nginx下使用LUA实现边下载边发送文件内容

package.path = '/usr/local/share/lua/5.1/?.lua;/usr/local/openresty/lualib/resty/?.lua;' 
package.cpath = '/usr/local/lib/lua/5.1/?.so;' 
 
require("curl") 
 
function build_w_cb(f) 
   return function(s,len) 
         ngx.print(s) 
         ngx.flush(true) 
      --local wlen = f:write(s) 
      --if (wlen ~= len) then 
    --  return len,"writeError" 
     -- else 
        return len,nil 
    --  end 
   end 
end 
 
file = io.open("/usr/local/openresty/nginx/html/me.ts", "w") 
if (file == nil) then 
    ngx.say ("Create File error") 
    return 
end 
ngx.header["Transfer-Encoding"] = 'chunked'; 
--Transfer-Encoding: chunked 
--download XML File 
xmlURL = "http://192.168.1.102/pxx/f1.ts" 
c = curl.easy_init()  
c:setopt(curl.OPT_URL, xmlURL) 
c:setopt(curl.OPT_WRITEFUNCTION, build_w_cb(file)) 
c:setopt(curl.OPT_FOLLOWLOCATION, 1) 
 
c:setopt(curl.OPT_USERAGENT, "ContentPreload-agent/1.0") 
c:setopt(curl.OPT_COOKIEFILE, "./curlpost.cookie") 
c:setopt(curl.OPT_CONNECTTIMEOUT, 5) 
c:setopt(curl.OPT_TIMEOUT, 3000) 
c:setopt(curl.OPT_NOSIGNAL, 1) 
 
ret,strerr = c:perform() 
 
file:close()