static int rand_status(void)
{
    CRYPTO_THREAD_ID cur;
    int ret;
    int do_not_lock;

    if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
        return 0;

    cur = CRYPTO_THREAD_get_current_id();
    /*
     * check if we already have the lock (could happen if a RAND_poll()
     * implementation calls RAND_status())
     */
    if (crypto_lock_rand) {
        CRYPTO_THREAD_read_lock(rand_tmp_lock);
        do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
        CRYPTO_THREAD_unlock(rand_tmp_lock);
    } else
        do_not_lock = 0;

    if (!do_not_lock) {
        CRYPTO_THREAD_write_lock(rand_lock);
        /*
         * Prevent deadlocks in case we end up in an async engine
         */
        ASYNC_block_pause();

        /*
         * prevent rand_bytes() from trying to obtain the lock again
         */
        CRYPTO_THREAD_write_lock(rand_tmp_lock);
        locking_threadid = cur;
        CRYPTO_THREAD_unlock(rand_tmp_lock);
        crypto_lock_rand = 1;
    }

    if (!initialized) {
        RAND_poll();
        initialized = 1;
    }

    ret = entropy >= ENTROPY_NEEDED;

    if (!do_not_lock) {
        /* before unlocking, we must clear 'crypto_lock_rand' */
        crypto_lock_rand = 0;

        ASYNC_unblock_pause();
        CRYPTO_THREAD_unlock(rand_lock);
    }

    return ret;
}

/* Implements the default OpenSSL RAND_add() method */
static int drbg_add(const void *buf, int num, double randomness)
{
    int ret = 0;
    RAND_DRBG *drbg = RAND_DRBG_get0_master();

    if (drbg == NULL)
        return 0;

    if (num < 0 || randomness < 0.0)
        return 0;

    if (randomness > (double)drbg->max_entropylen) {
        /*
         * The purpose of this check is to bound |randomness| by a
         * relatively small value in order to prevent an integer
         * overflow when multiplying by 8 in the rand_drbg_restart()
         * call below.
         */
        return 0;
    }

    CRYPTO_THREAD_write_lock(drbg->lock);
    ret = rand_drbg_restart(drbg, buf,
                            (size_t)(unsigned int)num,
                            (size_t)(8*randomness));
    CRYPTO_THREAD_unlock(drbg->lock);

    return ret;
}

/* Implements the default OpenSSL RAND_bytes() method */
static int drbg_bytes(unsigned char *out, int count)
{
    int ret = 0;
    size_t chunk;
    RAND_DRBG *drbg = RAND_DRBG_get0_public();

    if (drbg == NULL)
        return 0;

    CRYPTO_THREAD_write_lock(drbg->lock);
    if (drbg->state == DRBG_UNINITIALISED)
        goto err;

    for ( ; count > 0; count -= chunk, out += chunk) {
        chunk = count;
        if (chunk > drbg->max_request)
            chunk = drbg->max_request;
        ret = RAND_DRBG_generate(drbg, out, chunk, 0, NULL, 0);
        if (!ret)
            goto err;
    }
    ret = 1;

err:
    CRYPTO_THREAD_unlock(drbg->lock);
    return ret;
}

int X509_STORE_add_crl(X509_STORE *ctx, X509_CRL *x)
{
    X509_OBJECT *obj;
    int ret = 1;

    if (x == NULL)
        return 0;
    obj = X509_OBJECT_new();
    if (obj == NULL)
        return 0;
    obj->type = X509_LU_CRL;
    obj->data.crl = x;

    CRYPTO_THREAD_write_lock(ctx->lock);

    X509_OBJECT_up_ref_count(obj);

    if (X509_OBJECT_retrieve_match(ctx->objs, obj)) {
        X509_OBJECT_free(obj);
        X509err(X509_F_X509_STORE_ADD_CRL, X509_R_CERT_ALREADY_IN_HASH_TABLE);
        ret = 0;
    } else
        sk_X509_OBJECT_push(ctx->objs, obj);

