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cpython/Lib/test/test_struct.py

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from test.test_support import TestFailed, verbose, verify, vereq
import test.test_support
import struct
import array
import warnings
import sys
ISBIGENDIAN = sys.byteorder == "big"
del sys
verify((struct.pack('=i', 1)[0] == 0) == ISBIGENDIAN,
"bigendian determination appears wrong")
try:
import _struct
except ImportError:
PY_STRUCT_RANGE_CHECKING = 0
PY_STRUCT_OVERFLOW_MASKING = 1
PY_STRUCT_FLOAT_COERCE = 2
else:
PY_STRUCT_RANGE_CHECKING = getattr(_struct, '_PY_STRUCT_RANGE_CHECKING', 0)
PY_STRUCT_OVERFLOW_MASKING = getattr(_struct, '_PY_STRUCT_OVERFLOW_MASKING', 0)
PY_STRUCT_FLOAT_COERCE = getattr(_struct, '_PY_STRUCT_FLOAT_COERCE', 0)
def string_reverse(s):
return s[::-1]
def bigendian_to_native(value):
if ISBIGENDIAN:
return value
else:
return string_reverse(value)
def simple_err(func, *args):
try:
func(*args)
except struct.error:
pass
else:
raise TestFailed("%s%s did not raise struct.error" % (
func.__name__, args))
def any_err(func, *args):
try:
func(*args)
except (struct.error, TypeError):
pass
else:
raise TestFailed("%s%s did not raise error" % (
func.__name__, args))
def with_warning_restore(func):
def _with_warning_restore(*args, **kw):
with test.test_support.catch_warning():
# Grrr, we need this function to warn every time. Without removing
# the warningregistry, running test_tarfile then test_struct would fail
# on 64-bit platforms.
globals = func.__globals__
if '__warningregistry__' in globals:
del globals['__warningregistry__']
warnings.filterwarnings("error", r"""^struct.*""", DeprecationWarning)
warnings.filterwarnings("error", r""".*format requires.*""",
DeprecationWarning)
return func(*args, **kw)
return _with_warning_restore
def deprecated_err(func, *args):
try:
func(*args)
except (struct.error, TypeError):
pass
except DeprecationWarning:
if not PY_STRUCT_OVERFLOW_MASKING:
raise TestFailed("%s%s expected to raise struct.error" % (
func.__name__, args))
else:
raise TestFailed("%s%s did not raise error" % (
func.__name__, args))
deprecated_err = with_warning_restore(deprecated_err)
simple_err(struct.calcsize, 'Z')
sz = struct.calcsize('i')
if sz * 3 != struct.calcsize('iii'):
raise TestFailed('inconsistent sizes')
fmt = 'cbxxxxxxhhhhiillffd?'
fmt3 = '3c3b18x12h6i6l6f3d3?'
sz = struct.calcsize(fmt)
sz3 = struct.calcsize(fmt3)
if sz * 3 != sz3:
raise TestFailed('inconsistent sizes (3*%r -> 3*%d = %d, %r -> %d)' % (
fmt, sz, 3*sz, fmt3, sz3))
simple_err(struct.pack, 'iii', 3)
simple_err(struct.pack, 'i', 3, 3, 3)
simple_err(struct.pack, 'i', 'foo')
simple_err(struct.pack, 'P', 'foo')
simple_err(struct.unpack, 'd', b'flap')
s = struct.pack('ii', 1, 2)
simple_err(struct.unpack, 'iii', s)
simple_err(struct.unpack, 'i', s)
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
if verbose:
print("trying:", 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)
if (cp != c or bp != b or hp != h or ip != i or lp != l or
int(100 * fp) != int(100 * f) or int(100 * dp) != int(100 * d) or
tp != t):
# ^^^ calculate only to two decimal places
raise TestFailed("unpack/pack not transitive (%s, %s)" % (
str(format), str((cp, bp, hp, ip, lp, fp, dp, tp))))
# Test some of the new features in detail
# (format, argument, big-endian result, little-endian result, asymmetric)
tests = [
('c', 'a', 'a', 'a', 0),
('xc', 'a', '\0a', '\0a', 0),
('cx', 'a', 'a\0', 'a\0', 0),
('s', 'a', 'a', 'a', 0),
('0s', 'helloworld', '', '', 1),
('1s', 'helloworld', 'h', 'h', 1),
('9s', 'helloworld', 'helloworl', 'helloworl', 1),
