Mac Dev Center Mac OS X Reference Library Drivers, Kernel, & Hardware: User-Space Device Access I/O Kit Framework Reference

IOKitLib.h

Includes:

Overview

IOKitLib implements non-kernel task access to common IOKit object types - IORegistryEntry, IOService, IOIterator etc. These functions are generic - families may provide API that is more specific.
IOKitLib represents IOKit objects outside the kernel with the types io_object_t, io_registry_entry_t, io_service_t, & io_connect_t. Function names usually begin with the type of object they are compatible with - eg. IOObjectRelease can be used with any io_object_t. Inside the kernel, the c++ class hierarchy allows the subclasses of each object type to receive the same requests from user level clients, for example in the kernel, IOService is a subclass of IORegistryEntry, which means any of the IORegistryEntryXXX functions in IOKitLib may be used with io_service_t's as well as io_registry_t's. There are functions available to introspect the class of the kernel object which any io_object_t et al. represents. IOKit objects returned by all functions should be released with IOObjectRelease.

Functions

CFStringRef IOObjectCopyBundleIdentifierForClass: Return the bundle identifier of the given class.
CFStringRef IOObjectCopyClass: Return the class name of an IOKit object.
CFStringRef IOObjectCopySuperclassForClass: Return the superclass name of the given class.
IOBSDNameMatching: Create a matching dictionary that specifies an IOService match based on BSD device name.
IOConnectAddClient: Inform a connection of a second connection.
IOConnectAddRef: Adds a reference to the connect handle.
IOConnectGetService: Returns the IOService a connect handle was opened on.
IOConnectMapMemory: Map hardware or shared memory into the caller's task.
IOConnectMapMemory64: Map hardware or shared memory into the caller's task.
IOConnectRelease: Remove a reference to the connect handle.
IOConnectSetCFProperties: Set CF container based properties on a connection.
IOConnectSetCFProperty: Set a CF container based property on a connection.
IOConnectSetNotificationPort: Set a port to receive family specific notifications.
IOConnectUnmapMemory: Remove a mapping made with IOConnectMapMemory.
IOConnectUnmapMemory64: Remove a mapping made with IOConnectMapMemory64.
IOCreateReceivePort: Creates and returns a mach port suitable for receiving IOKit messages of the specified type.
IODispatchCalloutFromMessage: Dispatches callback notifications from a mach message.
IOIteratorIsValid: Checks an iterator is still valid.
IOIteratorNext: Returns the next object in an iteration.
IOIteratorReset: Resets an iteration back to the beginning.
IOKitGetBusyState: Returns the busyState of all IOServices.
IOKitWaitQuiet: Wait for a all IOServices' busyState to be zero.
IOMasterPort: Returns the mach port used to initiate communication with IOKit.
IONotificationPortCreate: Creates and returns a notification object for receiving IOKit notifications of new devices or state changes.
IONotificationPortDestroy: Destroys a notification object created with IONotificationPortCreate.
IONotificationPortGetMachPort: Returns a mach_port to be used to listen for notifications.
IONotificationPortGetRunLoopSource: Returns a CFRunLoopSource to be used to listen for notifications.
IOObjectConformsTo: Performs an OSDynamicCast operation on an IOKit object.
IOObjectCopyBundleIdentifierForClass IOObjectCopyBundleIdentifierForClass: Return the bundle identifier of the given class.
IOObjectCopyClass IOObjectCopyClass: Return the class name of an IOKit object.
IOObjectCopySuperclassForClass IOObjectCopySuperclassForClass: Return the superclass name of the given class.
IOObjectGetClass: Return the class name of an IOKit object.
IOObjectGetKernelRetainCount: Returns kernel retain count of an IOKit object.
IOObjectGetRetainCount: Returns kernel retain count of an IOKit object. Identical to IOObjectGetKernelRetainCount() but available prior to Mac OS 10.6.
IOObjectGetUserRetainCount: Returns the retain count for the current process of an IOKit object.
IOObjectIsEqualTo: Checks two object handles to see if they represent the same kernel object.
IOObjectRelease: Releases an object handle previously returned by IOKitLib.
IOObjectRetain: Retains an object handle previously returned by IOKitLib.
IOOpenFirmwarePathMatching: Create a matching dictionary that specifies an IOService match based on an OpenFirmware device path.
IORegistryCreateIterator: Create an iterator rooted at the registry root.
IORegistryEntryCreateCFProperties: Create a CF dictionary representation of a registry entry's property table.
IORegistryEntryCreateCFProperty: Create a CF representation of a registry entry's property.
IORegistryEntryCreateIterator: Create an iterator rooted at a given registry entry.
IORegistryEntryFromPath: Looks up a registry entry by path.
IORegistryEntryGetChildEntry: Returns the first child of a registry entry in a plane.
IORegistryEntryGetChildIterator: Returns an iterator over an registry entry's child entries in a plane.
IORegistryEntryGetLocationInPlane: Returns a C-string location assigned to a registry entry, in a specified plane.
IORegistryEntryGetName: Returns a C-string name assigned to a registry entry.
IORegistryEntryGetNameInPlane: Returns a C-string name assigned to a registry entry, in a specified plane.
IORegistryEntryGetParentEntry: Returns the first parent of a registry entry in a plane.
IORegistryEntryGetParentIterator: Returns an iterator over an registry entry's parent entries in a plane.
IORegistryEntryGetPath: Create a path for a registry entry.
IORegistryEntryGetRegistryEntryID: Returns an ID for the registry entry that is global to all tasks.
IORegistryEntryIDMatching: Create a matching dictionary that specifies an IOService match based on a registry entry ID.
IORegistryEntryInPlane: Determines if the registry entry is attached in a plane.
IORegistryEntrySearchCFProperty: Create a CF representation of a registry entry's property.
IORegistryEntrySetCFProperties: Set CF container based properties in a registry entry.
IORegistryEntrySetCFProperty: Set a CF container based property in a registry entry.
IORegistryGetRootEntry: Return a handle to the registry root.
IORegistryIteratorEnterEntry: Recurse into the current entry in the registry iteration.
IORegistryIteratorExitEntry: Exits a level of recursion, restoring the current entry.
IOServiceAddInterestNotification: Register for notification of state changes in an IOService.
IOServiceAddMatchingNotification: Look up registered IOService objects that match a matching dictionary, and install a notification request of new IOServices that match.
IOServiceClose: Close a connection to an IOService and destroy the connect handle.
IOServiceGetBusyState: Returns the busyState of an IOService.
IOServiceGetMatchingService: Look up a registered IOService object that matches a matching dictionary.
IOServiceGetMatchingServices: Look up registered IOService objects that match a matching dictionary.
IOServiceMatching: Create a matching dictionary that specifies an IOService class match.
IOServiceMatchPropertyTable: Match an IOService objects with matching dictionary.
IOServiceNameMatching: Create a matching dictionary that specifies an IOService name match.
IOServiceOFPathToBSDName: Utility to look up an IOService from its OpenFirmware device path, and return its BSD device name if available.
IOServiceOpen: A request to create a connection to an IOService.
IOServiceRequestProbe: A request to rescan a bus for device changes.
IOServiceWaitQuiet: Wait for an IOService's busyState to be zero.