    CRYPTO_THREAD_unlock(ctx->lock);

    return ret;
}

const RAND_METHOD *RAND_get_rand_method(void)
{
    const RAND_METHOD *tmp_meth = NULL;

    if (!RUN_ONCE(&rand_lock_init, do_rand_lock_init))
        return NULL;

    CRYPTO_THREAD_write_lock(rand_meth_lock);
    if (!default_RAND_meth) {
#ifndef OPENSSL_NO_ENGINE
        ENGINE *e = ENGINE_get_default_RAND();
        if (e) {
            default_RAND_meth = ENGINE_get_RAND(e);
            if (default_RAND_meth == NULL) {
                ENGINE_finish(e);
                e = NULL;
            }
        }
        if (e)
            funct_ref = e;
        else
#endif
            default_RAND_meth = RAND_OpenSSL();
    }
    tmp_meth = default_RAND_meth;
    CRYPTO_THREAD_unlock(rand_meth_lock);
    return tmp_meth;
}

/* No padding or other stuff needed.  We can call PKCS11 from here */
static int pkcs11_ecdsa_sign(const unsigned char *msg, unsigned int msg_len,
		unsigned char *sigret, unsigned int *siglen, PKCS11_KEY *key)
{
	int rv;
	PKCS11_SLOT *slot = KEY2SLOT(key);
	PKCS11_CTX *ctx = KEY2CTX(key);
	PKCS11_KEY_private *kpriv = PRIVKEY(key);
	PKCS11_SLOT_private *spriv = PRIVSLOT(slot);
	CK_MECHANISM mechanism;
	CK_ULONG ck_sigsize;

	ck_sigsize = *siglen;

	memset(&mechanism, 0, sizeof(mechanism));
	mechanism.mechanism = CKM_ECDSA;

	CRYPTO_THREAD_write_lock(PRIVSLOT(slot)->rwlock);
	rv = CRYPTOKI_call(ctx,
		C_SignInit(spriv->session, &mechanism, kpriv->object));
	if (!rv)
		rv = pkcs11_authenticate(key);
	if (!rv)
		rv = CRYPTOKI_call(ctx,
			C_Sign(spriv->session, (CK_BYTE *)msg, msg_len, sigret, &ck_sigsize));
	CRYPTO_THREAD_unlock(PRIVSLOT(slot)->rwlock);

	if (rv) {
		PKCS11err(PKCS11_F_PKCS11_EC_KEY_SIGN, pkcs11_map_err(rv));
		return -1;
	}
	*siglen = ck_sigsize;

	return ck_sigsize;
}

static int remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck)
{
    SSL_SESSION *r;
    int ret = 0;

    if ((c != NULL) && (c->session_id_length != 0)) {
        if (lck)
            CRYPTO_THREAD_write_lock(ctx->lock);
        if ((r = lh_SSL_SESSION_retrieve(ctx->sessions, c)) == c) {
            ret = 1;
            r = lh_SSL_SESSION_delete(ctx->sessions, c);
            SSL_SESSION_list_remove(ctx, c);
        }
        c->not_resumable = 1;

        if (lck)
            CRYPTO_THREAD_unlock(ctx->lock);

        if (ret)
            SSL_SESSION_free(r);

        if (ctx->remove_session_cb != NULL)
            ctx->remove_session_cb(ctx, c);
    } else
        ret = 0;
    return (ret);
}

/*
 * Free a functional reference to a engine type. This version is only used
 * internally.
 */
int engine_unlocked_finish(ENGINE *e, int unlock_for_handlers)
{
    int to_return = 1;

