The Giants have to get John Harbaugh into their building before they can decide not to let him out of the building with an offer that he can’t refuse.

And even padlocks on the doors won’t matter unless they first fulfill the Rooney Rule requirements and then find more common ground in an interview setting than the growing list of other desirable suitors pursuing Harbaugh.

Though Giants fans sensing a dangerous game is afoot are in a hurry to hire the Super Bowl-winning former Ravens coach (who was fired Tuesday), the process cannot be rushed: The search for the next head coach is going to extend into next week, and that means that more competition for Harbaugh’s services could enter a sticky equation.

“He is their home-run hire,” one NFL executive told The Post.