from collections import abc
import array
import math
import operator
import unittest
import struct
import sys
from test import support
ISBIGENDIAN = sys.byteorder == "big"
integer_codes = 'b', 'B', 'h', 'H', 'i', 'I', 'l', 'L', 'q', 'Q', 'n', 'N'
byteorders = '', '@', '=', '<', '>', '!'
def iter_integer_formats(byteorders=byteorders):
for code in integer_codes:
for byteorder in byteorders:
if (byteorder not in ('', '@') and code in ('n', 'N')):
continue
yield code, byteorder
def string_reverse(s):
return s[::-1]
def bigendian_to_native(value):
if ISBIGENDIAN:
return value
else:
return string_reverse(value)
class StructTest(unittest.TestCase):
def test_isbigendian(self):
self.assertEqual((struct.pack('=i', 1)[0] == 0), ISBIGENDIAN)
def test_consistence(self):
self.assertRaises(struct.error, struct.calcsize, 'Z')
sz = struct.calcsize('i')
self.assertEqual(sz * 3, struct.calcsize('iii'))
fmt = 'cbxxxxxxhhhhiillffd?'
fmt3 = '3c3b18x12h6i6l6f3d3?'
sz = struct.calcsize(fmt)
sz3 = struct.calcsize(fmt3)
self.assertEqual(sz * 3, sz3)
self.assertRaises(struct.error, struct.pack, 'iii', 3)
self.assertRaises(struct.error, struct.pack, 'i', 3, 3, 3)
self.assertRaises((TypeError, struct.error), struct.pack, 'i', 'foo')
self.assertRaises((TypeError, struct.error), struct.pack, 'P', 'foo')
self.assertRaises(struct.error, struct.unpack, 'd', b'flap')
s = struct.pack('ii', 1, 2)
self.assertRaises(struct.error, struct.unpack, 'iii', s)
self.assertRaises(struct.error, struct.unpack, 'i', s)
def test_transitiveness(self):
c = b'a'
b = 1
h = 255
i = 65535
l = 65536
f = 3.1415
d = 3.1415
t = True
for prefix in ('', '@', '<', '>', '=', '!'):
for format in ('xcbhilfd?', 'xcBHILfd?'):
format = prefix + format
s = struct.pack(format, c, b, h, i, l, f, d, t)
cp, bp, hp, ip, lp, fp, dp, tp = struct.unpack(format, s)
self.assertEqual(cp, c)
self.assertEqual(bp, b)
self.assertEqual(hp, h)
self.assertEqual(ip, i)
self.assertEqual(lp, l)
self.assertEqual(int(100 * fp), int(100 * f))
self.assertEqual(int(100 * dp), int(100 * d))
self.assertEqual(tp, t)
def test_new_features(self):
# Test some of the new features in detail
# (format, argument, big-endian result, little-endian result, asymmetric)
tests = [
('c', b'a', b'a', b'a', 0),
('xc', b'a', b'\0a', b'\0a', 0),
('cx', b'a', b'a\0', b'a\0', 0),
('s', b'a', b'a', b'a', 0),
('0s', b'helloworld', b'', b'', 1),
('1s', b'helloworld', b'h', b'h', 1),
('9s', b'helloworld', b'helloworl', b'helloworl', 1),
('10s', b'helloworld', b'helloworld', b'helloworld', 0),
('11s', b'helloworld', b'helloworld\0', b'helloworld\0', 1),
('20s', b'helloworld', b'helloworld'+10*b'\0', b'helloworld'+10*b'\0', 1),
('b', 7, b'\7', b'\7', 0),
('b', -7, b'\371', b'\371', 0),
('B', 7, b'\7', b'\7', 0),
('B', 249, b'\371', b'\371', 0),
('h', 700, b'\002\274', b'\274\002', 0),
('h', -700, b'\375D', b'D\375', 0),
('H', 700, b'\002\274', b'\274\002', 0),
('H', 0x10000-700, b'\375D', b'D\375', 0),
('i', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('i', -70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('I', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('I', 0x100000000-70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('l', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('l', -70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('L', 70000000, b'\004,\035\200', b'\200\035,\004', 0),