    /*
     * Reduce the functional reference count here so if it's the terminating
     * case, we can release the lock safely and call the finish() handler
     * without risk of a race. We get a race if we leave the count until
     * after and something else is calling "finish" at the same time -
     * there's a chance that both threads will together take the count from 2
     * to 0 without either calling finish().
     */
    e->funct_ref--;
    engine_ref_debug(e, 1, -1);
    if ((e->funct_ref == 0) && e->finish) {
        if (unlock_for_handlers)
            CRYPTO_THREAD_unlock(global_engine_lock);
        to_return = e->finish(e);
        if (unlock_for_handlers)
            CRYPTO_THREAD_write_lock(global_engine_lock);
        if (!to_return)
            return 0;
    }
    REF_ASSERT_ISNT(e->funct_ref < 0);
    /* Release the structural reference too */
    if (!engine_free_util(e, 0)) {
        ENGINEerr(ENGINE_F_ENGINE_UNLOCKED_FINISH, ENGINE_R_FINISH_FAILED);
        return 0;
    }
    return to_return;
}

/*
 * Return the EX_CALLBACKS from the |ex_data| array that corresponds to
 * a given class.  On success, *holds the lock.*
 */
static EX_CALLBACKS *get_and_lock(OPENSSL_CTX *ctx, int class_index)
{
    EX_CALLBACKS *ip;
    OSSL_EX_DATA_GLOBAL *global = NULL;

    if (class_index < 0 || class_index >= CRYPTO_EX_INDEX__COUNT) {
        CRYPTOerr(CRYPTO_F_GET_AND_LOCK, ERR_R_PASSED_INVALID_ARGUMENT);
        return NULL;
    }

    global = openssl_ctx_get_ex_data_global(ctx);
    if (global->ex_data_lock == NULL) {
        /*
         * This can happen in normal operation when using CRYPTO_mem_leaks().
         * The CRYPTO_mem_leaks() function calls OPENSSL_cleanup() which cleans
         * up the locks. Subsequently the BIO that CRYPTO_mem_leaks() uses gets
         * freed, which also attempts to free the ex_data. However
         * CRYPTO_mem_leaks() ensures that the ex_data is freed early (i.e.
         * before OPENSSL_cleanup() is called), so if we get here we can safely
         * ignore this operation. We just treat it as an error.
         */
         return NULL;
    }

    ip = &global->ex_data[class_index];
    CRYPTO_THREAD_write_lock(global->ex_data_lock);
    return ip;
}

int X509_STORE_add_crl(X509_STORE *ctx, X509_CRL *x)
{
    X509_OBJECT *obj;
    int ret = 1;

    if (x == NULL)
        return 0;
    obj = OPENSSL_malloc(sizeof(*obj));
    if (obj == NULL) {
        X509err(X509_F_X509_STORE_ADD_CRL, ERR_R_MALLOC_FAILURE);
        return 0;
    }
    obj->type = X509_LU_CRL;
    obj->data.crl = x;

    CRYPTO_THREAD_write_lock(ctx->lock);

    X509_OBJECT_up_ref_count(obj);

    if (X509_OBJECT_retrieve_match(ctx->objs, obj)) {
        X509_OBJECT_free_contents(obj);
        OPENSSL_free(obj);
        X509err(X509_F_X509_STORE_ADD_CRL, X509_R_CERT_ALREADY_IN_HASH_TABLE);
        ret = 0;
    } else
        sk_X509_OBJECT_push(ctx->objs, obj);

    CRYPTO_THREAD_unlock(ctx->lock);

