codegen.py

from ctypes import c_int, create_string_buffer, CDLL, CFUNCTYPE
import os, ctypes

PROT_NONE = 0x0
PROT_READ = 0x1
PROT_WRITE = 0x2
PROT_EXEC = 0x4
MAP_PRIVATE = 0x02
MAP_ANONYMOUS = 0x20

sx = 48691458
icodes = [0x90, 0xB8, 0x00, 0x00,
          0x00, 0x00, 0xC3]
for i in range(0, 4):
    icodes[i + 2] = (sx >> (i * 8)) & 0xFF
hcodes = ''
for c in icodes:
    hcodes += chr(c)
p = create_string_buffer(hcodes)

if os.name == 'posix':
    libc = CDLL("libc.so.6")
    mmap = libc.mmap
    memmove = libc.memmove
    vp = mmap(None,
              len(icodes),
              PROT_READ | PROT_WRITE | PROT_EXEC,
              MAP_ANONYMOUS | MAP_PRIVATE,
              0,
              0)
    memmove(vp, p, len(icodes))
    p = vp
elif os.name == 'nt':
    crt = CDLL("msvcrt")
    malloc = crt.malloc
    memmove = crt.memmove
    vp = malloc(len(icodes))
    memmove(vp, p, len(icodes))
    p = vp
else:
    print 'Unknown OS type'
    exit(-1)

functype = CFUNCTYPE(c_int)
f = functype(p)

print "Call f()"
x = f()
print x