('L', 0x100000000-70000000, b'\373\323\342\200', b'\200\342\323\373', 0),
('f', 2.0, b'@\000\000\000', b'\000\000\000@', 0),
('d', 2.0, b'@\000\000\000\000\000\000\000',
b'\000\000\000\000\000\000\000@', 0),
('f', -2.0, b'\300\000\000\000', b'\000\000\000\300', 0),
('d', -2.0, b'\300\000\000\000\000\000\000\000',
b'\000\000\000\000\000\000\000\300', 0),
('?', 0, b'\0', b'\0', 0),
('?', 3, b'\1', b'\1', 1),
('?', True, b'\1', b'\1', 0),
('?', [], b'\0', b'\0', 1),
('?', (1,), b'\1', b'\1', 1),
]
for fmt, arg, big, lil, asy in tests:
for (xfmt, exp) in [('>'+fmt, big), ('!'+fmt, big), ('<'+fmt, lil),
('='+fmt, ISBIGENDIAN and big or lil)]:
res = struct.pack(xfmt, arg)
self.assertEqual(res, exp)
self.assertEqual(struct.calcsize(xfmt), len(res))
rev = struct.unpack(xfmt, res)[0]
if rev != arg:
self.assertTrue(asy)
def test_calcsize(self):
expected_size = {
'b': 1, 'B': 1,
'h': 2, 'H': 2,
'i': 4, 'I': 4,
'l': 4, 'L': 4,
'q': 8, 'Q': 8,
}
# standard integer sizes
for code, byteorder in iter_integer_formats(('=', '<', '>', '!')):
format = byteorder+code
size = struct.calcsize(format)
self.assertEqual(size, expected_size[code])
# native integer sizes
native_pairs = 'bB', 'hH', 'iI', 'lL', 'nN', 'qQ'
for format_pair in native_pairs:
for byteorder in '', '@':
signed_size = struct.calcsize(byteorder + format_pair[0])
unsigned_size = struct.calcsize(byteorder + format_pair[1])
self.assertEqual(signed_size, unsigned_size)
# bounds for native integer sizes
self.assertEqual(struct.calcsize('b'), 1)
self.assertLessEqual(2, struct.calcsize('h'))
self.assertLessEqual(4, struct.calcsize('l'))
self.assertLessEqual(struct.calcsize('h'), struct.calcsize('i'))
self.assertLessEqual(struct.calcsize('i'), struct.calcsize('l'))
self.assertLessEqual(8, struct.calcsize('q'))
self.assertLessEqual(struct.calcsize('l'), struct.calcsize('q'))
self.assertGreaterEqual(struct.calcsize('n'), struct.calcsize('i'))
self.assertGreaterEqual(struct.calcsize('n'), struct.calcsize('P'))
def test_integers(self):
# Integer tests (bBhHiIlLqQnN).
import binascii
class IntTester(unittest.TestCase):
def __init__(self, format):
super(IntTester, self).__init__(methodName='test_one')
self.format = format
self.code = format[-1]
self.byteorder = format[:-1]
if not self.byteorder in byteorders:
raise ValueError("unrecognized packing byteorder: %s" %
self.byteorder)
self.bytesize = struct.calcsize(format)
self.bitsize = self.bytesize * 8
if self.code in tuple('bhilqn'):
self.signed = True
self.min_value = -(2**(self.bitsize-1))
self.max_value = 2**(self.bitsize-1) - 1
elif self.code in tuple('BHILQN'):
self.signed = False
self.min_value = 0
self.max_value = 2**self.bitsize - 1
else:
raise ValueError("unrecognized format code: %s" %
self.code)
def test_one(self, x, pack=struct.pack,
unpack=struct.unpack,
unhexlify=binascii.unhexlify):
format = self.format
if self.min_value <= x <= self.max_value:
expected = x
if self.signed and x < 0:
expected += 1 << self.bitsize
self.assertGreaterEqual(expected, 0)
expected = '%x' % expected
if len(expected) & 1:
expected = "0" + expected
expected = expected.encode('ascii')
expected = unhexlify(expected)
expected = (b"\x00" * (self.bytesize - len(expected)) +
expected)
if (self.byteorder == '<' or
self.byteorder in ('', '@', '=') and not ISBIGENDIAN):
expected = string_reverse(expected)
self.assertEqual(len(expected), self.bytesize)
