From 925c6e34635a9a8621b20c328670cbd23975327f Mon Sep 17 00:00:00 2001
From: Simon Ochsenreither <simon@ochsenreither.de>
Date: Fri, 9 Nov 2012 03:18:33 +0100
Subject: SI-6632 SI-6633 Fixes issues and data corruption in ListBuffer

 - Disallow negative positions for ListBuffer#insert/insertAll/update
 - Fix data corruption issue in ListBuffer#insert
---
 .../scala/collection/mutable/ListBuffer.scala      | 93 ++++++++++------------
 1 file changed, 44 insertions(+), 49 deletions(-)

(limited to 'src/library')

diff --git a/src/library/scala/collection/mutable/ListBuffer.scala b/src/library/scala/collection/mutable/ListBuffer.scala
index 53b2b57f50..53501a7267 100644
--- a/src/library/scala/collection/mutable/ListBuffer.scala
+++ b/src/library/scala/collection/mutable/ListBuffer.scala
@@ -129,29 +129,27 @@ final class ListBuffer[A]
    *  @throws Predef.IndexOutOfBoundsException if `n` is out of bounds.
    */
   def update(n: Int, x: A) {
-    try {
-      if (exported) copy()
-      if (n == 0) {
-        val newElem = new :: (x, start.tail);
-        if (last0 eq start) {
-          last0 = newElem
-        }
-        start = newElem
-      } else {
-        var cursor = start
-        var i = 1
-        while (i < n) {
-          cursor = cursor.tail
-          i += 1
-        }
-        val newElem = new :: (x, cursor.tail.tail)
-        if (last0 eq cursor.tail) {
-          last0 = newElem
-        }
-        cursor.asInstanceOf[::[A]].tl = newElem
+    // We check the bounds early, so that we don't trigger copying.
+    if (n < 0 || n >= len) throw new IndexOutOfBoundsException(n.toString)
+    if (exported) copy()
+    if (n == 0) {
+      val newElem = new :: (x, start.tail);
+      if (last0 eq start) {
+        last0 = newElem
+      }
+      start = newElem
+    } else {
+      var cursor = start
+      var i = 1
+      while (i < n) {
+        cursor = cursor.tail
+        i += 1
+      }
+      val newElem = new :: (x, cursor.tail.tail)
+      if (last0 eq cursor.tail) {
+        last0 = newElem
       }
-    } catch {
-      case ex: Exception => throw new IndexOutOfBoundsException(n.toString())
+      cursor.asInstanceOf[::[A]].tl = newElem
     }
   }
 
@@ -212,34 +210,31 @@ final class ListBuffer[A]
    *  @throws Predef.IndexOutOfBoundsException if `n` is out of bounds.
    */
   def insertAll(n: Int, seq: Traversable[A]) {
-    try {
-      if (exported) copy()
-      var elems = seq.toList.reverse
-      len += elems.length
-      if (n == 0) {
-        while (!elems.isEmpty) {
-          val newElem = new :: (elems.head, start)
-          if (start.isEmpty) last0 = newElem
-          start = newElem
-          elems = elems.tail
-        }
-      } else {
-        var cursor = start
-        var i = 1
-        while (i < n) {
-          cursor = cursor.tail
-          i += 1
-        }
-        while (!elems.isEmpty) {
-          val newElem = new :: (elems.head, cursor.tail)
-          if (cursor.tail.isEmpty) last0 = newElem
-          cursor.asInstanceOf[::[A]].tl = newElem
-          elems = elems.tail
-        }
+    // We check the bounds early, so that we don't trigger copying.
+    if (n < 0 || n > len) throw new IndexOutOfBoundsException(n.toString)
+    if (exported) copy()
+    var elems = seq.toList.reverse
+    len += elems.length
+    if (n == 0) {
+      while (!elems.isEmpty) {
+        val newElem = new :: (elems.head, start)
+        if (start.isEmpty) last0 = newElem
+        start = newElem
+        elems = elems.tail
+      }
+    } else {
+      var cursor = start
+      var i = 1
+      while (i < n) {
+        cursor = cursor.tail
+        i += 1
+      }
+      while (!elems.isEmpty) {
+        val newElem = new :: (elems.head, cursor.tail)
+        if (cursor.tail.isEmpty) last0 = newElem
+        cursor.asInstanceOf[::[A]].tl = newElem
+        elems = elems.tail
       }
-    } catch {
-      case ex: Exception =>
-        throw new IndexOutOfBoundsException(n.toString())
     }
   }
 
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