I'm trying to use the http_gunzip module as an example for a filter I am trying to write. I'm particularly interested in the buffer management.

The module has a value in its ctx stuct called last_buf

...
ngx_chain_t **last_out;
...

last_out is set in various places throughout the code. Sometimes to other chains in the ctx, sometimes to newly allocated chains.

But as far as I can tell, none of the code ever uses the value stored in last_out. (It seems to be a write-only variable :-)

Anybody know what I'm missing?