libbrillo: Add a way to construct FileDescriptor without duping FD

Add FileDescriptor(base::ScopedFD&&) and operator=(base::ScopedFD&&) to
create FileDescriptor without calling dup().
Also add release() to take the ownership of the FD without calling
dup().

BUG=None
TEST=build
Change-Id: Id96c3dc76e180bf11b674ad08d7d19f75f854c98
Reviewed-on: https://chromium-review.googlesource.com/1025332
Commit-Ready: Ryo Hashimoto <hashimoto@chromium.org>
Tested-by: Ryo Hashimoto <hashimoto@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/brillo/dbus/file_descriptor.h b/brillo/dbus/file_descriptor.h
index 2c4a01b..f7be44f 100644
--- a/brillo/dbus/file_descriptor.h
+++ b/brillo/dbus/file_descriptor.h
@@ -24,6 +24,7 @@ struct FileDescriptor {
   FileDescriptor() = default;
   FileDescriptor(int fd) : fd(dup(fd)) {}
   FileDescriptor(FileDescriptor&& other) : fd(std::move(other.fd)) {}
+  FileDescriptor(base::ScopedFD&& other) : fd(std::move(other)) {}
 
   inline FileDescriptor& operator=(int new_fd) {
     fd.reset(dup(new_fd));
@@ -35,6 +36,13 @@ struct FileDescriptor {
     return *this;
   }
 
+  FileDescriptor& operator=(base::ScopedFD&& other) {
+    fd = std::move(other);
+    return *this;
+  }
+
+  int release() { return fd.release(); }
+
   int get() const { return fd.get(); }
 
  private: