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/* 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.
*/
/*
* 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>
const char *testfile = "testfile.tmp";
static apr_pool_t *pool = NULL;
static void errmsg(const char *msg)
{
if (pool != NULL)
apr_pool_destroy(pool);
fprintf(stderr, msg);
exit(1);
}
static void errmsg2(const char *msg, apr_status_t rv)
{
char *newmsg;
char errstr[120];
apr_strerror(rv, errstr, sizeof errstr);
newmsg = apr_psprintf(pool, "%s: %s (%d)\n",
msg, errstr, rv);
errmsg(newmsg);
exit(1);
}
static void do_read(void)
{
apr_file_t *file;
apr_status_t status;
if (apr_file_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_file_lock(file, APR_FLOCK_EXCLUSIVE | APR_FLOCK_NONBLOCK);
if (!APR_STATUS_IS_EAGAIN(status)) {
char msg[200];
errmsg(apr_psprintf(pool, "Expected APR_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_file_lock(file, APR_FLOCK_EXCLUSIVE) != APR_SUCCESS)
errmsg("Could not establish lock on test file.");
printf(" got it.\n");
(void) apr_file_close(file);
printf("Exiting.\n");
}
static void do_write(void)
{
apr_file_t *file;
apr_status_t rv;
if (apr_file_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 ((rv = apr_file_lock(file, APR_FLOCK_EXCLUSIVE)) != APR_SUCCESS)
errmsg2("Could not lock the file", rv);
printf("Lock created.\nSleeping...");
fflush(stdout);
apr_sleep(apr_time_from_sec(30));
(void) apr_file_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_pool_create(&pool, NULL) != APR_SUCCESS)
errmsg("Could not create global pool.\n");
if (apr_getopt_init(&opt, pool, argc, argv) != APR_SUCCESS)
errmsg("Could not parse options.\n");
while ((status = apr_getopt(opt, "rf:", &optchar, &optarg)) == APR_SUCCESS) {
if (optchar == 'r')
++reader;
else if (optchar == 'f')
testfile = optarg;
}
if (status != APR_SUCCESS && status != APR_EOF) {
char msgbuf[80];
fprintf(stderr, "error: %s\n",
apr_strerror(status, msgbuf, sizeof msgbuf));
exit(1);
}
if (reader)
do_read();
else
do_write();
return 0;
}
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