5 CRYPTO_THREADID_set_callback, CRYPTO_THREADID_get_callback,
6 CRYPTO_THREADID_current, CRYPTO_THREADID_cmp, CRYPTO_THREADID_cpy,
7 CRYPTO_THREADID_hash, CRYPTO_set_locking_callback, CRYPTO_num_locks,
8 CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback,
9 CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid,
10 CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support
14 #include <openssl/crypto.h>
16 /* Don't use this structure directly. */
17 typedef struct crypto_threadid_st
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);
34 int CRYPTO_num_locks(void);
36 /* struct CRYPTO_dynlock_value needs to be defined by the user */
37 struct CRYPTO_dynlock_value;
39 void CRYPTO_set_dynlock_create_callback(struct CRYPTO_dynlock_value *
40 (*dyn_create_function)(const 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));
47 int CRYPTO_get_new_dynlockid(void);
49 void CRYPTO_destroy_dynlockid(int i);
51 void CRYPTO_lock(int mode, int n, const char *file, int line);
53 #define CRYPTO_w_lock(type) \
54 CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE,type,OPENSSL_FILE,OPENSSL_LINE)
55 #define CRYPTO_w_unlock(type) \
56 CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE,type,OPENSSL_FILE,OPENSSL_LINE)
57 #define CRYPTO_r_lock(type) \
58 CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ,type,OPENSSL_FILE,OPENSSL_LINE)
59 #define CRYPTO_r_unlock(type) \
60 CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ,type,OPENSSL_FILE,OPENSSL_LINE)
61 #define CRYPTO_add(addr,amount,type) \
62 CRYPTO_add_lock(addr,amount,type,OPENSSL_FILE,OPENSSL_LINE)
66 OpenSSL can safely be used in multi-threaded applications provided
67 that at least two callback functions are set, locking_function and
70 locking_function(int mode, int n, const char *file, int line) is
71 needed to perform locking on shared data structures.
72 (Note that OpenSSL uses a number of global data structures that
73 will be implicitly shared whenever multiple threads use OpenSSL.)
74 Multi-threaded applications will crash at random if it is not set.
76 locking_function() must be able to handle up to CRYPTO_num_locks()
77 different mutex locks. It sets the B<n>-th lock if B<mode> &
78 B<CRYPTO_LOCK>, and releases it otherwise.
80 B<file> and B<line> are the file number of the function setting the
81 lock. They can be useful for debugging.
83 threadid_func(CRYPTO_THREADID *id) is needed to record the currently-executing
84 thread's identifier into B<id>. The implementation of this callback should not
85 fill in B<id> directly, but should use CRYPTO_THREADID_set_numeric() if thread
86 IDs are numeric, or CRYPTO_THREADID_set_pointer() if they are pointer-based.
87 The B<id> must be unique for the duration of the execution of the program.
88 If the application does not register such a callback using
89 CRYPTO_THREADID_set_callback(), then a default implementation is used - on
90 Windows this uses the system's default thread identifying APIs, and on
91 all other platforms it uses the address of B<errno>. The latter is satisfactory
92 for thread-safety if and only if the platform has a thread-local error number
95 Once threadid_func() is registered, or if the built-in default implementation is
101 CRYPTO_THREADID_current() records the currently-executing thread ID into the
105 CRYPTO_THREADID_cmp() compares two thread IDs (returning zero for equality, ie.
106 the same semantics as memcmp()).
109 CRYPTO_THREADID_cpy() duplicates a thread ID value,
112 CRYPTO_THREADID_hash() returns a numeric value usable as a hash-table key. This
113 is usually the exact numeric or pointer-based thread ID used internally, however
114 this also handles the unusual case where pointers are larger than 'long'
115 variables and the platform's thread IDs are pointer-based - in this case, mixing
116 is done to attempt to produce a unique numeric value even though it is not as
117 wide as the platform's true thread IDs.
121 Additionally, OpenSSL supports dynamic locks, and sometimes, some parts
122 of OpenSSL need it for better performance. To enable this, the following
128 Three additional callback function, dyn_create_function, dyn_lock_function
129 and dyn_destroy_function.
132 A structure defined with the data that each lock needs to handle.
136 struct CRYPTO_dynlock_value has to be defined to contain whatever structure
137 is needed to handle locks.
139 dyn_create_function(const char *file, int line) is needed to create a
140 lock. Multi-threaded applications might crash at random if it is not set.
142 dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int line)
143 is needed to perform locking off dynamic lock numbered n. Multi-threaded
144 applications might crash at random if it is not set.
146 dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is
147 needed to destroy the lock l. Multi-threaded applications might crash at
148 random if it is not set.
150 CRYPTO_get_new_dynlockid() is used to create locks. It will call
151 dyn_create_function for the actual creation.
153 CRYPTO_destroy_dynlockid() is used to destroy locks. It will call
154 dyn_destroy_function for the actual destruction.
156 CRYPTO_lock() is used to lock and unlock the locks. mode is a bitfield
157 describing what should be done with the lock. n is the number of the
158 lock as returned from CRYPTO_get_new_dynlockid(). mode can be combined
159 from the following values. These values are pairwise exclusive, with
160 undefined behaviour if misused (for example, CRYPTO_READ and CRYPTO_WRITE
161 should not be used together):
170 CRYPTO_num_locks() returns the required number of locks.
172 CRYPTO_get_new_dynlockid() returns the index to the newly created lock.
174 The other functions return no values.
178 You can find out if OpenSSL was configured with thread support:
180 #define OPENSSL_THREAD_DEFINES
181 #include <openssl/opensslconf.h>
182 #if defined(OPENSSL_THREADS)
183 // thread support enabled
188 Also, dynamic locks are currently not used internally by OpenSSL, but
189 may do so in the future.
193 B<crypto/threads/mttest.c> shows examples of the callback functions on
194 Solaris, Irix and Win32.
198 B<CRYPTO_THREADID> and associated functions were introduced in OpenSSL 1.0.0
199 to replace (actually, deprecate) the previous CRYPTO_set_id_callback(),
200 CRYPTO_get_id_callback(), and CRYPTO_thread_id() functions which assumed
201 thread IDs to always be represented by 'unsigned long'.