CRYPTO_num_locks man page on DigitalUNIX

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threads(3)							    threads(3)

NAME
       threads,	     CRYPTO_set_locking_callback,      CRYPTO_set_id_callback,
       CRYPTO_num_locks,  CRYPTO_set_dynlock_create_callback,  CRYPTO_set_dyn‐
       lock_lock_callback,		  CRYPTO_set_dynlock_destroy_callback,
       CRYPTO_get_new_dynlockid,   CRYPTO_destroy_dynlockid,   CRYPTO_lock   -
       OpenSSL thread support

SYNOPSIS
       #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_dyn‐
       lock_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__)

DESCRIPTION
       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  applica‐
       tions 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

RETURN VALUES
       The CRYPTO_num_locks() function returns the required number of locks.

       CRYPTO_get_new_dynlockid() function returns the index to the newly cre‐
       ated lock.

       The other functions return no values.

NOTES
       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.

HISTORY
       The CRYPTO_set_locking_callback()  and  CRYPTO_set_id_callback()	 func‐
       tions  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.

SEE ALSO
       Functions: crypto(3)

								    threads(3)
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