Usage of the shadow field in ngx_buf_t?

Igor Sysoev igor at
Fri Dec 4 00:21:22 MSK 2009

On Thu, Dec 03, 2009 at 12:08:29PM -0800, Brian Pane wrote:

> Can someone explain (or point me to some documentation on) the meaning of
> the shadow field in ngx_buf_t?

This is ancient thing and I do not like it. It was initially introduced
in code used by proxy and fastcgi to bookkeeping buf's saved in temporary
files. But now I think this is overengineered thing. Then it also used
to bookkeeping in SSI filter. Probably, it should rwritten, too.

> I'm writing a body filter, and I'm trying to
> figure out whether the presence of a non-null shadow in a buffer means that
> I need to do any special processing.


Igor Sysoev

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