[PATCH] filter: basic write hooking infrastructure

[Jason at zx2c4.com (Jason A. Donenfeld)]

On Sun, Jan 12, 2014 at 11:52 PM, John Keeping <john at keeping.me.uk> wrote:
> Clever.  I've been looking at hooking in at a higher level before html.c
> escapes the output.  But I think the approach taken with source_filter
> may be a better way of getting the raw output to the filter.
>
> I can't help thinking it would be easier to just replace html_raw here
> though.  All our writes go through there anyway and we don't need to
> worry about writing to other file descriptors.

That was my original idea too. But then I saw that often times we
_don't_ actually use html_raw. Sometimes we printf directly, and other
times, git itself writes data. I don't want to maintain a patchset
against git, so it seemed like the lower level was the only way to go.