Initialization and setup

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

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...
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...

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 ENOSPC;

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.

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().

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