1#!/usr/bin/env ruby
2require 'unicorn_engine'
3require 'unicorn_engine/x86_const'
4require 'weakref'
5
6include UnicornEngine
7
8X86_CODE32 = "\x41" # INC ecx; DEC edx
9
10# memory address where emulation starts
11ADDRESS = 0x1000000
12
13# callback for tracing instructions
14hook_code = Proc.new do |uc, address, size, user_data|
15    puts("proc was run")
16end
17
18hook_code_weak = WeakRef.new hook_code
19
20begin
21    # Initialize emulator in X86-32bit mode
22    mu = Uc.new UC_ARCH_X86, UC_MODE_32
23    # map 2MB memory for this emulation
24    mu.mem_map(ADDRESS, 2 * 1024 * 1024)
25
26    # write machine code to be emulated to memory
27    mu.mem_write(ADDRESS, X86_CODE32)
28
29    # initialize machine registers
30    mu.reg_write(UC_X86_REG_ECX, 0x1234)
31    mu.reg_write(UC_X86_REG_EDX, 0x7890)
32
33    # tracing all instructions with customized callback
34    mu.hook_add(UC_HOOK_CODE, hook_code)
35
36    hook_code = nil # erase reference to proc
37
38    GC.start() # force garbage collection to test if proc is garbage collected
39
40    # emulate machine code in infinite time
41    mu.emu_start(ADDRESS, ADDRESS + X86_CODE32.bytesize)
42
43    mu = nil # erase reference to Uc because apparently it doesn't go out of scope after this?
44rescue UcError => e
45    puts("ERROR: %s" % e)
46    exit 1
47rescue NoMethodError => e
48    puts("proc was garbage collected and we tried to invoke `call` on something strange")
49    exit 1
50end
51
52GC.start()
53
54if hook_code_weak.weakref_alive?() then
55  puts("proc was not garbage collected")
56  exit 1
57end
58
59puts "test passed"
60exit 0
61