# Pack work?
got = pack(format, x)
self.assertEqual(got, expected)
# Unpack work?
retrieved = unpack(format, got)[0]
self.assertEqual(x, retrieved)
# Adding any byte should cause a "too big" error.
self.assertRaises((struct.error, TypeError), unpack, format,
b'\x01' + got)
else:
# x is out of range -- verify pack realizes that.
self.assertRaises((OverflowError, ValueError, struct.error),
pack, format, x)
def run(self):
from random import randrange
# Create all interesting powers of 2.
values = []
for exp in range(self.bitsize + 3):
values.append(1 << exp)
# Add some random values.
for i in range(self.bitsize):
val = 0
for j in range(self.bytesize):
val = (val << 8) | randrange(256)
values.append(val)
# Values absorbed from other tests
values.extend([300, 700000, sys.maxsize*4])
# Try all those, and their negations, and +-1 from
# them. Note that this tests all power-of-2
# boundaries in range, and a few out of range, plus
# +-(2**n +- 1).
for base in values:
for val in -base, base:
for incr in -1, 0, 1:
x = val + incr
self.test_one(x)
# Some error cases.
class NotAnInt:
def __int__(self):
return 42
# Objects with an '__index__' method should be allowed
# to pack as integers. That is assuming the implemented
# '__index__' method returns an 'int'.
class Indexable(object):
def __init__(self, value):
self._value = value
def __index__(self):
return self._value
# If the '__index__' method raises a type error, then
# '__int__' should be used with a deprecation warning.
class BadIndex(object):
def __index__(self):
raise TypeError
def __int__(self):
return 42
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
"a string")
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
randrange)
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
3+42j)
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
NotAnInt())
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
BadIndex())
# Check for legitimate values from '__index__'.
for obj in (Indexable(0), Indexable(10), Indexable(17),
Indexable(42), Indexable(100), Indexable(127)):
try:
struct.pack(format, obj)
except:
self.fail("integer code pack failed on object "
"with '__index__' method")
# Check for bogus values from '__index__'.
for obj in (Indexable(b'a'), Indexable('b'), Indexable(None),
Indexable({'a': 1}), Indexable([1, 2, 3])):
self.assertRaises((TypeError, struct.error),
struct.pack, self.format,
obj)
for code, byteorder in iter_integer_formats():
format = byteorder+code
t = IntTester(format)
t.run()
def test_nN_code(self):
# n and N don't exist in standard sizes
def assertStructError(func, *args, **kwargs):
with self.assertRaises(struct.error) as cm:
func(*args, **kwargs)
self.assertIn("bad char in struct format", str(cm.exception))
for code in 'nN':
for byteorder in ('=', '<', '>', '!'):
format = byteorder+code
assertStructError(struct.calcsize, format)
assertStructError(struct.pack, format, 0)
assertStructError(struct.unpack, format, b"")
def test_p_code(self):
# Test p ("Pascal string") code.
for code, input, expected, expectedback in [
('p', b'abc', b'\x00', b''),
('1p', b'abc', b'\x00', b''),
('2p', b'abc', b'\x01a', b'a'),
('3p', b'abc', b'\x02ab', b'ab'),
('4p', b'abc', b'\x03abc', b'abc'),
('5p', b'abc', b'\x03abc\x00', b'abc'),
('6p', b'abc', b'\x03abc\x00\x00', b'abc'),
('1000p', b'x'*1000, b'\xff' + b'x'*999, b'x'*255)]:
got = struct.pack(code, input)
self.assertEqual(got, expected)
(got,) = struct.unpack(code, got)
self.assertEqual(got, expectedback)
def test_705836(self):
