Input: uinput - support injecting multiple events in one write() call

Rework the code in uinput_inject_event so that it matches the code in
evdev_write and allows injecting more than one event, or zero events.

Signed-off-by: Ryan Mallon <rmallon@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 18 insertions, 8 deletions

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index a0a4bbaef02c..772835938a52 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -430,20 +430,30 @@ static int uinput_setup_device(struct uinput_device *udev,
         return retval;
 }
 
-static ssize_t uinput_inject_event(struct uinput_device *udev,
-                                   const char __user *buffer, size_t count)
+static ssize_t uinput_inject_events(struct uinput_device *udev,
+                                    const char __user *buffer, size_t count)
 {
         struct input_event ev;
+        size_t bytes = 0;
 
-        if (count < input_event_size())
+        if (count != 0 && count < input_event_size())
                 return -EINVAL;
 
-        if (input_event_from_user(buffer, &ev))
-                return -EFAULT;
+        while (bytes + input_event_size() <= count) {
+                /*
+                 * Note that even if some events were fetched successfully
+                 * we are still going to return EFAULT instead of partial
+                 * count to let userspace know that it got it's buffers
+                 * all wrong.
+                 */
+                if (input_event_from_user(buffer + bytes, &ev))
+                        return -EFAULT;
 
-        input_event(udev->dev, ev.type, ev.code, ev.value);
+                input_event(udev->dev, ev.type, ev.code, ev.value);
+                bytes += input_event_size();
+        }
 
-        return input_event_size();
+        return bytes;
 }
 
 static ssize_t uinput_write(struct file *file, const char __user *buffer,
@@ -460,7 +470,7 @@ static ssize_t uinput_write(struct file *file, const char __user *buffer,
                 return retval;
 
         retval = udev->state == UIST_CREATED ?
-                        uinput_inject_event(udev, buffer, count) :
+                        uinput_inject_events(udev, buffer, count) :
                         uinput_setup_device(udev, buffer, count);
 
         mutex_unlock(&udev->mutex);