1715 posts
Location
ACDC Town
Posted 24 February 2015 - 12:32 AM
I'm trying to make a file protection program that prevents people from writing to the file, while allowing read. However I am having problems trying to get that to work. I HAVE found that people had problems with fs.delete() where it outputs "Access denied", but I couldn't find anything to replicate it with. Can someone tell me how to make a file read-only, maybe if only for the current session?
376 posts
Location
[string "FindMe"]:23143: bad argument #1 to 'returnPos' (vector expected, got nil)
Posted 24 February 2015 - 01:16 AM
This sloppy code should work
local olddelete = fs.delete
local oldopen = fs.open
local oldcheck = fs.isReadOnly
local list = {["bm"] = true}
fs.delete = function(sFile)
if list[sFile] then
error("Access denied",0)
end
return olddelete(sFile)
end
fs.isReadOnly = function(sFile)
if list[sFile] then
return true
else
return oldcheck(sFile)
end
end
fs.open = function(sFile, sMode)
if list[sFile] and sMode ~= "r" and sMode ~= "rb" then
return nil
end
return oldopen(sFile,sMode)
end
EDIT : Haven't tested
EDIT 2: Fixed it
Edited on 24 February 2015 - 05:38 PM
1715 posts
Location
ACDC Town
Posted 24 February 2015 - 02:07 AM
That appears to made every single command say 'File not found'.
7083 posts
Location
Tasmania (AU)
Posted 24 February 2015 - 04:16 AM
fs.open() returns a file handle. Your replacement will need to return something, too.
The "override" table should be localised to prevent users altering its contents to fit their whims.
You seem to be "blacklisting" files in your "whitelist".
If fs.open() decides not to open a file in write mode, better that it return nil than a file handle in read mode.
It would be more efficient speed-wise to store your files as key-names (simply set to "true") - this would allow you to check if they're in the table without iterating through it.
724 posts
Location
Kinda lost
Posted 24 February 2015 - 09:52 AM
Also to note that lets assume you have file-path like "folder/file". You blacklisted that path. Someone could still open that file using file-path "folder/./file" or "/././././././folder/././././././file" or "/././././././folder/../folder/./././././file" that still points to same file due to how dot works but is different string as far as blacklist is concerned.
You can get around that by using fs.combine("",sPath) witch will gladly remove all unnecessary dots and parts of path from path you gave it.making "/././././././folder/././././././file", "folder/./file" and "/././././././folder/../folder/./././././file" back into "folder/file". Just something i learned working on my shell.
EDIT: Wait.. This is not "Ask a Pro"? I got lost.
Edited on 24 February 2015 - 09:57 AM
376 posts
Location
[string "FindMe"]:23143: bad argument #1 to 'returnPos' (vector expected, got nil)
Posted 24 February 2015 - 06:25 PM
Ahh, sorry about that. I really didn't put effort into it. I will patch up the code now.
7083 posts
Location
Tasmania (AU)
Posted 25 February 2015 - 12:22 AM
You can get around that by using fs.combine("",sPath)
Although that should work, I feel shell.resolve(sPath) would be more elegant.
724 posts
Location
Kinda lost
Posted 25 February 2015 - 12:52 AM
Writing that post I assumed that it would only work on full/absolute file paths. Personally I tend not to use shell api if I can.
Edited on 24 February 2015 - 11:52 PM