Re: [RFC/PATCH] config: honor file permission bits

> Because our updates to an existing file almost never makes
> modifications in place, and instead create a new "lockfile",
> propagate the permission bits from the original, copy the contents
> from the original file while tweaking the contents as needed, and
> then finally rename the lockfile to replace the original file, you
> cannot "protect" your .global configuration file from accidental
> clobbering by doing something like this:
> 
> 	$ chmod a-w $HOME/.gitconfig
> 
> Of course, if you make your $HOME directory unwritable, it may
> protect your .gitconfig from getting updated, but that goes totally
> against the intuition and is not how you would protect a regular
> file from getting overwritten.
> 
> Teach the configuration file writing machinery to inspect the
> permission bits of the original with access(2) and refrain from
> doing the usual "write a lockfile and replace the original with it"
> dance ourselves when we shouldn't be able to write it.