Merge lp:~gero-bare/midori/midori-fix-undef-behavior into lp:midori

[Gero.Bare]

Fix undefined behavior uint in mouse gestures

Fix two undefined behaviors.

First fix subtraction of two unsigned int. If the second operand is greater than the first, the result wraps around starting at MAX_UINT with is probably way more than intended.

Cast Double to Float. M_PI is a double which means promotes all the operation to double, but because the function fabsf takes a float, the result is truncated to float risking to give an erroneous answer.

[Cris Dywan (kalikiana)]

11 + //Remember x1,x2,y1,y2 are guint unsigned integers
12 + //substract a greater number from a lower is undefined
13 + //this guard that.

Good explanation. However please use correct English grammar.

// Remember that x1, x2, y1 and y2 are guint unsigned integers.
// Subtracting a greater number from a lower one is undefined.
// This guards against that.

14 + if ( x1 > x2)

18 + if ( y1 > y2)

Please use no space after the opening brace ie. "if (y1 > y2)".

30 + if (fabsf (angle - dir_angle) < DEVIANCE || fabsf (angle - dir_angle + 2 *(float)(M_PI)) < DEVIANCE)

Please leave a space after the asterisk ie. "+ 2 * (float)(M_PI)".

Sorry to be nit picking. With these stylistic changes it'll be good to go!

review: Needs Fixing

[Gero.Bare (gero-bare)]

Christian I hope We are good now. No problem, you are doing your work.

[Cris Dywan (kalikiana)]

Please update the comment as well. Again:

// Remember that x1, x2, y1 and y2 are guint unsigned integers.
// Subtracting a greater number from a lower one is undefined.
// This guards against that.

[Cris Dywan (kalikiana)]

Thanks a lot!

review: Approve

=== modified file 'extensions/mouse-gestures.c'
--- extensions/mouse-gestures.c	2013-10-30 00:05:40 +0000
+++ extensions/mouse-gestures.c	2014-11-22 18:46:45 +0000
@@ -128,8 +128,19 @@
 static guint
 dist_sqr (guint x1, guint y1, guint x2, guint y2)
 {
-    guint xdiff = abs(x1 - x2);
-    guint ydiff = abs(y1 - y2);
+    guint xdiff = 0, ydiff = 0;
+    // Remember that x1, x2, y1 and y2 are guint unsigned integers.
+    // Subtracting a greater number from a lower one is undefined.
+    // This guards against that.
+
+    if (x1 > x2)
+        xdiff = x1 - x2;
+    else
+        xdiff = x2 - x1;
+    if (y1 > y2)
+        ydiff = y1 - y2;
+    else
+        ydiff = y2 - y1;
     return xdiff * xdiff + ydiff * ydiff;
 }
 
@@ -159,7 +170,7 @@
         return distance < MINLENGTH / 2;
 
     float dir_angle = get_angle_for_direction (direction);
-    if (fabsf(angle - dir_angle) < DEVIANCE || fabsf(angle - dir_angle + 2 * M_PI) < DEVIANCE)
+    if (fabsf (angle - dir_angle) < DEVIANCE || fabsf (angle - dir_angle + 2 * (float)(M_PI)) < DEVIANCE)
         return TRUE;
 
     if(distance < MINLENGTH / 2)