1 files changed, 100 insertions, 0 deletions
diff --git a/js/xpconnect/loader/AutoMemMap.h b/js/xpconnect/loader/AutoMemMap.h
new file mode 100644
index 0000000000..54180d09e3
--- /dev/null
+++ b/js/xpconnect/loader/AutoMemMap.h
@@ -0,0 +1,100 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* 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/. */
+
+#ifndef loader_AutoMemMap_h
+#define loader_AutoMemMap_h
+
+#include "mozilla/FileUtils.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/RangedPtr.h"
+#include "mozilla/Result.h"
+
+#include <prio.h>
+
+class nsIFile;
+
+namespace mozilla {
+namespace ipc {
+class FileDescriptor;
+}
+
+namespace loader {
+
+class AutoMemMap {
+  typedef mozilla::ipc::FileDescriptor FileDescriptor;
+
+ public:
+  AutoMemMap() = default;
+
+  ~AutoMemMap();
+
+  Result<Ok, nsresult> init(nsIFile* file, int flags = PR_RDONLY, int mode = 0,
+                            PRFileMapProtect prot = PR_PROT_READONLY);
+
+  Result<Ok, nsresult> init(const FileDescriptor& file,
+                            PRFileMapProtect prot = PR_PROT_READONLY,
+                            size_t maybeSize = 0);
+
+  // Initializes the mapped memory with a shared memory handle. On
+  // Unix-like systems, this is identical to the above init() method. On
+  // Windows, the FileDescriptor must be a handle for a file mapping,
+  // rather than a file descriptor.
+  Result<Ok, nsresult> initWithHandle(const FileDescriptor& file, size_t size,
+                                      PRFileMapProtect prot = PR_PROT_READONLY);
+
+  void reset();
+
+  bool initialized() const { return addr; }
+
+  uint32_t size() const { return size_; }
+
+  template <typename T = void>
+  RangedPtr<T> get() {
+    MOZ_ASSERT(addr);
+    return {static_cast<T*>(addr), size_};
+  }
+
+  template <typename T = void>
+  const RangedPtr<T> get() const {
+    MOZ_ASSERT(addr);
+    return {static_cast<T*>(addr), size_};
+  }
+
+  size_t nonHeapSizeOfExcludingThis() { return size_; }
+
+  FileDescriptor cloneFileDescriptor() const;
+  FileDescriptor cloneHandle() const;
+
+  // Makes this mapping persistent. After calling this, the mapped memory
+  // will remained mapped, even after this instance is destroyed.
+  void setPersistent() { persistent_ = true; }
+
+ private:
+  Result<Ok, nsresult> initInternal(PRFileMapProtect prot,
+                                    size_t maybeSize = 0);
+
+  AutoFDClose fd;
+  PRFileMap* fileMap = nullptr;
+
+#ifdef XP_WIN
+  // We can't include windows.h in this header, since it gets included
+  // by some binding headers (which are explicitly incompatible with
+  // windows.h). So we can't use the HANDLE type here.
+  void* handle_ = nullptr;
+#endif
+
+  uint32_t size_ = 0;
+  void* addr = nullptr;
+
+  bool persistent_ = 0;
+
+  AutoMemMap(const AutoMemMap&) = delete;
+  void operator=(const AutoMemMap&) = delete;
+};
+
+}  // namespace loader
+}  // namespace mozilla
+
+#endif  // loader_AutoMemMap_h