Adding upstream version 1.7.2.upstream/1.7.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 803 insertions, 0 deletions

diff --git a/locks/os2/proc_mutex.c b/locks/os2/proc_mutex.c
new file mode 100644
index 0000000..a86c208
--- /dev/null
+++ b/locks/os2/proc_mutex.c
@@ -0,0 +1,289 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_general.h"
+#include "apr_lib.h"
+#include "apr_strings.h"
+#include "apr_portable.h"
+#include "apr_arch_proc_mutex.h"
+#include "apr_arch_file_io.h"
+#include <string.h>
+#include <stddef.h>
+
+#define CurrentTid (*_threadid)
+
+static char *fixed_name(const char *fname, apr_pool_t *pool)
+{
+    char *semname;
+
+    if (fname == NULL)
+        semname = NULL;
+    else {
+        /* Semaphores don't live in the file system, fix up the name */
+        while (*fname == '/' || *fname == '\\') {
+            fname++;
+        }
+
+        semname = apr_pstrcat(pool, "/SEM32/", fname, NULL);
+
+        if (semname[8] == ':') {
+            semname[8] = '$';
+        }
+    }
+
+    return semname;
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *vmutex)
+{
+    apr_proc_mutex_t *mutex = vmutex;
+    return apr_proc_mutex_destroy(mutex);
+}
+
+APR_DECLARE(const char *) apr_proc_mutex_lockfile(apr_proc_mutex_t *mutex)
+{
+    return NULL;
+}
+
+APR_DECLARE(apr_lockmech_e) apr_proc_mutex_mech(apr_proc_mutex_t *mutex)
+{
+    return APR_LOCK_DEFAULT;
+}
+
+APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex)
+{
+    return "os2sem";
+}
+
+APR_DECLARE(const char *) apr_proc_mutex_defname(void)
+{
+    return "os2sem";
+}
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_create(apr_proc_mutex_t **mutex,
+                                                const char *fname,
+                                                apr_lockmech_e mech,
+                                                apr_pool_t *pool)
+{
+    apr_proc_mutex_t *new;
+    ULONG rc;
+    char *semname;
+
+    if (mech != APR_LOCK_DEFAULT && mech != APR_LOCK_DEFAULT_TIMED) {
+        return APR_ENOTIMPL;
+    }
+
+    new = (apr_proc_mutex_t *)apr_palloc(pool, sizeof(apr_proc_mutex_t));
+    new->pool       = pool;
+    new->owner      = 0;
+    new->lock_count = 0;
+    *mutex = new;
+
+    semname = fixed_name(fname, pool);
+    rc = DosCreateMutexSem(semname, &(new->hMutex), DC_SEM_SHARED, FALSE);
+
+    if (!rc) {
+        apr_pool_cleanup_register(pool, new, apr_proc_mutex_cleanup, apr_pool_cleanup_null);
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_child_init(apr_proc_mutex_t **mutex,
+                                                    const char *fname,
+                                                    apr_pool_t *pool)
+{
+    apr_proc_mutex_t *new;
+    ULONG rc;
+    char *semname;
+
+    new = (apr_proc_mutex_t *)apr_palloc(pool, sizeof(apr_proc_mutex_t));
+    new->pool       = pool;
+    new->owner      = 0;
+    new->lock_count = 0;
+
+    semname = fixed_name(fname, pool);
+    rc = DosOpenMutexSem(semname, &(new->hMutex));
+    *mutex = new;
+
+    if (!rc) {
+        apr_pool_cleanup_register(pool, new, apr_proc_mutex_cleanup, apr_pool_cleanup_null);
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_lock(apr_proc_mutex_t *mutex)
+{
+    ULONG rc = DosRequestMutexSem(mutex->hMutex, SEM_INDEFINITE_WAIT);
+
+    if (rc == 0) {
+        mutex->owner = CurrentTid;
+        mutex->lock_count++;
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_trylock(apr_proc_mutex_t *mutex)
+{
+    ULONG rc = DosRequestMutexSem(mutex->hMutex, SEM_IMMEDIATE_RETURN);
+
+    if (rc == 0) {
+        mutex->owner = CurrentTid;
+        mutex->lock_count++;
+    }
+
+    return (rc == ERROR_TIMEOUT) ? APR_EBUSY : APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_timedlock(apr_proc_mutex_t *mutex,
+                                               apr_interval_time_t timeout)
+{
+    ULONG rc;
+    
+    if (timeout <= 0) {
+        rc = DosRequestMutexSem(mutex->hMutex, SEM_IMMEDIATE_RETURN);
+    }
+    else {
+        rc = DosRequestMutexSem(mutex->hMutex, apr_time_as_msec(timeout));
+    }
+
+    if (rc == 0) {
+        mutex->owner = CurrentTid;
+        mutex->lock_count++;