CFStringRef IOObjectCopyBundleIdentifierForClass

Return the bundle identifier of the given class.

CFStringRef IOObjectCopyBundleIdentifierForClass(
    CFStringRef classname) ;

Parameters

classname: The name of the class as a CFString.

Return Value

The resulting CFStringRef. This should be released by the caller. If a valid class name is not passed in, then NULL is returned.

Discussion

This function uses the OSMetaClass system in the kernel to derive the name of the kmod, which is the same as the bundle identifier.

Availability: Introduced in Mac OS X v10.4.

CFStringRef IOObjectCopyClass

Return the class name of an IOKit object.

CFStringRef IOObjectCopyClass(
    io_object_t object) ;

Parameters

object: The IOKit object.

Return Value

The resulting CFStringRef. This should be released by the caller. If a valid object is not passed in, then NULL is returned.

Discussion

This function does the same thing as IOObjectGetClass, but returns the result as a CFStringRef.

Availability: Introduced in Mac OS X v10.4.

CFStringRef IOObjectCopySuperclassForClass

Return the superclass name of the given class.

CFStringRef IOObjectCopySuperclassForClass(
    CFStringRef classname) ;

Parameters

classname: The name of the class as a CFString.

Return Value

The resulting CFStringRef. This should be released by the caller. If there is no superclass, or a valid class name is not passed in, then NULL is returned.

Discussion

This function uses the OSMetaClass system in the kernel to derive the name of the superclass of the class.

Availability: Introduced in Mac OS X v10.4.

IOBSDNameMatching

Create a matching dictionary that specifies an IOService match based on BSD device name.

CFMutableDictionaryRef IOBSDNameMatching( 
    mach_port_t masterPort, 
    uint32_t options, 
    const char * bsdName );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
options: No options are currently defined.
bsdName: The BSD name, as a const char *.

Return Value

The matching dictionary created, is returned on success, or zero on failure. The dictionary is commonly passed to IOServiceGetMatchingServices or IOServiceAddNotification which will consume a reference, otherwise it should be released with CFRelease by the caller.

Discussion

IOServices that represent BSD devices have an associated BSD name. This function creates a matching dictionary that will match IOService's with a given BSD name.

IOConnectAddClient

Inform a connection of a second connection.

kern_return_t IOConnectAddClient( 
    io_connect_t connect, 
    io_connect_t client );

Parameters

connect: The connect handle created by IOServiceOpen.
client: Another connect handle created by IOServiceOpen.

Return Value

A kern_return_t error code returned by the family.

Discussion

This is a generic method to inform a family connection of a second connection, and is rarely used.

IOConnectAddRef

Adds a reference to the connect handle.

kern_return_t IOConnectAddRef( 
    io_connect_t connect );

Parameters

connect: The connect handle created by IOServiceOpen.

Return Value

A kern_return_t error code.

Discussion

Adds a reference to the connect handle.

IOConnectGetService

Returns the IOService a connect handle was opened on.

kern_return_t IOConnectGetService( 
    io_connect_t connect, 
    io_service_t *service );

Parameters

connect: The connect handle created by IOServiceOpen.
service: On succes, the service handle the connection was opened on, which should be released with IOObjectRelease.

Return Value

A kern_return_t error code.

Discussion

Finds the service object a connection was opened on.

IOConnectMapMemory

Map hardware or shared memory into the caller's task.

#if !__LP64__ || defined(IOCONNECT_MAPMEMORY_10_6) 
 kern_return_t IOConnectMapMemory( 
    io_connect_t connect, 
    uint32_t memoryType, 
    task_port_t intoTask, 
    vm_address_t *atAddress, 
    vm_size_t *ofSize, 
    IOOptionBits options );  
#else 
 kern_return_t IOConnectMapMemory( 
    io_connect_t connect, 
    uint32_t memoryType, 
    task_port_t intoTask, 
    mach_vm_address_t *atAddress, 
    mach_vm_size_t *ofSize, 
    IOOptionBits options );  
#endif 
/* !__LP64__ || defined(IOCONNECT_MAPMEMORY_10_6) */

Parameters

connect: The connect handle created by IOServiceOpen.
memoryType: What is being requested to be mapped, not interpreted by IOKit and family defined. The family may support physical hardware or shared memory mappings.
intoTask: The task port for the task in which to create the mapping. This may be different to the task which the opened the connection.
atAddress: An in/out parameter - if the kIOMapAnywhere option is not set, the caller should pass the address where it requests the mapping be created, otherwise nothing need to set on input. The address of the mapping created is passed back on sucess.
ofSize: The size of the mapping created is passed back on success.

Return Value

A kern_return_t error code.

Discussion

This is a generic method to create a mapping in the callers task. The family will interpret the type parameter to determine what sort of mapping is being requested. Cache modes and placed mappings may be requested by the caller.

IOConnectMapMemory64

Map hardware or shared memory into the caller's task.

kern_return_t IOConnectMapMemory64( 
    io_connect_t connect, 
    uint32_t memoryType, 
    task_port_t intoTask, 
    mach_vm_address_t *atAddress, 
    mach_vm_size_t *ofSize, 
    IOOptionBits options );

Parameters

connect: The connect handle created by IOServiceOpen.
memoryType: What is being requested to be mapped, not interpreted by IOKit and family defined. The family may support physical hardware or shared memory mappings.
intoTask: The task port for the task in which to create the mapping. This may be different to the task which the opened the connection.
atAddress: An in/out parameter - if the kIOMapAnywhere option is not set, the caller should pass the address where it requests the mapping be created, otherwise nothing need to set on input. The address of the mapping created is passed back on sucess.
ofSize: The size of the mapping created is passed back on success.

Return Value

A kern_return_t error code.

Discussion

IOConnectRelease

Remove a reference to the connect handle.

kern_return_t IOConnectRelease( 
    io_connect_t connect );

Parameters

connect: The connect handle created by IOServiceOpen.

Return Value

A kern_return_t error code.

Discussion

Removes a reference to the connect handle. If the last reference is removed an implicit IOServiceClose is performed.

IOConnectSetCFProperties

Set CF container based properties on a connection.

kern_return_t IOConnectSetCFProperties( 
    io_connect_t connect, 
    CFTypeRef properties );

Parameters

connect: The connect handle created by IOServiceOpen.
properties: A CF container - commonly a CFDictionary but this is not enforced. The container should consist of objects which are understood by IOKit - these are currently : CFDictionary, CFArray, CFSet, CFString, CFData, CFNumber, CFBoolean, and are passed in the kernel as the corresponding OSDictionary etc. objects.