    return ret;
}

/*
 * This function retrieves the context structure from an ENGINE's "ex_data",
 * or if it doesn't exist yet, sets it up.
 */
static dynamic_data_ctx *dynamic_get_data_ctx(ENGINE *e)
{
    dynamic_data_ctx *ctx;
    if (dynamic_ex_data_idx < 0) {
        /*
         * Create and register the ENGINE ex_data, and associate our "free"
         * function with it to ensure any allocated contexts get freed when
         * an ENGINE goes underground.
         */
        int new_idx = ENGINE_get_ex_new_index(0, NULL, NULL, NULL,
                                              dynamic_data_ctx_free_func);
        if (new_idx == -1) {
            ENGINEerr(ENGINE_F_DYNAMIC_GET_DATA_CTX, ENGINE_R_NO_INDEX);
            return NULL;
        }
        CRYPTO_THREAD_write_lock(global_engine_lock);
        /* Avoid a race by checking again inside this lock */
        if (dynamic_ex_data_idx < 0) {
            /* Good, someone didn't beat us to it */
            dynamic_ex_data_idx = new_idx;
            new_idx = -1;
        }
        CRYPTO_THREAD_unlock(global_engine_lock);
        /*
         * In theory we could "give back" the index here if (new_idx>-1), but
         * it's not possible and wouldn't gain us much if it were.
         */
    }
    ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e, dynamic_ex_data_idx);
    /* Check if the context needs to be created */
    if ((ctx == NULL) && !dynamic_set_data_ctx(e, &ctx))
        /* "set_data" will set errors if necessary */
        return NULL;
    return ctx;
}

const RAND_METHOD *RAND_get_rand_method(void)
{
    const RAND_METHOD *tmp_meth = NULL;

    if (!RUN_ONCE(&rand_init, do_rand_init))
        return NULL;

    CRYPTO_THREAD_write_lock(rand_meth_lock);
    if (default_RAND_meth == NULL) {
#ifndef OPENSSL_NO_ENGINE
        ENGINE *e;

        /* If we have an engine that can do RAND, use it. */
        if ((e = ENGINE_get_default_RAND()) != NULL
                && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
            funct_ref = e;
            default_RAND_meth = tmp_meth;
        } else {
            ENGINE_finish(e);
            default_RAND_meth = &rand_meth;
        }
#else
        default_RAND_meth = &rand_meth;
#endif
    }
    tmp_meth = default_RAND_meth;
    CRYPTO_THREAD_unlock(rand_meth_lock);
    return tmp_meth;
}

void CRYPTO_secure_clear_free(void *ptr, size_t num,
                              const char *file, int line)
{
#ifdef IMPLEMENTED
    size_t actual_size;

    if (ptr == NULL)
        return;
    if (!CRYPTO_secure_allocated(ptr)) {
        OPENSSL_cleanse(ptr, num);
        CRYPTO_free(ptr, file, line);
        return;
    }
    CRYPTO_THREAD_write_lock(sec_malloc_lock);
    actual_size = sh_actual_size(ptr);
    CLEAR(ptr, actual_size);
    secure_mem_used -= actual_size;
    sh_free(ptr);
    CRYPTO_THREAD_unlock(sec_malloc_lock);
#else
    if (ptr == NULL)
        return;
    OPENSSL_cleanse(ptr, num);
    CRYPTO_free(ptr, file, line);
#endif /* IMPLEMENTED */
}

static int def_crl_lookup(X509_CRL *crl,
                          X509_REVOKED **ret, ASN1_INTEGER *serial,
                          X509_NAME *issuer)
{
    X509_REVOKED rtmp, *rev;
    int idx;
    rtmp.serialNumber = *serial;
    /*
     * Sort revoked into serial number order if not already sorted. Do this
     * under a lock to avoid race condition.
     */
    if (!sk_X509_REVOKED_is_sorted(crl->crl.revoked)) {
        CRYPTO_THREAD_write_lock(crl->lock);
        sk_X509_REVOKED_sort(crl->crl.revoked);
        CRYPTO_THREAD_unlock(crl->lock);
    }
    idx = sk_X509_REVOKED_find(crl->crl.revoked, &rtmp);
    if (idx < 0)
        return 0;
    /* Need to look for matching name */
    for (; idx < sk_X509_REVOKED_num(crl->crl.revoked); idx++) {
        rev = sk_X509_REVOKED_value(crl->crl.revoked, idx);
        if (ASN1_INTEGER_cmp(&rev->serialNumber, serial))
            return 0;
        if (crl_revoked_issuer_match(crl, issuer, rev)) {
            if (ret)
                *ret = rev;
            if (rev->reason == CRL_REASON_REMOVE_FROM_CRL)
                return 2;
            return 1;
        }
    }
    return 0;
}

