Hi On Fri, Jan 17, 2014 at 8:12 PM, Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> wrote: > Evemu [1] uses uinput to replay devices traces it has recorded. However, > the way evemu uses uinput is slightly different from how uinput is > supposed to be used. > Evemu relies on libevdev, which creates the device node through uinput. > It then injects events through the input device node directly (and it > completely skips the uinput node). > > Currently, libevdev relies 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 the event node without > having to rely on this heuristic. > > [1] http://www.freedesktop.org/wiki/Evemu/ > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> > --- > > Ok, I am resurrecting this. The original patch was sent last July here: > https://patchwork.kernel.org/patch/2827524/ > > changes since v2: > - the ioctl returns only the device name, thus I renamed the ioctl to UI_GET_SYSNAME > - reordered uinput_str_to_user() arguments > - be sure to terminate the user string we send by \0 > - abort if udev->state is not UIST_CREATED > - dropped the patch 1/2 (adding resolution to uinput) because I think David has > already it in one of his queues (ABS2 IIRC) > > I also posted the corresponding libevdev here: > http://lists.freedesktop.org/archives/input-tools/2014-January/000757.html > > Cheers, > Benjamin > > drivers/input/misc/uinput.c | 46 ++++++++++++++++++++++++++++++++++++++++++++- > include/linux/uinput.h | 2 ++ > include/uapi/linux/uinput.h | 13 ++++++++++++- > 3 files changed, 59 insertions(+), 2 deletions(-) > > diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c > index 7728359..0203219 100644 > --- a/drivers/input/misc/uinput.c > +++ b/drivers/input/misc/uinput.c > @@ -20,6 +20,8 @@ > * Author: Aristeu Sergio Rozanski Filho <aris@xxxxxxxxxxxxxxxxx> > * > * Changes/Revisions: > + * 0.4 01/09/2014 (Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>) > + * - add UI_GET_SYSNAME ioctl > * 0.3 09/04/2006 (Anssi Hannula <anssi.hannula@xxxxxxxxx>) > * - updated ff support for the changes in kernel interface > * - added MODULE_VERSION > @@ -670,6 +672,27 @@ 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) > +{ > + int len, ret; > + > + if (!str) > + return -ENOENT; > + > + len = strlen(str) + 1; > + if (len > maxlen) > + len = maxlen; > + > + ret = copy_to_user(dest, str, len); > + if (ret) > + return -EFAULT; > + > + /* force terminating '\0' */ > + ret = copy_to_user(dest + len - 1, "\0", 1); You must make sure "maxlen != 0", otherwise you write beyond buffer boundaries here. I'd say return -EINVAL in case maxlen == 0. btw., you can also use: put_user(0, (char*)dest + 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 +702,8 @@ 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) > @@ -831,7 +856,26 @@ static long uinput_ioctl_handler(struct file *file, unsigned int cmd, > break; > > default: > - retval = -EINVAL; > + retval = -EAGAIN; > + } > + > + if (retval == -EAGAIN) { Ehh, in case another ioctl returns -EAGAIN, we overwrite the error with -EINVAL below in the "default:" clause. Maybe we should first convert all the "break;" commands to "goto out;". Patch looks good to me. Thanks David > + 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); > + break; > + > + default: > + retval = -EINVAL; > + } > } > > out: > diff --git a/include/linux/uinput.h b/include/linux/uinput.h > index 0a4487d..0994c0d 100644 > --- a/include/linux/uinput.h > +++ b/include/linux/uinput.h > @@ -20,6 +20,8 @@ > * Author: Aristeu Sergio Rozanski Filho <aris@xxxxxxxxxxxxxxxxx> > * > * Changes/Revisions: > + * 0.4 01/09/2014 (Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>) > + * - 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 > diff --git a/include/uapi/linux/uinput.h b/include/uapi/linux/uinput.h > index fe46431..0389b48 100644 > --- a/include/uapi/linux/uinput.h > +++ b/include/uapi/linux/uinput.h > @@ -20,6 +20,8 @@ > * Author: Aristeu Sergio Rozanski Filho <aris@xxxxxxxxxxxxxxxxx> > * > * Changes/Revisions: > + * 0.4 01/09/2014 (Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>) > + * - 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. > -- > 1.8.3.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
