1 files changed, 104 insertions, 0 deletions
diff --git a/dom/fs/child/FileSystemThreadSafeStreamOwner.cpp b/dom/fs/child/FileSystemThreadSafeStreamOwner.cpp
new file mode 100644
index 0000000000..2b2d2913d9
--- /dev/null
+++ b/dom/fs/child/FileSystemThreadSafeStreamOwner.cpp
@@ -0,0 +1,104 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=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 "fs/FileSystemThreadSafeStreamOwner.h"
+
+#include "mozilla/CheckedInt.h"
+#include "mozilla/dom/FileSystemLog.h"
+#include "mozilla/dom/FileSystemWritableFileStream.h"
+#include "mozilla/dom/quota/QuotaCommon.h"
+#include "mozilla/dom/quota/ResultExtensions.h"
+#include "nsIOutputStream.h"
+#include "nsIRandomAccessStream.h"
+
+namespace mozilla::dom::fs {
+
+namespace {
+
+nsresult TruncFile(nsCOMPtr<nsIRandomAccessStream>& aStream, int64_t aEOF) {
+  int64_t offset = 0;
+  QM_TRY(MOZ_TO_RESULT(aStream->Tell(&offset)));
+
+  QM_TRY(MOZ_TO_RESULT(aStream->Seek(nsISeekableStream::NS_SEEK_SET, aEOF)));
+
+  QM_TRY(MOZ_TO_RESULT(aStream->SetEOF()));
+
+  QM_TRY(MOZ_TO_RESULT(aStream->Seek(nsISeekableStream::NS_SEEK_END, 0)));
+
+  // Restore original offset
+  QM_TRY(MOZ_TO_RESULT(aStream->Seek(nsISeekableStream::NS_SEEK_SET, offset)));
+
+  return NS_OK;
+}
+
+}  // namespace
+
+FileSystemThreadSafeStreamOwner::FileSystemThreadSafeStreamOwner(
+    FileSystemWritableFileStream* aWritableFileStream,
+    nsCOMPtr<nsIRandomAccessStream>&& aStream)
+    :
+#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
+      mWritableFileStream(aWritableFileStream),
+#endif
+      mStream(std::forward<nsCOMPtr<nsIRandomAccessStream>>(aStream)),
+      mClosed(false) {
+  MOZ_ASSERT(mWritableFileStream);
+}
+
+nsresult FileSystemThreadSafeStreamOwner::Truncate(uint64_t aSize) {
+  MOZ_DIAGNOSTIC_ASSERT(mWritableFileStream->IsCommandActive());
+
+  if (mClosed) {  // Multiple closes can end up in a queue
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
+
+  int64_t where = 0;
+  QM_TRY(MOZ_TO_RESULT(mStream->Tell(&where)));
+
+  // Truncate filehandle (can extend with 0's)
+  LOG(("%p: Truncate to %" PRIu64, this, aSize));
+  QM_TRY(MOZ_TO_RESULT(TruncFile(mStream, aSize)));
+
+  // Per non-normative text in the spec (2.5.3) we should adjust
+  // the cursor position to be within the new file size
+  if (static_cast<uint64_t>(where) > aSize) {
+    QM_TRY(MOZ_TO_RESULT(mStream->Seek(nsISeekableStream::NS_SEEK_END, 0)));
+  }
+
+  return NS_OK;
+}
+
+nsresult FileSystemThreadSafeStreamOwner::Seek(uint64_t aPosition) {
+  MOZ_DIAGNOSTIC_ASSERT(mWritableFileStream->IsCommandActive());
+
+  if (mClosed) {  // Multiple closes can end up in a queue
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
+
+  const auto checkedPosition = CheckedInt<int64_t>(aPosition);
+  if (!checkedPosition.isValid()) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  return mStream->Seek(nsISeekableStream::NS_SEEK_SET, checkedPosition.value());
+}
+
+void FileSystemThreadSafeStreamOwner::Close() {
+  if (mClosed) {  // Multiple closes can end up in a queue
+    return;
+  }
+
+  mClosed = true;
+  mStream->OutputStream()->Close();
+}
+
+nsCOMPtr<nsIOutputStream> FileSystemThreadSafeStreamOwner::OutputStream() {
+  MOZ_DIAGNOSTIC_ASSERT(mWritableFileStream->IsCommandActive());
+
+  return mStream->OutputStream();
+}
+
+}  // namespace mozilla::dom::fs