记录锁的使用

#include

#include

#include

 

static struct flock lock_it, unlock_it;
static int lock_fd = -1;

 

void lock_init(void)
{
 char lock_file[] = "/tmp/cheney.servers.lock.XXXXXX";

 lock_fd = mkstemp(lock_file);
 unlink(lock_file);

 lock_it.l_type = F_WRLCK;
 lock_it.l_whence = SEEK_SET;
 lock_it.l_start = 0;
 lock_it.l_len = 0;

 unlock_it.l_type = F_UNLCK;
 unlock_it.l_whence = SEEK_SET;
 unlock_it.l_start = 0;
 unlock_it.l_len = 0;
}

 

void lock_wait(void)
{
 int rc;

 while ((rc = fcntl(lock_fd, F_SETLKW, &lock_it)) < 0) {
  if (errno == EINTR)
   continue;
  else
   return;
 }
}

 

void lock_release(void)
{
 if (fcntl(lock_fd, F_SETLKW, &unlock_it) < 0)
  return;
}