1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
/*
* USAGE
*
* Start one process, no args, and place it into the background. Start a
* second process with the "-r" switch to attempt a read on the file
* created by the first process.
*
* $ ./testflock &
* ...messages...
* $ ./testflock -r
* ...messages...
*
* The first process will sleep for 30 seconds while holding a lock. The
* second process will attempt to grab it (non-blocking) and fail. It
* will then grab it with a blocking scheme. When the first process' 30
* seconds are up, it will exit (thus releasing its lock). The second
* process will acquire the lock, then exit.
*/
#include "apr_pools.h"
#include "apr_file_io.h"
#include "apr_time.h"
#include "apr_general.h"
#include "apr_getopt.h"
#include "apr_strings.h"
#include <stdlib.h>
#include <stdio.h>
#define TESTFILE "testfile.tmp"
static apr_pool_t *pool = NULL;
static void errmsg(const char *msg)
{
if (pool != NULL)
apr_destroy_pool(pool);
fprintf(stderr, msg);
exit(1);
}
static void do_read(void)
{
apr_file_t *file;
apr_status_t status;
if (apr_open(&file, TESTFILE, APR_WRITE,
APR_OS_DEFAULT, pool) != APR_SUCCESS)
errmsg("Could not open test file.\n");
printf("Test file opened.\n");
status = apr_lock_file(file, APR_FLOCK_EXCLUSIVE | APR_FLOCK_NONBLOCK);
if (!APR_STATUS_IS_EAGAIN(status)) {
char msg[200];
errmsg(apr_psprintf(pool, "Expected EAGAIN. Got %d: %s.\n",
status, apr_strerror(status, msg, sizeof(msg))));
}
printf("First attempt: we were properly locked out.\nWaiting for lock...");
fflush(stdout);
if (apr_lock_file(file, APR_FLOCK_EXCLUSIVE) != APR_SUCCESS)
errmsg("Could not establish lock on test file.");
printf(" got it.\n");
(void) apr_close(file);
printf("Exiting.\n");
}
static void do_write(void)
{
apr_file_t *file;
if (apr_open(&file, TESTFILE, APR_WRITE|APR_CREATE, APR_OS_DEFAULT,
pool) != APR_SUCCESS)
errmsg("Could not create file.\n");
printf("Test file created.\n");
if (apr_lock_file(file, APR_FLOCK_EXCLUSIVE) != APR_SUCCESS)
errmsg("Could not lock the file.\n");
printf("Lock created.\nSleeping...");
fflush(stdout);
apr_sleep(30000000); /* 30 seconds */
(void) apr_close(file);
printf(" done.\nExiting.\n");
}
int main(int argc, const char * const *argv)
{
int reader = 0;
apr_status_t status;
char optchar;
const char *optarg;
apr_getopt_t *opt;
if (apr_initialize() != APR_SUCCESS)
errmsg("Could not initialize APR.\n");
atexit(apr_terminate);
if (apr_create_pool(&pool, NULL) != APR_SUCCESS)
errmsg("Could not create global pool.\n");
if (apr_initopt(&opt, pool, argc, argv) != APR_SUCCESS)
errmsg("Could not parse options.\n");
while ((status = apr_getopt(opt, "r", &optchar, &optarg)) == APR_SUCCESS) {
if (optchar == 'r')
++reader;
}
if (reader)
do_read();
else
do_write();
return 0;
}
|
