1 files changed, 237 insertions, 0 deletions
diff --git a/ipc/chromium/src/base/shared_memory_win.cc b/ipc/chromium/src/base/shared_memory_win.cc
new file mode 100644
index 0000000000..1b156d4574
--- /dev/null
+++ b/ipc/chromium/src/base/shared_memory_win.cc
@@ -0,0 +1,237 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+// Copyright (c) 2006-2008 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 "base/shared_memory.h"
+
+#include "base/logging.h"
+#include "base/win_util.h"
+#include "base/string_util.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/RandomNum.h"
+#include "mozilla/WindowsVersion.h"
+#include "nsDebug.h"
+#include "nsString.h"
+
+namespace {
+// NtQuerySection is an internal (but believed to be stable) API and the
+// structures it uses are defined in nt_internals.h.
+// So we have to define them ourselves.
+typedef enum _SECTION_INFORMATION_CLASS {
+  SectionBasicInformation,
+} SECTION_INFORMATION_CLASS;
+
+typedef struct _SECTION_BASIC_INFORMATION {
+  PVOID BaseAddress;
+  ULONG Attributes;
+  LARGE_INTEGER Size;
+} SECTION_BASIC_INFORMATION, *PSECTION_BASIC_INFORMATION;
+
+typedef ULONG(__stdcall* NtQuerySectionType)(
+    HANDLE SectionHandle, SECTION_INFORMATION_CLASS SectionInformationClass,
+    PVOID SectionInformation, ULONG SectionInformationLength,
+    PULONG ResultLength);
+
+// Checks if the section object is safe to map. At the moment this just means
+// it's not an image section.
+bool IsSectionSafeToMap(HANDLE handle) {
+  static NtQuerySectionType nt_query_section_func =
+      reinterpret_cast<NtQuerySectionType>(
+          ::GetProcAddress(::GetModuleHandle(L"ntdll.dll"), "NtQuerySection"));
+  DCHECK(nt_query_section_func);
+
+  // The handle must have SECTION_QUERY access for this to succeed.
+  SECTION_BASIC_INFORMATION basic_information = {};
+  ULONG status =
+      nt_query_section_func(handle, SectionBasicInformation, &basic_information,
+                            sizeof(basic_information), nullptr);
+  if (status) {
+    return false;
+  }
+
+  return (basic_information.Attributes & SEC_IMAGE) != SEC_IMAGE;
+}
+
+}  // namespace
+
+namespace base {
+
+void SharedMemory::MappingDeleter::operator()(void* ptr) {
+  UnmapViewOfFile(ptr);
+}
+
+SharedMemory::~SharedMemory() = default;
+
+bool SharedMemory::SetHandle(SharedMemoryHandle handle, bool read_only) {
+  DCHECK(!mapped_file_);
+
+  external_section_ = true;
+  freezeable_ = false;  // just in case
+  mapped_file_.reset(handle);
+  read_only_ = read_only;
+  return true;
+}
+
+// static
+bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
+  return handle != nullptr;
+}
+
+// static
+SharedMemoryHandle SharedMemory::NULLHandle() { return nullptr; }
+
+bool SharedMemory::CreateInternal(size_t size, bool freezeable) {
+  DCHECK(!mapped_file_);
+  read_only_ = false;
+
+  // If the shared memory object has no DACL, any process can
+  // duplicate its handles with any access rights; e.g., re-add write
+  // access to a read-only handle.  To prevent that, we give it an
+  // empty DACL, so that no process can do that.
+  SECURITY_ATTRIBUTES sa, *psa = nullptr;
+  SECURITY_DESCRIPTOR sd;
+  ACL dacl;
+  nsAutoStringN<sizeof("MozSharedMem_") + 16 * 4> name;
+
+  if (freezeable) {
+    psa = &sa;
+    sa.nLength = sizeof(sa);
+    sa.lpSecurityDescriptor = &sd;
+    sa.bInheritHandle = FALSE;
+
+    if (NS_WARN_IF(!InitializeAcl(&dacl, sizeof(dacl), ACL_REVISION)) ||
+        NS_WARN_IF(
+            !InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION)) ||
+        NS_WARN_IF(!SetSecurityDescriptorDacl(&sd, TRUE, &dacl, FALSE))) {
+      return false;
+    }
+
+    // Older versions of Windows will silently ignore the security
+    // attributes unless the object has a name.
