safe wrap-around

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/state.c b/src/state.c
index eff9c3e..e5ca1c1 100644
--- a/src/state.c
+++ b/src/state.c
@@ -1,5 +1,6 @@
 #include "state.h"
 #include <stdlib.h>
+#include <limits.h>
 
 /******************************************************/
 
@@ -75,6 +76,13 @@ void modify_state(struct State *s,
         /* sort fingers in touching order */
         qsort(s->finger, s->nfinger, sizeof(struct FingerState), fincmp);
 
+        /* make sure wrap-around does not create very strange effects */
+        if (s->lastid > INT_MAX / 2) {
+                s->lastid = 0;
+                for (j = 0; j < s->nfinger; j++)
+                        s->finger[j].id = ++s->lastid;
+        }
+
         /* copy buttons */
         for (i = 0; i < DIM_BUTTON; i++)
                 s->button[i] = hw->button[i];