=pod =head1 NAME CRYPTO_THREADID_set_callback, CRYPTO_THREADID_get_callback, CRYPTO_THREADID_current, CRYPTO_THREADID_cmp, CRYPTO_THREADID_cpy, CRYPTO_THREADID_hash, CRYPTO_set_locking_callback, CRYPTO_num_locks, CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback, CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid, CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support =head1 SYNOPSIS #include /* Don't use this structure directly. */ typedef struct crypto_threadid_st { void *ptr; unsigned long val; } CRYPTO_THREADID; /* Only use CRYPTO_THREADID_set_[numeric|pointer]() within callbacks */ void CRYPTO_THREADID_set_numeric(CRYPTO_THREADID *id, unsigned long val); void CRYPTO_THREADID_set_pointer(CRYPTO_THREADID *id, void *ptr); int CRYPTO_THREADID_set_callback(void (*threadid_func)(CRYPTO_THREADID *)); void (*CRYPTO_THREADID_get_callback(void))(CRYPTO_THREADID *); void CRYPTO_THREADID_current(CRYPTO_THREADID *id); int CRYPTO_THREADID_cmp(const CRYPTO_THREADID *a, const CRYPTO_THREADID *b); void CRYPTO_THREADID_cpy(CRYPTO_THREADID *dest, const CRYPTO_THREADID *src); unsigned long CRYPTO_THREADID_hash(const CRYPTO_THREADID *id); int CRYPTO_num_locks(void); /* struct CRYPTO_dynlock_value needs to be defined by the user */ struct CRYPTO_dynlock_value; void CRYPTO_set_dynlock_create_callback(struct CRYPTO_dynlock_value * (*dyn_create_function)(char *file, int line)); void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function) (int mode, struct CRYPTO_dynlock_value *l, const char *file, int line)); void CRYPTO_set_dynlock_destroy_callback(void (*dyn_destroy_function) (struct CRYPTO_dynlock_value *l, const char *file, int line)); int CRYPTO_get_new_dynlockid(void); void CRYPTO_destroy_dynlockid(int i); void CRYPTO_lock(int mode, int n, const char *file, int line); #define CRYPTO_w_lock(type) \ CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE,type,__FILE__,__LINE__) #define CRYPTO_w_unlock(type) \ CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE,type,__FILE__,__LINE__) #define CRYPTO_r_lock(type) \ CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ,type,__FILE__,__LINE__) #define CRYPTO_r_unlock(type) \ CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ,type,__FILE__,__LINE__) #define CRYPTO_add(addr,amount,type) \ CRYPTO_add_lock(addr,amount,type,__FILE__,__LINE__) =head1 DESCRIPTION OpenSSL can safely be used in multi-threaded applications provided that at least two callback functions are set, locking_function and threadid_func. locking_function(int mode, int n, const char *file, int line) is needed to perform locking on shared data structures. (Note that OpenSSL uses a number of global data structures that will be implicitly shared whenever multiple threads use OpenSSL.) Multi-threaded applications will crash at random if it is not set. locking_function() must be able to handle up to CRYPTO_num_locks() different mutex locks. It sets the B-th lock if B & B, and releases it otherwise. B and B are the file number of the function setting the lock. They can be useful for debugging. threadid_func(CRYPTO_THREADID *id) is needed to record the currently-executing thread's identifier into B. The implementation of this callback should not fill in B directly, but should use CRYPTO_THREADID_set_numeric() if thread IDs are numeric, or CRYPTO_THREADID_set_pointer() if they are pointer-based. If the application does not register such a callback using CRYPTO_THREADID_set_callback(), then a default implementation is used - on Windows and BeOS this uses the system's default thread identifying APIs, and on all other platforms it uses the address of B. The latter is satisfactory for thread-safety if and only if the platform has a thread-local error number facility. Once threadid_func() is registered, or if the built-in default implementation is to be used; =over 4 =item * CRYPTO_THREADID_current() records the currently-executing thread ID into the given B object. =item * CRYPTO_THREADID_cmp() compares two thread IDs (returning zero for equality, ie. the same semantics as memcmp()). =item * CRYPTO_THREADID_cpy() duplicates a thread ID value, =item * CRYPTO_THREADID_hash() returns a numeric value usable as a hash-table key. This is usually the exact numeric or pointer-based thread ID used internally, however this also handles the unusual case where pointers are larger than 'long' variables and the platform's thread IDs are pointer-based - in this case, mixing is done to attempt to produce a unique numeric value even though it is not as wide as the platform's true thread IDs. =back Additionally, OpenSSL supports dynamic locks, and sometimes, some parts of OpenSSL need it for better performance. To enable this, the following is required: =over 4 =item * Three additional callback function, dyn_create_function, dyn_lock_function and dyn_destroy_function. =item * A structure defined with the data that each lock needs to handle. =back struct CRYPTO_dynlock_value has to be defined to contain whatever structure is needed to handle locks. dyn_create_function(const char *file, int line) is needed to create a lock. Multi-threaded applications might crash at random if it is not set. dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int line) is needed to perform locking off dynamic lock numbered n. Multi-threaded applications might crash at random if it is not set. dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is needed to destroy the lock l. Multi-threaded applications might crash at random if it is not set. CRYPTO_get_new_dynlockid() is used to create locks. It will call dyn_create_function for the actual creation. CRYPTO_destroy_dynlockid() is used to destroy locks. It will call dyn_destroy_function for the actual destruction. CRYPTO_lock() is used to lock and unlock the locks. mode is a bitfield describing what should be done with the lock. n is the number of the lock as returned from CRYPTO_get_new_dynlockid(). mode can be combined from the following values. These values are pairwise exclusive, with undefined behaviour if misused (for example, CRYPTO_READ and CRYPTO_WRITE should not be used together): CRYPTO_LOCK 0x01 CRYPTO_UNLOCK 0x02 CRYPTO_READ 0x04 CRYPTO_WRITE 0x08 =head1 RETURN VALUES CRYPTO_num_locks() returns the required number of locks. CRYPTO_get_new_dynlockid() returns the index to the newly created lock. The other functions return no values. =head1 NOTES You can find out if OpenSSL was configured with thread support: #define OPENSSL_THREAD_DEFINES #include #if defined(OPENSSL_THREADS) // thread support enabled #else // no thread support #endif Also, dynamic locks are currently not used internally by OpenSSL, but may do so in the future. =head1 EXAMPLES B shows examples of the callback functions on Solaris, Irix and Win32. =head1 HISTORY CRYPTO_set_locking_callback() is available in all versions of SSLeay and OpenSSL. CRYPTO_num_locks() was added in OpenSSL 0.9.4. All functions dealing with dynamic locks were added in OpenSSL 0.9.5b-dev. B and associated functions were introduced in OpenSSL 1.0.0 to replace (actually, deprecate) the previous CRYPTO_set_id_callback(), CRYPTO_get_id_callback(), and CRYPTO_thread_id() functions which assumed thread IDs to always be represented by 'unsigned long'. =head1 SEE ALSO L =cut