inject.lua

local function run(src, level)
    local level = level or 1
    level = level + 3
    assert(level >= 3)

    local function get(t, k)
        -- print('get:', k)
        -- print('bt:', debug.traceback())

        local level = level + 1

        local info = debug.getinfo(level, 'flnStuL')
        -- print(info.name)
        if info then
            local f = info.func

            local i = 1
            while true do
                local name, value = debug.getlocal(level, i)
                if not name then break end
                -- print('level,name,value:', level, name, value)
        
                -- if name:byte() ~= 40 then    -- '('
                if name == k then
                    -- debug.setlocal(level, name, value)
                    return value
                end
        
                i = i + 1
            end

            local i = 1
            while true do
                local name, value = debug.getupvalue(f, i)
                if not name then break end
        
                if name == k then
                    return value
                end
                i = i + 1
            end
        end

        return _G[k]
    end

    local function set(t, k, v)
        -- print('set:', t, k, v)
    
        local level = level + 1

        local info = debug.getinfo(level, 'flnStuL')
        if info then
            local f = info.func

            local i = 1
            while true do
                local name, value = debug.getlocal(level, i)
                if not name then break end

                -- if name:byte() ~= 40 then    -- '('
                if name == k then
                    debug.setlocal(level, i, v)
                    return
                end

                i = i + 1
            end

            local i = 1
            while true do
                local name, value = debug.getupvalue(f, i)
                if not name then break end
        
                if name == k then
                    debug.setupvalue(f, i, v)
                    return
                end
                i = i + 1
            end
        end
    
        if _G[k] then
            _G[k] = v
            return
        end
        -- if not find a local value or upvalue or global value, then raise an error 
        error("can not set ".. k) -- rawset(t, k, v)
    end

    local env = setmetatable({}, {__index = get, __newindex = set})

    local vargs = {} -- ...

    local info = debug.getinfo(level, 'flnStuL')
    if info then
        local i = 1
        while true do
            local vararg, value = debug.getlocal(level, -i)
            if not vararg then break end

            vargs[i] = value

            i = i + 1
        end
    end

    local func = load(src, "@hangj_inject", 'bt', env)
    if not func then return end
    local rets = table.pack(pcall(func, table.unpack(vargs)))
    if rets[1] then
        return table.unpack(rets, 1, rets.n)
    end
end


return run

test.lua

local inject = require('inject')

local g_a = 'g_a'

local function foo()
    print('foo')
end

local function fuck(...)
    local a = 'aaaa'

    print('a_before:', a)

    inject [[
        print('vargs:', ...)
        local lo = 'lo'
        lo = 'ol'
        a = 'bbb'
        g_a = 'gg_bb'
        print("fuck:", a, lo, g_a)

        foo()

        foo = function() print(g_a) end

        return 'hello world'
    ]]

    print('a_after:', a)
    print('g_a:', g_a)
end

fuck(6,7,8)

foo()

不同于 cloudwu 的实现方式，我用的是 metatable
https://github.com/cloudwu/skynet/blob/master/lualib/skynet/injectcode.lua

怎样在运行时插入运行一段 Lua 代码