There are adapter rings for different brand of cameras, however there are restrictions. One is the distance from mount flange to film, where this distance for the lens must be equal or larger than that for the body mount, otherwise there will be no infinity focusing.
For example Canon EOS is 44mm while Olympus 4/3 is 38.67mm. Many current mounts have larger distances so can be adapted to these 2 with infinity focus. Pentax K and M42 have the same distances of 45.46mm.
There may be mechanical obstructions. Canon EOS can't fit into Pentax K completely and no infinity focus due to flange distance. Pentax K lens have a protrusion which may interfere with mirror of 35mm / full frame bodies.