The preferred strategy of open()

The routines in cdrom.c are designed in such a way that a run-time configuration of the behavior of CDROM devices (of any type) can be carried out, by the CDROM_SET/CLEAR_OPTIONS ioctls. Thus, various modes of operation can be set:

CDO_AUTO_CLOSE | CDO_USE_FFLAGS | CDO_LOCK

This is the default setting. (With CDO_CHECK_TYPE it will be better, in the future.) If the device is not yet opened by any other process, and it is opened for data ( O_NONBLOCK is not set) and the tray is found open, an attempt to close the tray is made. Then, it is verified that a disc is in the drive and, if CDO_CHECK_TYPE is set, that its type is `data mode 1.' Only if all tests are passed, the return value is zero. The door is locked to prevent file system corruption. If opened for audio ( O_NONBLOCK is set), no actions are taken and a value of 0 will be returned.

0

Open() will always be successful, the option flags are ignored. Neither actions are undertaken, nor any integrity checks are made.

CDO_AUTO_CLOSE | CDO_AUTO_EJECT | CDO_LOCK

This mimics the behavior of the current sbpcd-driver. The option flags are ignored, the tray is closed on the first open, if necessary. Similarly, the tray is opened on the last release, i.e., if a CDROM is unmounted, it is automatically ejected, such that the user can replace it.