1251876Speter/* Licensed to the Apache Software Foundation (ASF) under one or more
2251876Speter * contributor license agreements.  See the NOTICE file distributed with
3251876Speter * this work for additional information regarding copyright ownership.
4251876Speter * The ASF licenses this file to You under the Apache License, Version 2.0
5251876Speter * (the "License"); you may not use this file except in compliance with
6251876Speter * the License.  You may obtain a copy of the License at
7251876Speter *
8251876Speter *     http://www.apache.org/licenses/LICENSE-2.0
9251876Speter *
10251876Speter * Unless required by applicable law or agreed to in writing, software
11251876Speter * distributed under the License is distributed on an "AS IS" BASIS,
12251876Speter * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13251876Speter * See the License for the specific language governing permissions and
14251876Speter * limitations under the License.
15251876Speter */
16251876Speter
17251876Speter#include "apr_file_info.h"
18251876Speter#include "apr_file_io.h"
19251876Speter#include "apr_sdbm.h"
20251876Speter
21251876Speter#include "sdbm_private.h"
22251876Speter#include "sdbm_tune.h"
23251876Speter
24251876Speter/* NOTE: this function may block until it acquires the lock */
25251876SpeterAPU_DECLARE(apr_status_t) apr_sdbm_lock(apr_sdbm_t *db, int type)
26251876Speter{
27251876Speter    apr_status_t status;
28251876Speter    int lock_type = type & APR_FLOCK_TYPEMASK;
29251876Speter
30251876Speter    if (!(lock_type == APR_FLOCK_SHARED || lock_type == APR_FLOCK_EXCLUSIVE))
31251876Speter        return APR_EINVAL;
32251876Speter
33251876Speter    if (db->flags & SDBM_EXCLUSIVE_LOCK) {
34251876Speter        ++db->lckcnt;
35251876Speter        return APR_SUCCESS;
36251876Speter    }
37251876Speter    else if (db->flags & SDBM_SHARED_LOCK) {
38251876Speter        /*
39251876Speter         * Cannot promote a shared lock to an exlusive lock
40251876Speter         * in a cross-platform compatibile manner.
41251876Speter         */
42251876Speter        if (type == APR_FLOCK_EXCLUSIVE)
43251876Speter            return APR_EINVAL;
44251876Speter        ++db->lckcnt;
45251876Speter        return APR_SUCCESS;
46251876Speter    }
47251876Speter    /*
48251876Speter     * zero size: either a fresh database, or one with a single,
49251876Speter     * unsplit data page: dirpage is all zeros.
50251876Speter     */
51251876Speter    if ((status = apr_file_lock(db->dirf, type)) == APR_SUCCESS)
52251876Speter    {
53251876Speter        apr_finfo_t finfo;
54251876Speter        if ((status = apr_file_info_get(&finfo, APR_FINFO_SIZE, db->dirf))
55251876Speter                != APR_SUCCESS) {
56251876Speter            (void) apr_file_unlock(db->dirf);
57251876Speter            return status;
58251876Speter        }
59251876Speter
60251876Speter        SDBM_INVALIDATE_CACHE(db, finfo);
61251876Speter
62251876Speter        ++db->lckcnt;
63251876Speter        if (type == APR_FLOCK_SHARED)
64251876Speter            db->flags |= SDBM_SHARED_LOCK;
65251876Speter        else if (type == APR_FLOCK_EXCLUSIVE)
66251876Speter            db->flags |= SDBM_EXCLUSIVE_LOCK;
67251876Speter    }
68251876Speter    return status;
69251876Speter}
70251876Speter
71251876SpeterAPU_DECLARE(apr_status_t) apr_sdbm_unlock(apr_sdbm_t *db)
72251876Speter{
73251876Speter    if (!(db->flags & (SDBM_SHARED_LOCK | SDBM_EXCLUSIVE_LOCK)))
74251876Speter        return APR_EINVAL;
75251876Speter    if (--db->lckcnt > 0)
76251876Speter        return APR_SUCCESS;
77251876Speter    db->flags &= ~(SDBM_SHARED_LOCK | SDBM_EXCLUSIVE_LOCK);
78251876Speter    return apr_file_unlock(db->dirf);
79251876Speter}
80