Naughty script that allows you to hide files in Garry's Mod. Lua replacement for gm_fshook.

fs_hider.lua

-- if you don't trust the hook library at this point you might wanna 
-- replace this with a local callback of sorts
hook.Add("ShouldHideFile", "", function(_, path)
	if path:match("custom_file.lua") then return true end
end)

-- hide our detours
local debug_info_cache = {}
local old_debug_getinfo = debug.getinfo
function debug.getinfo(fn, ...)
	if isfunction(fn) and debug_info_cache[fn] then
		return debug_info_cache[fn]
	else
		return old_debug_getinfo(fn, ...)
	end
end

-- dont reveal ourselves
debug_info_cache[debug.getinfo] = old_debug_getinfo(old_debug_getinfo)

-- detours
local read_detours = {
	{ FunctionName = "Read", Default = nil },
	{ FunctionName = "Time", Default = 0 },
	{ FunctionName = "IsDir", Default = false },
	{ FunctionName = "Exists", Default = false },
	{ FunctionName = "AsyncRead", Default = FSASYNC_ERR_FAILURE or -5 },
	{ FunctionName = "Rename", Default = false },
	{ FunctionName = "Size", Default = 0 },
	{ FunctionName = "CompileFile", Default = function() end, global = true },
	{ FunctionName = "include", Default = nil, global = true },
}

for _, detour in ipairs(read_detours) do
	local old_fn = detour.global and _G[detour.FunctionName] or _G.file[detour.FunctionName]
	if old_fn then
		local new_fn = function(path, ...)
			if hook.Run("ShouldHideFile", path) then return detour.Default end
			return old_fn(path, ...)
		end

		_G.file[detour.FunctionName] = new_fn
		debug_info_cache[new_fn] = old_debug_getinfo(old_fn)
	end
end

local write_detours = { "Append", "Write", "Open", "Delete", "CreateDir" }
for _, detour in ipairs(write_detours) do
	local old_fn = _G.file[detour]
	if old_fn then
		local new_fn = function(path, ...)
			if hook.Run("ShouldHideFile", path) then return false end
			return old_fn(path, ...)
		end

		_G.file[detour] = new_fn
		debug_info_cache[new_fn] = old_debug_getinfo(old_fn)
	end
end

local old_file_find = _G.file.Find
function file.Find(pattern, ...)
	local files, dirs = old_file_find(pattern, ...)

	local base_path = pattern:GetPathFromFilename()
	if #base_path > 0 and not base_path:EndsWith("/") then
		base_path = base_path .. "/"
	end

	local final_files = {}
	for _, file_name in pairs(files) do
		if hook.Run("ShouldHideFile", base_path .. file_name) then continue end
		table.insert(final_files, file_name)
	end

	local final_dirs = {}
	for _, dir_name in pairs(dirs) do
		if hook.Run("ShouldHideFile", base_path .. dir_name) then continue end
		table.insert(final_dirs, dir_name)
	end

	return final_files, final_dirs
end

debug_info_cache[file.Find] = old_debug_getinfo(old_file_find)