Fix FOO_MAX off-by-one

In linux/input.h each section's (e.g. ABS) FOO_MAX is the maximum FOO
value. Recent kernels define FOO_CNT as the maximum number of FOO there
will ever be. Hence using FOO_MAX to size the bit vectors representing
the capabilities of an evdev device is off by one.

Define FOO_CNT values for use with Linux kernels which lack them. Use
FOO_CNT whenever we need to know the number of bits needed -- usually to
calculate the number of longs needed.

When iterating over the values FOO_MAX still seems appropriate however
the loop test should include FOO_MAX rather than skip it.

Signed-off-by: Matt Helsley <matt.helsley@gmail.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

2 files changed, 34 insertions, 18 deletions

diff --git a/src/evdev.c b/src/evdev.c
index 38f9c08..b1e5c9a 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -236,14 +236,14 @@ static void
 PostKbdEvent(InputInfoPtr pInfo, struct input_event *ev, int value)
 {
     int code = ev->code + MIN_KEYCODE;
-    static char warned[KEY_MAX];
+    static char warned[KEY_CNT];
 
     /* Filter all repeated events from device.
        We'll do softrepeat in the server */
     if (value == 2)
 	return;
 
-    if (code > 255 && ev->code < KEY_MAX) {
+    if (code > 255 && ev->code <= KEY_MAX) {
 	if (!warned[ev->code])
 	    xf86Msg(X_WARNING, "%s: unable to handle keycode %d\n",
 		    pInfo->name, ev->code);
@@ -1223,12 +1223,12 @@ EvdevCacheCompare(InputInfoPtr pInfo, BOOL compare)
     int i;
 
     char name[1024]                  = {0};
-    long bitmask[NLONGS(EV_MAX)]      = {0};
-    long key_bitmask[NLONGS(KEY_MAX)] = {0};
-    long rel_bitmask[NLONGS(REL_MAX)] = {0};
-    long abs_bitmask[NLONGS(ABS_MAX)] = {0};
-    long led_bitmask[NLONGS(LED_MAX)] = {0};
-    struct input_absinfo absinfo[ABS_MAX];
+    long bitmask[NLONGS(EV_CNT)]      = {0};
+    long key_bitmask[NLONGS(KEY_CNT)] = {0};
+    long rel_bitmask[NLONGS(REL_CNT)] = {0};
+    long abs_bitmask[NLONGS(ABS_CNT)] = {0};
+    long led_bitmask[NLONGS(LED_CNT)] = {0};
+    struct input_absinfo absinfo[ABS_CNT];
 
     if (ioctl(pInfo->fd,
               EVIOCGNAME(sizeof(name) - 1), name) < 0) {
@@ -1287,7 +1287,7 @@ EvdevCacheCompare(InputInfoPtr pInfo, BOOL compare)
 
     memset(absinfo, 0, sizeof(absinfo));
 
-    for (i = 0; i < ABS_MAX; i++)
+    for (i = ABS_X; i <= ABS_MAX; i++)
     {
         if (TestBit(i, abs_bitmask))
         {
@@ -1323,9 +1323,9 @@ error:
 static int
 EvdevProbe(InputInfoPtr pInfo)
 {
-    long key_bitmask[NLONGS(KEY_MAX)] = {0};
-    long rel_bitmask[NLONGS(REL_MAX)] = {0};
-    long abs_bitmask[NLONGS(ABS_MAX)] = {0};
+    long key_bitmask[NLONGS(KEY_CNT)] = {0};
+    long rel_bitmask[NLONGS(REL_CNT)] = {0};
+    long abs_bitmask[NLONGS(ABS_CNT)] = {0};
     int i, has_axes, has_keys, num_buttons, has_scroll;
     int kernel24 = 0;
     EvdevPtr pEvdev = pInfo->private;
diff --git a/src/evdev.h b/src/evdev.h
index 2f58ae8..2698b30 100644
--- a/src/evdev.h
+++ b/src/evdev.h
@@ -40,6 +40,22 @@
 #include <xkbstr.h>
 #endif
 
+#ifndef EV_CNT /* linux 2.4 kernels and earlier lack _CNT defines */
+#define EV_CNT (EV_MAX+1)
+#endif
+#ifndef KEY_CNT
+#define KEY_CNT (KEY_MAX+1)
+#endif
+#ifndef REL_CNT
+#define REL_CNT (REL_MAX+1)
+#endif
+#ifndef ABS_CNT
+#define ABS_CNT (ABS_MAX+1)
+#endif
+#ifndef LED_CNT
+#define LED_CNT (LED_MAX+1)
+#endif
+
 #define EVDEV_MAXBUTTONS 32
 
 #if GET_ABI_MAJOR(ABI_XINPUT_VERSION) >= 3
@@ -123,12 +139,12 @@ typedef struct {
 
     /* Cached info from device. */
     char name[1024];
-    long bitmask[NLONGS(EV_MAX)];
-    long key_bitmask[NLONGS(KEY_MAX)];
-    long rel_bitmask[NLONGS(REL_MAX)];
-    long abs_bitmask[NLONGS(ABS_MAX)];
-    long led_bitmask[NLONGS(LED_MAX)];
-    struct input_absinfo absinfo[ABS_MAX];
+    long bitmask[NLONGS(EV_CNT)];
+    long key_bitmask[NLONGS(KEY_CNT)];
+    long rel_bitmask[NLONGS(REL_CNT)];
+    long abs_bitmask[NLONGS(ABS_CNT)];
+    long led_bitmask[NLONGS(LED_CNT)];
+    struct input_absinfo absinfo[ABS_CNT];
 
     /* minor/major number */
     dev_t min_maj;