From 63175f36d04ebbc58094c478477871c1f001263f Mon Sep 17 00:00:00 2001
From: Jon Michael Aanes <jonjmaa@gmail.com>
Date: Wed, 16 Dec 2015 00:05:18 +0100
Subject: [PATCH] Initial commit. Holy hell this code is terrible.

---
 README.md   |   5 +
 internal.py | 265 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 270 insertions(+)
 create mode 100644 README.md
 create mode 100644 internal.py

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..da263a5
--- /dev/null
+++ b/README.md
@@ -0,0 +1,5 @@
+
+# Infernal Interpreter & Devious Stack Painter #################################
+
+A very simple interpreter and stack tracer for the AMD x86_64 ABI written in
+Python. Does not support all commands as of yet (or anytime).
diff --git a/internal.py b/internal.py
new file mode 100644
index 0000000..1b71141
--- /dev/null
+++ b/internal.py
@@ -0,0 +1,265 @@
+
+import re
+import sys
+
+REGISTERS=["%rip","%rbp","%rsp","","%rax","%rdi","%r8","%r9"]
+OPTIONS = """register_node/.style={rectangle, draw=black!30,
+			 fill=black!5, very thick, minimum size=0.5, minimum width=20mm},
+			 text_node/.style={}"""
+
+class Emulator:
+
+	def __init__ (self, source_text):
+		self.registers = {}
+		for reg_name in REGISTERS:
+			self.registers[reg_name] = 0
+		self.stack = [0,1,2,3,4,5,6,7]
+		self.code = []
+		self.codep = []
+		self.linesExec = []
+		self.labels = {}
+		self.changes = {}
+		self.status = {}
+		self.text = ""
+		self.x_coord = 0
+		self.last_sp = 0
+		self.max_stack_size = 0
+		index = 0
+		for line in iter(source_text.splitlines()):
+			index = self.processSourceLine(line, index)
+
+	def getReg (self, reg_name):
+		return self.registers[reg_name]
+
+	def setRegs (self, reg_dict):
+		for reg_name, reg_val in reg_dict.iteritems():
+			self.registers[reg_name] = reg_val
+
+	def getVal (self, valText):
+		if valText[0] == "$":
+			return int(valText[1:])
+		elif valText[0] == "%":
+			return self.getReg(valText)
+		else:
+			raise "NOT A VALUE! UGHGUIHGUE!"
+
+	def compareVal (self, valT1, valT2):
+		val1 = self.getVal(valT2)
+		val2 = self.getVal(valT1)
+		self.status = {"g":val1>val2}
+
+	def writeRegs (self, line_nr=None):
+		self.text += self.draw((self.x_coord+1)*2.5-0.5, line_nr)
+		self.text += "\n"
+		self.x_coord += 1
+
+	def changedRegisters (self, *args):
+		for reg, val in args:
+			self.changes[reg] = val
+
+	def iterate (self):
+		old_rip = self.registers['%rip']
+		self.last_sp = self.registers['%rsp']
+		#self.linesExec.append(old_rip)
+		if self.registers['%rip'] >= len(self.code):
+			return False
+		instruct = self.code[self.registers['%rip']]
+		opcode = instruct[0]
+		self.changes = {}
+		#print(opcode, instruct)
+		if opcode == "push" or opcode == "pushq":
+			self.registers['%rsp'] = self.registers['%rsp'] + 1
+			self.stack[self.registers['%rsp']] = self.getReg(instruct[1])
+			self.changedRegisters(('%rsp',"change"),("m"+str(self.registers['%rsp']),"insert"))
+			self.max_stack_size = max(self.registers['%rsp'], self.max_stack_size)
+		elif opcode == "popq":
+			self.registers[instruct[1]] = self.stack[self.registers['%rsp']]
+			self.registers['%rsp'] = self.registers['%rsp'] - 1
+			self.changedRegisters(('%rsp',"change"),("m"+str(self.registers['%rsp']+1),"remove"))