('10s', 'helloworld', 'helloworld', 'helloworld', 0),
('11s', 'helloworld', 'helloworld\0', 'helloworld\0', 1),
('20s', 'helloworld', 'helloworld'+10*'\0', 'helloworld'+10*'\0', 1),
('b', 7, '\7', '\7', 0),
('b', -7, '\371', '\371', 0),
('B', 7, '\7', '\7', 0),
('B', 249, '\371', '\371', 0),
('h', 700, '\002\274', '\274\002', 0),
('h', -700, '\375D', 'D\375', 0),
('H', 700, '\002\274', '\274\002', 0),
('H', 0x10000-700, '\375D', 'D\375', 0),
('i', 70000000, '\004,\035\200', '\200\035,\004', 0),
('i', -70000000, '\373\323\342\200', '\200\342\323\373', 0),
('I', 70000000, '\004,\035\200', '\200\035,\004', 0),
('I', 0x100000000-70000000, '\373\323\342\200', '\200\342\323\373', 0),
('l', 70000000, '\004,\035\200', '\200\035,\004', 0),
('l', -70000000, '\373\323\342\200', '\200\342\323\373', 0),
('L', 70000000, '\004,\035\200', '\200\035,\004', 0),
('L', 0x100000000-70000000, '\373\323\342\200', '\200\342\323\373', 0),
('f', 2.0, '@\000\000\000', '\000\000\000@', 0),
('d', 2.0, '@\000\000\000\000\000\000\000',
'\000\000\000\000\000\000\000@', 0),
('f', -2.0, '\300\000\000\000', '\000\000\000\300', 0),
('d', -2.0, '\300\000\000\000\000\000\000\000',
'\000\000\000\000\000\000\000\300', 0),
('?', 0, '\0', '\0', 0),
('?', 3, '\1', '\1', 1),
('?', True, '\1', '\1', 0),
('?', [], '\0', '\0', 1),
('?', (1,), '\1', '\1', 1),
]
for fmt, arg, big, lil, asy in tests:
big = bytes(big, "latin-1")
lil = bytes(lil, "latin-1")
if verbose:
print("%r %r %r %r" % (fmt, arg, big, lil))
for (xfmt, exp) in [('>'+fmt, big), ('!'+fmt, big), ('<'+fmt, lil),
('='+fmt, ISBIGENDIAN and big or lil)]:
res = struct.pack(xfmt, arg)
if res != exp:
raise TestFailed("pack(%r, %r) -> %r # expected %r" % (
fmt, arg, res, exp))
n = struct.calcsize(xfmt)
if n != len(res):
raise TestFailed("calcsize(%r) -> %d # expected %d" % (
xfmt, n, len(res)))
rev = struct.unpack(xfmt, res)[0]
if isinstance(arg, str):
# Strings are returned as bytes since you can't know the encoding of
# the string when packed.
arg = bytes(arg, 'latin1')
if rev != arg and not asy:
raise TestFailed("unpack(%r, %r) -> (%r,) # expected (%r,)" % (
fmt, res, rev, arg))
###########################################################################
# Simple native q/Q tests.
has_native_qQ = 1
try:
struct.pack("q", 5)
except struct.error:
has_native_qQ = 0
if verbose:
print("Platform has native q/Q?", has_native_qQ and "Yes." or "No.")
any_err(struct.pack, "Q", -1) # can't pack -1 as unsigned regardless
simple_err(struct.pack, "q", "a") # can't pack string as 'q' regardless
simple_err(struct.pack, "Q", "a") # ditto, but 'Q'
def test_native_qQ():
nbytes = struct.calcsize('q')
# The expected values here are in big-endian format, primarily because
# I'm on a little-endian machine and so this is the clearest way (for
# me) to force the code to get exercised.
for format, input, expected in (
('q', -1, '\xff' * nbytes),
('q', 0, '\x00' * nbytes),
('Q', 0, '\x00' * nbytes),
('q', 1, '\x00' * (nbytes-1) + '\x01'),
('Q', (1 << (8*nbytes))-1, '\xff' * nbytes),
('q', (1 << (8*nbytes-1))-1, '\x7f' + '\xff' * (nbytes - 1))):
expected = bytes(expected, "latin-1")
got = struct.pack(format, input)
native_expected = bigendian_to_native(expected)
verify(got == native_expected,
"%r-pack of %r gave %r, not %r" %
(format, input, got, native_expected))
retrieved = struct.unpack(format, got)[0]
verify(retrieved == input,
"%r-unpack of %r gave %r, not %r" %
(format, got, retrieved, input))
if has_native_qQ:
test_native_qQ()
###########################################################################
# Standard integer tests (bBhHiIlLqQ).
import binascii
class IntTester:
# XXX Most std integer modes fail to test for out-of-range.
# The "i" and "l" codes appear to range-check OK on 32-bit boxes, but
# fail to check correctly on some 64-bit ones (Tru64 Unix + Compaq C
# reported by Mark Favas).
BUGGY_RANGE_CHECK = "bBhHiIlL"
def __init__(self, formatpair, bytesize):
assert len(formatpair) == 2
self.formatpair = formatpair
for direction in "<>!=":
for code in formatpair:
format = direction + code
verify(struct.calcsize(format) == bytesize)
self.bytesize = bytesize
self.bitsize = bytesize * 8
self.signed_code, self.unsigned_code = formatpair
self.unsigned_min = 0
self.unsigned_max = 2**self.bitsize - 1
self.signed_min = -(2**(self.bitsize-1))
self.signed_max = 2**(self.bitsize-1) - 1
def test_one(self, x, pack=struct.pack,
unpack=struct.unpack,
unhexlify=binascii.unhexlify):
if verbose:
print("trying std", self.formatpair, "on", x, "==", hex(x))
# Try signed.
code = self.signed_code
if self.signed_min <= x <= self.signed_max:
# Try big-endian.
expected = int(x)
if x < 0:
expected += 1 << self.bitsize
assert expected > 0
expected = hex(expected)[2:] # chop "0x"
if len(expected) & 1:
expected = "0" + expected
expected = unhexlify(expected)
expected = b"\x00" * (self.bytesize - len(expected)) + expected
# Pack work?
format = ">" + code
got = pack(format, x)
verify(got == expected,
"'%s'-pack of %r gave %r, not %r" %
(format, x, got, expected))
# Unpack work?
retrieved = unpack(format, got)[0]
verify(x == retrieved,
"'%s'-unpack of %r gave %r, not %r" %
(format, got, retrieved, x))
# Adding any byte should cause a "too big" error.
any_err(unpack, format, b'\x01' + got)
# Try little-endian.
format = "<" + code
expected = string_reverse(expected)
# Pack work?
got = pack(format, x)
verify(got == expected,
"'%s'-pack of %r gave %r, not %r" %
(format, x, got, expected))
# Unpack work?
retrieved = unpack(format, got)[0]
verify(x == retrieved,
"'%s'-unpack of %r gave %r, not %r" %
(format, got, retrieved, x))
# Adding any byte should cause a "too big" error.
any_err(unpack, format, b'\x01' + got)
else:
# x is out of range -- verify pack realizes that.
if not PY_STRUCT_RANGE_CHECKING and code in self.BUGGY_RANGE_CHECK:
if verbose:
print("Skipping buggy range check for code", code)
else:
deprecated_err(pack, ">" + code, x)
deprecated_err(pack, "<" + code, x)
# Much the same for unsigned.
code = self.unsigned_code
if self.unsigned_min <= x <= self.unsigned_max:
# Try big-endian.
format = ">" + code
expected = int(x)
expected = hex(expected)[2:] # chop "0x"
if len(expected) & 1:
expected = "0" + expected
expected = unhexlify(expected)
expected = b"\x00" * (self.bytesize - len(expected)) + expected
# Pack work?
got = pack(format, x)
verify(got == expected,
"'%s'-pack of %r gave %r, not %r" %
(format, x, got, expected))
# Unpack work?
retrieved = unpack(format, got)[0]
verify(x == retrieved,
"'%s'-unpack of %r gave %r, not %r" %
(format, got, retrieved, x))
# Adding any byte should cause a "too big" error.
any_err(unpack, format, b'\x01' + got)
# Try little-endian.
format = "<" + code
expected = string_reverse(expected)
# Pack work?
got = pack(format, x)
verify(got == expected,
"'%s'-pack of %r gave %r, not %r" %
(format, x, got, expected))
# Unpack work?
retrieved = unpack(format, got)[0]
verify(x == retrieved,
"'%s'-unpack of %r gave %r, not %r" %
(format, got, retrieved, x))
