Hi,

I'm writing a filter module which implies a backend to be sending XML with
information about files that have to be concatenated and sent to the client.

One way to send a file is to `ngx_read_file` into a buffer allocated in the
heap(pool) and push it onto the chain. However, I obviously can't allocate ~10G
in the heap. I have to send it chunk-by-chunk. How do I perform such kind of I/O?

Regards.