void engine_table_unregister(ENGINE_TABLE **table, ENGINE *e)
{
    CRYPTO_THREAD_write_lock(global_engine_lock);
    if (int_table_check(table, 0))
        lh_ENGINE_PILE_doall_ENGINE(&(*table)->piles, int_unregister_cb, e);
    CRYPTO_THREAD_unlock(global_engine_lock);
}

/*
 * Locks the given drbg. Locking a drbg which does not have locking
 * enabled is considered a successful no-op.
 *
 * Returns 1 on success, 0 on failure.
 */
int rand_drbg_lock(RAND_DRBG *drbg)
{
    if (drbg->lock != NULL)
        return CRYPTO_THREAD_write_lock(drbg->lock);

    return 1;
}

static void build_SYS_str_reasons(void)
{
    /* OPENSSL_malloc cannot be used here, use static storage instead */
    static char strerror_tab[NUM_SYS_STR_REASONS][LEN_SYS_STR_REASON];
    static int init = 1;
    int i;

    CRYPTO_THREAD_write_lock(err_string_lock);
    if (!init) {
        CRYPTO_THREAD_unlock(err_string_lock);
        return;
    }

    for (i = 1; i <= NUM_SYS_STR_REASONS; i++) {
        ERR_STRING_DATA *str = &SYS_str_reasons[i - 1];

        str->error = (unsigned long)i;
        if (str->string == NULL) {
            char (*dest)[LEN_SYS_STR_REASON] = &(strerror_tab[i - 1]);
            if (openssl_strerror_r(i, *dest, sizeof(*dest)))
                str->string = *dest;
        }
        if (str->string == NULL)
            str->string = "unknown";
    }

    /*
     * Now we still have SYS_str_reasons[NUM_SYS_STR_REASONS] = {0, NULL}, as
     * required by ERR_load_strings.
     */

    init = 0;

    CRYPTO_THREAD_unlock(err_string_lock);
}

/* RSA private key decryption */
int pkcs11_private_decrypt(int flen, const unsigned char *from, unsigned char *to,
		PKCS11_KEY *key, int padding)
{
	PKCS11_SLOT *slot = KEY2SLOT(key);
	PKCS11_CTX *ctx = KEY2CTX(key);
	PKCS11_KEY_private *kpriv = PRIVKEY(key);
	PKCS11_SLOT_private *spriv = PRIVSLOT(slot);
	CK_MECHANISM mechanism;
	CK_ULONG size = flen;
	CK_RV rv;

	if (pkcs11_mechanism(&mechanism, padding) < 0)
		return -1;

	CRYPTO_THREAD_write_lock(PRIVSLOT(slot)->rwlock);
	rv = CRYPTOKI_call(ctx,
		C_DecryptInit(spriv->session, &mechanism, kpriv->object));
	if (rv == CKR_USER_NOT_LOGGED_IN)
		rv = pkcs11_authenticate(key);
	if (!rv)
		rv = CRYPTOKI_call(ctx,
			C_Decrypt(spriv->session, (CK_BYTE *)from, size,
				(CK_BYTE_PTR)to, &size));
	CRYPTO_THREAD_unlock(PRIVSLOT(slot)->rwlock);

	if (rv) {
		PKCS11err(PKCS11_F_PKCS11_RSA_DECRYPT, pkcs11_map_err(rv));
		return -1;
	}

