bugfix: File::GetWaitableHandle() should call fileno()

[lawrence_danna]

Summary

If the file has m_stream, it may not have a m_descriptor.
GetWaitableHandle() should call GetDescriptor(), which will call
fileno(), so it will get waitable descriptor whenever one is available.

[labath]

Thanks for the fix. This sounds like it should be unit testable. Could add a test for that?

[lawrence_danna]

added a unit test

[labath]

Thanks for adding the test. LGTM, modulo some nits inline.

lldb/unittests/Host/CMakeLists.txt

14 ↗

(On Diff #221082)

Please keep the list sorted.

lldb/unittests/Host/FileTest.cpp

29–32 ↗

(On Diff #221082)

nit: change EXPECT_XXX to ASSERT_XXX as it does not make sense to continue the test if the assertions are not true.

[lawrence_danna]

nits fixed

[lawrence_danna]

nits fixed

lldb/source/Host/common/File.cpp

#else
     return fileno(m_stream);
 #endif
   }
 
   // Invalid descriptor and invalid stream, return invalid descriptor.
   return kInvalidDescriptor;
 }
 
-IOObject::WaitableHandle File::GetWaitableHandle() { return m_descriptor; }
+IOObject::WaitableHandle File::GetWaitableHandle() { return GetDescriptor(); }
 
 void File::SetDescriptor(int fd, bool transfer_ownership) {
   if (IsValid())
     Close();
   m_descriptor = fd;
   m_should_close_fd = transfer_ownership;
 }