+    if (!mozilla::IsWin8Point1OrLater()) {
+      name.AssignLiteral("MozSharedMem_");
+      for (size_t i = 0; i < 4; ++i) {
+        mozilla::Maybe<uint64_t> randomNum = mozilla::RandomUint64();
+        if (NS_WARN_IF(randomNum.isNothing())) {
+          return false;
+        }
+        name.AppendPrintf("%016llx", *randomNum);
+      }
+    }
+  }
+
+  mapped_file_.reset(CreateFileMapping(
+      INVALID_HANDLE_VALUE, psa, PAGE_READWRITE, 0, static_cast<DWORD>(size),
+      name.IsEmpty() ? nullptr : name.get()));
+  if (!mapped_file_) return false;
+
+  max_size_ = size;
+  freezeable_ = freezeable;
+  return true;
+}
+
+bool SharedMemory::ReadOnlyCopy(SharedMemory* ro_out) {
+  DCHECK(!read_only_);
+  CHECK(freezeable_);
+
+  if (ro_out == this) {
+    DCHECK(!memory_);
+  }
+
+  HANDLE ro_handle;
+  if (!::DuplicateHandle(GetCurrentProcess(), mapped_file_.release(),
+                         GetCurrentProcess(), &ro_handle,
+                         GENERIC_READ | FILE_MAP_READ, false,
+                         DUPLICATE_CLOSE_SOURCE)) {
+    // DUPLICATE_CLOSE_SOURCE applies even if there is an error.
+    return false;
+  }
+
+  freezeable_ = false;
+
+  ro_out->Close();
+  ro_out->mapped_file_.reset(ro_handle);
+  ro_out->max_size_ = max_size_;
+  ro_out->read_only_ = true;
+  ro_out->freezeable_ = false;
+  ro_out->external_section_ = external_section_;
+
+  return true;
+}
+
+bool SharedMemory::Map(size_t bytes, void* fixed_address) {
+  if (!mapped_file_) {
+    return false;
+  }
+
+  if (external_section_ && !IsSectionSafeToMap(mapped_file_.get())) {
+    return false;
+  }
+
+  void* mem = MapViewOfFileEx(
+      mapped_file_.get(),
+      read_only_ ? FILE_MAP_READ : FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, bytes,
+      fixed_address);
+  if (mem) {
+    MOZ_ASSERT(!fixed_address || mem == fixed_address,
+               "MapViewOfFileEx returned an expected address");
+    memory_.reset(mem);
+    return true;
+  }
+  return false;
+}
+
+void* SharedMemory::FindFreeAddressSpace(size_t size) {
+  void* memory = VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
+  if (memory) {
+    VirtualFree(memory, 0, MEM_RELEASE);
+  }
+  return memory;
+}
+
+bool SharedMemory::ShareToProcessCommon(ProcessId processId,
+                                        SharedMemoryHandle* new_handle,
+                                        bool close_self) {
+  freezeable_ = false;
+  *new_handle = 0;
+  DWORD access = FILE_MAP_READ | SECTION_QUERY;
+  DWORD options = 0;
+  HANDLE mapped_file;
+  HANDLE result;
+  if (!read_only_) {
+    access |= FILE_MAP_WRITE;
+  }
+  if (close_self) {
+    // DUPLICATE_CLOSE_SOURCE causes DuplicateHandle to close mapped_file.
+    mapped_file = mapped_file_.release();
+    options = DUPLICATE_CLOSE_SOURCE;
+    Unmap();
+  } else {
+    mapped_file = mapped_file_.get();
+  }
+
+  if (processId == GetCurrentProcId() && close_self) {
+    *new_handle = mapped_file;
+    return true;
+  }
+
+  if (!mozilla::ipc::DuplicateHandle(mapped_file, processId, &result, access,
+                                     options)) {
+    return false;
+  }
+
+  *new_handle = result;
+  return true;
+}
+
+void SharedMemory::Close(bool unmap_view) {
+  if (unmap_view) {
+    Unmap();
+  }
+
+  mapped_file_ = nullptr;
+}
+
+}  // namespace base