Return Value

A kern_return_t error code returned by the family.

Discussion

This is a generic method to pass a CF container of properties to the connection. The properties are interpreted by the family and commonly represent configuration settings, but may be interpreted as anything.

IOConnectSetCFProperty

Set a CF container based property on a connection.

kern_return_t IOConnectSetCFProperty( 
    io_connect_t connect, 
    CFStringRef propertyName, 
    CFTypeRef property );

Parameters

connect: The connect handle created by IOServiceOpen.
propertyName: The name of the property as a CFString.
property: A CF container - should consist of objects which are understood by IOKit - these are currently : CFDictionary, CFArray, CFSet, CFString, CFData, CFNumber, CFBoolean, and are passed in the kernel as the corresponding OSDictionary etc. objects.

Return Value

A kern_return_t error code returned by the object.

Discussion

This is a generic method to pass a CF property to the connection. The property is interpreted by the family and commonly represent configuration settings, but may be interpreted as anything.

IOConnectSetNotificationPort

Set a port to receive family specific notifications.

kern_return_t IOConnectSetNotificationPort( 
    io_connect_t connect, 
    uint32_t type, 
    mach_port_t port, 
    uintptr_t reference );

Parameters

connect: The connect handle created by IOServiceOpen.
type: The type of notification requested, not interpreted by IOKit and family defined.
port: The port to which to send notifications.
reference: Some families may support passing a reference parameter for the callers use with the notification.

Return Value

A kern_return_t error code.

Discussion

This is a generic method to pass a mach port send right to be be used by family specific notifications.

IOConnectUnmapMemory

Remove a mapping made with IOConnectMapMemory.

#if !__LP64__ || defined(IOCONNECT_MAPMEMORY_10_6) 
 kern_return_t IOConnectUnmapMemory( 
    io_connect_t connect, 
    uint32_t memoryType, 
    task_port_t fromTask, 
    vm_address_t atAddress );  
#else 
 kern_return_t IOConnectUnmapMemory( 
    io_connect_t connect, 
    uint32_t memoryType, 
    task_port_t fromTask, 
    mach_vm_address_t atAddress );  
#endif 
/* !__LP64__ || defined(IOCONNECT_MAPMEMORY_10_6) */

Parameters

connect: The connect handle created by IOServiceOpen.
memoryType: The memory type originally requested in IOConnectMapMemory.
intoTask: The task port for the task in which to remove the mapping. This may be different to the task which the opened the connection.
atAddress: The address of the mapping to be removed.

Return Value

A kern_return_t error code.

Discussion

This is a generic method to remove a mapping in the callers task.

IOConnectUnmapMemory64

Remove a mapping made with IOConnectMapMemory64.

kern_return_t IOConnectUnmapMemory64( 
    io_connect_t connect, 
    uint32_t memoryType, 
    task_port_t fromTask, 
    mach_vm_address_t atAddress );

Parameters

connect: The connect handle created by IOServiceOpen.
memoryType: The memory type originally requested in IOConnectMapMemory.
intoTask: The task port for the task in which to remove the mapping. This may be different to the task which the opened the connection.
atAddress: The address of the mapping to be removed.

Return Value

A kern_return_t error code.

Discussion

This is a generic method to remove a mapping in the callers task.

IOCreateReceivePort

Creates and returns a mach port suitable for receiving IOKit messages of the specified type.

kern_return_t IOCreateReceivePort(
    uint32_t msgType,
    mach_port_t *recvPort );

Parameters

msgType: Type of message to be sent to this port (kOSNotificationMessageID or kOSAsyncCompleteMessageID)
recvPort: The created port is returned.

Return Value

A kern_return_t error code.

Discussion

In the future IOKit may use specialized messages and ports instead of the standard ports created by mach_port_allocate(). Use this function instead of mach_port_allocate() to ensure compatibility with future revisions of IOKit.

IODispatchCalloutFromMessage

Dispatches callback notifications from a mach message.

void IODispatchCalloutFromMessage( 
    void *unused, 
    mach_msg_header_t *msg, 
    void *reference );

Parameters

unused: Not used, set to zero.
msg: A pointer to the message received.
reference: Pass the IONotificationPortRef for the object.

Discussion

A notification object may deliver notifications to a mach messaging client, which should call this function to generate the callbacks associated with the notifications arriving on the port.

IOIteratorIsValid

Checks an iterator is still valid.

boolean_t IOIteratorIsValid( 
    io_iterator_t iterator );

Parameters

iterator: An IOKit iterator handle.

Return Value

True if the iterator handle is valid, otherwise false is returned.

Discussion

Some iterators will be made invalid if changes are made to the structure they are iterating over. This function checks the iterator is still valid and should be called when IOIteratorNext returns zero. An invalid iterator can be reset and the iteration restarted.

IOIteratorNext

Returns the next object in an iteration.

io_object_t IOIteratorNext( 
    io_iterator_t iterator );

Parameters

iterator: An IOKit iterator handle.

Return Value

If the iterator handle is valid, the next element in the iteration is returned, otherwise zero is returned. The element should be released by the caller when it is finished.

Discussion

This function returns the next object in an iteration, or zero if no more remain or the iterator is invalid.

IOIteratorReset

Resets an iteration back to the beginning.

void IOIteratorReset( 
    io_iterator_t iterator );

Parameters

iterator: An IOKit iterator handle.

Discussion

If an iterator is invalid, or if the caller wants to start over, IOIteratorReset will set the iteration back to the beginning.

IOKitGetBusyState

Returns the busyState of all IOServices.

kern_return_t IOKitGetBusyState( 
    mach_port_t masterPort, 
    uint32_t *busyState );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
busyState: The busyState count is returned.

Return Value

A kern_return_t error code.

Discussion

Many activities in IOService are asynchronous. When registration, matching, or termination is in progress on an IOService, its busyState is increased by one. Change in busyState to or from zero also changes the IOService's provider's busyState by one, which means that an IOService is marked busy when any of the above activities is ocurring on it or any of its clients. IOKitGetBusyState returns the busy state of the root of the service plane which reflects the busy state of all IOServices.

IOKitWaitQuiet

Wait for a all IOServices' busyState to be zero.

kern_return_t IOKitWaitQuiet( 
    mach_port_t masterPort, 
    mach_timespec_t *waitTime );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
waitTime: Specifies a maximum time to wait.

Return Value

Returns an error code if mach synchronization primitives fail, kIOReturnTimeout, or kIOReturnSuccess.

Discussion

Blocks the caller until all IOServices are non busy, see IOKitGetBusyState.

IOMasterPort

Returns the mach port used to initiate communication with IOKit.

kern_return_t IOMasterPort(
    mach_port_t bootstrapPort, 
    mach_port_t *masterPort );

Parameters

bootstrapPort: Pass MACH_PORT_NULL for the default.
masterPort: The master port is returned.

Return Value

A kern_return_t error code.

