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utils🏓 add a -c switch to check the lock before reading/writing

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This is to verify that the fcntl F_GETLK call reports F_UNLCK if called
from a process already holding a lock. This is for example used by samba's
strict locking code in combination with "posix locking = true".

Signed-off-by: Michael Adam <obnox@samba.org>

(This used to be ctdb commit 4f42d17b74ce891691eee1cead498959cc8e4837)
This commit is contained in:
Michael Adam 2012-11-06 01:26:05 +01:00
parent 8732e2356f
commit 05cf7bce49
1 changed files with 40 additions and 2 deletions
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42
ctdb/utils/ping_pong/ping_pong.c
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@ -2,6 +2,7 @@
A ping-pong fcntl byte range lock test
Copyright (C) Andrew Tridgell 2002
Copyright (C) Michael Adam 2012
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -41,7 +42,7 @@
static struct timeval tp1,tp2;
static int do_reads, do_writes, use_mmap;
static int do_reads, do_writes, use_mmap, do_check;
static void start_timer(void)
{
@ -69,6 +70,36 @@ static int lock_range(int fd, int offset, int len)
return fcntl(fd,F_SETLKW,&lock);
}
/* check whether we could place a lock */
int check_lock(int fd, int offset, int len)
{
struct flock lock;
int ret;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = offset;
lock.l_len = len;
lock.l_pid = 0;
ret = fcntl(fd, F_GETLK, &lock);
if (ret != 0) {
printf("error calling fcntl F_GETLCK: %s\n", strerror(errno));
return -1;
}
if (lock.l_type == F_UNLCK) {
/* we would be able to place the lock */
return 0;
}
/* we would not be able to place lock */
printf("check_lock failed: lock held: "
"pid='%d', type='%d', start='%d', len='%d'\n",
(int)lock.l_pid, (int)lock.l_type, (int)lock.l_start, (int)lock.l_len);
return 1;
}
/* unlock a byte range in a open file */
static int unlock_range(int fd, int offset, int len)
{
@ -123,6 +154,9 @@ static void ping_pong(int fd, int num_locks)
printf("lock at %d failed! - %s\n",
(i+1) % num_locks, strerror(errno));
}
if (do_check) {
ret = check_lock(fd, i, 1);
}
if (do_reads) {
unsigned char c;
if (use_mmap) {
@ -169,7 +203,7 @@ int main(int argc, char *argv[])
int fd, num_locks;
int c;
while ((c = getopt(argc, argv, "rwm")) != -1) {
while ((c = getopt(argc, argv, "rwmc")) != -1) {
switch (c){
case 'w':
do_writes = 1;
@ -180,6 +214,9 @@ int main(int argc, char *argv[])
case 'm':
use_mmap = 1;
break;
case 'c':
do_check = 1;
break;
default:
fprintf(stderr, "Unknown option '%c'\n", c);
exit(1);
@ -194,6 +231,7 @@ int main(int argc, char *argv[])
printf(" -r do reads\n");
printf(" -w do writes\n");
printf(" -m use mmap\n");
printf(" -c check locks\n");
exit(1);
}