Forwardport of workaround for bug 71549

Make sure that a corrupted .ids file does not allocate huge amount
of memory by checking consistency of file length vs. number of
items expected.

The patch does not cure the original problem why the ids
file has corrupt content. I could not find a way how this can happen
up till now


svn path=/trunk/KDE/kdepim/; revision=633013

kmmsgdict.cpp

@@ -18,6 +18,7 @@
 #include <stdio.h>
 #include <unistd.h>
 
+#include <string.h>
 #include <errno.h>
 
 #include <config.h>
@@ -76,8 +77,7 @@ public:
   KMMsgDictREntry(int size = 0)
   {
     array.resize(size);
-    for (int i = 0; i < size; i++)
-      array.at(i) = 0;
+    memset(array.data(), 0, array.size() * sizeof(KMMsgDictEntry *));  // faster than a loop
     fp = 0;
     swapByteOrder = false;
     baseOffset = 0;
@@ -413,6 +413,19 @@ int KMMsgDict::readFolderIds( FolderStorage& storage )
   if (swapByteOrder)
      count = kmail_swap_32(count);
 
+  // quick consistency check to avoid allocating huge amount of memory
+  // due to reading corrupt file (#71549)
+  long pos = ftell(fp);       // store current position
+  fseek(fp, 0, SEEK_END);
+  long fileSize = ftell(fp);  // how large is the file ?
+  fseek(fp, pos, SEEK_SET);   // back to previous position
+
+  // the file must at least contain what we try to read below
+  if ( (fileSize - pos) < (count * sizeof(Q_UINT32)) ) {
+    fclose(fp);
+    return -1;
+  }
+
   KMMsgDictREntry *rentry = new KMMsgDictREntry(count);
 
   for (unsigned int index = 0; index < count; index++) {