Discussion

Functions that don't specify an existing object require the IOKit master port to be passed. This function obtains that port.

IONotificationPortCreate

Creates and returns a notification object for receiving IOKit notifications of new devices or state changes.

IONotificationPortRef IONotificationPortCreate( 
    mach_port_t masterPort );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.

Return Value

A reference to the notification object.

Discussion

Creates the notification object to receive notifications from IOKit of new device arrivals or state changes. The notification object can be supply a CFRunLoopSource, or mach_port_t to be used to listen for events.

IONotificationPortDestroy

Destroys a notification object created with IONotificationPortCreate.

void IONotificationPortDestroy( 
    IONotificationPortRef notify );

Parameters

notify: A reference to the notification object.

IONotificationPortGetMachPort

Returns a mach_port to be used to listen for notifications.

mach_port_t IONotificationPortGetMachPort( 
    IONotificationPortRef notify );

Parameters

notify: The notification object.

Return Value

A mach_port for the notification object.

Discussion

A notification object may deliver notifications to a mach messaging client if they listen for messages on the port obtained from this function. Callbacks associated with the notifications may be delivered by calling IODispatchCalloutFromMessage with messages received

IONotificationPortGetRunLoopSource

Returns a CFRunLoopSource to be used to listen for notifications.

CFRunLoopSourceRef IONotificationPortGetRunLoopSource( 
    IONotificationPortRef notify );

Parameters

notify: The notification object.

Return Value

A CFRunLoopSourceRef for the notification object.

Discussion

A notification object may deliver notifications to a CFRunLoop client by adding the run loop source returned by this function to the run loop.

IOObjectConformsTo

Performs an OSDynamicCast operation on an IOKit object.

boolean_t IOObjectConformsTo( 
    io_object_t object, 
    const io_name_t className );

Parameters

object: An IOKit object.
className: The name of the class, as a C-string.

Return Value

If the object handle is valid, and represents an object in the kernel that dynamic casts to the class true is returned, otherwise false.

Discussion

This function uses the OSMetaClass system in the kernel to determine if the object will dynamic cast to a class, specified as a C-string. In other words, if the object is of that class or a subclass.

IOObjectCopyBundleIdentifierForClass IOObjectCopyBundleIdentifierForClass

Return the bundle identifier of the given class.

CFStringRef IOObjectCopyBundleIdentifierForClass(
    CFStringRef classname) ;

Parameters

classname: The name of the class as a CFString.

Return Value

The resulting CFStringRef. This should be released by the caller. If a valid class name is not passed in, then NULL is returned.

Discussion

This function uses the OSMetaClass system in the kernel to derive the name of the kmod, which is the same as the bundle identifier.

Availability: Introduced in Mac OS X v10.4.

IOObjectCopyClass IOObjectCopyClass

Return the class name of an IOKit object.

CFStringRef IOObjectCopyClass(
    io_object_t object) ;

Parameters

object: The IOKit object.

Return Value

The resulting CFStringRef. This should be released by the caller. If a valid object is not passed in, then NULL is returned.

Discussion

This function does the same thing as IOObjectGetClass, but returns the result as a CFStringRef.

Availability: Introduced in Mac OS X v10.4.

IOObjectCopySuperclassForClass IOObjectCopySuperclassForClass

Return the superclass name of the given class.

CFStringRef IOObjectCopySuperclassForClass(
    CFStringRef classname) ;

Parameters

classname: The name of the class as a CFString.

Return Value

The resulting CFStringRef. This should be released by the caller. If there is no superclass, or a valid class name is not passed in, then NULL is returned.

Discussion

This function uses the OSMetaClass system in the kernel to derive the name of the superclass of the class.

Availability: Introduced in Mac OS X v10.4.

IOObjectGetClass

Return the class name of an IOKit object.

kern_return_t IOObjectGetClass( 
    io_object_t object, 
    io_name_t className );

Parameters

object: The IOKit object.
className: Caller allocated buffer to receive the name string.

Return Value

A kern_return_t error code.

Discussion

This function uses the OSMetaClass system in the kernel to derive the name of the class the object is an instance of.

IOObjectGetKernelRetainCount

Returns kernel retain count of an IOKit object.

uint32_t IOObjectGetKernelRetainCount( 
    io_object_t object ) ;

Parameters

object: An IOKit object.

Return Value

If the object handle is valid, the kernel objects retain count is returned, otherwise zero is returned.

Discussion

This function may be used in diagnostics to determine the current retain count of the kernel object at the kernel level.

Availability: Introduced in Mac OS X v10.6.

IOObjectGetRetainCount

Returns kernel retain count of an IOKit object. Identical to IOObjectGetKernelRetainCount() but available prior to Mac OS 10.6.

uint32_t IOObjectGetRetainCount( 
    io_object_t object );

Parameters

object: An IOKit object.

Return Value

If the object handle is valid, the kernel objects retain count is returned, otherwise zero is returned.

Discussion

This function may be used in diagnostics to determine the current retain count of the kernel object at the kernel level.

IOObjectGetUserRetainCount

Returns the retain count for the current process of an IOKit object.

uint32_t IOObjectGetUserRetainCount( 
    io_object_t object ) ;

Parameters

object: An IOKit object.

Return Value

If the object handle is valid, the objects user retain count is returned, otherwise zero is returned.

Discussion

This function may be used in diagnostics to determine the current retain count for the calling process of the kernel object.

Availability: Introduced in Mac OS X v10.6.

IOObjectIsEqualTo

Checks two object handles to see if they represent the same kernel object.

boolean_t IOObjectIsEqualTo( 
    io_object_t object, 
    io_object_t anObject );

Parameters

object: An IOKit object.
anObject: Another IOKit object.

Return Value

If both object handles are valid, and represent the same object in the kernel true is returned, otherwise false.

Discussion

If two object handles are returned by IOKitLib functions, this function will compare them to see if they represent the same kernel object.

IOObjectRelease

Releases an object handle previously returned by IOKitLib.

kern_return_t IOObjectRelease( 
    io_object_t object );

Parameters

object: The IOKit object to release.

Return Value

A kern_return_t error code.

Discussion

All objects returned by IOKitLib should be released with this function when access to them is no longer needed. Using the object after it has been released may or may not return an error, depending on how many references the task has to the same object in the kernel.

IOObjectRetain

Retains an object handle previously returned by IOKitLib.

kern_return_t IOObjectRetain( 
    io_object_t object );

Parameters

object: The IOKit object to retain.

Return Value

A kern_return_t error code.

Discussion

Gives the caller an additional reference to an existing object handle previously returned by IOKitLib.

IOOpenFirmwarePathMatching

Create a matching dictionary that specifies an IOService match based on an OpenFirmware device path.

CFMutableDictionaryRef IOOpenFirmwarePathMatching( 
    mach_port_t masterPort, 
    uint32_t options, 
    const char * path );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
options: No options are currently defined.
path: The OpenFirmware device path, as a const char *.

