Re: [RFC] Add posibility to preload stat information.

From: Jeff King <peff@peff.net>
Date: Mar 20, 2013, 16:48 UTC
Message-ID: <20130320164806.GA10752@sigill.intra.peff.net>
In-Reply-To: <1363781732-11396-1-git-send-email-iveqy@iveqy.com>

On Wed, Mar 20, 2013 at 01:15:32PM +0100, Fredrik Gustafsson wrote:

Show 5 quoted lines

> When entering a git working dir, optionally run a forked process that
> stat all files in the whole workdir and therefore loads stat information
> to RAM which will speedup things like git status and so on.
> 
> The feature is optional and by default it's off.

Kind of gross, but I guess it is useful to some people.

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> +__git_recursive_stat ()
> +{
> +	if test ! -e /tmp/gitbash.lock
> +	then
> +		touch /tmp/gitbash.lock

This is a tmp-race security hole. E.g., do:

  ln -s /etc/nologin /tmp/gitbash.lock

as a user; when root runs __git_recursive_stat, it will create /etc/nologin. It's not quite as bad as some other holes, because we only "touch" the file, not overwrite its contents, but you can see that it's possible to do some mischief.

Should this maybe just be ~/.gitbash.lock or something?

> +		cd $(git rev-parse --show-toplevel)
> +		find . | xargs stat 2&> /dev/null

The "stat" utility is not portable. But why not use git to do the reading? Then you can get the benefit of core.preloadindex, and you will not recurse into untracked directories that are ignored (i.e., ones that git would not go into anyway).

So maybe just run "git status >/dev/null"?

-Peff