Merge "Revert "init: use read_file and write_file to implement do_copy builtin"" am: 3428d0c2c0 am: 02d720eb27 am: 9817f4f317  -s ours
am: 4455aea407

Change-Id: Id2e90c0616f86ded9b4cf0423277c29d060bc2e9