libbrillo: add UdevDevice::Clone

UdevDevice does not allow access to the underlying libudev
struct, so give another way to copy UdevDevice objects.

BUG=chromium:986484
TEST=build, upcoming UdevWatcher changes

Change-Id: Ibe6d0ccd23e663e6e893312d42968701d2044d58
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/1827463
Tested-by: Eric Caruso <ejcaruso@chromium.org>
Commit-Queue: Eric Caruso <ejcaruso@chromium.org>
Reviewed-by: Anand Mistry <amistry@chromium.org>
Cr-Mirrored-From: https://chromium.googlesource.com/chromiumos/platform2
Cr-Mirrored-Commit: 4f80108567894cbcab38b877476be041f77f56a0

3 files changed, 9 insertions, 0 deletions

diff --git a/brillo/udev/mock_udev_device.h b/brillo/udev/mock_udev_device.h
index 9e0c2ef..6e812d1 100644
--- a/brillo/udev/mock_udev_device.h
+++ b/brillo/udev/mock_udev_device.h
@@ -57,6 +57,7 @@ class BRILLO_EXPORT MockUdevDevice : public UdevDevice {
               GetSysAttributeValue,
               (const char*),
               (const, override));
+  MOCK_METHOD(std::unique_ptr<UdevDevice>, Clone, (), (override));
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockUdevDevice);
diff --git a/brillo/udev/udev_device.cc b/brillo/udev/udev_device.cc
index b84fa36..2251699 100644
--- a/brillo/udev/udev_device.cc
+++ b/brillo/udev/udev_device.cc
@@ -121,4 +121,8 @@ const char* UdevDevice::GetSysAttributeValue(const char* attribute) const {
   return udev_device_get_sysattr_value(device_, attribute);
 }
 
+std::unique_ptr<UdevDevice> UdevDevice::Clone() {
+  return std::make_unique<UdevDevice>(device_);
+}
+
 }  // namespace brillo
diff --git a/brillo/udev/udev_device.h b/brillo/udev/udev_device.h
index 1f942a8..2704a22 100644
--- a/brillo/udev/udev_device.h
+++ b/brillo/udev/udev_device.h
@@ -95,6 +95,10 @@ class BRILLO_EXPORT UdevDevice {
   // Wraps udev_device_get_sysattr_value().
   virtual const char* GetSysAttributeValue(const char* attribute) const;
 
+  // Creates a copy of this UdevDevice pointing to the same underlying
+  // struct udev_device* (increasing its libudev reference count by 1).
+  virtual std::unique_ptr<UdevDevice> Clone();
+
  private:
   // Allows MockUdevDevice to invoke the private default constructor below.
   friend class MockUdevDevice;