1 files changed, 67 insertions, 0 deletions
diff --git a/devtools/shared/heapsnapshot/AutoMemMap.cpp b/devtools/shared/heapsnapshot/AutoMemMap.cpp
new file mode 100644
index 0000000000..8a7c89b4bf
--- /dev/null
+++ b/devtools/shared/heapsnapshot/AutoMemMap.cpp
@@ -0,0 +1,67 @@
+/* -*- 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(nsIFile* file, int flags, int mode,
+                          PRFileMapProtect prot) {
+  MOZ_ASSERT(!fd);
+  MOZ_ASSERT(!fileMap);
+  MOZ_ASSERT(!addr);
+
+  nsresult rv;
+  int64_t inputFileSize;
+  rv = file->GetFileSize(&inputFileSize);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // Check if the file is too big to memmap.
+  if (inputFileSize > int64_t(UINT32_MAX)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  fileSize = uint32_t(inputFileSize);
+
+  rv = file->OpenNSPRFileDesc(flags, mode, &fd);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  if (!fd) return NS_ERROR_UNEXPECTED;
+
+  fileMap = PR_CreateFileMap(fd, inputFileSize, prot);
+  if (!fileMap) return NS_ERROR_UNEXPECTED;
+
+  addr = PR_MemMap(fileMap, 0, fileSize);
+  if (!addr) return NS_ERROR_UNEXPECTED;
+
+  return NS_OK;
+}
+
+}  // namespace devtools
+}  // namespace mozilla