+    }
+
+    return (rc == ERROR_TIMEOUT) ? APR_TIMEUP : APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_unlock(apr_proc_mutex_t *mutex)
+{
+    ULONG rc;
+
+    if (mutex->owner == CurrentTid && mutex->lock_count > 0) {
+        mutex->lock_count--;
+        rc = DosReleaseMutexSem(mutex->hMutex);
+        return APR_FROM_OS_ERROR(rc);
+    }
+
+    return APR_SUCCESS;
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_proc_mutex_destroy(apr_proc_mutex_t *mutex)
+{
+    ULONG rc;
+    apr_status_t status = APR_SUCCESS;
+
+    if (mutex->owner == CurrentTid) {
+        while (mutex->lock_count > 0 && status == APR_SUCCESS) {
+            status = apr_proc_mutex_unlock(mutex);
+        }
+    }
+
+    if (status != APR_SUCCESS) {
+        return status;
+    }
+
+    if (mutex->hMutex == 0) {
+        return APR_SUCCESS;
+    }
+
+    rc = DosCloseMutexSem(mutex->hMutex);
+
+    if (!rc) {
+        mutex->hMutex = 0;
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+APR_PERMS_SET_ENOTIMPL(proc_mutex)
+
+APR_POOL_IMPLEMENT_ACCESSOR(proc_mutex)
+
+
+
+/* Implement OS-specific accessors defined in apr_portable.h */
+
+APR_DECLARE(apr_status_t) apr_os_proc_mutex_get_ex(apr_os_proc_mutex_t *ospmutex, 
+                                                   apr_proc_mutex_t *pmutex,
+                                                   apr_lockmech_e *mech)
+{
+    *ospmutex = pmutex->hMutex;
+    if (mech) {
+        *mech = APR_LOCK_DEFAULT;
+    }
+    return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_os_proc_mutex_get(apr_os_proc_mutex_t *ospmutex,
+                                                apr_proc_mutex_t *pmutex)
+{
+    return apr_os_proc_mutex_get_ex(ospmutex, pmutex, NULL);
+}
+
+APR_DECLARE(apr_status_t) apr_os_proc_mutex_put_ex(apr_proc_mutex_t **pmutex,
+                                                apr_os_proc_mutex_t *ospmutex,
+                                                apr_lockmech_e mech,
+                                                int register_cleanup,
+                                                apr_pool_t *pool)
+{
+    apr_proc_mutex_t *new;
+    if (pool == NULL) {
+        return APR_ENOPOOL;
+    }
+    if (mech != APR_LOCK_DEFAULT && mech != APR_LOCK_DEFAULT_TIMED) {
+        return APR_ENOTIMPL;
+    }
+
+    new = (apr_proc_mutex_t *)apr_palloc(pool, sizeof(apr_proc_mutex_t));
+    new->pool       = pool;
+    new->owner      = 0;
+    new->lock_count = 0;
+    new->hMutex     = *ospmutex;
+    *pmutex = new;
+
+    if (register_cleanup) {
+        apr_pool_cleanup_register(pool, *pmutex, apr_proc_mutex_cleanup,
+                                  apr_pool_cleanup_null);
+    }
+    return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_os_proc_mutex_put(apr_proc_mutex_t **pmutex,
+                                                apr_os_proc_mutex_t *ospmutex,
+                                                apr_pool_t *pool)
+{
+    return apr_os_proc_mutex_put_ex(pmutex, ospmutex, APR_LOCK_DEFAULT,
+                                    0, pool);
+}
+
diff --git a/locks/os2/thread_cond.c b/locks/os2/thread_cond.c
new file mode 100644
index 0000000..1b8698e
--- /dev/null
+++ b/locks/os2/thread_cond.c
@@ -0,0 +1,194 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_general.h"
+#include "apr_lib.h"
+#include "apr_strings.h"
+#include "apr_portable.h"
+#include "apr_arch_thread_mutex.h"
+#include "apr_arch_thread_cond.h"
+#include "apr_arch_file_io.h"
+#include <string.h>
+
+#ifndef DCE_POSTONE
+#define DCE_POSTONE   0x0800 // Post one flag
+#endif
+
+static apr_status_t thread_cond_cleanup(void *data)
+{
+    apr_thread_cond_t *cv = data;
+
+    if (cv->semaphore) {
+        DosCloseEventSem(cv->semaphore);
+    }
+
+    if (cv->mutex) {
+        DosCloseMutexSem(cv->mutex);
+    }
+
+    return APR_SUCCESS;
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_cond_create(apr_thread_cond_t **cond,
+                                                 apr_pool_t *pool)
+{
+    int rc;
+    apr_thread_cond_t *cv;
+
+    cv = apr_pcalloc(pool, sizeof(**cond));
+    rc = DosCreateEventSem(NULL, &cv->semaphore, DCE_POSTONE, FALSE);
+
