Devices on Unix/Linux (cont)
int ioctl(int FileDesc, int Request, void *Arg)
- manipulates parameters of special files (behind open
FileDesc)
-
Request is a device-specific request code,
-
Arg is either an integer modifier or pointer to data block
- requires
#include <sys/ioctl.h>, returns 0 if ok, -1 if error
Example: SCSI disk driver
-
HDIO_GETGEO ... get disk info in (heads,sectors,cylinders,...)
-
BLKGETSIZE ... get device size in sectors
- in both cases,
Arg is a pointer to an appropriate object
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