+		elif opcode == "movq" or opcode == "mov":
+			self.changedRegisters((instruct[2],"change"))
+			self.registers[instruct[2]] = self.getVal(instruct[1])
+		elif opcode == "cmpq":
+			self.compareVal(instruct[1],instruct[2])
+		elif opcode == "addq":
+			self.changedRegisters((instruct[2],"change"))
+			self.registers[instruct[2]] = self.getVal(instruct[2]) + self.getVal(instruct[1])
+		elif opcode == "subq":
+			self.changedRegisters((instruct[2],"change"))
+			self.registers[instruct[2]] = self.getVal(instruct[2]) - self.getVal(instruct[1])
+		elif opcode == "jg":
+			if self.status["g"]:
+				self.registers['%rip'] = self.labels[instruct[1]]
+		elif opcode == "jmp":
+			self.registers['%rip'] = self.labels[instruct[1]]
+
+		elif opcode == "call":
+			self.registers['%rsp'] = self.registers['%rsp'] + 1
+			self.stack[self.registers['%rsp']] = self.registers['%rip']+1
+			self.registers['%rip'] = self.labels[instruct[1]]
+			self.changedRegisters(('%rsp',"change"),("m"+str(self.registers['%rsp']),"insert"))
+			self.max_stack_size = max(self.registers['%rsp'], self.max_stack_size)
+		elif opcode == "leave":
+			self.registers["%rsp"] = self.registers["%rbp"]
+			self.registers["%rbp"] = self.stack[self.registers['%rsp']]
+			self.registers['%rsp'] = self.registers['%rsp'] - 1
+			self.changedRegisters(('%rbp',"change"))
+			self.changedRegisters(('%rsp',"change"),("m"+str(self.registers['%rsp']+1),"remove"))
+		elif opcode == "ret":
+			self.registers['%rip'] = self.stack[self.registers['%rsp']]
+			self.registers['%rsp'] = self.registers['%rsp'] - 1
+			self.changedRegisters(('%rsp',"change"),("m"+str(self.registers['%rsp']+1),"remove"))
+
+		if self.registers['%rip'] == old_rip:
+			self.registers['%rip'] += 1
+		else:
+			self.changedRegisters(('%rip',"change"))
+
+		self.writeRegs(old_rip)
+
+	def processSourceLine(self, line_text, index):
+		tokens = re.findall(r'[\w%:$#]+', line_text)
+		if len(tokens) <= 0:
+			return index
+		if tokens[0][-1] == ':':
+			self.labels[tokens[0][:-1]] = index
+			tokens = tokens[1:]
+		for i in range(len(tokens)):
+			if tokens[i][0] == "#":
+				tokens = tokens[:i]
+				break
+		self.code.append(tokens)
+		self.codep.append(line_text)
+		return index + 1
+
+	REG_STATUS_TO_COLOR = {"insert":"green","change":"yellow","remove":"red"}
+
+	def getRegColor (self, reg_name):
+		if reg_name in self.changes:
+			return self.REG_STATUS_TO_COLOR[self.changes[reg_name]]
+		else:
+			return "black"
+
+	def getLineSignature (self, line_nr):
+		return [ "\\"+token if token[0]=="$" or token[0]=="%" else token for token in self.code[line_nr] ]
+
+	def draw (self, x, line_nr=None):
+		x = str(x)
+		text = ""
+		pos = 0
+		for reg_name in REGISTERS:
+			reg_dect = "register_node, fill=" + self.getRegColor(reg_name)+"!10"
+			if reg_name != "":
+				text += "\t\\node["+reg_dect+"]("+reg_name[1:]+") at ("+x+", "+str(pos)+"){"+str(self.registers[reg_name])+"};\n"
+			pos -= 0.5
+
+		pos -= 1
+		base_sp = max(self.last_sp,self.registers['%rsp'])
+		if self.last_sp - 1 == self.registers['%rsp']:
+			pos += 0.5
+		for index in range(base_sp, -1,-1):
+			mem_name = "m"+str(index)