+    if (rc == 0) {
+        rc = DosCreateMutexSem(NULL, &cv->mutex, 0, FALSE);
+    }
+
+    *cond = cv;
+    cv->pool = pool;
+    apr_pool_cleanup_register(cv->pool, cv, thread_cond_cleanup,
+                              apr_pool_cleanup_null);
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+static apr_status_t thread_cond_timedwait(apr_thread_cond_t *cond,
+                                          apr_thread_mutex_t *mutex,
+                                          ULONG timeout_ms )
+{
+    ULONG rc;
+    apr_status_t rv = APR_SUCCESS;
+    int wake = FALSE;
+    unsigned long generation;
+
+    DosRequestMutexSem(cond->mutex, SEM_INDEFINITE_WAIT);
+    cond->num_waiting++;
+    generation = cond->generation;
+    DosReleaseMutexSem(cond->mutex);
+
+    apr_thread_mutex_unlock(mutex);
+
+    do {
+        rc = DosWaitEventSem(cond->semaphore, timeout_ms);
+
+        DosRequestMutexSem(cond->mutex, SEM_INDEFINITE_WAIT);
+
+        if (cond->num_wake) {
+            if (cond->generation != generation) {
+                cond->num_wake--;
+                cond->num_waiting--;
+                rv = APR_SUCCESS;
+                break;
+            } else {
+                wake = TRUE;
+            }
+        }
+        else if (rc != 0) {
+            cond->num_waiting--;
+            rv = APR_TIMEUP;
+            break;
+        }
+
+        DosReleaseMutexSem(cond->mutex);
+
+        if (wake) {
+            wake = FALSE;
+            DosPostEventSem(cond->semaphore);
+        }
+    } while (1);
+
+    DosReleaseMutexSem(cond->mutex);
+    apr_thread_mutex_lock(mutex);
+    return rv;
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_cond_wait(apr_thread_cond_t *cond,
+                                               apr_thread_mutex_t *mutex)
+{
+    return thread_cond_timedwait(cond, mutex, SEM_INDEFINITE_WAIT);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_cond_timedwait(apr_thread_cond_t *cond,
+                                                    apr_thread_mutex_t *mutex,
+                                                    apr_interval_time_t timeout)
+{
+    ULONG timeout_ms = (timeout >= 0) ? apr_time_as_msec(timeout)
+                                      : SEM_INDEFINITE_WAIT;
+    return thread_cond_timedwait(cond, mutex, timeout_ms);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_cond_signal(apr_thread_cond_t *cond)
+{
+    int wake = FALSE;
+
+    DosRequestMutexSem(cond->mutex, SEM_INDEFINITE_WAIT);
+
+    if (cond->num_waiting > cond->num_wake) {
+        wake = TRUE;
+        cond->num_wake++;
+        cond->generation++;
+    }
+
+    DosReleaseMutexSem(cond->mutex);
+
+    if (wake) {
+        DosPostEventSem(cond->semaphore);
+    }
+
+    return APR_SUCCESS;
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_cond_broadcast(apr_thread_cond_t *cond)
+{
+    unsigned long num_wake = 0;
+
+    DosRequestMutexSem(cond->mutex, SEM_INDEFINITE_WAIT);
+
+    if (cond->num_waiting > cond->num_wake) {
+        num_wake = cond->num_waiting - cond->num_wake;
+        cond->num_wake = cond->num_waiting;
+        cond->generation++;
+    }
+
+    DosReleaseMutexSem(cond->mutex);
+
+    for (; num_wake; num_wake--) {
+        DosPostEventSem(cond->semaphore);
+    }
+
+    return APR_SUCCESS;
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_cond_destroy(apr_thread_cond_t *cond)
+{
+    return apr_pool_cleanup_run(cond->pool, cond, thread_cond_cleanup);
+}
+
+
+
+APR_POOL_IMPLEMENT_ACCESSOR(thread_cond)
diff --git a/locks/os2/thread_mutex.c b/locks/os2/thread_mutex.c
new file mode 100644
index 0000000..fea188d
--- /dev/null
+++ b/locks/os2/thread_mutex.c
@@ -0,0 +1,120 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_general.h"
+#include "apr_lib.h"
+#include "apr_strings.h"
+#include "apr_portable.h"
+#include "apr_arch_thread_mutex.h"
+#include "apr_arch_file_io.h"
+#include <string.h>
+#include <stddef.h>
+
+static apr_status_t thread_mutex_cleanup(void *themutex)
+{
+    apr_thread_mutex_t *mutex = themutex;
+    return apr_thread_mutex_destroy(mutex);
+}
+
+
+
+/* XXX: Need to respect APR_THREAD_MUTEX_[UN]NESTED flags argument
+ *      or return APR_ENOTIMPL!!!
