The lens in the photos at the link you provided is indeed an EF mount lens. It appears to be a design from the early 1990s. Be aware that older third party lenses may or may not be completely compatible with newer Canon bodies. Most Sigma lenses from that era are not compatible with Canon bodies made since 2001. When mounted on a post 2001 Canon body the camera indicates an "Error 99" code.

Although Canon makes all of their new bodies compatible with every Canon EF lens ever made, they don't guarantee compatibility with third party lens makers. Since Canon does not share their proprietary data with other lens makers, companies such as Sigma and Tamron design their lenses using reverse engineering. In the past some Sigma lenses have not been 100% compatible with newer Canon bodies released after the Sigma lens was designed. In some cases Sigma has offered to re-chip the lenses to bring them up to compatibility with the newer bodies, but for a lens that old I doubt that is a possibility.

Based on my own experience using pre-2001 Sigma lenses on later Canon bodies, you can shoot in M mode with it as long as you set the aperture in your camera to match the maximum aperture of the lens. You will be unable to stop down and you will need to focus manually as well. The best home for a lens such as this is with an owner of a early film EOS body that would control the aperture and auto focus of the lens.