Use the server's device list for duplicate detection (#78309)

EvdevAddDevice/EvdevRemoveDevice keep a reference to the device to detect
duplicate devices based on the dev_t.

EvdevAddDevices was called during PreInit, EvdevRemoveDevice was called during
DEVICE_CLOSE. That makes it imbalanced if the device succeeds PreInit but the
server skips everything else because MAX_DEVICES is exceeded. So for all
devices after MAX_DEVICES, we'd add a reference but never remove it,
eventually reading/writing past evdev_devices.

The server keeps the list of devices for us anyway, so remove the copy of all
the pointers and instead run through the device list the server gives us.

X.Org Bug 78309 <http://bugs.freedesktop.org/show_bug.cgi?id=78309>

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

src/evdev.c

@@ -68,11 +68,6 @@
 /* removed from server, purge when dropping support for server 1.10 */
 #define XI86_SEND_DRAG_EVENTS   0x08
 
-#ifndef MAXDEVICES
-#include <inputstr.h> /* for MAX_DEVICES */
-#define MAXDEVICES MAX_DEVICES
-#endif
-
 #define ArrayLength(a) (sizeof(a) / (sizeof((a)[0])))
 
 #define MIN_KEYCODE 8
@@ -146,11 +141,6 @@ static Atom prop_device;
 static Atom prop_virtual;
 static Atom prop_scroll_dist;
 
-/* All devices the evdev driver has allocated and knows about.
- * MAXDEVICES is safe as null-terminated array, as two devices (VCP and VCK)
- * cannot be used by evdev, leaving us with a space of 2 at the end. */
-static EvdevPtr evdev_devices[MAXDEVICES] = {NULL};
-
 static int EvdevSwitchMode(ClientPtr client, DeviceIntPtr device, int mode)
 {
     InputInfoPtr pInfo;
@@ -216,58 +206,23 @@ static BOOL
 EvdevIsDuplicate(InputInfoPtr pInfo)
 {
     EvdevPtr pEvdev = pInfo->private;
-    EvdevPtr* dev   = evdev_devices;
+    InputInfoPtr d;
 
-    if (pEvdev->min_maj)
+    nt_list_for_each_entry(d, xf86FirstLocalDevice(), next)
     {
-        while(*dev)
-        {
-            if ((*dev) != pEvdev &&
-                (*dev)->min_maj &&
-                (*dev)->min_maj == pEvdev->min_maj)
-                return TRUE;
-            dev++;
-        }
-    }
-    return FALSE;
-}
+        EvdevPtr e;
 
-/**
- * Add to internal device list.
- */
-static void
-EvdevAddDevice(InputInfoPtr pInfo)
-{
-    EvdevPtr pEvdev = pInfo->private;
-    EvdevPtr* dev = evdev_devices;
-
-    while(*dev)
-        dev++;
-
-    *dev = pEvdev;
-}
-
-/**
- * Remove from internal device list.
- */
-static void
-EvdevRemoveDevice(InputInfoPtr pInfo)
-{
-    EvdevPtr pEvdev = pInfo->private;
-    EvdevPtr *dev   = evdev_devices;
-    int count       = 0;
+        if (strcmp(d->drv->driverName, "evdev") != 0)
+            continue;
 
-    while(*dev)
-    {
-        count++;
-        if (*dev == pEvdev)
-        {
-            memmove(dev, dev + 1,
-                    sizeof(evdev_devices) - (count * sizeof(EvdevPtr)));
-            break;
-        }
-        dev++;
+        e = (EvdevPtr)d->private;
+        if (e != pEvdev &&
+            e->min_maj &&
+            e->min_maj == pEvdev->min_maj)
+            return TRUE;
     }
+
+    return FALSE;
 }
 
 static BOOL
@@ -2026,7 +1981,6 @@ EvdevProc(DeviceIntPtr device, int what)
 	xf86IDrvMsg(pInfo, X_INFO, "Close\n");
         EvdevCloseDevice(pInfo);
         EvdevFreeMasks(pEvdev);
-        EvdevRemoveDevice(pInfo);
         pEvdev->min_maj = 0;
 	break;
 
@@ -2659,8 +2613,6 @@ EvdevPreInit(InputDriverPtr drv, InputInfoPtr pInfo, int flags)
                                          pInfo->type_name);
     pInfo->type_name = pEvdev->type_name;
 
-    EvdevAddDevice(pInfo);
-
     if (pEvdev->flags & EVDEV_BUTTON_EVENTS)
     {
         EvdevMBEmuPreInit(pInfo);