+ */
+APR_DECLARE(apr_status_t) apr_thread_mutex_create(apr_thread_mutex_t **mutex,
+                                                  unsigned int flags,
+                                                  apr_pool_t *pool)
+{
+    apr_thread_mutex_t *new_mutex;
+    ULONG rc;
+
+    new_mutex = (apr_thread_mutex_t *)apr_palloc(pool, sizeof(apr_thread_mutex_t));
+    new_mutex->pool = pool;
+
+    rc = DosCreateMutexSem(NULL, &(new_mutex->hMutex), 0, FALSE);
+    *mutex = new_mutex;
+
+    if (!rc)
+        apr_pool_cleanup_register(pool, new_mutex, thread_mutex_cleanup, apr_pool_cleanup_null);
+
+    return APR_OS2_STATUS(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_mutex_lock(apr_thread_mutex_t *mutex)
+{
+    ULONG rc = DosRequestMutexSem(mutex->hMutex, SEM_INDEFINITE_WAIT);
+    return APR_OS2_STATUS(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_mutex_trylock(apr_thread_mutex_t *mutex)
+{
+    ULONG rc = DosRequestMutexSem(mutex->hMutex, SEM_IMMEDIATE_RETURN);
+
+    return (rc == ERROR_TIMEOUT) ? APR_EBUSY : APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_mutex_timedlock(apr_thread_mutex_t *mutex,
+                                                 apr_interval_time_t timeout)
+{
+    ULONG rc;
+
+    if (timeout <= 0) {
+        rc = DosRequestMutexSem(mutex->hMutex, SEM_IMMEDIATE_RETURN);
+    }
+    else {
+        rc = DosRequestMutexSem(mutex->hMutex, apr_time_as_msec(timeout));
+    }
+
+    return (rc == ERROR_TIMEOUT) ? APR_TIMEUP : APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_mutex_unlock(apr_thread_mutex_t *mutex)
+{
+    ULONG rc = DosReleaseMutexSem(mutex->hMutex);
+    return APR_OS2_STATUS(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_mutex_destroy(apr_thread_mutex_t *mutex)
+{
+    ULONG rc;
+
+    if (mutex->hMutex == 0)
+        return APR_SUCCESS;
+
+    while (DosReleaseMutexSem(mutex->hMutex) == 0);
+
+    rc = DosCloseMutexSem(mutex->hMutex);
+
+    if (!rc) {
+        mutex->hMutex = 0;
+        return APR_SUCCESS;
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+APR_POOL_IMPLEMENT_ACCESSOR(thread_mutex)
+
diff --git a/locks/os2/thread_rwlock.c b/locks/os2/thread_rwlock.c
new file mode 100644
index 0000000..195a56b
--- /dev/null
+++ b/locks/os2/thread_rwlock.c
@@ -0,0 +1,200 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_general.h"
+#include "apr_lib.h"
+#include "apr_strings.h"
+#include "apr_portable.h"
+#include "apr_arch_thread_rwlock.h"
+#include "apr_arch_file_io.h"
+#include <string.h>
+
+static apr_status_t thread_rwlock_cleanup(void *therwlock)
+{
+    apr_thread_rwlock_t *rwlock = therwlock;
+    return apr_thread_rwlock_destroy(rwlock);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_create(apr_thread_rwlock_t **rwlock,
+                                                   apr_pool_t *pool)
+{
+    apr_thread_rwlock_t *new_rwlock;
+    ULONG rc;
+
+    new_rwlock = (apr_thread_rwlock_t *)apr_palloc(pool, sizeof(apr_thread_rwlock_t));
+    new_rwlock->pool = pool;
+    new_rwlock->readers = 0;
+
+    rc = DosCreateMutexSem(NULL, &(new_rwlock->write_lock), 0, FALSE);
+
+    if (rc)
+        return APR_FROM_OS_ERROR(rc);
+
+    rc = DosCreateEventSem(NULL, &(new_rwlock->read_done), 0, FALSE);
+
+    if (rc)
+        return APR_FROM_OS_ERROR(rc);
+
+    *rwlock = new_rwlock;
+
+    if (!rc)
+        apr_pool_cleanup_register(pool, new_rwlock, thread_rwlock_cleanup,
+                                  apr_pool_cleanup_null);
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_rdlock(apr_thread_rwlock_t *rwlock)
+{
+    ULONG rc, posts;
+
+    rc = DosRequestMutexSem(rwlock->write_lock, SEM_INDEFINITE_WAIT);
+
+    if (rc)
+        return APR_FROM_OS_ERROR(rc);
+
+    /* We've successfully acquired the writer mutex so we can't be locked
+     * for write which means it's ok to add a reader lock. The writer mutex
+     * doubles as race condition protection for the readers counter.
