2007-10-27 Marek Safar <marek.safar@gmail.com>

[mono.git] / mcs / class / corlib / System / Array.cs

diff --git a/mcs/class/corlib/System/Array.cs b/mcs/class/corlib/System/Array.cs
index 67f4db84cb4ee436353db1e82f4f0ae71ff5a9d4..b0653b0169a5da70c7b59b05bbeca7238b9ac337 100644 (file)
--- a/mcs/class/corlib/System/Array.cs
+++ b/mcs/class/corlib/System/Array.cs
@@ -840,7 +840,9 @@ namespace System
                        int iCmp = 0;
                        try {
                                while (iMin <= iMax) {
-                                       int iMid = (iMin + iMax) / 2;
+                                       // Be careful with overflow
+                                       // http://googleresearch.blogspot.com/2006/06/extra-extra-read-all-about-it-nearly.html
+                                       int iMid = iMin + ((iMax - iMin) / 2);
                                        object elt = array.GetValueImpl (iMid);
 
                                        iCmp = comparer.Compare (elt, value);
@@ -1486,7 +1488,9 @@ namespace System
                        int low = low0;
                        int high = high0;
 
-                       object objPivot = keys.GetValueImpl ((low + high) / 2);
+                       // Be careful with overflows
+                       int mid = low + ((high - low) / 2);
+                       object objPivot = keys.GetValueImpl (mid);
 
                        while (low <= high) {
                                // Move the walls in
@@ -1684,7 +1688,9 @@ namespace System
                        int low = low0;
                        int high = high0;
 
-                       K keyPivot = keys [(low + high) / 2];
+                       // Be careful with overflows
+                       int mid = low + ((high - low) / 2);
+                       K keyPivot = keys [mid];
 
                        while (low <= high) {
                                // Move the walls in
@@ -1733,7 +1739,9 @@ namespace System
                        int low = low0;
                        int high = high0;
 
-                       T keyPivot = array [(low + high) / 2];
+                       // Be careful with overflows
+                       int mid = low + ((high - low) / 2);
+                       T keyPivot = array [mid];
 
                        while (low <= high) {
                                // Move the walls in
@@ -2050,7 +2058,8 @@ namespace System
                        int iCmp = 0;
                        try {
                                while (iMin <= iMax) {
-                                       int iMid = (iMin + iMax) / 2;
+                                       // Be careful with overflows
+                                       int iMid = iMin + ((iMax - iMin) / 2);
                                        iCmp = comparer.Compare (value, array [iMid]);
 
                                        if (iCmp == 0)