mirror of https://github.com/python/cpython
bpo-40286: Add randbytes() method to random.Random (GH-19527)
Add random.randbytes() function and random.Random.randbytes() method to generate random bytes. Modify secrets.token_bytes() to use SystemRandom.randbytes() rather than calling directly os.urandom(). Rename also genrand_int32() to genrand_uint32(), since it returns an unsigned 32-bit integer, not a signed integer. The _random module is now built with Py_BUILD_CORE_MODULE defined.
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@ -112,6 +112,13 @@ Bookkeeping functions
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:meth:`randrange` to handle arbitrarily large ranges.
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.. function:: randbytes(n)
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Generate *n* random bytes.
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.. versionadded:: 3.9
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Functions for integers
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----------------------
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@ -353,6 +353,12 @@ The documentation string is now shown not only for class, function,
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method etc, but for any object that has its own ``__doc__`` attribute.
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(Contributed by Serhiy Storchaka in :issue:`40257`.)
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random
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------
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Add a new :attr:`random.Random.randbytes` method: generate random bytes.
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(Contributed by Victor Stinner in :issue:`40286`.)
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signal
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------
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@ -739,6 +739,12 @@ class SystemRandom(Random):
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x = int.from_bytes(_urandom(numbytes), 'big')
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return x >> (numbytes * 8 - k) # trim excess bits
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def randbytes(self, n):
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"""Generate n random bytes."""
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# os.urandom(n) fails with ValueError for n < 0
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# and returns an empty bytes string for n == 0.
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return _urandom(n)
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def seed(self, *args, **kwds):
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"Stub method. Not used for a system random number generator."
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return None
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@ -819,6 +825,7 @@ weibullvariate = _inst.weibullvariate
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getstate = _inst.getstate
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setstate = _inst.setstate
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getrandbits = _inst.getrandbits
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randbytes = _inst.randbytes
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if hasattr(_os, "fork"):
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_os.register_at_fork(after_in_child=_inst.seed)
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@ -14,7 +14,6 @@ __all__ = ['choice', 'randbelow', 'randbits', 'SystemRandom',
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import base64
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import binascii
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import os
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from hmac import compare_digest
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from random import SystemRandom
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@ -44,7 +43,7 @@ def token_bytes(nbytes=None):
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"""
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if nbytes is None:
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nbytes = DEFAULT_ENTROPY
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return os.urandom(nbytes)
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return _sysrand.randbytes(nbytes)
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def token_hex(nbytes=None):
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"""Return a random text string, in hexadecimal.
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@ -291,6 +291,22 @@ class TestBasicOps:
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k = sum(randrange(6755399441055744) % 3 == 2 for i in range(n))
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self.assertTrue(0.30 < k/n < .37, (k/n))
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def test_randbytes(self):
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# Verify ranges
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for n in range(1, 10):
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data = self.gen.randbytes(n)
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self.assertEqual(type(data), bytes)
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self.assertEqual(len(data), n)
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self.assertEqual(self.gen.randbytes(0), b'')
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# Verify argument checking
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self.assertRaises(TypeError, self.gen.randbytes)
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self.assertRaises(TypeError, self.gen.randbytes, 1, 2)
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self.assertRaises(ValueError, self.gen.randbytes, -1)
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self.assertRaises(TypeError, self.gen.randbytes, 1.0)
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try:
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random.SystemRandom().random()
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except NotImplementedError:
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@ -747,6 +763,41 @@ class MersenneTwister_TestBasicOps(TestBasicOps, unittest.TestCase):
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c = self.gen.choices(population, cum_weights=cum_weights, k=10000)
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self.assertEqual(a, c)
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def test_randbytes(self):
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super().test_randbytes()
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# Mersenne Twister randbytes() is deterministic
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# and does not depend on the endian and bitness.
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seed = 8675309
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expected = b'f\xf9\xa836\xd0\xa4\xf4\x82\x9f\x8f\x19\xf0eo\x02'
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self.gen.seed(seed)
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self.assertEqual(self.gen.randbytes(16), expected)
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# randbytes(0) must not consume any entropy
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self.gen.seed(seed)
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self.assertEqual(self.gen.randbytes(0), b'')
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self.assertEqual(self.gen.randbytes(16), expected)
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# Four randbytes(4) calls give the same output than randbytes(16)
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self.gen.seed(seed)
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self.assertEqual(b''.join([self.gen.randbytes(4) for _ in range(4)]),
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expected)
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# Each randbytes(2) or randbytes(3) call consumes 4 bytes of entropy
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self.gen.seed(seed)
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expected2 = b''.join(expected[i:i + 2]
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for i in range(0, len(expected), 4))
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self.assertEqual(b''.join(self.gen.randbytes(2) for _ in range(4)),
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expected2)
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self.gen.seed(seed)
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expected3 = b''.join(expected[i:i + 3]
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for i in range(0, len(expected), 4))
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self.assertEqual(b''.join(self.gen.randbytes(3) for _ in range(4)),
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expected3)
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def gamma(z, sqrt2pi=(2.0*pi)**0.5):
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# Reflection to right half of complex plane
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if z < 0.5:
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@ -0,0 +1,2 @@
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Add :func:`random.randbytes` function and
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:meth:`random.Random.randbytes` method to generate random bytes.