Return Value

Discussion

Certain IOServices (currently, block and ethernet boot devices) may be looked up by a path that specifies their location in the OpenFirmware device tree, represented in the registry by the kIODeviceTreePlane plane. This function creates a matching dictionary that will match IOService's found with a given OpenFirmware device path.

IORegistryCreateIterator

Create an iterator rooted at the registry root.

kern_return_t IORegistryCreateIterator( 
    mach_port_t masterPort, 
    const io_name_t plane, 
    IOOptionBits options, 
    io_iterator_t * iterator );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
options: kIORegistryIterateRecursively may be set to recurse automatically into each entry as it is returned from IOIteratorNext calls on the registry iterator.
iterator: A created iterator handle, to be released by the caller when it has finished with it.

Return Value

A kern_return_t error code.

Discussion

This method creates an IORegistryIterator in the kernel that is set up with options to iterate children of the registry root entry, and to recurse automatically into entries as they are returned, or only when instructed with calls to IORegistryIteratorEnterEntry. The iterator object keeps track of entries that have been recursed into previously to avoid loops.

IORegistryEntryCreateCFProperties

Create a CF dictionary representation of a registry entry's property table.

kern_return_t IORegistryEntryCreateCFProperties( 
    io_registry_entry_t entry, 
    CFMutableDictionaryRef *properties, 
    CFAllocatorRef allocator, 
    IOOptionBits options );

Parameters

entry: The registry entry handle whose property table to copy.
properties: A CFDictionary is created and returned the caller on success. The caller should release with CFRelease.
allocator: The CF allocator to use when creating the CF containers.
options: No options are currently defined.

Return Value

A kern_return_t error code.

Discussion

This function creates an instantaneous snapshot of a registry entry's property table, creating a CFDictionary analogue in the caller's task. Not every object available in the kernel is represented as a CF container; currently OSDictionary, OSArray, OSSet, OSSymbol, OSString, OSData, OSNumber, OSBoolean are created as their CF counterparts.

IORegistryEntryCreateCFProperty

Create a CF representation of a registry entry's property.

CFTypeRef IORegistryEntryCreateCFProperty( 
    io_registry_entry_t entry, 
    CFStringRef key, 
    CFAllocatorRef allocator, 
    IOOptionBits options );

Parameters

entry: The registry entry handle whose property to copy.
key: A CFString specifying the property name.
allocator: The CF allocator to use when creating the CF container.
options: No options are currently defined.

Return Value

A CF container is created and returned the caller on success. The caller should release with CFRelease.

Discussion

IORegistryEntryCreateIterator

Create an iterator rooted at a given registry entry.

kern_return_t IORegistryEntryCreateIterator( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    IOOptionBits options, 
    io_iterator_t * iterator );

Parameters

entry: The root entry to begin the iteration at.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
options: kIORegistryIterateRecursively may be set to recurse automatically into each entry as it is returned from IOIteratorNext calls on the registry iterator. kIORegistryIterateParents may be set to iterate the parents of each entry, by default the children are iterated.
iterator: A created iterator handle, to be released by the caller when it has finished with it.

Return Value

A kern_return_t error code.

Discussion

This method creates an IORegistryIterator in the kernel that is set up with options to iterate children or parents of a root entry, and to recurse automatically into entries as they are returned, or only when instructed with calls to IORegistryIteratorEnterEntry. The iterator object keeps track of entries that have been recursed into previously to avoid loops.

IORegistryEntryFromPath

Looks up a registry entry by path.

io_registry_entry_t IORegistryEntryFromPath( 
    mach_port_t masterPort, 
    const io_string_t path );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
path: A C-string path.

Return Value

A handle to the IORegistryEntry witch was found with the path, to be released with IOObjectRelease by the caller, or MACH_PORT_NULL on failure.

Discussion

This function parses paths to lookup registry entries. The path should begin with ':' If there are characters remaining unparsed after an entry has been looked up, this is considered an invalid lookup. Paths are further documented in IORegistryEntry.h

IORegistryEntryGetChildEntry

Returns the first child of a registry entry in a plane.

kern_return_t IORegistryEntryGetChildEntry( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    io_registry_entry_t * child );

Parameters

entry: The registry entry whose child to look up.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
child: The first child of the registry entry, on success. The child must be released by the caller.

Return Value

A kern_return_t error code.

Discussion

This function will return the child which first attached to a registry entry in a plane.

IORegistryEntryGetChildIterator

Returns an iterator over an registry entry's child entries in a plane.

kern_return_t IORegistryEntryGetChildIterator( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    io_iterator_t * iterator );

Parameters

entry: The registry entry whose children to iterate over.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
iterator: The created iterator over the children of the entry, on success. The iterator must be released when the iteration is finished.

Return Value

A kern_return_t error code.

Discussion

This method creates an iterator which will return each of a registry entry's child entries in a specified plane.

IORegistryEntryGetLocationInPlane

Returns a C-string location assigned to a registry entry, in a specified plane.

kern_return_t IORegistryEntryGetLocationInPlane( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    io_name_t location );

Parameters

entry: The registry entry handle whose name to look up.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
location: The caller's buffer to receive the location string.

Return Value

A kern_return_t error code.

Discussion

Registry entries can given a location string in a particular plane, or globally. If the entry has had a location set in the specified plane that location string will be returned, otherwise the global location string is returned. If no global location string has been set, an error is returned.

IORegistryEntryGetName

Returns a C-string name assigned to a registry entry.

kern_return_t IORegistryEntryGetName( 
    io_registry_entry_t entry, 
    io_name_t name );

Parameters

entry: The registry entry handle whose name to look up.
name: The caller's buffer to receive the name.

Return Value

A kern_return_t error code.

Discussion

Registry entries can be named in a particular plane, or globally. This function returns the entry's global name. The global name defaults to the entry's meta class name if it has not been named.

IORegistryEntryGetNameInPlane

Returns a C-string name assigned to a registry entry, in a specified plane.

kern_return_t IORegistryEntryGetNameInPlane( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    io_name_t name );

Parameters

entry: The registry entry handle whose name to look up.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
name: The caller's buffer to receive the name.

Return Value

A kern_return_t error code.

Discussion

Registry entries can be named in a particular plane, or globally. This function returns the entry's name in the specified plane or global name if it has not been named in that plane. The global name defaults to the entry's meta class name if it has not been named.

IORegistryEntryGetParentEntry

Returns the first parent of a registry entry in a plane.

kern_return_t IORegistryEntryGetParentEntry( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    io_registry_entry_t * parent );

Parameters

entry: The registry entry whose parent to look up.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
child: The first parent of the registry entry, on success. The parent must be released by the caller.

Return Value

A kern_return_t error code.

Discussion

This function will return the parent to which the registry entry was first attached in a plane.

