#!/usr/bin/env python2.7

import platform
import struct

if platform.system() == "Java":
  print "Jython %s" % platform.python_version()
else:
  print "Python %s" % platform.python_version()
print platform.version()

# First write the file
f = file("seek-test.out", "wb")
for x in range(256):
  f.write(chr(x))
f.close()

# Reopen it
f = file("seek-test.out", "rb+")

# Read forward from beginning
for x in range(256):
  assert f.tell() == x, "before read: pos should be %d but was %d" % (x, f.tell())
  c = struct.unpack("B", f.read(1))[0]
  assert f.tell() == x+1, "after read: pos should be %d but was %d" % (x+1, f.tell())
  assert c == x, "expected %d; got %d" % (x, c)

# Read backward from end
f.seek(-1, 2) # seek to end
for x in range(255, -1, -1):
  assert f.tell() == x, "before read: pos should be %d but was %d" % (x, f.tell())
  c = ord(f.read(1))
  assert c == x, "expected %d; got %d" % (x, c)
  assert f.tell() == x+1, "after read: pos should be %d but was %d" % (x+1, f.tell())
  if x > 0:
    f.seek(-2, 1)

print "No errors"