1 files changed, 80 insertions, 0 deletions
diff --git a/dom/localstorage/SnappyUtils.cpp b/dom/localstorage/SnappyUtils.cpp
new file mode 100644
index 0000000000..cf47421bc5
--- /dev/null
+++ b/dom/localstorage/SnappyUtils.cpp
@@ -0,0 +1,80 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SnappyUtils.h"
+
+#include <stddef.h>
+#include "mozilla/Assertions.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/fallible.h"
+#include "nsDebug.h"
+#include "nsString.h"
+#include "snappy/snappy.h"
+
+namespace mozilla::dom {
+
+static_assert(SNAPPY_VERSION == 0x010109);
+
+bool SnappyCompress(const nsACString& aSource, nsACString& aDest) {
+  MOZ_ASSERT(!aSource.IsVoid());
+
+  size_t uncompressedLength = aSource.Length();
+
+  if (uncompressedLength <= 16) {
+    aDest.SetIsVoid(true);
+    return true;
+  }
+
+  size_t compressedLength = snappy::MaxCompressedLength(uncompressedLength);
+
+  if (NS_WARN_IF(!aDest.SetLength(compressedLength, fallible))) {
+    return false;
+  }
+
+  snappy::RawCompress(aSource.BeginReading(), uncompressedLength,
+                      aDest.BeginWriting(), &compressedLength);
+
+  if (compressedLength >= uncompressedLength) {
+    aDest.SetIsVoid(true);
+    return true;
+  }
+
+  if (NS_WARN_IF(!aDest.SetLength(compressedLength, fallible))) {
+    return false;
+  }
+
+  return true;
+}
+
+bool SnappyUncompress(const nsACString& aSource, nsACString& aDest) {
+  MOZ_ASSERT(!aSource.IsVoid());
+
+  const char* compressed = aSource.BeginReading();
+
+  auto compressedLength = static_cast<size_t>(aSource.Length());
+
+  size_t uncompressedLength = 0u;
+  if (!snappy::GetUncompressedLength(compressed, compressedLength,
+                                     &uncompressedLength)) {
+    return false;
+  }
+
+  CheckedUint32 checkedLength(uncompressedLength);
+  if (!checkedLength.isValid()) {
+    return false;
+  }
+
+  aDest.SetLength(checkedLength.value());
+
+  if (!snappy::RawUncompress(compressed, compressedLength,
+                             aDest.BeginWriting())) {
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace mozilla::dom