# Adding any byte should cause a "too big" error.
any_err(unpack, format, b'\x01' + got)
else:
# x is out of range -- verify pack realizes that.
if not PY_STRUCT_RANGE_CHECKING and code in self.BUGGY_RANGE_CHECK:
if verbose:
print("Skipping buggy range check for code", code)
else:
deprecated_err(pack, ">" + code, x)
deprecated_err(pack, "<" + code, 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)
# 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
try:
x = int(x)
except OverflowError:
pass
self.test_one(x)
# Some error cases.
for direction in "<>":
for code in self.formatpair:
for badobject in "a string", 3+42j, randrange:
any_err(struct.pack, direction + code, badobject)
for args in [("bB", 1),
("hH", 2),
("iI", 4),
("lL", 4),
("qQ", 8)]:
t = IntTester(*args)
t.run()
###########################################################################
# The p ("Pascal string") code.
def test_p_code():
for code, input, expected, expectedback in [
('p','abc', '\x00', b''),
('1p', 'abc', '\x00', b''),
('2p', 'abc', '\x01a', b'a'),
('3p', 'abc', '\x02ab', b'ab'),
('4p', 'abc', '\x03abc', b'abc'),
('5p', 'abc', '\x03abc\x00', b'abc'),
('6p', 'abc', '\x03abc\x00\x00', b'abc'),
('1000p', 'x'*1000, '\xff' + 'x'*999, b'x'*255)]:
expected = bytes(expected, "latin-1")
got = struct.pack(code, input)
if got != expected:
raise TestFailed("pack(%r, %r) == %r but expected %r" %
(code, input, got, expected))
(got,) = struct.unpack(code, got)
if got != expectedback:
raise TestFailed("unpack(%r, %r) == %r but expected %r" %
(code, input, got, expectedback))
test_p_code()
###########################################################################
# 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.
def test_705836():
import math
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.
verify(base == unpacked)
bigpacked = struct.pack(">f", smaller)
verify(bigpacked == string_reverse(packed),
">f pack should be byte-reversal of <f pack")
unpacked = struct.unpack(">f", bigpacked)[0]
verify(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]
verify(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)
try:
packed = struct.pack(">f", big)
except OverflowError:
pass
else:
raise TestFailed("expected OverflowError")
test_705836()
###########################################################################
# SF bug 1229380. No struct.pack exception for some out of range integers
def test_1229380():
import sys
for endian in ('', '>', '<'):
for fmt in ('B', 'H', 'I', 'L'):
deprecated_err(struct.pack, endian + fmt, -1)
deprecated_err(struct.pack, endian + 'B', 300)
deprecated_err(struct.pack, endian + 'H', 70000)
deprecated_err(struct.pack, endian + 'I', sys.maxsize * 4)
deprecated_err(struct.pack, endian + 'L', sys.maxsize * 4)
if PY_STRUCT_RANGE_CHECKING:
test_1229380()
###########################################################################
# SF bug 1530559. struct.pack raises TypeError where it used to convert.
def check_float_coerce(format, number):
if PY_STRUCT_FLOAT_COERCE == 2:
# Test for pre-2.5 struct module
packed = struct.pack(format, number)
floored = struct.unpack(format, packed)[0]
if floored != int(number):
raise TestFailed("did not correcly coerce float to int")
return
try:
func(*args)
except (struct.error, TypeError):
if PY_STRUCT_FLOAT_COERCE:
raise TestFailed("expected DeprecationWarning for float coerce")
except DeprecationWarning:
if not PY_STRUCT_FLOAT_COERCE:
raise TestFailed("expected to raise struct.error for float coerce")
else:
raise TestFailed("did not raise error for float coerce")
check_float_coerce = with_warning_restore(deprecated_err)
def test_1530559():
for endian in ('', '>', '<'):
for fmt in ('B', 'H', 'I', 'L', 'b', 'h', 'i', 'l'):
check_float_coerce(endian + fmt, 1.0)
check_float_coerce(endian + fmt, 1.5)
test_1530559()
