set chip-epoch and security-domain in device tree by replacing two un…

…used variables, support reading device trees outside an im4p

modifydevicetree.py

@@ -18,6 +18,9 @@ def writenode(nodebytes, nodeoffset, nodedepth):
		ptr += writenode(nodebytes, nodeoffset + ptr, nodedepth + 1)
	return ptr

def padStringNull(instr, lenstr=32):
	return instr.encode("ascii") + b"\x00"*(lenstr - len(instr))

def writeproperty(nodebytes, nodeoffset, nodedepth):
	kPropNameLength = 32
	propname = nodebytes[nodeoffset:nodeoffset + kPropNameLength].rstrip(b"\x00").decode("utf-8")
@@ -32,6 +35,14 @@ def writeproperty(nodebytes, nodeoffset, nodedepth):
	if propname == "random-seed":
		print("setting random seed")
		w32(nodebytes, nodeoffset + ptr, 0xdeadf00d)
	if propname == "dram-vendor-id":
		print("Removing dram-vendor-id")
		nodebytes[nodeoffset:nodeoffset + kPropNameLength] = padStringNull("chip-epoch")
		nodebytes[nodeoffset + ptr:nodeoffset + ptr + proplen] = b"\x00" * proplen
	if propname == "display-corner-radius":
		print("Removing display-corner-radius")
		nodebytes[nodeoffset:nodeoffset + kPropNameLength] = padStringNull("security-domain")
		nodebytes[nodeoffset + ptr:nodeoffset + ptr + proplen] = b"\x00" * proplen
	ptr += proplen
	ptr = (ptr + 0x3) & ~0x3 #round up to nearest 4
	return ptr

readdevicetree.py

@@ -50,7 +50,7 @@ def writeproperty(nodebytes, nodeoffset, nodedepth):
def printone(filename):
	with open(filename, "rb") as infile:
		indata = infile.read()
	devicetreebytes = devicetreefromim4p(indata)
	devicetreebytes = devicetreefromim4p(indata) if indata[0x7:0x7+4] == b"IM4P" else indata
	writenode(devicetreebytes, 0, 0)

if __name__ == "__main__":