Bug 781256 - 'Share FileDescriptors across processes in preparation for OS-level sandbox'. r=khuey+cjones.

ipc/glue/FileDescriptor.cpp

@@ -0,0 +1,65 @@
+/* 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 "FileDescriptor.h"
+
+#include "mozilla/Assertions.h"
+#include "nsDebug.h"
+
+#ifdef XP_WIN
+#include <windows.h>
+#define INVALID_HANDLE INVALID_HANDLE_VALUE
+#else
+#include <unistd.h>
+#define INVALID_HANDLE -1
+#endif
+
+using mozilla::ipc::FileDescriptor;
+
+FileDescriptor::FileDescriptor()
+: mHandle(INVALID_HANDLE)
+{ }
+
+FileDescriptor::PickleType
+FileDescriptor::ShareTo(const FileDescriptor::IPDLPrivate&,
+                        FileDescriptor::ProcessHandle aOtherProcess) const
+{
+#ifdef XP_WIN
+  if (mHandle == INVALID_HANDLE) {
+    return INVALID_HANDLE;
+  }
+
+  PlatformHandleType newHandle;
+  if (!DuplicateHandle(GetCurrentProcess(), mHandle, aOtherProcess, &newHandle,
+                       0, FALSE, DUPLICATE_SAME_ACCESS)) {
+    NS_WARNING("Failed to duplicate file handle!");
+    return INVALID_HANDLE;
+  }
+
+  return newHandle;
+#else // XP_WIN
+  if (mHandle == INVALID_HANDLE) {
+    return base::FileDescriptor();
+  }
+
+  PlatformHandleType newHandle = dup(mHandle);
+  if (newHandle < 0) {
+    NS_WARNING("Failed to duplicate file descriptor!");
+    return base::FileDescriptor();
+  }
+
+  // This file descriptor must be closed once the caller is done using it, so
+  // pass true here for the 'auto_close' argument.
+  return base::FileDescriptor(newHandle, true);
+#endif
+
+  MOZ_NOT_REACHED("Must not get here!");
+  return PickleType();
+}
+
+bool
+FileDescriptor::IsValid() const
+{
+  return mHandle != INVALID_HANDLE;
+}