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How do we tell if a function is sandboxed?

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Posted by

Shaun Biggs USA (644 posts) Bio

Date

Wed 17 Jun 2009 05:35 AM (UTC)

Message

So I was trying to make a bit of a debugging log for a plugin of mine which has had issues running on a clanmate's computer. While testing, I forgot that io.open() was sandboxed. Is there any way to have a script check to see if a function is sandboxed before attempting to access the function? I would much rather check before having a bunch of errors pop up on the screen.

The functions are actually different:
print( io.open )
print( io.write )
print( io.read )
function: 00DE55F8
function: 00DE5490
function: 00DE6060

Would it be possible to have a sandboxed() function which the other functions could reference if they are sandboxed, rather than having a new function created each time doing the same exact thing?

a = function() end
b = a
print( a.."\n"..b )
function: 013A84A0
function: 013A84A0

This way we can check if a function is sandboxed with a quick comparison, or a world.sandboxed( foo ) function returning true/false. I'm hoping this exists already, and I just do not know of it yet.

It is much easier to fight for one's ideals than to live up to them.

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Posted by Nick Gammon Australia (23,158 posts) Bio Forum Administrator

Date

Reply #1 on Wed 17 Jun 2009 06:47 AM (UTC)

Amended on Wed 17 Jun 2009 06:48 AM (UTC) by Nick Gammon

Message

If io.open is sandboxed, it will be a Lua function. If not, it will be a C function.

For example, if not sandboxed:


/tprint (debug.getinfo (io.open, "S"))

"source"="=[C]"
"what"="C"
"lastlinedefined"=-1
"linedefined"=-1
"short_src"="[C]"

If sandboxed:


/tprint (debug.getinfo (io.open, "S"))

"source"="Sandbox"
"what"="Lua"
"lastlinedefined"=42
"linedefined"=38
"short_src"="[string "Sandbox"]"

As you can see, most (er, all) of the debug info is different if it is sandboxed. So something like this could be used:


if debug.getinfo (io.open, "S").source == "Sandbox" then
  print ("warning, io.open sandboxed")
end -- if

- Nick Gammon

www.gammon.com.au, www.mushclient.com

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Posted by Shaun Biggs USA (644 posts) Bio

Date Reply #2 on Wed 17 Jun 2009 09:40 AM (UTC)

Message

Thank you very much. That makes what I am doing much easier. I am can now check to see if I can deal with logging some debugging information with a quick check. Just in case anyone else will find it useful:


loggable = true
for _,v in pairs( io ) do
  if type(v) == "function" then
    if debug.getinfo (v, "S").source == "Sandbox" then
      loggable = false
    end -- if sandboxed
  end -- check only functions
end

It is much easier to fight for one's ideals than to live up to them.

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