Merge lp:~dandrader/mir/hack_lp1233944 into lp:mir

[Daniel d'Andrada]

Fix for LP#1233944

Fixes the Mir-side of bug https://bugs.launchpad.net/mir/+bug/1233944

Event files are first created with root:root permissions and only later
udev rules are applied to it, changing its permissions to root:android-input
and therefore making it readable by unity8-mir

in short: Retry opening a file once its permissions changed as it might be
readable now.

The best thing to do is replacing usage of inotify with libudev, but that's a
way bigger change that will left to be done at a later time.

Fixes bug 1233944.

But further work might be required (likely outside mir) due to the following error message when android-input loads the autopilot-finger device file:

"""
[InputReader] Touch device 'autopilot-finger' did not report support for X or Y axis! The device will be inoperable.
"""

[Robert Carr (robertcarr)]

+1

review: Approve

[Robert Carr (robertcarr)]

I'm worried this may lead to opening devices multiple times. Digging deeper.

review: Needs Information

[Robert Carr (robertcarr)]

I think this can lead to open devices multiple times (ending with multiple instances in the mDevices member). I think the behavior is a little unclear here...so I've proposed a small fix:

https://code.launchpad.net/~robertcarr/mir/1233944-addendum/+merge/188896

review: Needs Fixing

=== modified file '3rd_party/android-input/android/frameworks/base/services/input/EventHub.cpp'
--- 3rd_party/android-input/android/frameworks/base/services/input/EventHub.cpp	2013-05-28 17:52:18 +0000
+++ 3rd_party/android-input/android/frameworks/base/services/input/EventHub.cpp	2013-10-02 17:17:25 +0000
@@ -223,7 +223,7 @@
     LOG_ALWAYS_FATAL_IF(mEpollFd < 0, "Could not create epoll instance.  errno=%d", errno);
 
     mINotifyFd = inotify_init();
-    int result = inotify_add_watch(mINotifyFd, DEVICE_PATH, IN_DELETE | IN_CREATE);
+    int result = inotify_add_watch(mINotifyFd, DEVICE_PATH, IN_DELETE | IN_CREATE | IN_ATTRIB);
     LOG_ALWAYS_FATAL_IF(result < 0, "Could not register INotify for %s.  errno=%d",
             DEVICE_PATH, errno);
 
@@ -1416,6 +1416,14 @@
             strcpy(filename, event->name);
             if(event->mask & IN_CREATE) {
                 openDeviceLocked(devname);
+            } else if (event->mask & IN_ATTRIB) {
+                Device* device = getDeviceByPathLocked(devname);
+                if (!device) {
+                    ALOGI("Retry opening device file %s", devname);
+                    // file permissions might have changed, making the device readable now
+                    // let's retry opening it
+                    openDeviceLocked(devname);
+                }
             } else {
                 ALOGI("Removing device '%s' due to inotify event\n", devname);
                 closeDeviceByPathLocked(devname);