manga.lua

local path, ext =
  ngx.var.path, ngx.var.ext

local images_dir = "/usr/local/var/www/manga/img/" -- where images come from
local cache_dir = "/usr/local/var/www/manga/cache/" -- where images are cached

local function return_not_found(msg)
  ngx.status = ngx.HTTP_NOT_FOUND
  ngx.header["Content-type"] = "text/html"
  ngx.say(msg or "not found")
  ngx.exit(0)
end

local source_fname = images_dir .. path

-- make sure the file exists
local file = io.open(source_fname)

if not file then
  return_not_found()
end

file:close()

local dest_fname = cache_dir .. path

-- resize the image
os.execute("/usr/local/var/www/manga/manga.out " .. source_fname .. ' ' .. dest_fname);

ngx.exec(ngx.var.request_uri)