Shanghai chore jacket, light cotton garment with frog fasteners and western style collar, as opposed to a mao style collar - famously worn by Marseille and Corsican dockers, and Picasso.  S/M size (21.5" pit to pit), marked size 52 (like a French 40/42, UK12).
3 patch pockets, 1 inner pocket. 5 front buttons. pretty round collar.
Made in China.