Replaces Roblox Studio's splash screen with another image.

splash-patch.lua

-- Replaces Roblox Studio's splash screen with another image.
--
-- Usage:
--
--     lua splash-patch.lua [STUDIO_PATH] [IMAGE_PATH]
--
-- Specifying no options prompts for input.


-- First KB of original splash image file
local splashSig =
'\137\080\078\071\013\010\026\010\000\000\000\013\073\072\068\082' ..
'\000\000\002\063\000\000\001\070\008\006\000\000\000\133\105\254' ..
'\163\000\000\000\025\116\069\088\116\083\111\102\116\119\097\114' ..
'\101\000\065\100\111\098\101\032\073\109\097\103\101\082\101\097' ..
'\100\121\113\201\101\060\000\000\003\102\105\084\088\116\088\077' ..
'\076\058\099\111\109\046\097\100\111\098\101\046\120\109\112\000' ..
'\000\000\000\000\060\063\120\112\097\099\107\101\116\032\098\101' ..
'\103\105\110\061\034\239\187\191\034\032\105\100\061\034\087\053' ..
'\077\048\077\112\067\101\104\105\072\122\114\101\083\122\078\084' ..
'\099\122\107\099\057\100\034\063\062\032\060\120\058\120\109\112' ..
'\109\101\116\097\032\120\109\108\110\115\058\120\061\034\097\100' ..
'\111\098\101\058\110\115\058\109\101\116\097\047\034\032\120\058' ..
'\120\109\112\116\107\061\034\065\100\111\098\101\032\088\077\080' ..
'\032\067\111\114\101\032\053\046\048\045\099\048\054\048\032\054' ..
'\049\046\049\051\052\055\055\055\044\032\050\048\049\048\047\048' ..
'\050\047\049\050\045\049\055\058\051\050\058\048\048\032\032\032' ..
'\032\032\032\032\032\034\062\032\060\114\100\102\058\082\068\070' ..
'\032\120\109\108\110\115\058\114\100\102\061\034\104\116\116\112' ..
'\058\047\047\119\119\119\046\119\051\046\111\114\103\047\049\057' ..
'\057\057\047\048\050\047\050\050\045\114\100\102\045\115\121\110' ..
'\116\097\120\045\110\115\035\034\062\032\060\114\100\102\058\068' ..
'\101\115\099\114\105\112\116\105\111\110\032\114\100\102\058\097' ..
'\098\111\117\116\061\034\034\032\120\109\108\110\115\058\120\109' ..
'\112\077\077\061\034\104\116\116\112\058\047\047\110\115\046\097' ..
'\100\111\098\101\046\099\111\109\047\120\097\112\047\049\046\048' ..
'\047\109\109\047\034\032\120\109\108\110\115\058\115\116\082\101' ..
'\102\061\034\104\116\116\112\058\047\047\110\115\046\097\100\111' ..
'\098\101\046\099\111\109\047\120\097\112\047\049\046\048\047\115' ..
'\084\121\112\101\047\082\101\115\111\117\114\099\101\082\101\102' ..
'\035\034\032\120\109\108\110\115\058\120\109\112\061\034\104\116' ..
'\116\112\058\047\047\110\115\046\097\100\111\098\101\046\099\111' ..
'\109\047\120\097\112\047\049\046\048\047\034\032\120\109\112\077' ..
'\077\058\079\114\105\103\105\110\097\108\068\111\099\117\109\101' ..
'\110\116\073\068\061\034\120\109\112\046\100\105\100\058\070\055' ..
'\055\070\049\049\055\052\048\055\050\048\054\056\049\049\056\067' ..
'\049\052\056\054\068\053\052\057\052\069\066\065\055\056\034\032' ..
'\120\109\112\077\077\058\068\111\099\117\109\101\110\116\073\068' ..
'\061\034\120\109\112\046\100\105\100\058\051\054\056\052\066\066' ..
'\066\068\055\055\057\069\049\049\069\050\057\056\054\057\070\053' ..
'\052\070\051\053\065\049\054\051\048\056\034\032\120\109\112\077' ..
'\077\058\073\110\115\116\097\110\099\101\073\068\061\034\120\109' ..
'\112\046\105\105\100\058\051\054\056\052\066\066\066\067\055\055' ..
'\057\069\049\049\069\050\057\056\054\057\070\053\052\070\051\053' ..
'\065\049\054\051\048\056\034\032\120\109\112\058\067\114\101\097' ..
'\116\111\114\084\111\111\108\061\034\065\100\111\098\101\032\080' ..
'\104\111\116\111\115\104\111\112\032\067\083\053\032\077\097\099' ..
'\105\110\116\111\115\104\034\062\032\060\120\109\112\077\077\058' ..
'\068\101\114\105\118\101\100\070\114\111\109\032\115\116\082\101' ..
'\102\058\105\110\115\116\097\110\099\101\073\068\061\034\120\109' ..
'\112\046\105\105\100\058\055\056\048\050\068\067\055\048\056\055' ..
'\050\053\054\056\049\049\057\050\066\048\056\056\051\067\070\050' ..
'\056\065\068\067\049\069\034\032\115\116\082\101\102\058\100\111' ..
'\099\117\109\101\110\116\073\068\061\034\120\109\112\046\100\105' ..
'\100\058\070\055\055\070\049\049\055\052\048\055\050\048\054\056' ..
'\049\049\056\067\049\052\056\054\068\053\052\057\052\069\066\065' ..
'\055\056\034\047\062\032\060\047\114\100\102\058\068\101\115\099' ..
'\114\105\112\116\105\111\110\062\032\060\047\114\100\102\058\082' ..
'\068\070\062\032\060\047\120\058\120\109\112\109\101\116\097\062' ..
'\032\060\063\120\112\097\099\107\101\116\032\101\110\100\061\034' ..
'\114\034\063\062\034\132\044\033\000\004\054\168\073\068\065\084' ..
'\120\218\236\189\075\147\108\201\113\038\230\017\113\078\102\086' ..
'\213\125\245\003\232\110\000\236\006\241\006\009\014\031\067\138' ..
'\052\138\028\113\052\102\090\104\057\166\149\068\141\073\090\201' ..
'\076\043\237\180\156\063\160\181\022\179\213\102\076\102\050\027'

