rsrcdbmgr_devno_attach()

Arguments:

name

The name of the class of devices that you want to get the major number for. This string can be anything, but can't include any slashes. Various names are defined in in <sys/ftype.h>; see Class names, below.

minor_request

The minor device number that you want to reserve, or -1 to let the system assign the next available minor number.

flags

Presently, there are no flags; pass zero for this argument.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The rsrcdbmgr_devno_attach() function reserves a device number that consists of:

• a major number that corresponds to the given device class. If there isn't already a major number associated with the class, a new major number is assigned to it.
• a minor number that's based on minor_request. If minor_request is -1, the function returns the first free minor number in the specified class.

There's a maximum of 64 major numbers (0 through 63) on the system, and a maximum of 1024 minor numbers (0 through 1023) per major number.

Major and minor numbers are used only by resource managers and are exposed through the rdev member of the iofunc_attr_t structure, and correspondingly the st_rdev member of the stat structure. They aren't required for proper operation; on simple devices, an entry will be simulated for you.

If the requested device number is already in use (whether by the calling process or a different process), this function returns -1 and sets errno to EINVAL.

To detach a device, call rsrcdbmgr_devno_detach(). If you don't detach a device, it's released when the process that attached it terminates.

Class names

As mentioned above, the name of the class of devices can be anything, but can't include any slashes. The following class names are defined in <sys/ftype.h>:

Returns:

A dev_t object that contains the major and minor numbers, or (dev_t)-1 if an error occurs (errno is set).

You can extract the major and minor number values from the dev_t object by using the major() and minor() macros defined in <sys/types.h>. For more information, see the documentation for stat().

Errors:

EINTR

The call was interrupted by a signal.

EINVAL

One of the following occurred:

• The requested name and number are already in use.
• An argument was invalid.

ENOMEM

Insufficient memory to allocate internal data structures.

EPERM

The calling process doesn't have the required permission; see procmgr_ability().

Examples:

#include <sys/rsrcdbmgr.h>

char      *dev_name;
int       myminor_request, flags=0;
dev_t     major_minor;

major_minor = rsrcdbmgr_devno_attach
              ( dev_name, myminor_request, flags );

…

rsrcdbmgr_devno_detach( major_minor, flags );

Classification:

QNX OS