# SF bug 705836. "<f" and ">f" had a severe rounding bug, where a carry
# from the low-order discarded bits could propagate into the exponent
# field, causing the result to be wrong by a factor of 2.
for base in range(1, 33):
# smaller <- largest representable float less than base.
delta = 0.5
while base - delta / 2.0 != base:
delta /= 2.0
smaller = base - delta
# Packing this rounds away a solid string of trailing 1 bits.
packed = struct.pack("<f", smaller)
unpacked = struct.unpack("<f", packed)[0]
# This failed at base = 2, 4, and 32, with unpacked = 1, 2, and
# 16, respectively.
self.assertEqual(base, unpacked)
bigpacked = struct.pack(">f", smaller)
self.assertEqual(bigpacked, string_reverse(packed))
unpacked = struct.unpack(">f", bigpacked)[0]
self.assertEqual(base, unpacked)
# Largest finite IEEE single.
big = (1 << 24) - 1
big = math.ldexp(big, 127 - 23)
packed = struct.pack(">f", big)
unpacked = struct.unpack(">f", packed)[0]
self.assertEqual(big, unpacked)
# The same, but tack on a 1 bit so it rounds up to infinity.
big = (1 << 25) - 1
big = math.ldexp(big, 127 - 24)
self.assertRaises(OverflowError, struct.pack, ">f", big)
def test_1530559(self):
for code, byteorder in iter_integer_formats():
format = byteorder + code
self.assertRaises(struct.error, struct.pack, format, 1.0)
self.assertRaises(struct.error, struct.pack, format, 1.5)
self.assertRaises(struct.error, struct.pack, 'P', 1.0)
self.assertRaises(struct.error, struct.pack, 'P', 1.5)
def test_unpack_from(self):
test_string = b'abcd01234'
fmt = '4s'
s = struct.Struct(fmt)
for cls in (bytes, bytearray):
data = cls(test_string)
self.assertEqual(s.unpack_from(data), (b'abcd',))
self.assertEqual(s.unpack_from(data, 2), (b'cd01',))
self.assertEqual(s.unpack_from(data, 4), (b'0123',))
for i in range(6):
self.assertEqual(s.unpack_from(data, i), (data[i:i+4],))
for i in range(6, len(test_string) + 1):
self.assertRaises(struct.error, s.unpack_from, data, i)
for cls in (bytes, bytearray):
data = cls(test_string)
self.assertEqual(struct.unpack_from(fmt, data), (b'abcd',))
self.assertEqual(struct.unpack_from(fmt, data, 2), (b'cd01',))
self.assertEqual(struct.unpack_from(fmt, data, 4), (b'0123',))
for i in range(6):
self.assertEqual(struct.unpack_from(fmt, data, i), (data[i:i+4],))
for i in range(6, len(test_string) + 1):
self.assertRaises(struct.error, struct.unpack_from, fmt, data, i)
# keyword arguments
self.assertEqual(s.unpack_from(buffer=test_string, offset=2),
(b'cd01',))
def test_pack_into(self):
test_string = b'Reykjavik rocks, eow!'
writable_buf = array.array('b', b' '*100)
fmt = '21s'
s = struct.Struct(fmt)
# Test without offset
s.pack_into(writable_buf, 0, test_string)
from_buf = writable_buf.tobytes()[:len(test_string)]
self.assertEqual(from_buf, test_string)
# Test with offset.
s.pack_into(writable_buf, 10, test_string)
from_buf = writable_buf.tobytes()[:len(test_string)+10]
self.assertEqual(from_buf, test_string[:10] + test_string)
# Go beyond boundaries.
small_buf = array.array('b', b' '*10)
self.assertRaises((ValueError, struct.error), s.pack_into, small_buf, 0,
test_string)
self.assertRaises((ValueError, struct.error), s.pack_into, small_buf, 2,
test_string)
# Test bogus offset (issue 3694)
sb = small_buf
self.assertRaises((TypeError, struct.error), struct.pack_into, b'', sb,
None)
def test_pack_into_fn(self):
test_string = b'Reykjavik rocks, eow!'
