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/* test whether fcntl locking works on this system */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_FCNTL_H
#include <sys/fcntl.h>
#endif
#include <errno.h>
static int sys_waitpid(pid_t pid,int *status,int options)
{
#ifdef HAVE_WAITPID
return waitpid(pid,status,options);
#else /* USE_WAITPID */
return wait4(pid, status, options, NULL);
#endif /* USE_WAITPID */
}
#define DATA "conftest.fcntl"
#ifndef SEEK_SET
#define SEEK_SET 0
#endif
/* lock a byte range in a open file */
int main(int argc, char *argv[])
{
struct flock lock;
int fd, pid, ret, status=1;
if (!(pid=fork())) {
sleep(2);
fd = open(DATA, O_RDONLY);
if (fd == -1) exit(1);
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 4;
lock.l_pid = getpid();
lock.l_type = F_WRLCK;
/* check if a lock applies */
ret = fcntl(fd,F_GETLK,&lock);
if ((ret == -1) ||
(lock.l_type == F_UNLCK)) {
exit(1);
} else {
exit(0);
}
}
fd = open(DATA, O_RDWR|O_CREAT|O_TRUNC, 0600);
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 4;
lock.l_pid = getpid();
/* set a 4 byte write lock */
fcntl(fd,F_SETLK,&lock);
sys_waitpid(pid, &status, 0);
unlink(DATA);
exit(status);
}
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