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Input: uinput - add UI_GET_SYSNAME ioctl to retrieve the sysfs path

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uinput is used in the xorg-integration-tests suite and in the wayland
test suite. These automated tests suites create many virtual input
devices and then hook something to read these newly created devices.

Currently, uinput does not provide the created input device, which means
that we rely on an heuristic to guess which input node was created.
The problem is that is heuristic is subjected to races between different
uinput devices or even with physical devices. Having a way to retrieve
the sysfs path allows us to find without any doubts the event node.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Benjamin Tissoires 2014-01-30 17:20:24 -08:00 committed by Dmitry Torokhov
parent 9d51e801db
commit e3480a61fc
3 changed files with 57 additions and 1 deletions
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43
drivers/input/misc/uinput.c
View File

@ -20,6 +20,8 @@
* Author: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
*
* Changes/Revisions:
* 0.4 01/09/2014 (Benjamin Tissoires <benjamin.tissoires@redhat.com>)
* - add UI_GET_SYSNAME ioctl
* 0.3 09/04/2006 (Anssi Hannula <anssi.hannula@gmail.com>)
* - updated ff support for the changes in kernel interface
* - added MODULE_VERSION
@ -670,6 +672,31 @@ static int uinput_ff_upload_from_user(const char __user *buffer,
__ret; \
})
static int uinput_str_to_user(void __user *dest, const char *str,
unsigned int maxlen)
{
char __user *p = dest;
int len, ret;
if (!str)
return -ENOENT;
if (maxlen == 0)
return -EINVAL;
len = strlen(str) + 1;
if (len > maxlen)
len = maxlen;
ret = copy_to_user(p, str, len);
if (ret)
return -EFAULT;
/* force terminating '\0' */
ret = put_user(0, p + len - 1);
return ret ? -EFAULT : len;
}
static long uinput_ioctl_handler(struct file *file, unsigned int cmd,
unsigned long arg, void __user *p)
{
@ -679,6 +706,8 @@ static long uinput_ioctl_handler(struct file *file, unsigned int cmd,
struct uinput_ff_erase ff_erase;
struct uinput_request *req;
char *phys;
const char *name;
unsigned int size;
retval = mutex_lock_interruptible(&udev->mutex);
if (retval)
@ -831,6 +860,20 @@ static long uinput_ioctl_handler(struct file *file, unsigned int cmd,
goto out;
}
size = _IOC_SIZE(cmd);
/* Now check variable-length commands */
switch (cmd & ~IOCSIZE_MASK) {
case UI_GET_SYSNAME(0):
if (udev->state != UIST_CREATED) {
retval = -ENOENT;
goto out;
}
name = dev_name(&udev->dev->dev);
retval = uinput_str_to_user(p, name, size);
goto out;
}
retval = -EINVAL;
out:
mutex_unlock(&udev->mutex);

2
include/linux/uinput.h
View File

@ -20,6 +20,8 @@
* Author: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
*
* Changes/Revisions:
* 0.4 01/09/2014 (Benjamin Tissoires <benjamin.tissoires@redhat.com>)
* - add UI_GET_SYSNAME ioctl
* 0.3 24/05/2006 (Anssi Hannula <anssi.hannulagmail.com>)
* - update ff support for the changes in kernel interface
* - add UINPUT_VERSION

13
include/uapi/linux/uinput.h
View File

@ -20,6 +20,8 @@
* Author: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
*
* Changes/Revisions:
* 0.4 01/09/2014 (Benjamin Tissoires <benjamin.tissoires@redhat.com>)
* - add UI_GET_SYSNAME ioctl
* 0.3 24/05/2006 (Anssi Hannula <anssi.hannulagmail.com>)
* - update ff support for the changes in kernel interface
* - add UINPUT_VERSION
@ -35,7 +37,7 @@
#include <linux/types.h>
#include <linux/input.h>
#define UINPUT_VERSION 3
#define UINPUT_VERSION 4
struct uinput_ff_upload {
@ -73,6 +75,15 @@ struct uinput_ff_erase {
#define UI_BEGIN_FF_ERASE _IOWR(UINPUT_IOCTL_BASE, 202, struct uinput_ff_erase)
#define UI_END_FF_ERASE _IOW(UINPUT_IOCTL_BASE, 203, struct uinput_ff_erase)
/**
* UI_GET_SYSNAME - get the sysfs name of the created uinput device
*
* @return the sysfs name of the created virtual input device.
* The complete sysfs path is then /sys/devices/virtual/input/--NAME--
* Usually, it is in the form "inputN"
*/
#define UI_GET_SYSNAME(len) _IOC(_IOC_READ, UINPUT_IOCTL_BASE, 300, len)
/*
* To write a force-feedback-capable driver, the upload_effect
* and erase_effect callbacks in input_dev must be implemented.