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
19#if APR_HAVE_FCNTL_H
20#include <fcntl.h>
21#endif
22#ifdef HAVE_SYS_FILE_H
23#include <sys/file.h>
24#endif
25
26APR_DECLARE(apr_status_t) apr_file_lock(apr_file_t *thefile, int type)
27{
28    int rc;
29
30#if defined(HAVE_FCNTL_H)
31    {
32        struct flock l = { 0 };
33        int fc;
34
35        l.l_whence = SEEK_SET;  /* count l_start from start of file */
36        l.l_start = 0;          /* lock from start of file */
37        l.l_len = 0;            /* lock to end of file */
38        if ((type & APR_FLOCK_TYPEMASK) == APR_FLOCK_SHARED)
39            l.l_type = F_RDLCK;
40        else
41            l.l_type = F_WRLCK;
42
43        fc = (type & APR_FLOCK_NONBLOCK) ? F_SETLK : F_SETLKW;
44
45        /* keep trying if fcntl() gets interrupted (by a signal) */
46        while ((rc = fcntl(thefile->filedes, fc, &l)) < 0 && errno == EINTR)
47            continue;
48
49        if (rc == -1) {
50            /* on some Unix boxes (e.g., Tru64), we get EACCES instead
51             * of EAGAIN; we don't want APR_STATUS_IS_EAGAIN() matching EACCES
52             * since that breaks other things, so fix up the retcode here
53             */
54            if (errno == EACCES) {
55                return EAGAIN;
56            }
57            return errno;
58        }
59    }
60#elif defined(HAVE_SYS_FILE_H)
61    {
62        int ltype;
63
64        if ((type & APR_FLOCK_TYPEMASK) == APR_FLOCK_SHARED)
65            ltype = LOCK_SH;
66        else
67            ltype = LOCK_EX;
68        if ((type & APR_FLOCK_NONBLOCK) != 0)
69            ltype |= LOCK_NB;
70
71        /* keep trying if flock() gets interrupted (by a signal) */
72        while ((rc = flock(thefile->filedes, ltype)) < 0 && errno == EINTR)
73            continue;
74
75        if (rc == -1)
76            return errno;
77    }
78#else
79#error No file locking mechanism is available.
80#endif
81
82    return APR_SUCCESS;
83}
84
85APR_DECLARE(apr_status_t) apr_file_unlock(apr_file_t *thefile)
86{
87    int rc;
88
89#if defined(HAVE_FCNTL_H)
90    {
91        struct flock l = { 0 };
92
93        l.l_whence = SEEK_SET;  /* count l_start from start of file */
94        l.l_start = 0;          /* lock from start of file */
95        l.l_len = 0;            /* lock to end of file */
96        l.l_type = F_UNLCK;
97
98        /* keep trying if fcntl() gets interrupted (by a signal) */
99        while ((rc = fcntl(thefile->filedes, F_SETLKW, &l)) < 0
100               && errno == EINTR)
101            continue;
102
103        if (rc == -1)
104            return errno;
105    }
106#elif defined(HAVE_SYS_FILE_H)
107    {
108        /* keep trying if flock() gets interrupted (by a signal) */
109        while ((rc = flock(thefile->filedes, LOCK_UN)) < 0 && errno == EINTR)
110            continue;
111
112        if (rc == -1)
113            return errno;
114    }
115#else
116#error No file locking mechanism is available.
117#endif
118
119    return APR_SUCCESS;
120}
121