1threads(3) OpenSSL threads(3)
2
6 CRYPTO_THREADID_set_callback, CRYPTO_THREADID_get_callback,
7 CRYPTO_THREADID_current, CRYPTO_THREADID_cmp, CRYPTO_THREADID_cpy,
8 CRYPTO_THREADID_hash, CRYPTO_set_locking_callback, CRYPTO_num_locks,
9 CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback,
10 CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid,
11 CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support
12
14 #include <openssl/crypto.h>
15 /* Don't use this structure directly. */
17 typedef struct crypto_threadid_st
18 {
19 void *ptr;
20 unsigned long val;
21 } CRYPTO_THREADID;
22 /* Only use CRYPTO_THREADID_set_[numeric|pointer]() within callbacks */
23 void CRYPTO_THREADID_set_numeric(CRYPTO_THREADID *id, unsigned long val);
24 void CRYPTO_THREADID_set_pointer(CRYPTO_THREADID *id, void *ptr);
25 int CRYPTO_THREADID_set_callback(void (*threadid_func)(CRYPTO_THREADID *));
26 void (*CRYPTO_THREADID_get_callback(void))(CRYPTO_THREADID *);
27 void CRYPTO_THREADID_current(CRYPTO_THREADID *id);
28 int CRYPTO_THREADID_cmp(const CRYPTO_THREADID *a,
29 const CRYPTO_THREADID *b);
30 void CRYPTO_THREADID_cpy(CRYPTO_THREADID *dest,
31 const CRYPTO_THREADID *src);
32 unsigned long CRYPTO_THREADID_hash(const CRYPTO_THREADID *id);
33 int CRYPTO_num_locks(void);
35 /* struct CRYPTO_dynlock_value needs to be defined by the user */
37 struct CRYPTO_dynlock_value;
38 void CRYPTO_set_dynlock_create_callback(struct CRYPTO_dynlock_value *
40 (*dyn_create_function)(char *file, int line));
41 void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function)
42 (int mode, struct CRYPTO_dynlock_value *l,
43 const char *file, int line));
44 void CRYPTO_set_dynlock_destroy_callback(void (*dyn_destroy_function)
45 (struct CRYPTO_dynlock_value *l, const char *file, int line));
46 int CRYPTO_get_new_dynlockid(void);
48 void CRYPTO_destroy_dynlockid(int i);
50 void CRYPTO_lock(int mode, int n, const char *file, int line);
52 #define CRYPTO_w_lock(type) \
54 CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE,type,__FILE__,__LINE__)
55 #define CRYPTO_w_unlock(type) \
56 CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE,type,__FILE__,__LINE__)
57 #define CRYPTO_r_lock(type) \
58 CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ,type,__FILE__,__LINE__)
59 #define CRYPTO_r_unlock(type) \
60 CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ,type,__FILE__,__LINE__)
61 #define CRYPTO_add(addr,amount,type) \
62 CRYPTO_add_lock(addr,amount,type,__FILE__,__LINE__)
63
65 OpenSSL can safely be used in multi-threaded applications provided that
66 at least two callback functions are set, locking_function and
67 threadid_func.
68 locking_function(int mode, int n, const char *file, int line) is needed
70 to perform locking on shared data structures. (Note that OpenSSL uses
71 a number of global data structures that will be implicitly shared
72 whenever multiple threads use OpenSSL.) Multi-threaded applications
73 will crash at random if it is not set.
74 locking_function() must be able to handle up to CRYPTO_num_locks()
76 different mutex locks. It sets the n-th lock if mode & CRYPTO_LOCK, and
77 releases it otherwise.
78 file and line are the file number of the function setting the lock.
80 They can be useful for debugging.
81 threadid_func(CRYPTO_THREADID *id) is needed to record the currently-
83 executing thread's identifier into id. The implementation of this
84 callback should not fill in id directly, but should use
85 CRYPTO_THREADID_set_numeric() if thread IDs are numeric, or
86 CRYPTO_THREADID_set_pointer() if they are pointer-based. If the
87 application does not register such a callback using
88 CRYPTO_THREADID_set_callback(), then a default implementation is used -
89 on Windows and BeOS this uses the system's default thread identifying
90 APIs, and on all other platforms it uses the address of errno. The
91 latter is satisfactory for thread-safety if and only if the platform
92 has a thread-local error number facility.
