DEVICE_STATUS ([open_type,] filename$)
This function returns a value representing the current status of the device to which the specified filename$ points and can be used to check if an error will be generated when you try to access the given file. The open_type defaults to 2 and can take the following values:
-1: Use for OPEN or OPEN_NEW
0: Use for OPEN
1: Use for OPEN_IN
2: Use for OPEN_NEW
If an open_type of 2 is specified, then the function will try to create the file and return an error code if this is not possible. The temporary file is deleted in all cases.
If an open_type of 0 is specified then the function will try to open the file for exclusive two way access and report any errors.
If an open_type of 1 is specified the function opens the specified file for read only access, which means that it does not care if a channel is already open to the file from another program.
Finally, if an open_type of -1 is specified, the function will first of all try to open a channel to the file, returning -8 if it already exists and can therefore be read.
If it does not already exist, the function will try to create a temporary file and then read back from it to check that the device can be written to and read from, reporting any errors which are found. Any temporary file is then deleted by the function. This enables IN USE and bad or changed medium errors can be detected!
If the open is successful the amount of free space on the drive is returned akin to DEVICE_SPACE, otherwise a standard QDOS error code is returned.
Current versions of this fuction have difficulty returning the amount of space on large capacity drives, such as hard disks. It assumes that a sector contains 512 bytes and will only cope with a maximum of 65535 sectors.
Due to a bug in the QL’s hardware, it is impossible to check if a microdrive is read only. In this instance, you will get a bad or changed medium error code (-16).
See DEVICE_SPACE for an example.