IORegistryEntryGetParentIterator

Returns an iterator over an registry entry's parent entries in a plane.

kern_return_t IORegistryEntryGetParentIterator( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    io_iterator_t * iterator );

Parameters

entry: The registry entry whose parents to iterate over.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
iterator: The created iterator over the parents of the entry, on success. The iterator must be released when the iteration is finished.

Return Value

A kern_return_t error.

Discussion

This method creates an iterator which will return each of a registry entry's parent entries in a specified plane.

IORegistryEntryGetPath

Create a path for a registry entry.

kern_return_t IORegistryEntryGetPath( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    io_string_t path );

Parameters

entry: The registry entry handle whose path to look up.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
path: A char buffer allocated by the caller.

Return Value

IORegistryEntryGetPath will fail if the entry is not attached in the plane, or if the buffer is not large enough to contain the path.

Discussion

The path for a registry entry is copied to the caller's buffer. The path describes the entry's attachment in a particular plane, which must be specified. The path begins with the plane name followed by a colon, and then followed by '/' separated path components for each of the entries between the root and the registry entry. An alias may also exist for the entry, and will be returned if available.

IORegistryEntryGetRegistryEntryID

Returns an ID for the registry entry that is global to all tasks.

kern_return_t IORegistryEntryGetRegistryEntryID( 
    io_registry_entry_t entry, 
    uint64_t *entryID );

Parameters

entry: The registry entry handle whose ID to look up.
entryID: The resulting ID.

Return Value

A kern_return_t error code.

Discussion

The entry ID returned by IORegistryEntryGetRegistryEntryID can be used to identify a registry entry across all tasks. A registry entry may be looked up by its entryID by creating a matching dictionary with IORegistryEntryIDMatching() to be used with the IOKit matching functions. The ID is valid only until the machine reboots.

IORegistryEntryIDMatching

Create a matching dictionary that specifies an IOService match based on a registry entry ID.

CFMutableDictionaryRef IORegistryEntryIDMatching( 
    uint64_t entryID );

Parameters

entryID: The registry entry ID to be found.

Return Value

Discussion

This function creates a matching dictionary that will match a registered, active IOService found with the given registry entry ID. The entry ID for a registry entry is returned by IORegistryEntryGetRegistryEntryID().

IORegistryEntryInPlane

Determines if the registry entry is attached in a plane.

boolean_t IORegistryEntryInPlane( 
    io_registry_entry_t entry, 
    const io_name_t plane );

Parameters

entry: The registry entry.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.

Return Value

If the entry has a parent in the plane, true is returned, otherwise false is returned.

Discussion

This method determines if the entry is attached in a plane to any other entry.

IORegistryEntrySearchCFProperty

Create a CF representation of a registry entry's property.

CFTypeRef IORegistryEntrySearchCFProperty( 
    io_registry_entry_t entry, 
    const io_name_t plane, 
    CFStringRef key, 
    CFAllocatorRef allocator, 
    IOOptionBits options );

Parameters

entry: The registry entry at which to start the search.
plane: The name of an existing registry plane. Plane names are defined in IOKitKeys.h, eg. kIOServicePlane.
key: A CFString specifying the property name.
allocator: The CF allocator to use when creating the CF container.
options: kIORegistryIterateRecursively may be set to recurse automatically into the registry hierarchy. Without this option, this method degenerates into the standard IORegistryEntryCreateCFProperty() call. kIORegistryIterateParents may be set to iterate the parents of the entry, in place of the children.

Return Value

A CF container is created and returned the caller on success. The caller should release with CFRelease.

Discussion

This function creates an instantaneous snapshot of a registry entry property, creating a CF container analogue in the caller's task. Not every object available in the kernel is represented as a CF container; currently OSDictionary, OSArray, OSSet, OSSymbol, OSString, OSData, OSNumber, OSBoolean are created as their CF counterparts. This function will search for a property, starting first with specified registry entry's property table, then iterating recusively through either the parent registry entries or the child registry entries of this entry. Once the first occurrence is found, it will lookup and return the value of the property, using the same semantics as IORegistryEntryCreateCFProperty. The iteration keeps track of entries that have been recursed into previously to avoid loops.

IORegistryEntrySetCFProperties

Set CF container based properties in a registry entry.

kern_return_t IORegistryEntrySetCFProperties( 
    io_registry_entry_t entry, 
    CFTypeRef properties );

Parameters

entry: The registry entry whose properties to set.
properties: A CF container - commonly a CFDictionary but this is not enforced. The container should consist of objects which are understood by IOKit - these are currently : CFDictionary, CFArray, CFSet, CFString, CFData, CFNumber, CFBoolean, and are passed in the kernel as the corresponding OSDictionary etc. objects.

Return Value

A kern_return_t error code returned by the object.

Discussion

This is a generic method to pass a CF container of properties to an object in the registry. Setting properties in a registry entry is not generally supported, it is more common to support IOConnectSetCFProperties for connection based property setting. The properties are interpreted by the object.

IORegistryEntrySetCFProperty

Set a CF container based property in a registry entry.

kern_return_t IORegistryEntrySetCFProperty( 
    io_registry_entry_t entry, 
    CFStringRef propertyName, 
    CFTypeRef property );

Parameters

entry: The registry entry whose property to set.
propertyName: The name of the property as a CFString.
property: A CF container - should consist of objects which are understood by IOKit - these are currently : CFDictionary, CFArray, CFSet, CFString, CFData, CFNumber, CFBoolean, and are passed in the kernel as the corresponding OSDictionary etc. objects.

Return Value

A kern_return_t error code returned by the object.

Discussion

This is a generic method to pass a CF container as a property to an object in the registry. Setting properties in a registry entry is not generally supported, it is more common to support IOConnectSetCFProperty for connection based property setting. The property is interpreted by the object.

IORegistryGetRootEntry

Return a handle to the registry root.

io_registry_entry_t IORegistryGetRootEntry( 
    mach_port_t masterPort );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.

Return Value

A handle to the IORegistryEntry root instance, to be released with IOObjectRelease by the caller, or MACH_PORT_NULL on failure.

Discussion

This method provides an accessor to the root of the registry for the machine. The root may be passed to a registry iterator when iterating a plane, and contains properties that describe the available planes, and diagnostic information for IOKit.

IORegistryIteratorEnterEntry

Recurse into the current entry in the registry iteration.

kern_return_t IORegistryIteratorEnterEntry( 
    io_iterator_t iterator );

Return Value

A kern_return_t error code.

Discussion

This method makes the current entry, ie. the last entry returned by IOIteratorNext, the root in a new level of recursion.

IORegistryIteratorExitEntry

Exits a level of recursion, restoring the current entry.

kern_return_t IORegistryIteratorExitEntry( 
    io_iterator_t iterator );

Return Value

kIOReturnSuccess if a level of recursion was undone, kIOReturnNoDevice if no recursive levels are left in the iteration.

Discussion

This method undoes an IORegistryIteratorEnterEntry, restoring the current entry. If there are no more levels of recursion to exit false is returned, otherwise true is returned.

