up to \fICRYPTO_num_locks()\fR
217 different mutex locks. It sets the \fBn\fR\-th lock if \fBmode\fR &
218 \&\fB\s-1CRYPTO_LOCK\s0\fR, and releases it otherwise.
219 .PP
220 \&\fBfile\fR and \fBline\fR are the file number of the function setting the
221 lock. They can be useful for debugging.
222 .PP
223 threadid_func(\s-1CRYPTO_THREADID\s0 *id) is needed to record the currently-executing
224 thread's identifier into \fBid\fR. The implementation of this callback should not
225 fill in \fBid\fR directly, but should use \fICRYPTO_THREADID_set_numeric()\fR if thread
226 IDs are numeric, or \fICRYPTO_THREADID_set_pointer()\fR if they are pointer-based.
227 If the application does not register such a callback using
228 \&\fICRYPTO_THREADID_set_callback()\fR, then a default implementation is used \- on
229 Windows and BeOS this uses the system's default thread identifying APIs, and on
230 all other platforms it uses the address of \fBerrno\fR. The latter is satisfactory
231 for thread-safety if and only if the platform has a thread-local error number
232 facility.
233 .PP
234 Once \fIthreadid_func()\fR is registered, or if the built-in default implementation is
235 to be used;
236 .IP "\(bu" 4
237 \&\fICRYPTO_THREADID_current()\fR records the currently-executing thread \s-1ID\s0 into the
238 given \fBid\fR object.
239 .IP "\(bu" 4
240 \&\fICRYPTO_THREADID_cmp()\fR compares two thread IDs (returning zero for equality, ie.
241 the same semantics as \fImemcmp()\fR).
242 .IP "\(bu" 4
243 \&\fICRYPTO_THREADID_cpy()\fR duplicates a thread \s-1ID\s0 value,
244 .IP "\(bu" 4
245 \&\fICRYPTO_THREADID_hash()\fR returns a numeric value usable as a hash-table key. This
246 is usually the exact numeric or pointer-based thread \s-1ID\s0 used internally, however
247 this also handles the unusual case where pointers are larger than 'long'
248 variables and the platform's thread IDs are pointer-based \- in this case, mixing
249 is done to attempt to produce a unique numeric value even though it is not as
250 wide as the platform's true thread IDs.
251 .PP
252 Additionally, OpenSSL supports dynamic locks, and sometimes, some parts
253 of OpenSSL need it for better performance. To enable this, the following
254 is required:
255 .IP "\(bu" 4
256 Three additional callback function, dyn_create_function, dyn_lock_function
257 and dyn_destroy_function.
258 .IP "\(bu" 4
259 A structure defined with the data that each lock needs to handle.
260 .PP
261 struct CRYPTO_dynlock_value has to be defined to contain whatever structure
262 is needed to handle locks.
263 .PP
264 dyn_create_function(const char *file, int line) is needed to create a
265 lock. Multi-threaded applications might crash at random if it is not set.
266 .PP
267 dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int line)
268 is needed to perform locking off dynamic lock numbered n. Multi-threaded
269 applications might crash at random if it is not set.
270 .PP
271 dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is
272 needed to destroy the lock l. Multi-threaded applications might crash at
273 random if it is not set.
274 .PP
275 \&\fICRYPTO_get_new_dynlockid()\fR is used to create locks. It will call
276 dyn_create_function for the actual creation.
277 .PP
278 \&\fICRYPTO_destroy_dynlockid()\fR is used to destroy locks. It will call
279 dyn_destroy_function for the actual destruction.
280 .PP
281 \&\fICRYPTO_lock()\fR is used to lock and unlock the locks. mode is a bitfield
282 describing what should be done with the lock. n is the number of the
283 lock as returned from \fICRYPTO_get_new_dynlockid()\fR. mode can be combined
284 from the following values. These values are pairwise exclusive, with
285 undefined behaviour if misused (for example, \s-1CRYPTO_READ\s0 and \s-1CRYPTO_WRITE\s0
286 should not be used together):
287 .PP
288 .Vb 4
289 \& CRYPTO_LOCK 0x01
290 \& CRYPTO_UNLOCK 0x02
291 \& CRYPTO_READ 0x04
292 \& CRYPTO_WRITE 0x08
293 .Ve
294 .SH "RETURN VALUES"
295 .IX Header "RETURN VALUES"
296 \&\fICRYPTO_num_locks()\fR returns the required number of locks.
297 .PP
298 \&\fICRYPTO_get_new_dynlockid()\fR returns the index to the newly created lock.
299 .PP
300 The other functions return no values.
301 .SH "NOTES"
302 .IX Header "NOTES"
303 You can find out if OpenSSL was configured with thread support:
304 .PP
305 .Vb 7
306 \& #define OPENSSL_THREAD_DEFINES
307 \& #include <openssl/opensslconf.h>
308 \& #if defined(OPENSSL_THREADS)
309 \& // thread support enabled
310 \& #else
311 \& // no thread support
312 \& #endif
313 .Ve
314 .PP
315 Also, dynamic locks are currently not used internally by OpenSSL, but
316 may do so in the future.
317 .SH "EXAMPLES"
318 .IX Header "EXAMPLES"
319 \&\fBcrypto/threads/mttest.c\fR shows examples of the callback functions on
320 Solaris, Irix and Win32.
321 .SH "HISTORY"
322 .IX Header "HISTORY"
323 \&\fICRYPTO_set_locking_callback()\fR is
324 available in all versions of SSLeay and OpenSSL.
325 \&\fICRYPTO_num_locks()\fR was added in OpenSSL 0.9.4.
326 All functions dealing with dynamic locks were added in OpenSSL 0.9.5b\-dev.
327 \&\fB\s-1CRYPTO_THREADID\s0\fR and associated functions were introduced in OpenSSL 0.9.9
328 to replace (actually, deprecate) the previous \fICRYPTO_set_id_callback()\fR,
329 \&\fICRYPTO_get_id_callback()\fR, and \fICRYPTO_thread_id()\fR functions which assumed
330 thread IDs to always be represented by 'unsigned long'.
331 .SH "SEE ALSO"
332 .IX Header "SEE ALSO"
333 \&\fIcrypto\fR\|(3)