Re: [PATCH 1/2] uinput: Support injecting multiple events in one write() call

On 11/09/13 10:14, Dmitry Torokhov wrote:

Hi Ryan,

On Wed, Sep 11, 2013 at 09:32:52AM +1000, Ryan Mallon wrote:

quoted

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 <redacted>
---
 drivers/input/misc/uinput.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index a0a4bba..6aea346 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c

@@ -434,16 +434,20 @@ static ssize_t uinput_inject_event(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) {
+		if (input_event_from_user(buffer + bytes, &ev))
+			return -EFAULT;

Unless the failure is in the very first packet we should tell the user
how many bytes we have transferred successfully instead of returning
-EFAULT.

Good point. evdev is also broken in this regard, I'll send a follow-up
patch for that once you are happy with this one. Updated patch is below:

~Ryan

---

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index a0a4bba..92ca2c5 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c

@@ -434,16 +434,20 @@ static ssize_t uinput_inject_event(struct uinput_device *u
                                   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) {
+               if (input_event_from_user(buffer + bytes, &ev))
+                       return bytes ?: -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,