writable_buf = array.array('b', b' '*100)
fmt = '21s'
pack_into = lambda *args: struct.pack_into(fmt, *args)
# Test without offset.
pack_into(writable_buf, 0, test_string)
from_buf = writable_buf.tobytes()[:len(test_string)]
self.assertEqual(from_buf, test_string)
# Test with offset.
pack_into(writable_buf, 10, test_string)
from_buf = writable_buf.tobytes()[:len(test_string)+10]
self.assertEqual(from_buf, test_string[:10] + test_string)
# Go beyond boundaries.
small_buf = array.array('b', b' '*10)
self.assertRaises((ValueError, struct.error), pack_into, small_buf, 0,
test_string)
self.assertRaises((ValueError, struct.error), pack_into, small_buf, 2,
test_string)
def test_unpack_with_buffer(self):
# SF bug 1563759: struct.unpack doesn't support buffer protocol objects
data1 = array.array('B', b'\x12\x34\x56\x78')
data2 = memoryview(b'\x12\x34\x56\x78') # XXX b'......XXXX......', 6, 4
for data in [data1, data2]:
value, = struct.unpack('>I', data)
self.assertEqual(value, 0x12345678)
def test_bool(self):
class ExplodingBool(object):
def __bool__(self):
raise OSError
for prefix in tuple("<>!=")+('',):
false = (), [], [], '', 0
true = [1], 'test', 5, -1, 0xffffffff+1, 0xffffffff/2
falseFormat = prefix + '?' * len(false)
packedFalse = struct.pack(falseFormat, *false)
unpackedFalse = struct.unpack(falseFormat, packedFalse)
trueFormat = prefix + '?' * len(true)
packedTrue = struct.pack(trueFormat, *true)
unpackedTrue = struct.unpack(trueFormat, packedTrue)
self.assertEqual(len(true), len(unpackedTrue))
self.assertEqual(len(false), len(unpackedFalse))
for t in unpackedFalse:
self.assertFalse(t)
for t in unpackedTrue:
self.assertTrue(t)
packed = struct.pack(prefix+'?', 1)
self.assertEqual(len(packed), struct.calcsize(prefix+'?'))
if len(packed) != 1:
self.assertFalse(prefix, msg='encoded bool is not one byte: %r'
%packed)
try:
struct.pack(prefix + '?', ExplodingBool())
except OSError:
pass
else:
self.fail("Expected OSError: struct.pack(%r, "
"ExplodingBool())" % (prefix + '?'))
for c in [b'\x01', b'\x7f', b'\xff', b'\x0f', b'\xf0']:
self.assertTrue(struct.unpack('>?', c)[0])
def test_count_overflow(self):
hugecount = '{}b'.format(sys.maxsize+1)
self.assertRaises(struct.error, struct.calcsize, hugecount)
hugecount2 = '{}b{}H'.format(sys.maxsize//2, sys.maxsize//2)
self.assertRaises(struct.error, struct.calcsize, hugecount2)
def test_trailing_counter(self):
store = array.array('b', b' '*100)
# format lists containing only count spec should result in an error
self.assertRaises(struct.error, struct.pack, '12345')
self.assertRaises(struct.error, struct.unpack, '12345', b'')
self.assertRaises(struct.error, struct.pack_into, '12345', store, 0)
self.assertRaises(struct.error, struct.unpack_from, '12345', store, 0)
# Format lists with trailing count spec should result in an error
self.assertRaises(struct.error, struct.pack, 'c12345', 'x')
self.assertRaises(struct.error, struct.unpack, 'c12345', b'x')
self.assertRaises(struct.error, struct.pack_into, 'c12345', store, 0,
'x')
self.assertRaises(struct.error, struct.unpack_from, 'c12345', store,
0)
# Mixed format tests
self.assertRaises(struct.error, struct.pack, '14s42', 'spam and eggs')
self.assertRaises(struct.error, struct.unpack, '14s42',
b'spam and eggs')
self.assertRaises(struct.error, struct.pack_into, '14s42', store, 0,
'spam and eggs')
self.assertRaises(struct.error, struct.unpack_from, '14s42', store, 0)
def test_Struct_reinitialization(self):
