From e980bf58fcd406c392eec35a8b2ac3aa2c7908b7 Mon Sep 17 00:00:00 2001
From: Chung-yih Wang <cywang@chromium.org>
Date: Thu, 6 Dec 2012 17:43:04 +0800
Subject: [PATCH] Add block reading support

    This patch adds a new xinput property "Block Event Reading" that blocks
    event reading by skipping read() calls in ReadInput() in order to
    generate the SYN_DROPPED event for testing the SYN_DROPPED handling.
---
 src/debug.c | 37 +++++++++++++++++++++++++++++++++++++
 src/evdev.c |  6 +++++-
 src/evdev.h |  5 +++++
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/src/debug.c b/src/debug.c
index 493dec8..b685eb5 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -19,10 +19,12 @@
 #include <xf86Xinput.h>
 #include <X11/Xatom.h>
 
+#define XI_PROP_BLOCK_READ_INPUT "Block Event Reading"
 #define XI_PROP_DUMP_DEBUG_LOG "Dump Debug Log"
 
 #define INPUT_EVENTS_LOG_FILE "/var/log/xorg/evdev_input_events.dat"
 
+static Atom block_read_prop;
 static Atom dump_debug_log_prop;
 
 static void
@@ -141,3 +143,38 @@ EvdevDebugInitProperty(DeviceIntPtr dev)
     XIRegisterPropertyHandler(dev, EvdevDebugSetProperty,
         EvdevDebugGetProperty, NULL);
 }
+
+static int
+EvdevBlockSetProperty(DeviceIntPtr dev, Atom atom,
+                      XIPropertyValuePtr val, BOOL checkonly)
+{
+    InputInfoPtr pInfo = dev->public.devicePrivate;
+    EvdevPtr pEvdev = pInfo->private;
+
+    if (atom == block_read_prop) {
+        if (val->type != XA_INTEGER || val->format != 8 || val->size != 1)
+            return BadMatch;
+
+        if (!checkonly)
+            pEvdev->block_input = *(BOOL *)val->data;
+    }
+    return Success;
+}
+
+void
+EvdevBlockInitProperty(DeviceIntPtr dev)
+{
+    InputInfoPtr pInfo = dev->public.devicePrivate;
+    EvdevPtr pEvdev = pInfo->private;
+
+    block_read_prop = MakeAtom(XI_PROP_BLOCK_READ_INPUT,
+        strlen(XI_PROP_BLOCK_READ_INPUT), TRUE);
+
+    pEvdev->block_input = FALSE;
+
+    XIChangeDeviceProperty(dev, block_read_prop, XA_INTEGER,
+        /* format */ 8, PropModeReplace, /* size */ 1,
+        &pEvdev->block_input, FALSE);
+    XISetDevicePropertyDeletable(dev, block_read_prop, FALSE);
+    XIRegisterPropertyHandler(dev, EvdevBlockSetProperty, NULL, NULL);
+}
diff --git a/src/evdev.c b/src/evdev.c
index f2cba5e..dc4b6b1 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -1573,11 +1573,14 @@ EvdevReadInput(InputInfoPtr pInfo)
     struct input_event ev[NUM_EVENTS];
     int i, len = sizeof(ev);
     BOOL sync_evdev_state = FALSE;
+    EvdevPtr pEvdev = pInfo->private;
+
+    if (pEvdev->block_input)
+        return;
 
     while (len == sizeof(ev))
     {
 #ifdef MULTITOUCH
-        EvdevPtr pEvdev = pInfo->private;
 
         if (pEvdev->mtdev)
             len = mtdev_get(pEvdev->mtdev, pInfo->fd, ev, NUM_EVENTS) *
@@ -2366,6 +2369,7 @@ EvdevInit(DeviceIntPtr device)
     EvdevAppleInitProperty(device);
     EvdevDebugAllocateBuffer(pEvdev);
     EvdevDebugInitProperty(device);
+    EvdevBlockInitProperty(device);
 
     return Success;
 }
diff --git a/src/evdev.h b/src/evdev.h
index 38beb98..6ce774e 100644
--- a/src/evdev.h
+++ b/src/evdev.h
@@ -291,6 +291,8 @@ typedef struct {
     BOOL                    scroll_axes;
     EvdevRelWheelRec        wheel;       /* scroll state for REL_WHEEL */
     EvdevRelWheelRec        hwheel;      /* scroll state for REL_HWHEEL */
+
+    BOOL                    block_input; /* block read for SYN_DROPPED test */
 } EvdevRec, *EvdevPtr;
 
 typedef struct {
@@ -352,8 +354,11 @@ void Evdev3BEmuInitProperty(DeviceIntPtr);
 void EvdevWheelEmuInitProperty(DeviceIntPtr);
 void EvdevDragLockInitProperty(DeviceIntPtr);
 void EvdevAppleInitProperty(DeviceIntPtr);
+
+/* For debugging and testing */
 void EvdevDebugInitProperty(DeviceIntPtr);
 void EvdevDebugAllocateBuffer(EvdevPtr);
 void EvdevDebugFreeBuffer(EvdevPtr);
+void EvdevBlockInitProperty(DeviceIntPtr);
 
 #endif
-- 
1.8.1.5