Craftception

i basically want to make a virtualbox-based system in cc, basically if LyqydOS tried to run in it, and tried to save a file as "/LyqydOS/data" then it would save as "/emu/LyqydOS/data" if you get what im saying
is there any way to do this?

If understand what you're asking correctly, you could modify the fs api to append your base directory to any path trying to be read/written to. However, you'll need to make sure that callers can still access the 'rom' files.

Maybe something like this?

local baseDir = "/emu/"
local oldFs = {}

for name, func in pairs(_G.fs) do
    oldFS[name] = func
end

for name, func in pairs(oldFs) do
    _G.fs[name] = function(path, ...)
        path = shell.resolve(path)

        if oldFS.isReadOnly(path) then
            return oldFs[name](path, ...)
        end

        return oldFs[name](baseDir .. path, ...)
    end
end

This is, of course, untested.

How would I modify the fs api?

That is not needed:

Grim Reaper, on 27 June 2015 - 01:18 AM said:

for name, func in pairs(_G.fs) do
	oldFS[name] = func
end

Just use

local oldFS = _G.fs

Creeper9207, on 27 June 2015 - 05:30 AM said:

How would I modify the fs api?

The fs api table is not read only
you can use

fs.open = function()
  --somestrangecode xD
end

Oh btw Grim, your code would override fs.combine() so this code:

path1 = "testdir"
path2 = "fileintestdir"
path = fs.combine(path1,path2)
fs.open(path,"r")
--continuing with code

would open
/emu/emu/testdir/fileintestdir

Luca0208, on 27 June 2015 - 07:07 AM said:

That is not needed:

Grim Reaper, on 27 June 2015 - 01:18 AM said:

for name, func in pairs(_G.fs) do
	oldFS[name] = func
end

Just use

local oldFS = _G.fs

That won't work, because that simply assigns _fs as a pointer to the _G.fs table, which we later change the values of. Sure, you can make the _G.fs table an entirely new table, but then the version of fs io uses won't be overridden.

I need something that would essentially run out-of-the-box

local baseDir = "/emu/"
local oldFs = {}

for name, func in pairs(_G.fs) do
    oldFS[name] = func
end

for name, func in pairs(oldFs) do
    _G.fs[name] = function(path, ...)
        path = shell.resolve(path)

        if oldFS.isReadOnly(path) then
            return oldFs[name](path, ...)
        end

        return oldFs[name](baseDir .. path, ...)
    end
end
_G.fs.combine = oldFs.combine

Try this. It's a slightly modified version of Grim's code, it should work. Unless, of course, he got something wrong when he wrote it.

Luca0208, on 27 June 2015 - 07:07 AM said:

That is not needed:

Grim Reaper, on 27 June 2015 - 01:18 AM said:

for name, func in pairs(_G.fs) do
	oldFS[name] = func
end

Just use

local oldFS = _G.fs

That code is needed, I think, because you must make a copy of the original fs api functions. Simply doing

local oldFS = _G.fs

means that the oldFS table simply points to the _G.fs table. So, by overwriting _G.fs, you overwrite oldFS as well, leaving the original and critical fs api functions nowhere to be found.

Luca0208, on 27 June 2015 - 07:12 AM said:

Oh btw Grim, your code would override fs.combine() so this code:

path1 = "testdir"
path2 = "fileintestdir"
path = fs.combine(path1,path2)
fs.open(path,"r")
--continuing with code

would open
/emu/emu/testdir/fileintestdir

You're absolutely right about this one. I don't use the entirety of the fs api much, so my knowledge of its contents is lacking.

Yami's code should work to correct that.