Upgrade to OpenSSL 0.9.8h.
[dragonfly.git] / secure / lib / libcrypto / man / threads.3
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129.\" ========================================================================
130.\"
131.IX Title "threads 3"
aac4ff6f 132.TH threads 3 "2008-09-06" "0.9.8h" "OpenSSL"
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133.SH "NAME"
134CRYPTO_set_locking_callback, CRYPTO_set_id_callback, CRYPTO_num_locks,
135CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback,
136CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid,
137CRYPTO_destroy_dynlockid, CRYPTO_lock \- OpenSSL thread support
138.SH "SYNOPSIS"
8b0cefbb 139.IX Header "SYNOPSIS"
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140.Vb 1
141\& #include <openssl/crypto.h>
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142.Ve
143.PP
144.Vb 2
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145\& void CRYPTO_set_locking_callback(void (*locking_function)(int mode,
146\& int n, const char *file, int line));
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147.Ve
148.PP
149.Vb 1
984263bc 150\& void CRYPTO_set_id_callback(unsigned long (*id_function)(void));
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151.Ve
152.PP
153.Vb 1
984263bc 154\& int CRYPTO_num_locks(void);
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155.Ve
156.PP
157.Vb 2
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158\& /* struct CRYPTO_dynlock_value needs to be defined by the user */
159\& struct CRYPTO_dynlock_value;
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160.Ve
161.PP
162.Vb 7
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163\& void CRYPTO_set_dynlock_create_callback(struct CRYPTO_dynlock_value *
164\& (*dyn_create_function)(char *file, int line));
165\& void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function)
166\& (int mode, struct CRYPTO_dynlock_value *l,
167\& const char *file, int line));
168\& void CRYPTO_set_dynlock_destroy_callback(void (*dyn_destroy_function)
169\& (struct CRYPTO_dynlock_value *l, const char *file, int line));
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170.Ve
171.PP
172.Vb 1
984263bc 173\& int CRYPTO_get_new_dynlockid(void);
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174.Ve
175.PP
176.Vb 1
984263bc 177\& void CRYPTO_destroy_dynlockid(int i);
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178.Ve
179.PP
180.Vb 1
984263bc 181\& void CRYPTO_lock(int mode, int n, const char *file, int line);
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182.Ve
183.PP
184.Vb 10
984263bc 185\& #define CRYPTO_w_lock(type) \e
aac4ff6f 186\& CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE,type,__FILE__,__LINE__)
984263bc 187\& #define CRYPTO_w_unlock(type) \e
aac4ff6f 188\& CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE,type,__FILE__,__LINE__)
984263bc 189\& #define CRYPTO_r_lock(type) \e
aac4ff6f 190\& CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ,type,__FILE__,__LINE__)
984263bc 191\& #define CRYPTO_r_unlock(type) \e
aac4ff6f 192\& CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ,type,__FILE__,__LINE__)
984263bc 193\& #define CRYPTO_add(addr,amount,type) \e
aac4ff6f 194\& CRYPTO_add_lock(addr,amount,type,__FILE__,__LINE__)
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195.Ve
196.SH "DESCRIPTION"
8b0cefbb 197.IX Header "DESCRIPTION"
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198OpenSSL can safely be used in multi-threaded applications provided
199that at least two callback functions are set.
200.PP
8b0cefbb 201locking_function(int mode, int n, const char *file, int line) is
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202needed to perform locking on shared data structures.
203(Note that OpenSSL uses a number of global data structures that
204will be implicitly shared whenever multiple threads use OpenSSL.)
205Multi-threaded applications will crash at random if it is not set.
206.PP
8b0cefbb 207\&\fIlocking_function()\fR must be able to handle up to \fICRYPTO_num_locks()\fR
984263bc 208different mutex locks. It sets the \fBn\fR\-th lock if \fBmode\fR &
8b0cefbb 209\&\fB\s-1CRYPTO_LOCK\s0\fR, and releases it otherwise.
984263bc 210.PP
8b0cefbb 211\&\fBfile\fR and \fBline\fR are the file number of the function setting the
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212lock. They can be useful for debugging.
213.PP
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214id_function(void) is a function that returns a thread \s-1ID\s0, for example
215\&\fIpthread_self()\fR if it returns an integer (see \s-1NOTES\s0 below). It isn't
984263bc 216needed on Windows nor on platforms where \fIgetpid()\fR returns a different
a561f9ff 217\&\s-1ID\s0 for each thread (see \s-1NOTES\s0 below).