# Issue 9422: there was a memory leak when reinitializing a
# Struct instance. This test can be used to detect the leak
# when running with regrtest -L.
s = struct.Struct('i')
s.__init__('ii')
def check_sizeof(self, format_str, number_of_codes):
# The size of 'PyStructObject'
totalsize = support.calcobjsize('2n3P')
# The size taken up by the 'formatcode' dynamic array
totalsize += struct.calcsize('P3n0P') * (number_of_codes + 1)
support.check_sizeof(self, struct.Struct(format_str), totalsize)
@support.cpython_only
def test__sizeof__(self):
for code in integer_codes:
self.check_sizeof(code, 1)
self.check_sizeof('BHILfdspP', 9)
self.check_sizeof('B' * 1234, 1234)
self.check_sizeof('fd', 2)
self.check_sizeof('xxxxxxxxxxxxxx', 0)
self.check_sizeof('100H', 1)
self.check_sizeof('187s', 1)
self.check_sizeof('20p', 1)
self.check_sizeof('0s', 1)
self.check_sizeof('0c', 0)
def test_boundary_error_message(self):
regex1 = (
r'pack_into requires a buffer of at least 6 '
r'bytes for packing 1 bytes at offset 5 '
r'\(actual buffer size is 1\)'
)
with self.assertRaisesRegex(struct.error, regex1):
struct.pack_into('b', bytearray(1), 5, 1)
regex2 = (
r'unpack_from requires a buffer of at least 6 '
r'bytes for unpacking 1 bytes at offset 5 '
r'\(actual buffer size is 1\)'
)
with self.assertRaisesRegex(struct.error, regex2):
struct.unpack_from('b', bytearray(1), 5)
def test_boundary_error_message_with_negative_offset(self):
byte_list = bytearray(10)
with self.assertRaisesRegex(
struct.error,
r'no space to pack 4 bytes at offset -2'):
struct.pack_into('<I', byte_list, -2, 123)
with self.assertRaisesRegex(
struct.error,
'offset -11 out of range for 10-byte buffer'):
struct.pack_into('<B', byte_list, -11, 123)
with self.assertRaisesRegex(
struct.error,
r'not enough data to unpack 4 bytes at offset -2'):
struct.unpack_from('<I', byte_list, -2)
with self.assertRaisesRegex(
struct.error,
"offset -11 out of range for 10-byte buffer"):
struct.unpack_from('<B', byte_list, -11)
def test_boundary_error_message_with_large_offset(self):
# Test overflows cause by large offset and value size (issue 30245)
regex1 = (
r'pack_into requires a buffer of at least ' + str(sys.maxsize + 4) +
r' bytes for packing 4 bytes at offset ' + str(sys.maxsize) +
r' \(actual buffer size is 10\)'
)
with self.assertRaisesRegex(struct.error, regex1):
struct.pack_into('<I', bytearray(10), sys.maxsize, 1)
regex2 = (
r'unpack_from requires a buffer of at least ' + str(sys.maxsize + 4) +
r' bytes for unpacking 4 bytes at offset ' + str(sys.maxsize) +
r' \(actual buffer size is 10\)'
)
with self.assertRaisesRegex(struct.error, regex2):
struct.unpack_from('<I', bytearray(10), sys.maxsize)
def test_issue29802(self):
