#!/usr/bin/env python2

#

# Utility to dump bytecode into a human readable form.

#

import os

import sys

import struct

import optparse

def decode_string(buf, off):

strlen, = struct.unpack('>L', buf[off:off+4])

off += 4

strdata = buf[off:off+strlen]

off += strlen

return off, strdata

def sanitize_string(val):

# Don't try to UTF-8 decode, just escape non-printable ASCII.

def f(c):

if ord(c) < 0x20 or ord(c) > 0x7e or c in '\'"':

return '\\x%02x' % ord(c)

else:

return c

return "'" + ''.join(map(f, val)) + "'"

def decode_sanitize_string(buf, off):

off, val = decode_string(buf, off)

return off, sanitize_string(val)

def dump_function(buf, off, ind):

count_inst, count_const, count_funcs = struct.unpack('>LLL', buf[off:off+12])

off += 12

print('%sInstructions: %d' % (ind, count_inst))

print('%sConstants: %d' % (ind, count_const))

print('%sInner functions: %d' % (ind, count_funcs))

# Line numbers present, assuming debugger support; otherwise 0.

nregs, nargs, start_line, end_line = struct.unpack('>HHLL', buf[off:off+12])

off += 12

print('%sNregs: %d' % (ind, nregs))

print('%sNargs: %d' % (ind, nargs))

print('%sStart line number: %d' % (ind, start_line))

print('%sEnd line number: %d' % (ind, end_line))

compfunc_flags, = struct.unpack('>L', buf[off:off+4])

off += 4

print('%sduk_hcompiledfunction flags: 0x%08x' % (ind, compfunc_flags))

for i in xrange(count_inst):

ins, = struct.unpack('>L', buf[off:off+4])

off += 4

print('%s %06d: %08lx' % (ind, i, ins))

print('%sConstants:' % ind)

for i in xrange(count_const):

const_type, = struct.unpack('B', buf[off:off+1])

off += 1

if const_type == 0x00:

off, strdata = decode_sanitize_string(buf, off)

print('%s %06d: %s' % (ind, i, strdata))

elif const_type == 0x01:

num, = struct.unpack('>d', buf[off:off+8])

off += 8

print('%s %06d: %f' % (ind, i, num))

else:

raise Exception('invalid constant type: %d' % const_type)

for i in xrange(count_funcs):

print('%sInner function %d:' % (ind, i))

off = dump_function(buf, off, ind + ' ')

val, = struct.unpack('>L', buf[off:off+4])

off += 4

print('%s.length: %d' % (ind, val))

off, val = decode_sanitize_string(buf, off)

print('%s.name: %s' % (ind, val))

off, val = decode_sanitize_string(buf, off)

print('%s.fileName: %s' % (ind, val))

off, val = decode_string(buf, off) # actually a buffer

print('%s._Pc2line: %s' % (ind, val.encode('hex')))

while True:

off, name = decode_string(buf, off)

if name == '':

break

name = sanitize_string(name)

val, = struct.unpack('>L', buf[off:off+4])

off += 4

print('%s_Varmap[%s] = %d' % (ind, name, val))

num_formals, = struct.unpack('>L', buf[off:off+4])

off += 4

if num_formals != 0xffffffff:

print('%s_Formals: %d formal arguments' % (ind, num_formals))

for idx in xrange(num_formals):

off, name = decode_string(buf, off)

name = sanitize_string(name)

print('%s_Formals[%d] = %s' % (ind, idx, name))

else:

print('%s_Formals: absent' % ind)

return off

def dump_bytecode(buf, off, ind):

sig, = struct.unpack('B', buf[off:off+1])

print('%sSignature byte: 0x%02x' % (ind, sig))

off += 1

if sig == 0xff:

raise Exception('pre-Duktape 2.2 0xFF signature byte (signature byte is 0xBF since Duktape 2.2)')

if sig != 0xbf:

raise Exception('invalid signature byte: %d' % sig)

off = dump_function(buf, off, ind + ' ')

return off

def main():

parser = optparse.OptionParser()

parser.add_option('--hex-decode', dest='hex_decode', default=False, action='store_true', help='Input file is ASCII hex encoded, decode before dump')

(opts, args) = parser.parse_args()

with open(args[0], 'rb') as f:

d = f.read()

if opts.hex_decode:

d = d.strip()

d = d.decode('hex')

dump_bytecode(d, 0, '')

if __name__ == '__main__':

main()