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218.PP
219Additionally, OpenSSL supports dynamic locks, and sometimes, some parts
220of OpenSSL need it for better performance. To enable this, the following
221is required:
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222.IP "* Three additional callback function, dyn_create_function, dyn_lock_function and dyn_destroy_function." 4
223.IX Item "Three additional callback function, dyn_create_function, dyn_lock_function and dyn_destroy_function."
224.PD 0
225.IP "* A structure defined with the data that each lock needs to handle." 4
226.IX Item "A structure defined with the data that each lock needs to handle."
227.PD
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228.PP
229struct CRYPTO_dynlock_value has to be defined to contain whatever structure
230is needed to handle locks.
231.PP
8b0cefbb 232dyn_create_function(const char *file, int line) is needed to create a
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233lock. Multi-threaded applications might crash at random if it is not set.
234.PP
8b0cefbb 235dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int line)
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236is needed to perform locking off dynamic lock numbered n. Multi-threaded
237applications might crash at random if it is not set.
238.PP
8b0cefbb 239dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is
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240needed to destroy the lock l. Multi-threaded applications might crash at
241random if it is not set.
242.PP
8b0cefbb 243\&\fICRYPTO_get_new_dynlockid()\fR is used to create locks. It will call
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244dyn_create_function for the actual creation.
245.PP
8b0cefbb 246\&\fICRYPTO_destroy_dynlockid()\fR is used to destroy locks. It will call
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247dyn_destroy_function for the actual destruction.
248.PP
8b0cefbb 249\&\fICRYPTO_lock()\fR is used to lock and unlock the locks. mode is a bitfield
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250describing what should be done with the lock. n is the number of the
251lock as returned from \fICRYPTO_get_new_dynlockid()\fR. mode can be combined
252from the following values. These values are pairwise exclusive, with
253undefined behaviour if misused (for example, \s-1CRYPTO_READ\s0 and \s-1CRYPTO_WRITE\s0
254should not be used together):
255.PP
256.Vb 4
257\& CRYPTO_LOCK 0x01
258\& CRYPTO_UNLOCK 0x02
259\& CRYPTO_READ 0x04
260\& CRYPTO_WRITE 0x08
261.Ve
262.SH "RETURN VALUES"
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263.IX Header "RETURN VALUES"
264\&\fICRYPTO_num_locks()\fR returns the required number of locks.
984263bc 265.PP
8b0cefbb 266\&\fICRYPTO_get_new_dynlockid()\fR returns the index to the newly created lock.
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267.PP
268The other functions return no values.
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269.SH "NOTES"
270.IX Header "NOTES"
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271You can find out if OpenSSL was configured with thread support:
272.PP
273.Vb 7
274\& #define OPENSSL_THREAD_DEFINES
275\& #include <openssl/opensslconf.h>
a561f9ff 276\& #if defined(OPENSSL_THREADS)
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277\& // thread support enabled
278\& #else
279\& // no thread support
280\& #endif
281.Ve
8b0cefbb 282.PP
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283Also, dynamic locks are currently not used internally by OpenSSL, but
284may do so in the future.
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285.PP
286Defining id_function(void) has it's own issues. Generally speaking,
287\&\fIpthread_self()\fR should be used, even on platforms where \fIgetpid()\fR gives
288different answers in each thread, since that may depend on the machine
289the program is run on, not the machine where the program is being
290compiled. For instance, Red Hat 8 Linux and earlier used
291LinuxThreads, whose \fIgetpid()\fR returns a different value for each
292thread. Red Hat 9 Linux and later use \s-1NPTL\s0, which is
aac4ff6f 293Posix\-conformant, and has a \fIgetpid()\fR that returns the same value for
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294all threads in a process. A program compiled on Red Hat 8 and run on
295Red Hat 9 will therefore see \fIgetpid()\fR returning the same value for
296all threads.
297.PP
298There is still the issue of platforms where \fIpthread_self()\fR returns
299something other than an integer. This is a bit unusual, and this
300manual has no cookbook solution for that case.
984263bc 301.SH "EXAMPLES"
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302.IX Header "EXAMPLES"
303\&\fBcrypto/threads/mttest.c\fR shows examples of the callback functions on
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304Solaris, Irix and Win32.
305.SH "HISTORY"
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306.IX Header "HISTORY"
307\&\fICRYPTO_set_locking_callback()\fR and \fICRYPTO_set_id_callback()\fR are
984263bc 308available in all versions of SSLeay and OpenSSL.
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309\&\fICRYPTO_num_locks()\fR was added in OpenSSL 0.9.4.
310All functions dealing with dynamic locks were added in OpenSSL 0.9.5b\-dev.
984263bc 311.SH "SEE ALSO"
74dab6c2 312.IX Header "SEE ALSO"
8b0cefbb 313\&\fIcrypto\fR\|(3)