# When the second argument of struct.unpack() was of wrong type
# the Struct object was decrefed twice and the reference to
# deallocated object was left in a cache.
with self.assertRaises(TypeError):
struct.unpack('b', 0)
# Shouldn't crash.
self.assertEqual(struct.unpack('b', b'a'), (b'a'[0],))
def test_format_attr(self):
s = struct.Struct('=i2H')
self.assertEqual(s.format, '=i2H')
# use a bytes string
s2 = struct.Struct(s.format.encode())
self.assertEqual(s2.format, s.format)
def test_issue35714(self):
# Embedded null characters should not be allowed in format strings.
for s in '\0', '2\0i', b'\0':
with self.assertRaisesRegex(struct.error,
'embedded null character'):
struct.calcsize(s)
class UnpackIteratorTest(unittest.TestCase):
"""
Tests for iterative unpacking (struct.Struct.iter_unpack).
"""
def test_construct(self):
def _check_iterator(it):
self.assertIsInstance(it, abc.Iterator)
self.assertIsInstance(it, abc.Iterable)
s = struct.Struct('>ibcp')
it = s.iter_unpack(b"")
_check_iterator(it)
it = s.iter_unpack(b"1234567")
_check_iterator(it)
# Wrong bytes length
with self.assertRaises(struct.error):
s.iter_unpack(b"123456")
with self.assertRaises(struct.error):
s.iter_unpack(b"12345678")
# Zero-length struct
s = struct.Struct('>')
with self.assertRaises(struct.error):
s.iter_unpack(b"")
with self.assertRaises(struct.error):
s.iter_unpack(b"12")
def test_iterate(self):
s = struct.Struct('>IB')
b = bytes(range(1, 16))
it = s.iter_unpack(b)
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertEqual(next(it), (0x0b0c0d0e, 15))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_arbitrary_buffer(self):
s = struct.Struct('>IB')
b = bytes(range(1, 11))
it = s.iter_unpack(memoryview(b))
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_length_hint(self):
lh = operator.length_hint
s = struct.Struct('>IB')
b = bytes(range(1, 16))
it = s.iter_unpack(b)
self.assertEqual(lh(it), 3)
next(it)
self.assertEqual(lh(it), 2)
next(it)
self.assertEqual(lh(it), 1)
next(it)
self.assertEqual(lh(it), 0)
self.assertRaises(StopIteration, next, it)
self.assertEqual(lh(it), 0)
def test_module_func(self):
# Sanity check for the global struct.iter_unpack()
it = struct.iter_unpack('>IB', bytes(range(1, 11)))
self.assertEqual(next(it), (0x01020304, 5))
self.assertEqual(next(it), (0x06070809, 10))
self.assertRaises(StopIteration, next, it)
self.assertRaises(StopIteration, next, it)
def test_half_float(self):
# Little-endian examples from:
# http://en.wikipedia.org/wiki/Half_precision_floating-point_format
format_bits_float__cleanRoundtrip_list = [
(b'\x00\x3c', 1.0),
(b'\x00\xc0', -2.0),
(b'\xff\x7b', 65504.0), # (max half precision)
(b'\x00\x04', 2**-14), # ~= 6.10352 * 10**-5 (min pos normal)
(b'\x01\x00', 2**-24), # ~= 5.96046 * 10**-8 (min pos subnormal)
(b'\x00\x00', 0.0),
(b'\x00\x80', -0.0),
(b'\x00\x7c', float('+inf')),
(b'\x00\xfc', float('-inf')),
(b'\x55\x35', 0.333251953125), # ~= 1/3
]
for le_bits, f in format_bits_float__cleanRoundtrip_list:
be_bits = le_bits[::-1]
self.assertEqual(f, struct.unpack('<e', le_bits)[0])
self.assertEqual(le_bits, struct.pack('<e', f))
self.assertEqual(f, struct.unpack('>e', be_bits)[0])
self.assertEqual(be_bits, struct.pack('>e', f))
if sys.byteorder == 'little':
self.assertEqual(f, struct.unpack('e', le_bits)[0])
self.assertEqual(le_bits, struct.pack('e', f))
else:
self.assertEqual(f, struct.unpack('e', be_bits)[0])
self.assertEqual(be_bits, struct.pack('e', f))
# Check for NaN handling:
format_bits__nan_list = [
('<e', b'\x01\xfc'),
('<e', b'\x00\xfe'),
('<e', b'\xff\xff'),
('<e', b'\x01\x7c'),
('<e', b'\x00\x7e'),
('<e', b'\xff\x7f'),
]
for formatcode, bits in format_bits__nan_list:
self.assertTrue(math.isnan(struct.unpack('<e', bits)[0]))
self.assertTrue(math.isnan(struct.unpack('>e', bits[::-1])[0]))
