1 files changed, 158 insertions, 0 deletions
diff --git a/js/xpconnect/loader/AutoMemMap.cpp b/js/xpconnect/loader/AutoMemMap.cpp
new file mode 100644
index 0000000000..7ce26a9a33
--- /dev/null
+++ b/js/xpconnect/loader/AutoMemMap.cpp
@@ -0,0 +1,158 @@
+/* -*- 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 "AutoMemMap.h"
+#include "ScriptPreloader-inl.h"
+
+#include "mozilla/Unused.h"
+#include "mozilla/Try.h"
+#include "mozilla/ipc/FileDescriptor.h"
+#include "nsIFile.h"
+
+#include <private/pprio.h>
+
+namespace mozilla {
+namespace loader {
+
+using namespace mozilla::ipc;
+
+AutoMemMap::~AutoMemMap() { reset(); }
+
+FileDescriptor AutoMemMap::cloneFileDescriptor() const {
+  if (fd.get()) {
+    auto handle =
+        FileDescriptor::PlatformHandleType(PR_FileDesc2NativeHandle(fd.get()));
+    return FileDescriptor(handle);
+  }
+  return FileDescriptor();
+}
+
+Result<Ok, nsresult> AutoMemMap::init(nsIFile* file, int flags, int mode,
+                                      PRFileMapProtect prot) {
+  MOZ_ASSERT(!fd);
+
+  MOZ_TRY(file->OpenNSPRFileDesc(flags, mode, getter_Transfers(fd)));
+
+  return initInternal(prot);
+}
+
+Result<Ok, nsresult> AutoMemMap::init(const FileDescriptor& file,
+                                      PRFileMapProtect prot, size_t maybeSize) {
+  MOZ_ASSERT(!fd);
+  if (!file.IsValid()) {
+    return Err(NS_ERROR_INVALID_ARG);
+  }
+
+  auto handle = file.ClonePlatformHandle();
+
+  fd.reset(PR_ImportFile(PROsfd(handle.get())));
+  if (!fd) {
+    return Err(NS_ERROR_FAILURE);
+  }
+  Unused << handle.release();
+
+  return initInternal(prot, maybeSize);
+}
+
+Result<Ok, nsresult> AutoMemMap::initInternal(PRFileMapProtect prot,
+                                              size_t maybeSize) {
+  MOZ_ASSERT(!fileMap);
+  MOZ_ASSERT(!addr);
+
+  if (maybeSize > 0) {
+    // Some OSes' shared memory objects can't be stat()ed, either at
+    // all (Android) or without loosening the sandbox (Mac) so just
+    // use the size.
+    size_ = maybeSize;
+  } else {
+    // But if we don't have the size, assume it's a regular file and
+    // ask for it.
+    PRFileInfo64 fileInfo;
+    MOZ_TRY(PR_GetOpenFileInfo64(fd.get(), &fileInfo));
+
+    if (fileInfo.size > UINT32_MAX) {
+      return Err(NS_ERROR_INVALID_ARG);
+    }
+    size_ = fileInfo.size;
+  }
+
+  fileMap = PR_CreateFileMap(fd.get(), 0, prot);
+  if (!fileMap) {
+    return Err(NS_ERROR_FAILURE);
+  }
+
+  addr = PR_MemMap(fileMap, 0, size_);
+  if (!addr) {
+    return Err(NS_ERROR_FAILURE);
+  }
+
+  return Ok();
+}
+
+#ifdef XP_WIN
+
+Result<Ok, nsresult> AutoMemMap::initWithHandle(const FileDescriptor& file,
+                                                size_t size,
+                                                PRFileMapProtect prot) {
+  MOZ_ASSERT(!fd);
+  MOZ_ASSERT(!handle_);
+  if (!file.IsValid()) {
+    return Err(NS_ERROR_INVALID_ARG);
+  }
+
+  handle_ = file.ClonePlatformHandle().release();
+
+  MOZ_ASSERT(!addr);
+
+  size_ = size;
+
+  addr = MapViewOfFile(
+      handle_, prot == PR_PROT_READONLY ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
+      0, 0, size);
+  if (!addr) {
+    return Err(NS_ERROR_FAILURE);
+  }
+
+  return Ok();
+}
+
+FileDescriptor AutoMemMap::cloneHandle() const {
+  return FileDescriptor(handle_);
+}
+
+#else
+
+Result<Ok, nsresult> AutoMemMap::initWithHandle(const FileDescriptor& file,
+                                                size_t size,
+                                                PRFileMapProtect prot) {
+  MOZ_DIAGNOSTIC_ASSERT(size > 0);
+  return init(file, prot, size);
+}
+
+FileDescriptor AutoMemMap::cloneHandle() const { return cloneFileDescriptor(); }
+
+#endif
+
+void AutoMemMap::reset() {
+  if (addr && !persistent_) {
+    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;
+  }
+#ifdef XP_WIN
+  if (handle_) {
+    CloseHandle(handle_);
+    handle_ = nullptr;
+  }
+#endif
+  fd = nullptr;
+}
+
+}  // namespace loader
+}  // namespace mozilla