1 files changed, 116 insertions, 0 deletions
diff --git a/js/xpconnect/src/XPCSelfHostedShmem.cpp b/js/xpconnect/src/XPCSelfHostedShmem.cpp
new file mode 100644
index 0000000000..e5c8578ccd
--- /dev/null
+++ b/js/xpconnect/src/XPCSelfHostedShmem.cpp
@@ -0,0 +1,116 @@
+/* -*- 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 "XPCSelfHostedShmem.h"
+#include "xpcprivate.h"
+
+// static
+mozilla::StaticRefPtr<xpc::SelfHostedShmem>
+    xpc::SelfHostedShmem::sSelfHostedXdr;
+
+NS_IMPL_ISUPPORTS(xpc::SelfHostedShmem, nsIMemoryReporter)
+
+// static
+xpc::SelfHostedShmem& xpc::SelfHostedShmem::GetSingleton() {
+  MOZ_ASSERT_IF(!sSelfHostedXdr, NS_IsMainThread());
+
+  if (!sSelfHostedXdr) {
+    sSelfHostedXdr = new SelfHostedShmem;
+  }
+
+  return *sSelfHostedXdr;
+}
+
+void xpc::SelfHostedShmem::InitMemoryReporter() {
+  mozilla::RegisterWeakMemoryReporter(this);
+}
+
+// static
+void xpc::SelfHostedShmem::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+  // NOTE: We cannot call UnregisterWeakMemoryReporter(sSelfHostedXdr) as the
+  // service is shutdown at the time this call is made. In any cases, this would
+  // already be done when the memory reporter got destroyed.
+  sSelfHostedXdr = nullptr;
+}
+
+void xpc::SelfHostedShmem::InitFromParent(ContentType aXdr) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mLen, "Shouldn't call this more than once");
+
+  size_t len = aXdr.Length();
+  auto shm = mozilla::MakeUnique<base::SharedMemory>();
+  if (NS_WARN_IF(!shm->CreateFreezeable(len))) {
+    return;
+  }
+
+  if (NS_WARN_IF(!shm->Map(len))) {
+    return;
+  }
+
+  void* address = shm->memory();
+  memcpy(address, aXdr.Elements(), aXdr.LengthBytes());
+
+  base::SharedMemory roCopy;
+  if (NS_WARN_IF(!shm->ReadOnlyCopy(&roCopy))) {
+    return;
+  }
+
+  mMem = std::move(shm);
+  mHandle = roCopy.TakeHandle();
+  mLen = len;
+}
+
+bool xpc::SelfHostedShmem::InitFromChild(::base::SharedMemoryHandle aHandle,
+                                         size_t aLen) {
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mLen, "Shouldn't call this more than once");
+
+  auto shm = mozilla::MakeUnique<base::SharedMemory>();
+  if (NS_WARN_IF(!shm->SetHandle(std::move(aHandle), /* read_only */ true))) {
+    return false;
+  }
+
+  if (NS_WARN_IF(!shm->Map(aLen))) {
+    return false;
+  }
+
+  // Note: mHandle remains empty, as content processes are not spawning more
+  // content processes.
+  mMem = std::move(shm);
+  mLen = aLen;
+  return true;
+}
+
+xpc::SelfHostedShmem::ContentType xpc::SelfHostedShmem::Content() const {
+  if (!mMem) {
+    MOZ_ASSERT(mLen == 0);
+    return ContentType();
+  }
+  return ContentType(reinterpret_cast<uint8_t*>(mMem->memory()), mLen);
+}
+
+const mozilla::UniqueFileHandle& xpc::SelfHostedShmem::Handle() const {
+  return mHandle;
+}
+
+NS_IMETHODIMP
+xpc::SelfHostedShmem::CollectReports(nsIHandleReportCallback* aHandleReport,
+                                     nsISupports* aData, bool aAnonymize) {
+  // If this is the parent process, then we have a handle and this instance owns
+  // the data and shares it with other processes, otherwise this is shared data.
+  if (XRE_IsParentProcess()) {
+    // This does not exactly report the amount of data mapped by the system,
+    // but the space requested when creating the handle.
+    MOZ_COLLECT_REPORT("explicit/js-non-window/shared-memory/self-hosted-xdr",
+                       KIND_NONHEAP, UNITS_BYTES, mLen,
+                       "Memory used to initialize the JS engine with the "
+                       "self-hosted code encoded by the parent process.");
+  }
+  return NS_OK;
+}