A directory : /home/ABC having rwx for all users (owner, group, other) [rwxrwxrwx]
Three users: test1,test2,test3
test1 create file f1 inside ABC and all the permissions for all users are taken away. [- - - - - - - - -]
test2 opens ABC and edits f1 through vim editor and then saves it using override. [wq!]
now test2 becomes user and group owner of f1 and also new contents are stored and original file was overwritten.
Please tell me when f1 had no permission for anybody, how test2 was able to overwrite the file and take its ownership?