# Check that packing produces a bit pattern representing a quiet NaN:
# all exponent bits and the msb of the fraction should all be 1.
packed = struct.pack('<e', math.nan)
self.assertEqual(packed[1] & 0x7e, 0x7e)
packed = struct.pack('<e', -math.nan)
self.assertEqual(packed[1] & 0x7e, 0x7e)
# Checks for round-to-even behavior
format_bits_float__rounding_list = [
('>e', b'\x00\x01', 2.0**-25 + 2.0**-35), # Rounds to minimum subnormal
('>e', b'\x00\x00', 2.0**-25), # Underflows to zero (nearest even mode)
('>e', b'\x00\x00', 2.0**-26), # Underflows to zero
('>e', b'\x03\xff', 2.0**-14 - 2.0**-24), # Largest subnormal.
('>e', b'\x03\xff', 2.0**-14 - 2.0**-25 - 2.0**-65),
('>e', b'\x04\x00', 2.0**-14 - 2.0**-25),
('>e', b'\x04\x00', 2.0**-14), # Smallest normal.
('>e', b'\x3c\x01', 1.0+2.0**-11 + 2.0**-16), # rounds to 1.0+2**(-10)
('>e', b'\x3c\x00', 1.0+2.0**-11), # rounds to 1.0 (nearest even mode)
('>e', b'\x3c\x00', 1.0+2.0**-12), # rounds to 1.0
('>e', b'\x7b\xff', 65504), # largest normal
('>e', b'\x7b\xff', 65519), # rounds to 65504
('>e', b'\x80\x01', -2.0**-25 - 2.0**-35), # Rounds to minimum subnormal
('>e', b'\x80\x00', -2.0**-25), # Underflows to zero (nearest even mode)
('>e', b'\x80\x00', -2.0**-26), # Underflows to zero
('>e', b'\xbc\x01', -1.0-2.0**-11 - 2.0**-16), # rounds to 1.0+2**(-10)
('>e', b'\xbc\x00', -1.0-2.0**-11), # rounds to 1.0 (nearest even mode)
('>e', b'\xbc\x00', -1.0-2.0**-12), # rounds to 1.0
('>e', b'\xfb\xff', -65519), # rounds to 65504
]
for formatcode, bits, f in format_bits_float__rounding_list:
self.assertEqual(bits, struct.pack(formatcode, f))
# This overflows, and so raises an error
format_bits_float__roundingError_list = [
# Values that round to infinity.
('>e', 65520.0),
('>e', 65536.0),
('>e', 1e300),
('>e', -65520.0),
('>e', -65536.0),
('>e', -1e300),
('<e', 65520.0),
('<e', 65536.0),
('<e', 1e300),
('<e', -65520.0),
('<e', -65536.0),
('<e', -1e300),
]
for formatcode, f in format_bits_float__roundingError_list:
self.assertRaises(OverflowError, struct.pack, formatcode, f)
# Double rounding
format_bits_float__doubleRoundingError_list = [
('>e', b'\x67\xff', 0x1ffdffffff * 2**-26), # should be 2047, if double-rounded 64>32>16, becomes 2048
]
for formatcode, bits, f in format_bits_float__doubleRoundingError_list:
self.assertEqual(bits, struct.pack(formatcode, f))
if __name__ == '__main__':
unittest.main()