###########################################################################
# Packing and unpacking to/from memory views.
# Copied and modified from unittest.
def assertRaises(excClass, callableObj, *args, **kwargs):
try:
callableObj(*args, **kwargs)
except excClass:
return
else:
raise TestFailed("%s not raised." % excClass)
def test_unpack_from():
test_string = b'abcd01234'
fmt = '4s'
s = struct.Struct(fmt)
for cls in (bytes, bytearray):
if verbose:
print("test_unpack_from using", cls.__name__)
data = cls(test_string)
if not isinstance(data, (bytes, bytearray)):
bytes_data = bytes(data, 'latin1')
else:
bytes_data = data
vereq(s.unpack_from(data), (b'abcd',))
vereq(s.unpack_from(data, 2), (b'cd01',))
vereq(s.unpack_from(data, 4), (b'0123',))
for i in range(6):
vereq(s.unpack_from(data, i), (bytes_data[i:i+4],))
for i in range(6, len(test_string) + 1):
simple_err(s.unpack_from, data, i)
for cls in (bytes, bytearray):
data = cls(test_string)
vereq(struct.unpack_from(fmt, data), (b'abcd',))
vereq(struct.unpack_from(fmt, data, 2), (b'cd01',))
vereq(struct.unpack_from(fmt, data, 4), (b'0123',))
for i in range(6):
vereq(struct.unpack_from(fmt, data, i), (bytes_data[i:i+4],))
for i in range(6, len(test_string) + 1):
simple_err(struct.unpack_from, fmt, data, i)
def test_pack_into():
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.tostring()[:len(test_string)]
vereq(from_buf, test_string)
# Test with offset.
s.pack_into(writable_buf, 10, test_string)
from_buf = writable_buf.tostring()[:len(test_string)+10]
vereq(from_buf, test_string[:10] + test_string)
# Go beyond boundaries.
small_buf = array.array('b', b' '*10)
assertRaises(struct.error, s.pack_into, small_buf, 0, test_string)
assertRaises(struct.error, s.pack_into, small_buf, 2, test_string)
def test_pack_into_fn():
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.tostring()[:len(test_string)]
vereq(from_buf, test_string)
# Test with offset.
pack_into(writable_buf, 10, test_string)
from_buf = writable_buf.tostring()[:len(test_string)+10]
vereq(from_buf, test_string[:10] + test_string)
# Go beyond boundaries.
small_buf = array.array('b', b' '*10)
assertRaises(struct.error, pack_into, small_buf, 0, test_string)
assertRaises(struct.error, pack_into, small_buf, 2, test_string)
def test_unpack_with_memoryview():
# SF bug 1563759: struct.unpack doens'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)
vereq(value, 0x12345678)
# Test methods to pack and unpack from memoryviews rather than strings.
test_unpack_from()
test_pack_into()
test_pack_into_fn()
test_unpack_with_memoryview()
def test_bool():
for prefix in tuple("<>!=")+('',):
false = (), [], [], '', 0
true = [1], 'test', 5, -1, 0xffffffff+1, 0xffffffff/2
falseFormat = prefix + '?' * len(false)
if verbose:
print('trying bool pack/unpack on', false, 'using format', falseFormat)
packedFalse = struct.pack(falseFormat, *false)
unpackedFalse = struct.unpack(falseFormat, packedFalse)
trueFormat = prefix + '?' * len(true)
if verbose:
print('trying bool pack/unpack on', true, 'using format', trueFormat)
packedTrue = struct.pack(trueFormat, *true)
unpackedTrue = struct.unpack(trueFormat, packedTrue)
if len(true) != len(unpackedTrue):
raise TestFailed('unpacked true array is not of same size as input')
if len(false) != len(unpackedFalse):
raise TestFailed('unpacked false array is not of same size as input')
for t in unpackedFalse:
if t is not False:
raise TestFailed('%r did not unpack as False' % t)
for t in unpackedTrue:
if t is not True:
raise TestFailed('%r did not unpack as false' % t)
if prefix and verbose:
print('trying size of bool with format %r' % (prefix+'?'))
packed = struct.pack(prefix+'?', 1)
if len(packed) != struct.calcsize(prefix+'?'):
raise TestFailed('packed length is not equal to calculated size')
if len(packed) != 1 and prefix:
raise TestFailed('encoded bool is not one byte: %r' % packed)
elif not prefix and verbose:
print('size of bool in native format is %i' % (len(packed)))
for c in [b'\x01', b'\x7f', b'\xff', b'\x0f', b'\xf0']:
if struct.unpack('>?', c)[0] is not True:
raise TestFailed('%c did not unpack as True' % c)
test_bool()
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