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List:       kde-commits
Subject:    branches/KDE/4.2/kdelibs/kdeui/util
From:       Michael Pyne <mpyne () purinchu ! net>
Date:       2009-05-29 14:09:26
Message-ID: 1243606166.437031.1510.nullmailer () svn ! kde ! org
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SVN commit 974498 by mpyne:

Backport invalid aliasing crash for for KPixmapCache to 4.2 branch.

This may possibly make it to 4.2.4 but that's up to release team as it's
past tagging date.

BUG:182026


 M  +13 -13    kpixmapcache.cpp  


--- branches/KDE/4.2/kdelibs/kdeui/util/kpixmapcache.cpp #974497:974498
@@ -289,15 +289,11 @@
     // Holds info about mmapped file
     struct MmapInfo
     {
-        MmapInfo()  { file = 0; memory = 0; }
+        MmapInfo()  { file = 0; indexHeader = 0; }
         QFile* file;  // If this is not null, then the file is mmapped
 
-        // Convenience aliases.  This probably breaks some C++ aliasing rule or something. :-/
-        union {
-            char* memory;
-            KPixmapCacheIndexHeader *indexHeader;
-            KPixmapCacheDataHeader *dataHeader;
-        };
+        // This points to the mmap'ed file area.
+        KPixmapCacheIndexHeader *indexHeader;
 
         quint32 size;  // Number of currently used bytes
         quint32 available;  // Number of available bytes (including those reserved for mmap)
@@ -474,9 +470,9 @@
         info->file = 0;
         return false;
     }
-    info->memory = reinterpret_cast<char*>(indexMem);
+    info->indexHeader = reinterpret_cast<KPixmapCacheIndexHeader *>(indexMem);
 #ifdef HAVE_MADVISE
-    madvise(info->memory, info->size, MADV_WILLNEED);
+    madvise(indexMem, info->size, MADV_WILLNEED);
 #endif
 
     info->file->close();
@@ -496,8 +492,8 @@
 void KPixmapCache::Private::unmmapFile(MmapInfo* info)
 {
     if (info->file) {
-        info->file->unmap(reinterpret_cast<uchar*>(info->memory));
-        info->memory = 0;
+        info->file->unmap(reinterpret_cast<uchar*>(info->indexHeader));
+        info->indexHeader = 0;
         info->available = 0;
         info->size = 0;
 
@@ -523,7 +519,9 @@
         fi.refresh();
         if(fi.exists() && fi.size() == mIndexMmapInfo.available) {
             // Create the device
-            device = new KPCMemoryDevice(mIndexMmapInfo.memory, &mIndexMmapInfo.size, mIndexMmapInfo.available);
+            device = new KPCMemoryDevice(
+                             reinterpret_cast<char*>(mIndexMmapInfo.indexHeader),
+                             &mIndexMmapInfo.size, mIndexMmapInfo.available);
         }
 
         // Is it possible to have a valid cache with no file?  If not it would be easier
@@ -592,7 +590,9 @@
         fi.refresh();
         if (fi.exists() && fi.size() == mDataMmapInfo.available) {
             // Create the device
-            return new KPCMemoryDevice(mDataMmapInfo.memory, &mDataMmapInfo.size, mDataMmapInfo.available);
+            return new KPCMemoryDevice(
+                           reinterpret_cast<char*>(mDataMmapInfo.indexHeader),
+                           &mDataMmapInfo.size, mDataMmapInfo.available);
         }
         else
             return 0;

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