IOServiceAddInterestNotification

kern_return_t IOServiceAddInterestNotification( 
    IONotificationPortRef notifyPort, 
    io_service_t service, 
    const io_name_t interestType, 
    IOServiceInterestCallback callback, 
    void * refCon, 
    io_object_t * notification );

Parameters

notifyPort: A IONotificationPortRef object that controls how messages will be sent when the notification is fired. See IONotificationPortCreate.
interestType: A notification type from IOKitKeys.h
kIOGeneralInterest General state changes delivered via the IOService::message API.
kIOBusyInterest Delivered when the IOService changes its busy state to or from zero. The message argument contains the new busy state causing the notification.
callback: A callback function called when the notification fires, with messageType and messageArgument for the state change.
refCon: A reference constant for the callbacks use.
notification: An object handle is returned on success, and should be released by the caller when the notification is to be destroyed.

Return Value

A kern_return_t error code.

Discussion

IOService objects deliver notifications of their state changes to their clients via the IOService::message API, and to other interested parties including callers of this function. Message type s are defined IOKit/IOMessage.h.

IOServiceAddMatchingNotification

Look up registered IOService objects that match a matching dictionary, and install a notification request of new IOServices that match.

kern_return_t IOServiceAddMatchingNotification( 
    IONotificationPortRef notifyPort, 
    const io_name_t notificationType, 
    CFDictionaryRef matching, 
    IOServiceMatchingCallback callback, 
    void * refCon, 
    io_iterator_t * notification );

Parameters

notifyPort: A IONotificationPortRef object that controls how messages will be sent when the armed notification is fired. When the notification is delivered, the io_iterator_t representing the notification should be iterated through to pick up all outstanding objects. When the iteration is finished the notification is rearmed. See IONotificationPortCreate.
notificationType: A notification type from IOKitKeys.h
kIOPublishNotification Delivered when an IOService is registered.
kIOFirstPublishNotification Delivered when an IOService is registered, but only once per IOService instance. Some IOService's may be reregistered when their state is changed.
kIOMatchedNotification Delivered when an IOService has had all matching drivers in the kernel probed and started.
kIOFirstMatchNotification Delivered when an IOService has had all matching drivers in the kernel probed and started, but only once per IOService instance. Some IOService's may be reregistered when their state is changed.
kIOTerminatedNotification Delivered after an IOService has been terminated.
matching: A CF dictionary containing matching information, of which one reference is always consumed by this function (Note prior to the Tiger release there was a small chance that the dictionary might not be released if there was an error attempting to serialize the dictionary). IOKitLib can construct matching dictionaries for common criteria with helper functions such as IOServiceMatching, IOServiceNameMatching, IOBSDNameMatching, IOOpenFirmwarePathMatching.
callback: A callback function called when the notification fires.
refCon: A reference constant for the callbacks use.
notification: An iterator handle is returned on success, and should be released by the caller when the notification is to be destroyed. The notification is armed when the iterator is emptied by calls to IOIteratorNext - when no more objects are returned, the notification is armed. Note the notification is not armed when first created.

Return Value

A kern_return_t error code.

Discussion

This is the preferred method of finding IOService objects that may arrive at any time. The type of notification specifies the state change the caller is interested in, on IOService's that match the match dictionary. Notification types are identified by name, and are defined in IOKitKeys.h. The matching information used in the matching dictionary may vary depending on the class of service being looked up.

IOServiceClose

Close a connection to an IOService and destroy the connect handle.

kern_return_t IOServiceClose( 
    io_connect_t connect );

Parameters

connect: The connect handle created by IOServiceOpen. It will be destroyed by this function, and should not be released with IOObjectRelease.

Return Value

A kern_return_t error code.

Discussion

A connection created with the IOServiceOpen should be closed when the connection is no longer to be used with IOServiceClose.

IOServiceGetBusyState

Returns the busyState of an IOService.

kern_return_t IOServiceGetBusyState( 
    io_service_t service, 
    uint32_t *busyState );

Parameters

service: The IOService whose busyState to return.
busyState: The busyState count is returned.

Return Value

A kern_return_t error code.

Discussion

IOServiceGetMatchingService

Look up a registered IOService object that matches a matching dictionary.

io_service_t IOServiceGetMatchingService( 
    mach_port_t masterPort, 
    CFDictionaryRef matching );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
matching: A CF dictionary containing matching information, of which one reference is always consumed by this function (Note prior to the Tiger release there was a small chance that the dictionary might not be released if there was an error attempting to serialize the dictionary). IOKitLib can construct matching dictionaries for common criteria with helper functions such as IOServiceMatching, IOServiceNameMatching, IOBSDNameMatching, IOOpenFirmwarePathMatching.

Return Value

The first service matched is returned on success. The service must be released by the caller.

Discussion

This is the preferred method of finding IOService objects currently registered by IOKit (that is, objects that have had their registerService() methods invoked). To find IOService objects that aren't yet registered, use an iterator as created by IORegistryEntryCreateIterator(). IOServiceAddMatchingNotification can also supply this information and install a notification of new IOServices. The matching information used in the matching dictionary may vary depending on the class of service being looked up.

IOServiceGetMatchingServices

Look up registered IOService objects that match a matching dictionary.

kern_return_t IOServiceGetMatchingServices( 
    mach_port_t masterPort, 
    CFDictionaryRef matching, 
    io_iterator_t *existing );

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
matching: A CF dictionary containing matching information, of which one reference is always consumed by this function (Note prior to the Tiger release there was a small chance that the dictionary might not be released if there was an error attempting to serialize the dictionary). IOKitLib can construct matching dictionaries for common criteria with helper functions such as IOServiceMatching, IOServiceNameMatching, IOBSDNameMatching, IOOpenFirmwarePathMatching.
existing: An iterator handle is returned on success, and should be released by the caller when the iteration is finished.

Return Value

A kern_return_t error code.

Discussion

IOServiceMatching

Create a matching dictionary that specifies an IOService class match.

CFMutableDictionaryRef IOServiceMatching( 
    const char * name );

Parameters

name: The class name, as a const C-string. Class matching is successful on IOService's of this class or any subclass.

Return Value

Discussion

A very common matching criteria for IOService is based on its class. IOServiceMatching will create a matching dictionary that specifies any IOService of a class, or its subclasses. The class is specified by C-string name.

IOServiceMatchPropertyTable

Match an IOService objects with matching dictionary.

kern_return_t IOServiceMatchPropertyTable( 
    io_service_t service, 
    CFDictionaryRef matching, 
    boolean_t *matches );

Parameters

service: The IOService object to match.
matching: A CF dictionary containing matching information. IOKitLib can construct matching dictionaries for common criteria with helper functions such as IOServiceMatching, IOServiceNameMatching, IOBSDNameMatching, IOOpenFirmwarePathMatching.
matches: The boolean result is returned.