+     */
+    rwlock->readers++;
+    DosResetEventSem(rwlock->read_done, &posts);
+    rc = DosReleaseMutexSem(rwlock->write_lock);
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_tryrdlock(apr_thread_rwlock_t *rwlock)
+{
+    /* As above but with different wait time */
+    ULONG rc, posts;
+
+    rc = DosRequestMutexSem(rwlock->write_lock, SEM_IMMEDIATE_RETURN);
+
+    if (rc)
+        return APR_FROM_OS_ERROR(rc);
+
+    rwlock->readers++;
+    DosResetEventSem(rwlock->read_done, &posts);
+    rc = DosReleaseMutexSem(rwlock->write_lock);
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_wrlock(apr_thread_rwlock_t *rwlock)
+{
+    ULONG rc;
+
+    rc = DosRequestMutexSem(rwlock->write_lock, SEM_INDEFINITE_WAIT);
+
+    if (rc)
+        return APR_FROM_OS_ERROR(rc);
+
+    /* We've got the writer lock but we have to wait for all readers to
+     * unlock before it's ok to use it
+     */
+
+    if (rwlock->readers) {
+        rc = DosWaitEventSem(rwlock->read_done, SEM_INDEFINITE_WAIT);
+
+        if (rc)
+            DosReleaseMutexSem(rwlock->write_lock);
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_trywrlock(apr_thread_rwlock_t *rwlock)
+{
+    ULONG rc;
+
+    rc = DosRequestMutexSem(rwlock->write_lock, SEM_IMMEDIATE_RETURN);
+
+    if (rc)
+        return APR_FROM_OS_ERROR(rc);
+
+    /* We've got the writer lock but we have to wait for all readers to
+     * unlock before it's ok to use it
+     */
+
+    if (rwlock->readers) {
+        /* There are readers active, give up */
+        DosReleaseMutexSem(rwlock->write_lock);
+        rc = ERROR_TIMEOUT;
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_unlock(apr_thread_rwlock_t *rwlock)
+{
+    ULONG rc;
+
+    /* First, guess that we're unlocking a writer */
+    rc = DosReleaseMutexSem(rwlock->write_lock);
+
+    if (rc == ERROR_NOT_OWNER) {
+        /* Nope, we must have a read lock */
+        if (rwlock->readers) {
+            DosEnterCritSec();
+            rwlock->readers--;
+
+            if (rwlock->readers == 0) {
+                DosPostEventSem(rwlock->read_done);
+            }
+
+            DosExitCritSec();
+            rc = 0;
+        }
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+
+
+APR_DECLARE(apr_status_t) apr_thread_rwlock_destroy(apr_thread_rwlock_t *rwlock)
+{
+    ULONG rc;
+
+    if (rwlock->write_lock == 0)
+        return APR_SUCCESS;
+
+    while (DosReleaseMutexSem(rwlock->write_lock) == 0);
+
+    rc = DosCloseMutexSem(rwlock->write_lock);
+
+    if (!rc) {
+        rwlock->write_lock = 0;
+        DosCloseEventSem(rwlock->read_done);
+        return APR_SUCCESS;
+    }
+
+    return APR_FROM_OS_ERROR(rc);
+}
+
+APR_POOL_IMPLEMENT_ACCESSOR(thread_rwlock)
+