local pathStudio, pathImage = ...

if not pathStudio or not pathImage then
	print("Input the path to a Roblox Studio executable:")
	pathStudio = io.read()

	print("Input the path to an image:")
	pathImage = io.read()
end

local studio, err = io.open(pathStudio, 'r+b')
if not studio then
	print("cannot open studio file:", err)
	return
end

local image, err = io.open(pathImage, 'rb')
if not image then
	print("cannot open image file:", err)
	return
end

-- Scan executable for splash signature
local offset
local sizeStudio = studio:seek('end')
local chsize = #splashSig*2
local inc = #splashSig
local n = 0
while n < sizeStudio do
	studio:seek('set', n)
	local chunk = ''
	while #chunk < chsize do
		local ch = studio:read(chsize-#chunk)
		if not ch then
			ch = studio:read(chsize-#chunk)
			if not ch then break end
		end
		chunk = chunk .. ch
	end
	if #chunk ~= chsize then break end
	offset = chunk:find(splashSig, 1, true)
	if offset then
		offset = n + offset - 1
		break
	end

	n = n + inc
end

if not offset then
	print("could not locate splash image in executable")
	return
end

-- Scan for end of image to get the file size
studio:seek('set', offset)
local IEND = '\73\69\78\68\174\66\96\130'
local offend
local chsize = 2^11
local inc = 2^10
local n = 0
while n < sizeStudio do
	studio:seek('set', n)
	local chunk = studio:read(chsize)

	local _, e = chunk:find(IEND, 1, true)
	if e then
		offend = n + e - 1
		break
	end

	n = n + inc
end

local sizeImage = image:seek('end')
if offend-offset > sizeImage then
	print(string.format("file size of the image (%d bytes) is too large (must be no greater than %d bytes)", sizeImage, offend-offset))
	return
end

-- Create a backup of Studio file
local backup, err = io.open(pathStudio .. '.bak', 'wb')
if not backup then
	print("could not create studio backup:", err)
end
local chsize = 2^13
studio:seek('set')
while true do
	local chunk = studio:read(chsize)
	if not chunk then break end
	backup:write(chunk)
end
backup:flush()
backup:close()

-- Overwrite splash
local chsize = 2^13
image:seek('set')
studio:seek('set', offset)
while true do
	local chunk = image:read(chsize)
	if not chunk then break end
	studio:write(chunk)
end
studio:flush()
studio:close()
image:close()

I think your LUA script is broken. It might be because their new splash screen does not match the one your script is looking for. Try updating it.