Initialization and setup

Initialization, initial setup and file descriptor handling. More...

Typedefs
typedef void(*	libevdev_log_func_t )(enum libevdev_log_priority priority, void *data, const char *file, int line, const char *func, const char *format, va_list args)
	Logging function called by library-internal logging. More...

Enumerations
enum	libevdev_log_priority { LIBEVDEV_LOG_ERROR, LIBEVDEV_LOG_INFO, LIBEVDEV_LOG_DEBUG }
enum	libevdev_grab_mode { LIBEVDEV_GRAB, LIBEVDEV_UNGRAB }

Functions
struct libevdev *	libevdev_new (void)
	Initialize a new libevdev device. More...
int	libevdev_new_from_fd (int fd, struct libevdev **dev)
	Initialize a new libevdev device from the given fd. More...
void	libevdev_free (struct libevdev *dev)
	Clean up and free the libevdev struct. More...
void	libevdev_set_log_function (libevdev_log_func_t logfunc, void *data)
	Set a printf-style logging handler for library-internal logging. More...
void	libevdev_set_log_priority (enum libevdev_log_priority priority)
	Define the minimum level to be printed to the log handler. More...
enum libevdev_log_priority	libevdev_get_log_priority (void)
int	libevdev_grab (struct libevdev *dev, enum libevdev_grab_mode grab)
	Grab or ungrab the device through a kernel EVIOCGRAB. More...
int	libevdev_set_fd (struct libevdev *dev, int fd)
	Set the fd for this struct and initialize internal data. More...
int	libevdev_change_fd (struct libevdev *dev, int fd)
	Change the fd for this device, without re-reading the actual device. More...
int	libevdev_get_fd (const struct libevdev *dev)

Detailed Description

Initialization, initial setup and file descriptor handling.

These functions are the main entry points for users of libevdev, usually a caller will use this series of calls:

struct libevdev *dev;
int err;

dev = libevdev_new();
if (!dev)
        return ENOMEM;

err = libevdev_set_fd(dev, fd);
if (err < 0) {
        printf("Failed (errno %d): %s\n", -err, strerror(-err));

libevdev_free(dev);

libevdev_set_fd() is the central call and initializes the internal structs for the device at the given fd. libevdev functions will fail if called before libevdev_set_fd() unless documented otherwise.

Typedef Documentation

typedef void(* libevdev_log_func_t)(enum libevdev_log_priority priority, void *data, const char *file, int line, const char *func, const char *format, va_list args)

Logging function called by library-internal logging.

This function is expected to treat its input like printf would.

Parameters

priority	Log priority of this message
data	User-supplied data pointer (see libevdev_set_log_function())
file	libevdev source code file generating this message
line	libevdev source code line generating this message
func	libevdev source code function generating this message
format	printf-style format string
args	List of arguments

See Also

libevdev_set_log_function

Enumeration Type Documentation

enum libevdev_grab_mode

Enumerator
LIBEVDEV_GRAB	Grab the device if not currently grabbed.
LIBEVDEV_UNGRAB	Ungrab the device if currently grabbed.

enum libevdev_log_priority

Enumerator
LIBEVDEV_LOG_ERROR	critical errors and application bugs
LIBEVDEV_LOG_INFO	informational messages
LIBEVDEV_LOG_DEBUG	debug information

Function Documentation

int libevdev_change_fd	(	struct libevdev *	dev,
		int	fd
	)

Change the fd for this device, without re-reading the actual device.

If the fd changes after initializing the device, for example after a VT-switch in the X.org X server, this function updates the internal fd to the newly opened. No check is made that new fd points to the same device. If the device has changed, libevdev's behavior is undefined.

The fd may be open in O_RDONLY or O_RDWR.

It is an error to call this function before calling libevdev_set_fd().

Parameters

dev	The evdev device, already initialized with libevdev_set_fd()
fd	The new fd

Returns

0 on success, or -1 on failure.

See Also

libevdev_set_fd

void libevdev_free

(

struct libevdev *

dev

)

Clean up and free the libevdev struct.

After completion, the struct libevdev is invalid and must not be used.

Parameters

dev	The evdev device

Note

This function may be called before libevdev_set_fd().

int libevdev_get_fd

(

const struct libevdev *

dev

)

Parameters

dev	The evdev device

Returns

The previously set fd, or -1 if none had been set previously.

Note

This function may be called before libevdev_set_fd().

enum libevdev_log_priority libevdev_get_log_priority

(

void

)

Returns

the current log level

int libevdev_grab	(	struct libevdev *	dev,
		enum libevdev_grab_mode	grab
	)

Grab or ungrab the device through a kernel EVIOCGRAB.

This prevents other clients (including kernel-internal ones such as rfkill) from receiving events from this device.

This is generally a bad idea. Don't do this.

Grabbing an already grabbed device, or ungrabbing an ungrabbed device is a noop and always succeeds.

Parameters

dev	The evdev device, already initialized with libevdev_set_fd()
grab	If true, grab the device. Otherwise ungrab the device.

Returns

0 if the device was successfull grabbed or ungrabbed, or a negative errno in case of failure.

struct libevdev* libevdev_new ( void  )

read

Initialize a new libevdev device.

This function only allocates the required memory and initializes the struct to sane default values. To actually hook up the device to a kernel device, use libevdev_set_fd().

Memory allocated through libevdev_new() must be released by the caller with libevdev_free().

See Also

libevdev_set_fd

libevdev_free

int libevdev_new_from_fd	(	int	fd,
		struct libevdev **	dev
	)

Initialize a new libevdev device from the given fd.

This is a shortcut for

int err;
struct libevdev *dev = libevdev_new();
err = libevdev_set_fd(dev, fd);

Parameters

	fd	A file descriptor to the device in O_RDWR or O_RDONLY mode.
[out]	dev	The newly initialized evdev device.

Returns

On success, zero is returned and dev is set to the newly allocated struct. On failure, a negative errno is returned and the value of dev is undefined.

See Also

libevdev_free

int libevdev_set_fd	(	struct libevdev *	dev,
		int	fd
	)

Set the fd for this struct and initialize internal data.

The fd must be in O_RDONLY or O_RDWR mode.

This function may only be called once per device. If the device changed and you need to re-read a device, use libevdev_free() and libevdev_new(). If you need to change the fd after closing and re-opening the same device, use libevdev_change_fd().

Unless otherwise specified, libevdev function behavior is undefined until a successfull call to libevdev_set_fd().

Parameters

dev	The evdev device
fd	The file descriptor for the device

Returns

0 on success, or a negative error code on failure

See Also

libevdev_change_fd

libevdev_new

libevdev_free

void libevdev_set_log_function	(	libevdev_log_func_t	logfunc,
		void *	data
	)

Set a printf-style logging handler for library-internal logging.

The default logging function is to stdout.

Parameters

logfunc	The logging function for this device. If NULL, the current logging function is unset and no logging is performed.
data	User-specific data passed to the log handler.

Note

This function may be called before libevdev_set_fd().

void libevdev_set_log_priority

(

enum libevdev_log_priority

priority

)

Define the minimum level to be printed to the log handler.

Messages higher than this level are printed, others are discarded. This is a global setting and applies to any future logging messages.

Parameters

priority

Minimum priority to be printed to the log.