From: salamond <jarodzz@...>
Date: 2012-06-27T23:19:18+09:00
Subject: Re: how about adding method hook

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Hi, Henry.

thanks for the info.

method missing might be a good option.

class Process
  def run; end
end

class FileUtils
  def mkdir; end
end

class Agent
  def method_missing
    if Process.new.respond_to(method) || FileUtiles.response_to(method)
      do_as_me
         Process.new.send(method)
      end
   end
end

sort of like this. what do you think?




On Wed, Jun 27, 2012 at 6:26 PM, Henry Maddocks <hmaddocks@me.com> wrote:

>
> On 27/06/2012, at 8:12 PM, salamond <jarodzz@gmail.com> wrote:
>
> Hi, guys.
>
> I want An agent on machine, so that it can fake user actions.
>
> ...
>
> My problem is, I have a very long list of actions, like mv, touch, mkdir,
> rm, etc.
> I don't want to add save and restore euid for all methods.
>
>
> First thing I'd do is remove all the duplication, maybe something like
> this...
>
> class Agent
>   def initialize(user, dir)
>     @user = user
>     @dir = dir
>   end
>
>   def as_me_do
>     bak = Process.euid
>       yield
>
>   ensure # hat tip Robert
>     Process.euid = bak
>   end
>
>   def mkdir(dir)
>     as_me_do {`mkdir`}
>   end
>
>   def create_file(file, content)
>     as_me_do {`echo #{content} > #{file}`}
>   end
> end
>
> The next step might be more obvious.
>
> I kind of guess here I should use some meta programming skills. here's
> what i tried.
>
>
> Defining methods is going to be tricky, because you don't have consistent
> method signatures and system calls. Maybe a have a hash of methods =>
> system calls and method missing?
>
> Also, why back ticks, why not use ruby File methods?
>
> Henry
>
>

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Hi, Henry.<div><br></div><div>thanks for the info.</div><div><br></div><div=
>method missing might be a good option.</div><div><br></div><div>class Proc=
ess</div><div>=A0 def run; end</div><div>end</div><div><br></div><div>class=
 FileUtils</div>
<div>=A0 def mkdir; end</div><div>end</div><div><br></div><div>class Agent<=
/div><div>=A0 def method_missing</div><div>=A0 =A0 if Process.new.respond_t=
o(method) || FileUtiles.response_to(method)</div><div>=A0 =A0 =A0 do_as_me<=
/div><div>
=A0 =A0 =A0 =A0 =A0Process.new.send(method)</div><div>=A0 =A0 =A0 end</div>=
<div>=A0 =A0end</div><div>end</div><div><br></div><div>sort of like this. w=
hat do you think?</div><div><br></div><div><br></div><div><br><br><div clas=
s=3D"gmail_quote">
On Wed, Jun 27, 2012 at 6:26 PM, Henry Maddocks <span dir=3D"ltr">&lt;<a hr=
ef=3D"mailto:hmaddocks@me.com" target=3D"_blank">hmaddocks@me.com</a>&gt;</=
span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8e=
x;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor=3D"#FFFFFF"><div class=3D"im"><div><br></div><div>On 27/06/201=
2, at 8:12 PM, salamond &lt;<a href=3D"mailto:jarodzz@gmail.com" target=3D"=
_blank">jarodzz@gmail.com</a>&gt; wrote:<br><br></div><div></div></div><blo=
ckquote type=3D"cite">
<div><div class=3D"im">Hi, guys.<div><br></div><div>I want An agent on mach=
ine, so that it can fake user actions.</div><div><br></div></div><div>...</=
div><div class=3D"im"><div><br></div><div>My problem is, I have a very long=
 list of actions, like mv, touch, mkdir, rm, etc.</div>
<div>
I don&#39;t want to add save and restore euid for all methods.</div></div><=
/div></blockquote><div><br></div><div>First thing I&#39;d do is remove all =
the duplication, maybe something like this...</div><div><br></div><span><di=
v class=3D"im">
<div>class Agent</div><div>=A0 def initialize(user, dir)</div><div>=A0 =A0 =
@user =3D user</div><div>=A0 =A0 @dir =3D dir</div><div>=A0 end</div><div><=
br></div></div><div>=A0 def as_me_do</div><div>=A0 =A0 bak =3D Process.euid=
</div><div>=A0 =A0 =A0 yield</div>
<div><br></div><div>=A0 ensure # hat tip Robert</div><div>=A0 =A0 Process.e=
uid =3D bak</div><div>=A0 end</div><div><br></div><div>=A0 def mkdir(dir)</=
div><div>=A0 =A0 as_me_do {<span>`mkdir`}</span></div><div>=A0 end</div><di=
v><br></div><div>
=A0 def create_file(file, content)</div><div>=A0 =A0 as_me_do {<span>`echo =
#{content} &gt; #{file}`}</span></div><div>=A0 end</div><div>end</div></spa=
n><div><br></div><div>The next step might be more obvious.</div><br><blockq=
uote type=3D"cite">
<div><div>I kind of guess here I should use some meta programming skills. h=
ere&#39;s what i tried.</div>
</div></blockquote><br><div>Defining methods is going to be tricky, because=
 you don&#39;t have consistent method signatures and system calls. Maybe a =
have a hash of methods =3D&gt; system calls and method missing?</div><div>
<br></div><div>Also, why back ticks, why not use ruby File methods?</div><s=
pan class=3D"HOEnZb"><font color=3D"#888888"><div><br></div><div>Henry</div=
><div><br></div></font></span></div></blockquote></div><br></div>

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