93 Once threadid_func() is registered, or if the built-in default
95 implementation is to be used;
96 · CRYPTO_THREADID_current() records the currently-executing thread ID
98 into the given id object.
99 · CRYPTO_THREADID_cmp() compares two thread IDs (returning zero for
101 equality, ie. the same semantics as memcmp()).
102 · CRYPTO_THREADID_cpy() duplicates a thread ID value,
104 · CRYPTO_THREADID_hash() returns a numeric value usable as a hash-
106 table key. This is usually the exact numeric or pointer-based
107 thread ID used internally, however this also handles the unusual
108 case where pointers are larger than 'long' variables and the
109 platform's thread IDs are pointer-based - in this case, mixing is
110 done to attempt to produce a unique numeric value even though it is
111 not as wide as the platform's true thread IDs.
112 Additionally, OpenSSL supports dynamic locks, and sometimes, some parts
114 of OpenSSL need it for better performance. To enable this, the
115 following is required:
116 · Three additional callback function, dyn_create_function,
118 dyn_lock_function and dyn_destroy_function.
119 · A structure defined with the data that each lock needs to handle.
121 struct CRYPTO_dynlock_value has to be defined to contain whatever
123 structure is needed to handle locks.
124 dyn_create_function(const char *file, int line) is needed to create a
126 lock. Multi-threaded applications might crash at random if it is not
127 set.
128 dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int
130 line) is needed to perform locking off dynamic lock numbered n. Multi-
131 threaded applications might crash at random if it is not set.
132 dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is
134 needed to destroy the lock l. Multi-threaded applications might crash
135 at random if it is not set.
136 CRYPTO_get_new_dynlockid() is used to create locks. It will call
138 dyn_create_function for the actual creation.
139 CRYPTO_destroy_dynlockid() is used to destroy locks. It will call
141 dyn_destroy_function for the actual destruction.
142 CRYPTO_lock() is used to lock and unlock the locks. mode is a bitfield
144 describing what should be done with the lock. n is the number of the
145 lock as returned from CRYPTO_get_new_dynlockid(). mode can be combined
146 from the following values. These values are pairwise exclusive, with
147 undefined behaviour if misused (for example, CRYPTO_READ and
148 CRYPTO_WRITE should not be used together):
149 CRYPTO_LOCK 0x01
151 CRYPTO_UNLOCK 0x02
152 CRYPTO_READ 0x04
153 CRYPTO_WRITE 0x08
154
156 CRYPTO_num_locks() returns the required number of locks.
157 CRYPTO_get_new_dynlockid() returns the index to the newly created lock.
159 The other functions return no values.
161
163 You can find out if OpenSSL was configured with thread support:
164 #define OPENSSL_THREAD_DEFINES
166 #include <openssl/opensslconf.h>
167 #if defined(OPENSSL_THREADS)
168 // thread support enabled
169 #else
170 // no thread support
171 #endif
172 Also, dynamic locks are currently not used internally by OpenSSL, but
174 may do so in the future.
175
177 crypto/threads/mttest.c shows examples of the callback functions on
178 Solaris, Irix and Win32.
179
181 CRYPTO_set_locking_callback() is available in all versions of SSLeay
182 and OpenSSL. CRYPTO_num_locks() was added in OpenSSL 0.9.4. All
183 functions dealing with dynamic locks were added in OpenSSL 0.9.5b-dev.
184 CRYPTO_THREADID and associated functions were introduced in OpenSSL
185 1.0.0 to replace (actually, deprecate) the previous
186 CRYPTO_set_id_callback(), CRYPTO_get_id_callback(), and
187 CRYPTO_thread_id() functions which assumed thread IDs to always be
188 represented by 'unsigned long'.
189
191 crypto(3)
1921.0.2k 2017-01-26 threads(3)