如何调试和分析Luci

最近把luci代码深入地剖析了一遍．说实话刚开始看的时候也是云里雾里,特别是dispatch函数, 这其间也是参考了几篇文章, 特此感谢.

刚开始看luci代码确实就和逆向没啥区别,　需要揣摩作者对于各个变量的用途．　于是我就想了一个办法, 就是把每个变量都打印出来.

为此我在/usr/lib/lua/luci目录下引入了log.lua模块:

local M = {}

local tconcat = table.concat  
local tinsert = table.insert  
local srep = string.rep

local function local_print(str)  
    local dbg = io.open("/tmp/luci.output", "a+")
    local str = str or ""
    if dbg then
        dbg:write(str..'\n')
        dbg:close()
    end
end

function M.print(...)  
    local dbg = io.open("/tmp/luci.output", "a+")
    if dbg then
        dbg:write(os.date("[%H:%M:%S]: "))
        for _, o in ipairs({...}) do
            dbg:write(tostring(o)..'  ')
        end
        dbg:write("\n")
        dbg:close()
    end
end

function M.print_r(data, depth)  
    local depth = depth or 3
    local cstring = ""; 
    local top_flag = true

    local function table_len(t)
    local i = 0
    for k, v in pairs(t) do
        i = i + 1
    end
    return i
    end

    local function tableprint(data,cstring, local_depth)
        if data == nil then 
            local_print("core.print data is nil");
        end 

        local cs = cstring .. "    ";
    if top_flag then
            local_print(cstring .."{");
        top_flag = false
    end
        if(type(data)=="table") then
            for k, v in pairs(data) do
        if type(v) ~= "table" then
            if type(v) == "string" then
                        local_print(cs..tostring(k).." = ".."'"..tostring(v).."'");
            else
                        local_print(cs..tostring(k).." = "..tostring(v));
            end
        elseif table_len(v) == 0 then
            local_print(cs..tostring(k).." = ".."{}")
        elseif local_depth < depth then
                    local_print(cs..tostring(k).." = {");
                      tableprint(v,cs,local_depth+1);
        else
            local_print(cs..tostring(k).." = ".."{*}")
        end
            end 
        else
            local_print(cs..tostring(data));
        end 
        local_print(cstring .."}");
    end 

    tableprint(data,cstring,0);
end

return M  

你可以在luci目录下任何一个地方调用

local log = require "luci.log"  
log.print("Hello World")  
log.print_r({"Hello", "World"})  

另外, log模块将输出信息到/tmp/luci.ouput下面, 我们可以用tail命令跟踪.

# tail -f /tmp/luci.output

于是通过这个小小的模块, 得以一窥这个openwrt上著名的程序. 确实很有趣, 有时间我会详细的把luci框架分析写下来.

另外luci程序自带了一个debug模块, 这是一个用来分析内存占用情况的模块, 你也可以在dispatcher.lua模块中开启.它的信息记录在/tmp/memtrace中.

参考

• Luci实现框架
• Luci tutorials
• wifidog在OpenWrt路由器上添加LuCI的模块