Keep track of remaining fd when devices are removed

Sometimes the wrong fd was accessed when the device was addressed
by device id.

The earlier implementation assumed that two arrays were in sync
but one of them was compacted when devices were removed. Instead
of that dependency the device now keeps track of it's file descriptor.

Change-Id: I2b8a793d76b89ab464ae830482b309fe86031671

Author: Jens Gulin

include/ui/EventHub.h

@@ -117,6 +117,7 @@ class EventHub : public RefBase
         uint8_t*        keyBitmask;
         KeyLayoutMap*   layoutMap;
         String8         keylayoutFilename;
+        int             fd;
         device_t*       next;
 
         device_t(int32_t _id, const char* _path, const char* name);

libs/ui/EventHub.cpp

@@ -57,7 +57,6 @@
 #define ID_MASK  0x0000ffff
 #define SEQ_MASK 0x7fff0000
 #define SEQ_SHIFT 16
-#define id_to_index(id)         ((id&ID_MASK)+1)
 
 #ifndef ABS_MT_TOUCH_MAJOR
 #define ABS_MT_TOUCH_MAJOR      0x30    /* Major axis of touching ellipse */
@@ -84,7 +83,7 @@ static inline int max(int v1, int v2)
 
 EventHub::device_t::device_t(int32_t _id, const char* _path, const char* name)
     : id(_id), path(_path), name(name), classes(0)
-    , keyBitmask(NULL), layoutMap(new KeyLayoutMap()), next(NULL) {
+    , keyBitmask(NULL), layoutMap(new KeyLayoutMap()), fd(-1), next(NULL) {
 }
 
 EventHub::device_t::~device_t() {
@@ -143,11 +142,12 @@ int EventHub::getAbsoluteInfo(int32_t deviceId, int axis, int *outMinValue,
 
     struct input_absinfo info;
 
-    if(ioctl(mFDs[id_to_index(device->id)].fd, EVIOCGABS(axis), &info)) {
+    if(ioctl(device->fd, EVIOCGABS(axis), &info)) {
         LOGE("Error reading absolute controller %d for device %s fd %d\n",
-             axis, device->name.string(), mFDs[id_to_index(device->id)].fd);
+             axis, device->name.string(), device->fd);
         return -1;
     }
+
     *outMinValue = info.minimum;
     *outMaxValue = info.maximum;
     *outFlat = info.flat;
@@ -178,8 +178,7 @@ int EventHub::getSwitchState(int32_t deviceId, int sw) const
     if (sw >= 0 && sw <= SW_MAX) {
         uint8_t sw_bitmask[(SW_MAX+7)/8];
         memset(sw_bitmask, 0, sizeof(sw_bitmask));
-        if (ioctl(mFDs[id_to_index(device->id)].fd,
-                   EVIOCGSW(sizeof(sw_bitmask)), sw_bitmask) >= 0) {
+        if (ioctl(device->fd, EVIOCGSW(sizeof(sw_bitmask)), sw_bitmask) >= 0) {
             return test_bit(sw, sw_bitmask) ? 1 : 0;
         }
     }
@@ -202,8 +201,7 @@ int EventHub::getScancodeState(int32_t deviceId, int code) const
     if (code >= 0 && code <= KEY_MAX) {
         uint8_t key_bitmask[(KEY_MAX+7)/8];
         memset(key_bitmask, 0, sizeof(key_bitmask));
-        if (ioctl(mFDs[id_to_index(device->id)].fd,
-                   EVIOCGKEY(sizeof(key_bitmask)), key_bitmask) >= 0) {
+        if (ioctl(device->fd, EVIOCGKEY(sizeof(key_bitmask)), key_bitmask) >= 0) {
             return test_bit(code, key_bitmask) ? 1 : 0;
         }
     }
@@ -227,8 +225,7 @@ int EventHub::getKeycodeState(int32_t deviceId, int code) const
 
     uint8_t key_bitmask[(KEY_MAX+7)/8];
     memset(key_bitmask, 0, sizeof(key_bitmask));
-    if (ioctl(mFDs[id_to_index(device->id)].fd,
-               EVIOCGKEY(sizeof(key_bitmask)), key_bitmask) >= 0) {
+    if (ioctl(device->fd, EVIOCGKEY(sizeof(key_bitmask)), key_bitmask) >= 0) {
         #if 0
         for (size_t i=0; i<=KEY_MAX; i++) {
             LOGI("(Scan code %d: down=%d)", i, test_bit(i, key_bitmask));
@@ -599,6 +596,7 @@ int EventHub::open_device(const char *deviceName)
         return -1;
     }
 
+    device->fd = fd;
     mFDs[mFDCount].fd = fd;
     mFDs[mFDCount].events = POLLIN;