1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "apr_arch_file_io.h"
18
19APR_DECLARE(apr_status_t) apr_file_lock(apr_file_t *thefile, int type)
20{
21#ifdef _WIN32_WCE
22    /* The File locking is unsuported on WCE */
23    return APR_ENOTIMPL;
24#else
25    const DWORD len = 0xffffffff;
26    DWORD flags;
27
28    flags = ((type & APR_FLOCK_NONBLOCK) ? LOCKFILE_FAIL_IMMEDIATELY : 0)
29          + (((type & APR_FLOCK_TYPEMASK) == APR_FLOCK_SHARED)
30                                       ? 0 : LOCKFILE_EXCLUSIVE_LOCK);
31    if (apr_os_level >= APR_WIN_NT) {
32        /* Syntax is correct, len is passed for LengthLow and LengthHigh*/
33        OVERLAPPED offset;
34        memset (&offset, 0, sizeof(offset));
35        if (!LockFileEx(thefile->filehand, flags, 0, len, len, &offset))
36            return apr_get_os_error();
37    }
38    else {
39        /* On Win9x, LockFile() never blocks.  Hack in a crufty poll.
40         *
41         * Note that this hack exposes threads to being unserviced forever,
42         * in the situation that the given lock has low availability.
43         * When implemented in the kernel, LockFile will typically use
44         * FIFO or round robin distribution to ensure all threads get
45         * one crack at the lock; but in this case we can't emulate that.
46         *
47         * However Win9x are barely maintainable anyways, if the user does
48         * choose to build to them, this is the best we can do.
49         */
50        while (!LockFile(thefile->filehand, 0, 0, len, 0)) {
51            DWORD err = GetLastError();
52            if ((err == ERROR_LOCK_VIOLATION) && !(type & APR_FLOCK_NONBLOCK))
53            {
54                Sleep(500); /* pause for a half second */
55                continue;   /* ... and then poll again */
56            }
57            return APR_FROM_OS_ERROR(err);
58        }
59    }
60
61    return APR_SUCCESS;
62#endif /* !defined(_WIN32_WCE) */
63}
64
65APR_DECLARE(apr_status_t) apr_file_unlock(apr_file_t *thefile)
66{
67#ifdef _WIN32_WCE
68    return APR_ENOTIMPL;
69#else
70    DWORD len = 0xffffffff;
71
72    if (apr_os_level >= APR_WIN_NT) {
73        /* Syntax is correct, len is passed for LengthLow and LengthHigh*/
74        OVERLAPPED offset;
75        memset (&offset, 0, sizeof(offset));
76        if (!UnlockFileEx(thefile->filehand, 0, len, len, &offset))
77            return apr_get_os_error();
78    }
79    else {
80        if (!UnlockFile(thefile->filehand, 0, 0, len, 0))
81            return apr_get_os_error();
82    }
83
84    return APR_SUCCESS;
85#endif /* !defined(_WIN32_WCE) */
86}
87