1 files changed, 64 insertions, 0 deletions
diff --git a/dom/heapsnapshot/AutoMemMap.cpp b/dom/heapsnapshot/AutoMemMap.cpp
new file mode 100644
index 0000000000..e725a99c65
--- /dev/null
+++ b/dom/heapsnapshot/AutoMemMap.cpp
@@ -0,0 +1,64 @@
+/* -*- 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 "mozilla/devtools/AutoMemMap.h"
+
+#include "mozilla/Unused.h"
+#include "nsDebug.h"
+
+namespace mozilla {
+namespace devtools {
+
+AutoMemMap::~AutoMemMap()
+{
+  if (addr) {
+    Unused << NS_WARN_IF(PR_MemUnmap(addr, size()) != PR_SUCCESS);
+    addr = nullptr;
+  }
+
+  if (fileMap) {
+    Unused << NS_WARN_IF(PR_CloseFileMap(fileMap) != PR_SUCCESS);
+    fileMap = nullptr;
+  }
+
+  if (fd) {
+    Unused << NS_WARN_IF(PR_Close(fd) != PR_SUCCESS);
+    fd = nullptr;
+  }
+}
+
+nsresult
+AutoMemMap::init(const char* filePath, int flags, int mode, PRFileMapProtect prot)
+{
+  MOZ_ASSERT(!fd);
+  MOZ_ASSERT(!fileMap);
+  MOZ_ASSERT(!addr);
+
+  if (PR_GetFileInfo64(filePath, &fileInfo) != PR_SUCCESS)
+    return NS_ERROR_FILE_NOT_FOUND;
+
+  // Check if the file is too big to memmap.
+  if (fileInfo.size > int64_t(UINT32_MAX))
+    return NS_ERROR_INVALID_ARG;
+  auto length = uint32_t(fileInfo.size);
+
+  fd = PR_Open(filePath, flags, flags);
+  if (!fd)
+    return NS_ERROR_UNEXPECTED;
+
+  fileMap = PR_CreateFileMap(fd, fileInfo.size, prot);
+  if (!fileMap)
+    return NS_ERROR_UNEXPECTED;
+
+  addr = PR_MemMap(fileMap, 0, length);
+  if (!addr)
+    return NS_ERROR_UNEXPECTED;
+
+  return NS_OK;
+}
+
+} // namespace devtools
+} // namespace mozilla