	return size;
}

/*
 * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
 *
 * If the DRBG has a parent, then the required amount of entropy input
 * is fetched using the parent's RAND_DRBG_generate().
 *
 * Otherwise, the entropy is polled from the system entropy sources
 * using RAND_POOL_acquire_entropy().
 *
 * If a random pool has been added to the DRBG using RAND_add(), then
 * its entropy will be used up first.
 */
size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
                        unsigned char **pout,
                        int entropy, size_t min_len, size_t max_len)
{
    size_t ret = 0;
    size_t entropy_available = 0;
    RAND_POOL *pool = RAND_POOL_new(entropy, min_len, max_len);

    if (pool == NULL)
        return 0;

    if (drbg->pool) {
        RAND_POOL_add(pool,
                      RAND_POOL_buffer(drbg->pool),
                      RAND_POOL_length(drbg->pool),
                      RAND_POOL_entropy(drbg->pool));
        RAND_POOL_free(drbg->pool);
        drbg->pool = NULL;
    }

    if (drbg->parent) {
        size_t bytes_needed = RAND_POOL_bytes_needed(pool, 8);
        unsigned char *buffer = RAND_POOL_add_begin(pool, bytes_needed);

        if (buffer != NULL) {
            size_t bytes = 0;

            /*
             * Get random from parent, include our state as additional input.
             * Our lock is already held, but we need to lock our parent before
             * generating bits from it.
             */
            if (drbg->parent->lock)
                CRYPTO_THREAD_write_lock(drbg->parent->lock);
            if (RAND_DRBG_generate(drbg->parent,
                                   buffer, bytes_needed,
                                   0,
                                   (unsigned char *)drbg, sizeof(*drbg)) != 0)
                bytes = bytes_needed;
            if (drbg->parent->lock)
                CRYPTO_THREAD_unlock(drbg->parent->lock);

            entropy_available = RAND_POOL_add_end(pool, bytes, 8 * bytes);
        }

    } else {
        /* Get entropy by polling system entropy sources. */
        entropy_available = RAND_POOL_acquire_entropy(pool);
    }

    if (entropy_available > 0) {
        ret   = RAND_POOL_length(pool);
        *pout = RAND_POOL_detach(pool);
    }

    RAND_POOL_free(pool);
    return ret;
}

static void build_SYS_str_reasons(void)
{
    /* OPENSSL_malloc cannot be used here, use static storage instead */
    static char strerror_pool[SPACE_SYS_STR_REASONS];
    char *cur = strerror_pool;
    size_t cnt = 0;
    static int init = 1;
    int i;
    int saveerrno = get_last_sys_error();

    CRYPTO_THREAD_write_lock(err_string_lock);
    if (!init) {
        CRYPTO_THREAD_unlock(err_string_lock);
        return;
    }

    for (i = 1; i <= NUM_SYS_STR_REASONS; i++) {
        ERR_STRING_DATA *str = &SYS_str_reasons[i - 1];

        str->error = ERR_PACK(ERR_LIB_SYS, 0, i);
        if (str->string == NULL) {
            if (openssl_strerror_r(i, cur, sizeof(strerror_pool) - cnt)) {
                size_t l = strlen(cur);

                str->string = cur;
                cnt += l;
                if (cnt > sizeof(strerror_pool))
                    cnt = sizeof(strerror_pool);
                cur += l;

                /*
                 * VMS has an unusual quirk of adding spaces at the end of
                 * some (most? all?) messages.  Lets trim them off.
                 */
                while (ossl_isspace(cur[-1])) {
                    cur--;
                    cnt--;
                }
                *cur++ = '\0';
                cnt++;
            }
        }
        if (str->string == NULL)
            str->string = "unknown";
    }

    /*
     * Now we still have SYS_str_reasons[NUM_SYS_STR_REASONS] = {0, NULL}, as
     * required by ERR_load_strings.
     */

    init = 0;

    CRYPTO_THREAD_unlock(err_string_lock);
    /* openssl_strerror_r could change errno, but we want to preserve it */
    set_sys_error(saveerrno);
    err_load_strings(SYS_str_reasons);
}