CRYPTO_THREAD_run_once,
CRYPTO_THREAD_lock_new, CRYPTO_THREAD_read_lock, CRYPTO_THREAD_write_lock,
-CRYPTO_THREAD_unlock, CRYPTO_THREAD_lock_free, CRYPTO_atomic_add - OpenSSL thread support
+CRYPTO_THREAD_unlock, CRYPTO_THREAD_lock_free,
+CRYPTO_atomic_add, CRYPTO_atomic_or, CRYPTO_atomic_load - OpenSSL thread support
=head1 SYNOPSIS
void CRYPTO_THREAD_lock_free(CRYPTO_RWLOCK *lock);
int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock);
+ int CRYPTO_atomic_or(uint64_t *val, uint64_t op, uint64_t *ret,
+ CRYPTO_RWLOCK *lock);
+ int CRYPTO_atomic_load(uint64_t *val, uint64_t *ret, CRYPTO_RWLOCK *lock);
=head1 DESCRIPTION
The following multi-threading function are provided:
-=over 4
+=over 2
=item *
+
CRYPTO_THREAD_run_once() can be used to perform one-time initialization.
-The B<once> argument must be a pointer to a static object of type
+The I<once> argument must be a pointer to a static object of type
B<CRYPTO_ONCE> that was statically initialized to the value
B<CRYPTO_ONCE_STATIC_INIT>.
-The B<init> argument is a pointer to a function that performs the desired
+The I<init> argument is a pointer to a function that performs the desired
exactly once initialization.
In particular, this can be used to allocate locks in a thread-safe manner,
which can then be used with the locking functions below.
=item *
+
CRYPTO_THREAD_lock_new() allocates, initializes and returns a new read/write
lock.
=item *
-CRYPTO_THREAD_read_lock() locks the provided B<lock> for reading.
+
+CRYPTO_THREAD_read_lock() locks the provided I<lock> for reading.
=item *
-CRYPTO_THREAD_write_lock() locks the provided B<lock> for writing.
+
+CRYPTO_THREAD_write_lock() locks the provided I<lock> for writing.
=item *
-CRYPTO_THREAD_unlock() unlocks the previously locked B<lock>.
+
+CRYPTO_THREAD_unlock() unlocks the previously locked I<lock>.
=item *
-CRYPTO_THREAD_lock_frees() frees the provided B<lock>.
+
+CRYPTO_THREAD_lock_free() frees the provided I<lock>.
=item *
-CRYPTO_atomic_add() atomically adds B<amount> to B<val> and returns the
-result of the operation in B<ret>. B<lock> will be locked, unless atomic
+
+CRYPTO_atomic_add() atomically adds I<amount> to I<*val> and returns the
+result of the operation in I<*ret>. I<lock> will be locked, unless atomic
operations are supported on the specific platform. Because of this, if a
variable is modified by CRYPTO_atomic_add() then CRYPTO_atomic_add() must
-be the only way that the variable is modified.
+be the only way that the variable is modified. If atomic operations are not
+supported and I<lock> is NULL, then the function will fail.
+
+=item *
+
+CRYPTO_atomic_or() performs an atomic bitwise or of I<op> and I<*val> and stores
+the result back in I<*val>. It also returns the result of the operation in
+I<*ret>. I<lock> will be locked, unless atomic operations are supported on the
+specific platform. Because of this, if a variable is modified by
+CRYPTO_atomic_or() or read by CRYPTO_atomic_load() then CRYPTO_atomic_or() must
+be the only way that the variable is modified. If atomic operations are not
+supported and I<lock> is NULL, then the function will fail.
+
+=item *
+
+CRYPTO_atomic_load() atomically loads the contents of I<*val> into I<*ret>.
+I<lock> will be locked, unless atomic operations are supported on the specific
+platform. Because of this, if a variable is modified by CRYPTO_atomic_or() or
+read by CRYPTO_atomic_load() then CRYPTO_atomic_load() must be the only way that
+the variable is read. If atomic operations are not supported and I<lock> is
+NULL, then the function will fail.
