Permissions in std::tempfile::mkdtemp

[catamorphism]

There's a comment in std::tempfile::mkdtemp that says "FIXME: u+rwx". I assume the idea here is to set the r, w and x bits for U to 1 and leave other bits unchanged from the default, rather than setting the permissions for the new directory to a fixed bit pattern. But I don't really know the details of how permissions bits work, so I'm filing this.

[killerswan]

Hex 1c0 is octal 700 (decimal 448), which sets the permission to rwx------.

We may just want to set it to rwxrwxrwx (octal 777, decimal 484) and let the system default reduce that to whatever it wants, e.g., rwxrw-rw-, but I'm not entirely sure if it would bitwise and with the default like I expect, or just overwrite it.

[thestinger]

I think this should definitely use 700 like the POSIX mkdtemp, otherwise it's not usable for safely making a temporary work area within a world-writable directory. If it starts off allowing other users to create files in it, you can't then use regular file names inside it without fear of them already being created - possibly as hardlinks. I can't really think of a use case for a randomized directory name which other users have read/write permissions on.

[catamorphism]

Fixed in 0a8c039