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

[Gero.Bare]

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.

[lp:~gero-bare/midori/midori-fix-undef-behavior]

6827. By Gero.Bare on 2014-11-05

Add a comentary of warning.

[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

[lp:~gero-bare/midori/midori-fix-undef-behavior]

6828. By Gero.Bare on 2014-11-08

Fix style issues.

[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.

[lp:~gero-bare/midori/midori-fix-undef-behavior]

6829. By Gero.Bare on 2014-11-09

Updated comment.

Unmerged revisions

=== modified file 'extensions/mouse-gestures.c'
--- extensions/mouse-gestures.c	2013-10-30 00:05:40 +0000
+++ extensions/mouse-gestures.c	2014-11-09 15:53:49 +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)