=head1 NAME
-CRYPTO_set_locking_callback, CRYPTO_set_id_callback, CRYPTO_num_locks,
+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
#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));
+ /* 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;
=head1 DESCRIPTION
OpenSSL can safely be used in multi-threaded applications provided
-that at least two callback functions are set.
+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.
B<file> and B<line> are the file number of the function setting the
lock. They can be useful for debugging.
-id_function(void) is a function that returns a thread ID, for example
-pthread_self() if it returns an integer (see NOTES below). It isn't
-needed on Windows nor on platforms where getpid() returns a different
-ID for each thread (see NOTES below).
+threadid_func(CRYPTO_THREADID *id) is needed to record the currently-executing
+thread's identifier into B<id>. The implementation of this callback should not
+fill in B<id> 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<errno>. 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<id> 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
Also, dynamic locks are currently not used internally by OpenSSL, but
may do so in the future.
-Defining id_function(void) has it's own issues. Generally speaking,
-pthread_self() should be used, even on platforms where getpid() gives
-different answers in each thread, since that may depend on the machine
-the program is run on, not the machine where the program is being
-compiled. For instance, Red Hat 8 Linux and earlier used
-LinuxThreads, whose getpid() returns a different value for each
-thread. Red Hat 9 Linux and later use NPTL, which is
-Posix-conformant, and has a getpid() that returns the same value for
-all threads in a process. A program compiled on Red Hat 8 and run on
-Red Hat 9 will therefore see getpid() returning the same value for
-all threads.
-
-There is still the issue of platforms where pthread_self() returns
-something other than an integer. This is a bit unusual, and this
-manual has no cookbook solution for that case.
-
=head1 EXAMPLES
B<crypto/threads/mttest.c> shows examples of the callback functions on
=head1 HISTORY
-CRYPTO_set_locking_callback() and CRYPTO_set_id_callback() are
+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<CRYPTO_THREADID> and associated functions were introduced in OpenSSL 0.9.9
+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
projects / openssl.git / blobdiff