fba61ef227
This fixes a race condition where another thread may fork() before CLOEXEC is set, unintentionally passing the descriptor to the child process. This commit only adds O_CLOEXEC flags to open() or openat() calls where no fcntl(fd, F_SETFD, FD_CLOEXEC) follows. The separate fcntl() call still leaves a race window so it should be fixed later.