=back
CRYPTO_THREAD_lock_new() returns the allocated lock, or NULL on error.
-CRYPTO_THREAD_lock_frees() returns no value.
+CRYPTO_THREAD_lock_free() returns no value.
-The other functions return 1 on success or 0 on error.
+The other functions return 1 on success, or 0 on error.
=head1 NOTES
On Windows platforms the CRYPTO_THREAD_* types and functions in the
-openssl/crypto.h header are dependent on some of the types customarily
-made available by including windows.h. The application developer is
-likely to require control over when the latter is included, commonly as
-one of the first included headers. Therefore it is defined as an
-application developer's responsibility to include windows.h prior to
-crypto.h where use of CRYPTO_THREAD_* types and functions is required.
+F<< <openssl/crypto.h> >> header are dependent on some of the types
+customarily made available by including F<< <windows.h> >>. The application
+developer is likely to require control over when the latter is included,
+commonly as one of the first included headers. Therefore, it is defined as an
+application developer's responsibility to include F<< <windows.h> >> prior to
+F<< <openssl/crypto.h> >> where use of CRYPTO_THREAD_* types and functions is
+required.
+
+=head1 EXAMPLES
+
+You can find out if OpenSSL was configured with thread support:
-=head1 EXAMPLE
+ #include <openssl/opensslconf.h>
+ #if defined(OPENSSL_THREADS)
+ /* thread support enabled */
+ #else
+ /* no thread support */
+ #endif
This example safely initializes and uses a lock.
- #ifdef _WIN32
- # include <windows.h>
- #endif
- #include <openssl/crypto.h>
-
- static CRYPTO_ONCE once = CRYPTO_ONCE_STATIC_INIT;
- static CRYPTO_RWLOCK *lock;
-
- static void myinit(void)
- {
- lock = CRYPTO_THREAD_lock_new();
- }
-
- static int mylock(void)
- {
- if (!CRYPTO_THREAD_run_once(&once, void init) || lock == NULL)
- return 0;
- return CRYPTO_THREAD_write_lock(lock);
- }
-
- static int myunlock(void)
- {
- return CRYPTO_THREAD_unlock(lock);
- }
-
- int serialized(void)
- {
- int ret = 0;
-
- if (mylock()) {
- /* Your code here, do not return without releasing the lock! */
- ret = ... ;
- }
- myunlock();
- return ret;
- }
+ #ifdef _WIN32
+ # include <windows.h>
+ #endif
+ #include <openssl/crypto.h>
+
+ static CRYPTO_ONCE once = CRYPTO_ONCE_STATIC_INIT;
+ static CRYPTO_RWLOCK *lock;
+
+ static void myinit(void)
+ {
+ lock = CRYPTO_THREAD_lock_new();
+ }
+
+ static int mylock(void)
+ {
+ if (!CRYPTO_THREAD_run_once(&once, void init) || lock == NULL)
+ return 0;
+ return CRYPTO_THREAD_write_lock(lock);
+ }
+
+ static int myunlock(void)
+ {
+ return CRYPTO_THREAD_unlock(lock);
+ }
+
+ int serialized(void)
+ {
+ int ret = 0;
+
+ if (mylock()) {
+ /* Your code here, do not return without releasing the lock! */
+ ret = ... ;
+ }
+ myunlock();
+ return ret;
+ }
Finalization of locks is an advanced topic, not covered in this example.
This can only be done at process exit or when a dynamically loaded library is
The simplest solution is to just "leak" the lock in applications and not
repeatedly load/unload shared libraries that allocate locks.
-=head1 NOTES
-
-You can find out if OpenSSL was configured with thread support:
-
- #include <openssl/opensslconf.h>
- #if defined(OPENSSL_THREADS)
- // thread support enabled
- #else
- // no thread support
- #endif
-
=head1 SEE ALSO
-L<crypto(7)>
+L<crypto(7)>, L<openssl-threads(7)>.
=head1 COPYRIGHT
-Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
-Licensed under the OpenSSL license (the "License"). You may not use
+Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.
projects / thirdparty / openssl.git / blobdiff