`OpenOptions::mode` applies only when the file is created, so opening one
that already exists keeps whatever mode it had. For `append_file` that is
the normal case rather than the odd one -- every write to a transcript
after the first -- and for `create_file` it happens on every rewrite. A
file made wrong by an older version or by hand would have stayed
world-readable for as long as it was only ever appended to.
This is the same reasoning as `create_dir`'s second call, which was
already here and already commented. Missing it on the file paths was the
kind of gap that only shows when the two are read side by side, which is
an argument for this crate existing rather than against it.
Set through the open handle rather than the path, so nothing can swap
what is at that path between the open and the chmod.
Caught by ai-app's session reviewing the module I had taken from their
code, which is the review this repo is supposed to make possible.
iris
861e6a329b