1threads(3)                          OpenSSL                         threads(3)
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NAME

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

SYNOPSIS

14        #include <openssl/crypto.h>
15
16        /* 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
34        int CRYPTO_num_locks(void);
35
36        /* struct CRYPTO_dynlock_value needs to be defined by the user */
37        struct CRYPTO_dynlock_value;
38
39        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
47        int CRYPTO_get_new_dynlockid(void);
48
49        void CRYPTO_destroy_dynlockid(int i);
50
51        void CRYPTO_lock(int mode, int n, const char *file, int line);
52
53        #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

DESCRIPTION

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
69       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
75       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
79       file and line are the file number of the function setting the lock.
80       They can be useful for debugging.
81
82       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
94       Once threadid_func() is registered, or if the built-in default
95       implementation is to be used;
96
97       ·   CRYPTO_THREADID_current() records the currently-executing thread ID
98           into the given id object.
99
100       ·   CRYPTO_THREADID_cmp() compares two thread IDs (returning zero for
101           equality, ie.  the same semantics as memcmp()).
102
103       ·   CRYPTO_THREADID_cpy() duplicates a thread ID value,
104
105       ·   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
113       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
117       ·   Three additional callback function, dyn_create_function,
118           dyn_lock_function and dyn_destroy_function.
119
120       ·   A structure defined with the data that each lock needs to handle.
121
122       struct CRYPTO_dynlock_value has to be defined to contain whatever
123       structure is needed to handle locks.
124
125       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
129       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
133       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
137       CRYPTO_get_new_dynlockid() is used to create locks.  It will call
138       dyn_create_function for the actual creation.
139
140       CRYPTO_destroy_dynlockid() is used to destroy locks.  It will call
141       dyn_destroy_function for the actual destruction.
142
143       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
150               CRYPTO_LOCK     0x01
151               CRYPTO_UNLOCK   0x02
152               CRYPTO_READ     0x04
153               CRYPTO_WRITE    0x08
154

RETURN VALUES

156       CRYPTO_num_locks() returns the required number of locks.
157
158       CRYPTO_get_new_dynlockid() returns the index to the newly created lock.
159
160       The other functions return no values.
161

NOTES

163       You can find out if OpenSSL was configured with thread support:
164
165        #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
173       Also, dynamic locks are currently not used internally by OpenSSL, but
174       may do so in the future.
175

EXAMPLES

177       crypto/threads/mttest.c shows examples of the callback functions on
178       Solaris, Irix and Win32.
179

HISTORY

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

SEE ALSO

191       crypto(3)
192
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1951.0.2k                            2017-01-26                        threads(3)
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