threads, CRYPTO_set_locking_callback, CRYPTO_set_id_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
#include <openssl/crypto.h>
void CRYPTO_set_locking_callback(
void (*locking_function)(int mode, int n, const
char *file, int line) ); void CRYPTO_set_id_callback(
unsigned long (*id_function)(void) ); 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__)
OpenSSL can safely be used in multi-threaded applications
provided that at least two callback functions are set.
The locking_function(int mode, int n, const char *file,
int line) is needed to perform locking on shared data
structures. Multi-threaded applications will crash at random
if it is not set.
The 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.
The file and line are the file number of the function setting
the lock. They can be useful for debugging.
The id_function(void) function returns a thread ID. It is
not needed on Windows nor on platforms where getpid()
returns a different ID for each thread (most notably
Linux).
Additionally, OpenSSL supports dynamic locks, and some
parts of OpenSSL need it for better performance. To
enable this, the following is required: Three additional
callback functions: dyn_create_function, dyn_lock_function
and dyn_destroy_function. A structure defined with the
data that each lock needs to handle.
The struct CRYPTO_dynlock_value has to be defined to contain
whatever structure is needed to handle locks.
The 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.
The 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.
The 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.
The CRYPTO_get_new_dynlockid() function is used to create
locks. It will call dyn_create_function for the actual
creation.
The CRYPTO_destroy_dynlockid() function is used to destroy
locks. It will call dyn_destroy_function for the actual
destruction.
The CRYPTO_lock() function is used to lock and unlock the
locks. The mode is a bitfield describing what should be
done with the lock. The value of n is the number of the
lock as returned from the CRYPTO_get_new_dynlockid() function.
The mode can be combined from the following values.
These values are pairwise exclusive, with undefined behavior
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
The CRYPTO_num_locks() function returns the required number
of locks.
CRYPTO_get_new_dynlockid() function returns the index to
the newly created lock.
The other functions return no values.
You can determine if OpenSSL was configured with thread
support: #define OPENSSL_THREAD_DEFINES #include
<openssl/opensslconf.h> #if defined(THREADS)
// thread support enabled #else
// no thread support #endif
Also, dynamic locks are not used internally by OpenSSL.
The CRYPTO_set_locking_callback() and CRYPTO_set_id_callback()
functions are available in all versions of SSLeay
and OpenSSL. The CRYPTO_num_locks() function was added in
OpenSSL 0.9.4. All functions dealing with dynamic locks
were added in OpenSSL 0.9.5b-dev.
Functions: crypto(3)
threads(3)
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