+			reg_dect = "register_node, fill=" + self.getRegColor(mem_name)+"!10"
+			text += "\t\\node["+reg_dect+"]("+mem_name+") at ("+x+", "+str(pos)+"){"+str(self.stack[index])+"};\n"
+			pos -= 0.5
+
+		if line_nr != None:
+			pos = 2
+			signature = self.getLineSignature(line_nr)
+			try:
+				for i in range(3):
+					text += "\t\\node[text_node]() at ("+str(float(x)-1.25)+", "+str(pos)+"){"+signature[i]+"};\n"
+					pos -= 0.5
+			except:
+				pass
+		#for line_nr in self.linesExec:
+		#	text += "\t\\node[text_node]() at ("+x+", "+str(pos)+"){"+self.codep[line_nr]+"};\n"
+		self.linesExec = []
+
+		return text
+
+	def drawNames (self, x, stack_size=8):
+		x = str(x)
+		text = ""
+		pos = 0
+		for reg_name in REGISTERS:
+			text += "\t\\node[text_node]("+reg_name[1:]+") at ("+x+", "+str(pos)+"){"+reg_name[1:]+"};\n"
+			pos -= 0.5
+
+		text += "\t\\node[text_node]() at ("+x+", "+str(pos-0.5)+"){TOS+1};\n"
+		text += "\t\\node[text_node]() at ("+x+", "+str(pos-1)+"){TOS};\n"
+		pos -= 1.5
+		for index in range(1,stack_size+1):
+			mem_name = "m"+str(index)
+			text += "\t\\node[text_node]() at ("+x+", "+str(pos)+"){TOS-"+str(index)+"};\n"
+			pos -= 0.5
+
+		return text
+
+fib_prog = """
+fib:    push %rbp       # push previous base pointer
+		movq %rsp,%rbp  # setup new base pointer
+if:     cmpq $1, %rdi  # if (a-1) > 0: goto long
+		jg long
+quick:  movq %rdi, %rax
+		jmp return
+long:   pushq %rdi      # Push a onto the stack
+		subq $1, %rdi
+		call fib        # Call fib(a-1)
+		pushq %rax      # Push fib(a-1) onto the stack
+		subq $1, %rdi
+		call fib        # Call fib(a-2)
+		popq %rdi        # pop fib(a-1) into rdi
+		addq %rdi, %rax  # rax = fib(a-1)+fib(a-2)
+		popq %rdi        # Garentee that a lies in rdi.
+return: leave           # Clean up (stack pointers?)
+		ret             # return m (rax)
+"""
+
+fib_iter_prog = """
+fib:    push %rbp       # push previous base pointer
+        movq %rsp,%rbp  # setup new base pointer
+
+if:     cmpq $1,   %rdi # if (a-1) > 0: goto loops
+        jg loops
+
+quick:  movq %rdi, %rax
+        jmp return
+
+loops:	movq %rdi, %r8   # i (r8) = a
+		movq $1,   %rdi	 # minus_one (rdi) = 1
+		movq $0,   %rax	 # minus_two (rax) = 0
+
+loopb:	movq %rdi, %9  # r = minus_one
+		addq %rax,  %rdi  # minus_one += minus_two
+		movq %9, %rax   # minus_two = r
+		subq $1,   %r8   # i--
+		cmpq $0,   %r8   # if a > 0
+		jg loopb
+
+return:	leave           # Clean up
+        ret             # return m (rax)
+"""
+
+if __name__ == "__main__":
+	try:
+		a = int(sys.argv[1])
+	except:
+		a = 2
+	new_em = Emulator(fib_iter_prog)
+	new_em.stack = ["junk...","calling eip"]
+	for i in range(100):
+		new_em.stack.append(0)
+	new_em.setRegs({'%rip':0,'%rbp':'old bp','%rsp':1,'%rdi':a})
+	print("Running for fib("+str(a)+")")
+	new_em.writeRegs()
+	while True:
+		if new_em.iterate() == False:
+			break
+	new_em.text += new_em.drawNames(0, new_em.max_stack_size)
+	print("fib("+str(a)+") = "+str(new_em.registers["%rax"]))
+	with open("tikz.tex","w") as f:
+		f.write("\\documentclass{standalone}\n\n\usepackage{tikz}\\begin{document}\n")
+		f.write("\\begin{tikzpicture}["+OPTIONS+"]\n")
+		f.write(new_em.text)
+		f.write("\\end{tikzpicture}\n\\end{document}")