Add a MD5 checksum to the BDIC header....

third_party/hunspell/google/bdict.cc

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "third_party/hunspell/google/bdict.h"
+
+// static
+bool hunspell::BDict::Verify(const char* bdict_data, size_t bdict_length) {
+  if (bdict_length <= sizeof(hunspell::BDict::Header))
+    return false;
+
+  const BDict::Header* header =
+      reinterpret_cast<const hunspell::BDict::Header*>(bdict_data);
+  if (header->signature != hunspell::BDict::SIGNATURE ||
+      header->major_version > hunspell::BDict::MAJOR_VERSION ||
+      header->dic_offset > bdict_length)
+    return false;
+
+  // Get the affix header, make sure there is enough room for it.
+  if (header->aff_offset + sizeof(hunspell::BDict::AffHeader) > bdict_length)
+    return false;
+
+  // Make sure there is enough room for the affix group count dword.
+  const hunspell::BDict::AffHeader* aff_header =
+      reinterpret_cast<const hunspell::BDict::AffHeader*>(
+          &bdict_data[header->aff_offset]);
+  if (aff_header->affix_group_offset + sizeof(uint32) > bdict_length)
+    return false;
+
+  // The new BDICT header has a MD5 digest of the dictionary data. Compare the
+  // MD5 digest of the data with the one in the BDICT header.
+  if (header->major_version >= 2) {
+    MD5Digest digest;
+    MD5Sum(aff_header, bdict_length - header->aff_offset, &digest);
+    if (memcmp(&digest, &header->digest, sizeof(digest)))
+      return false;
+  }
+
+  return true;
+}