From 81dae1c0f37ed0b9e4ec6bc1febad273391f518e Mon Sep 17 00:00:00 2001
From: Zeno Albisser <zeno.albisser@nokia.com>
Date: Fri, 12 Feb 2010 09:15:10 +0100
Subject: Fix for using QContiguousCache with default constructor or capacity=0

Reviewed-by: Peter Hartmann
---
 src/corelib/tools/qcontiguouscache.h               | 35 +++++++++++++---------
 .../auto/qcontiguouscache/tst_qcontiguouscache.cpp | 12 ++++++++
 2 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/src/corelib/tools/qcontiguouscache.h b/src/corelib/tools/qcontiguouscache.h
index 1f7fdb2..aa5603d 100644
--- a/src/corelib/tools/qcontiguouscache.h
+++ b/src/corelib/tools/qcontiguouscache.h
@@ -221,22 +221,29 @@ void QContiguousCache<T>::setCapacity(int asize)
     x.d->alloc = asize;
     x.d->count = qMin(d->count, asize);
     x.d->offset = d->offset + d->count - x.d->count;
-    x.d->start = x.d->offset % x.d->alloc;
-    T *dest = x.p->array + (x.d->start + x.d->count-1) % x.d->alloc;
-    T *src = p->array + (d->start + d->count-1) % d->alloc;
+    if(asize)
+        x.d->start = x.d->offset % x.d->alloc;
+    else
+        x.d->start = 0;
+
     int oldcount = x.d->count;
-    while (oldcount--) {
-        if (QTypeInfo<T>::isComplex) {
-            new (dest) T(*src);
-        } else {
-            *dest = *src;
+    if(oldcount)
+    {
+        T *dest = x.p->array + (x.d->start + x.d->count-1) % x.d->alloc;
+        T *src = p->array + (d->start + d->count-1) % d->alloc;
+        while (oldcount--) {
+            if (QTypeInfo<T>::isComplex) {
+                new (dest) T(*src);
+            } else {
+                *dest = *src;
+            }
+            if (dest == x.p->array)
+                dest = x.p->array + x.d->alloc;
+            dest--;
+            if (src == p->array)
+                src = p->array + d->alloc;
+            src--;
         }
-        if (dest == x.p->array)
-            dest = x.p->array + x.d->alloc;
-        dest--;
-        if (src == p->array)
-            src = p->array + d->alloc;
-        src--;
     }
     /* free old */
     free(p);
diff --git a/tests/auto/qcontiguouscache/tst_qcontiguouscache.cpp b/tests/auto/qcontiguouscache/tst_qcontiguouscache.cpp
index 5a23274..f64e815 100644
--- a/tests/auto/qcontiguouscache/tst_qcontiguouscache.cpp
+++ b/tests/auto/qcontiguouscache/tst_qcontiguouscache.cpp
@@ -71,6 +71,8 @@ private slots:
     void contiguousCacheBenchmark();
 
     void setCapacity();
+
+    void zeroCapacity();
 };
 
 QTEST_MAIN(tst_QContiguousCache)
@@ -476,4 +478,14 @@ void tst_QContiguousCache::setCapacity()
     }
 }
 
+void tst_QContiguousCache::zeroCapacity()
+{
+    QContiguousCache<int> contiguousCache;
+    QCOMPARE(contiguousCache.capacity(),0);
+    contiguousCache.setCapacity(10);
+    QCOMPARE(contiguousCache.capacity(),10);
+    contiguousCache.setCapacity(0);
+    QCOMPARE(contiguousCache.capacity(),0);
+}
+
 #include "tst_qcontiguouscache.moc"
-- 
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