SCO OpenServer

close(D2oddi)

close -- relinquish access to a device

Synopsis

   #include <sys/file.h>
   #include <sys/open.h>
   
   void prefixclose(dev_t dev, int flag, int otyp);

Description

The close( ) entry point routine ends the connection between the user process and the previously-opened device and prepares the device and software so that they are ready to be opened again.

Arguments

dev: device number
flag: flag with which the file was opened. The value is merely a reference to be used as needed; it does not control how the file is closed. The flag is taken from the f_flag member of the file structure. open(D2oddi) lists the supported flags.
otyp: parameter used to determine how many times a device was opened and for what reasons. The flags assume that the open( ) routine may be called many times, but the close( ) routine is called by the kernel only on the last close of a device. See open(D2oddi) for a list of supported values.

Return values

None.

Usage

A device may be opened simultaneously by multiple processes and the open(D2oddi) driver routine is called for each open, but, unless the OTYP_LYR otyp is used, the device is closed only by the last close system call (after all forked processes have been closed). The kernel calls the driver's close( ) routine when the last process using the device issues a close call or exits. Block device close routines can also be called when the device is being unmounted (see umount. A close( ) routine should use the flag parameters that are listed on the open(D2oddi) manual page when applicable. The close( ) routine should make the device available for later use by performing the following:

deallocate buffers from a private buffering scheme
unlock resources that were locked in the open( ) routine
flush buffers
notify the device of the close operation

Adhere to the following guidelines:

If an error occurs during the close( ) routine, the driver should call the seterror(D3oddi) function or set the u.u_error member of the user structure directly. Test u.u_error before assigning a value; if an error exists already, do not change the value.

TTY

The close( ) routine in a TTY driver should call the ttclose(D3oddi) function, then disconnect the link to the terminal and return to the caller. Multithreaded TTY drivers call ttyclose( ) through the run_ld(D3oddi) function.

Context and synchronization

Blockable context. The driver can block but cannot do operations such as copyout(D3) that require access to the requesting process's address space.

Hardware applicability

All

Version applicability

oddi: 1, 2, 2mp, 3, 3mp, 4, 4mp, 5, 5mp, 6, 6mp

SVR5 DDI compatibility

The close(D2) entry point routine provides similar functionality for DDI drivers, although note that the syntax is different.

External dependencies

Drivers that contain a close(D2oddi) routine must have a c in the function list of the mdevice(F) file.

References

open(D2mdi), open(D2oddi), open(D2osdi), open(D2str), open(S) , close(S)