Return Value

A kern_return_t error code.

Discussion

This function calls the matching method of an IOService object and returns the boolean result.

IOServiceNameMatching

Create a matching dictionary that specifies an IOService name match.

CFMutableDictionaryRef IOServiceNameMatching( 
    const char * name );

Parameters

name: The IOService name, as a const C-string.

Return Value

Discussion

A common matching criteria for IOService is based on its name. IOServiceNameMatching will create a matching dictionary that specifies an IOService with a given name. Some IOServices created from the OpenFirmware device tree will perform name matching on the standard OF compatible, name, model properties.

IOServiceOFPathToBSDName

Utility to look up an IOService from its OpenFirmware device path, and return its BSD device name if available.

kern_return_t IOServiceOFPathToBSDName(
    mach_port_t masterPort, 
    const io_name_t openFirmwarePath, 
    io_name_t bsdName);

Parameters

masterPort: The master port obtained from IOMasterPort(). Pass kIOMasterPortDefault to look up the default master port.
openFirmwarePath: The OpenFirmware device path, as a const char *.
bsdName: The BSD name, as a const char *, is copied to the callers buffer.

Return Value

A kern_return_t error code.

Discussion

Certain IOServices (currently, block and ethernet boot devices) may be looked up by a path that specifies their location in the OpenFirmware device tree, represented in the registry by the kIODeviceTreePlane plane. This function looks up an IOService object with a given OpenFirmware device path, and returns its associated BSD device name.

IOServiceOpen

A request to create a connection to an IOService.

kern_return_t IOServiceOpen( 
    io_service_t service, 
    task_port_t owningTask, 
    uint32_t type, 
    io_connect_t *connect );

Parameters

service: The IOService object to open a connection to, usually obtained via the IOServiceGetMatchingServices or IOServiceAddNotification APIs.
owningTask: The mach task requesting the connection.
type: A constant specifying the type of connection to be created, interpreted only by the IOService's family.
connect: An io_connect_t handle is returned on success, to be used with the IOConnectXXX APIs. It should be destroyed with IOServiceClose().

Return Value

A return code generated by IOService::newUserClient.

Discussion

A non kernel client may request a connection be opened via the IOServiceOpen() library function, which will call IOService::newUserClient in the kernel. The rules & capabilities of user level clients are family dependent, the default IOService implementation returns kIOReturnUnsupported.

IOServiceRequestProbe

A request to rescan a bus for device changes.

kern_return_t IOServiceRequestProbe( 
    io_service_t service, 
    uint32_t options );

Parameters

service: The IOService object to request a rescan, usually obtained via the IOServiceGetMatchingServices or IOServiceAddNotification APIs.
options: An options mask, interpreted only by the IOService's family.

Return Value

A return code generated by IOService::requestProbe.

Discussion

A non kernel client may request a bus or controller rescan for added or removed devices, if the bus family does automatically notice such changes. For example, SCSI bus controllers do not notice device changes. The implementation of this routine is family dependent, and the default IOService implementation returns kIOReturnUnsupported.

IOServiceWaitQuiet

Wait for an IOService's busyState to be zero.

kern_return_t IOServiceWaitQuiet( 
    io_service_t service, 
    mach_timespec_t *waitTime );

Parameters

service: The IOService wait on.
waitTime: Specifies a maximum time to wait.

Return Value

Returns an error code if mach synchronization primitives fail, kIOReturnTimeout, or kIOReturnSuccess.

Discussion

Blocks the caller until an IOService is non busy, see IOServiceGetBusyState.

Constants

kIOMasterPortDefault: The default mach port used to initiate communication with IOKit.

kIOMasterPortDefault

The default mach port used to initiate communication with IOKit.

extern const mach_port_t kIOMasterPortDefault;

Discussion

When specifying a master port to IOKit functions, the NULL argument indicates "use the default". This is a synonym for NULL, if you'd rather use a named constant.

Typedefs

IOAsyncCallback: standard callback function for asynchronous I/O requests with lots of extra arguments beyond a refcon and result code.
IOAsyncCallback0: standard callback function for asynchronous I/O requests with no extra arguments beyond a refcon and result code.
IOAsyncCallback1: standard callback function for asynchronous I/O requests with one extra argument beyond a refcon and result code. This is often a count of the number of bytes transferred
IOAsyncCallback2: standard callback function for asynchronous I/O requests with two extra arguments beyond a refcon and result code.
IOServiceInterestCallback: Callback function to be notified of changes in state of an IOService.
IOServiceMatchingCallback: Callback function to be notified of IOService publication.

IOAsyncCallback

standard callback function for asynchronous I/O requests with lots of extra arguments beyond a refcon and result code.

typedef void ( *IOAsyncCallback)(
    void *refcon,
    IOReturn result,
    void **args, 
    uint32_t numArgs);

Fields

refcon: The refcon passed into the original I/O request
result: The result of the I/O operation
args: Array of extra arguments
numArgs: Number of extra arguments

IOAsyncCallback0

standard callback function for asynchronous I/O requests with no extra arguments beyond a refcon and result code.

typedef void ( *IOAsyncCallback0)(
    void *refcon,
    IOReturn result);

Fields

refcon: The refcon passed into the original I/O request
result: The result of the I/O operation

IOAsyncCallback1

standard callback function for asynchronous I/O requests with one extra argument beyond a refcon and result code. This is often a count of the number of bytes transferred

typedef void ( *IOAsyncCallback1)(
    void *refcon,
    IOReturn result,
    void *arg0);

Fields

refcon: The refcon passed into the original I/O request
result: The result of the I/O operation
arg0: Extra argument

IOAsyncCallback2

standard callback function for asynchronous I/O requests with two extra arguments beyond a refcon and result code.

typedef void ( *IOAsyncCallback2)(
    void *refcon,
    IOReturn result,
    void *arg0,
    void *arg1);

Fields

refcon: The refcon passed into the original I/O request
result: The result of the I/O operation
arg0: Extra argument
arg1: Extra argument

IOServiceInterestCallback

Callback function to be notified of changes in state of an IOService.

typedef void ( *IOServiceInterestCallback)( 
    void *refcon, 
    io_service_t service, 
    uint32_t messageType, 
    void *messageArgument );

Fields

refcon: The refcon passed when the notification was installed.
service: The IOService whose state has changed.
messageType: A messageType enum, defined by IOKit/IOMessage.h or by the IOService's family.
messageArgument: An argument for the message, dependent on the messageType. If the message data is larger than sizeof(void*), then messageArgument contains a pointer to the message data; otherwise, messageArgument contains the message data.

IOServiceMatchingCallback

Callback function to be notified of IOService publication.

typedef void ( *IOServiceMatchingCallback)( 
    void *refcon, 
    io_iterator_t iterator );

Fields

refcon: The refcon passed when the notification was installed.
iterator: The notification iterator which now has new objects.

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Last Updated: 2009-10-15