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@ -174,7 +174,7 @@ _symtable symtablemodule.c
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#_weakref _weakref.c # basic weak reference support
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#_testcapi _testcapimodule.c # Python C API test module
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#_testinternalcapi _testinternalcapi.c -I$(srcdir)/Include/internal -DPy_BUILD_CORE_MODULE # Python internal C API test module
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#_random _randommodule.c # Random number generator
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#_random _randommodule.c -DPy_BUILD_CORE_MODULE # Random number generator
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#_elementtree -I$(srcdir)/Modules/expat -DHAVE_EXPAT_CONFIG_H -DUSE_PYEXPAT_CAPI _elementtree.c # elementtree accelerator
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#_pickle _pickle.c # pickle accelerator
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#_datetime _datetimemodule.c # datetime accelerator
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@ -11,7 +11,7 @@
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* renamed genrand_res53() to random_random() and wrapped
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in python calling/return code.
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* genrand_int32() and the helper functions, init_genrand()
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* genrand_uint32() and the helper functions, init_genrand()
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and init_by_array(), were declared static, wrapped in
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Python calling/return code. also, their global data
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references were replaced with structure references.
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@ -67,9 +67,9 @@
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/* ---------------------------------------------------------------*/
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#include "Python.h"
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#include <time.h> /* for seeding to current time */
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#include "pycore_byteswap.h" // _Py_bswap32()
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#ifdef HAVE_PROCESS_H
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# include <process.h> /* needed for getpid() */
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# include <process.h> // getpid()
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#endif
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/* Period parameters -- These are all magic. Don't change. */
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@ -116,7 +116,7 @@ class _random.Random "RandomObject *" "&Random_Type"
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/* generates a random number on [0,0xffffffff]-interval */
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static uint32_t
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genrand_int32(RandomObject *self)
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genrand_uint32(RandomObject *self)
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{
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uint32_t y;
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static const uint32_t mag01[2] = {0x0U, MATRIX_A};
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@ -171,7 +171,7 @@ static PyObject *
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_random_Random_random_impl(RandomObject *self)
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/*[clinic end generated code: output=117ff99ee53d755c input=afb2a59cbbb00349]*/
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{
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uint32_t a=genrand_int32(self)>>5, b=genrand_int32(self)>>6;
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uint32_t a=genrand_uint32(self)>>5, b=genrand_uint32(self)>>6;
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return PyFloat_FromDouble((a*67108864.0+b)*(1.0/9007199254740992.0));
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}
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@ -481,7 +481,7 @@ _random_Random_getrandbits_impl(RandomObject *self, int k)
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}
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if (k <= 32) /* Fast path */
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return PyLong_FromUnsignedLong(genrand_int32(self) >> (32 - k));
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return PyLong_FromUnsignedLong(genrand_uint32(self) >> (32 - k));
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words = (k - 1) / 32 + 1;
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wordarray = (uint32_t *)PyMem_Malloc(words * 4);
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@ -498,7 +498,7 @@ _random_Random_getrandbits_impl(RandomObject *self, int k)
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for (i = words - 1; i >= 0; i--, k -= 32)
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#endif
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{
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r = genrand_int32(self);
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r = genrand_uint32(self);
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if (k < 32)
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r >>= (32 - k); /* Drop least significant bits */
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wordarray[i] = r;
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@ -510,6 +510,56 @@ _random_Random_getrandbits_impl(RandomObject *self, int k)
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return result;
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}
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/*[clinic input]
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_random.Random.randbytes
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self: self(type="RandomObject *")
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n: Py_ssize_t
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/
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Generate n random bytes.
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[clinic start generated code]*/
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static PyObject *
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_random_Random_randbytes_impl(RandomObject *self, Py_ssize_t n)
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/*[clinic end generated code: output=67a28548079a17ea input=7ba658a24150d233]*/
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{
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if (n < 0) {
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PyErr_SetString(PyExc_ValueError,
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"number of bytes must be non-negative");
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return NULL;
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}
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if (n == 0) {
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/* Don't consume any entropy */
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return PyBytes_FromStringAndSize(NULL, 0);
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}
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PyObject *bytes = PyBytes_FromStringAndSize(NULL, n);
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if (bytes == NULL) {
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return NULL;
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}
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uint8_t *ptr = (uint8_t *)PyBytes_AS_STRING(bytes);
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do {
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uint32_t word = genrand_uint32(self);
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#if PY_LITTLE_ENDIAN
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/* Convert to big endian */
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word = _Py_bswap32(word);
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#endif
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if (n < 4) {
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memcpy(ptr, &word, n);
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break;
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}
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memcpy(ptr, &word, 4);
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ptr += 4;
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n -= 4;
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} while (n);
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return bytes;
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}
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static PyObject *
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random_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
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{
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@ -539,6 +589,7 @@ static PyMethodDef random_methods[] = {
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_RANDOM_RANDOM_GETSTATE_METHODDEF
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_RANDOM_RANDOM_SETSTATE_METHODDEF
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_RANDOM_RANDOM_GETRANDBITS_METHODDEF
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_RANDOM_RANDOM_RANDBYTES_METHODDEF
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{NULL, NULL} /* sentinel */
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};
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@ -114,4 +114,45 @@ _random_Random_getrandbits(RandomObject *self, PyObject *arg)
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exit:
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return return_value;
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}
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/*[clinic end generated code: output=a7feb0c9c8d1b627 input=a9049054013a1b77]*/
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PyDoc_STRVAR(_random_Random_randbytes__doc__,
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"randbytes($self, n, /)\n"
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"--\n"
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"\n"
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"Generate n random bytes.");
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#define _RANDOM_RANDOM_RANDBYTES_METHODDEF \
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{"randbytes", (PyCFunction)_random_Random_randbytes, METH_O, _random_Random_randbytes__doc__},
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static PyObject *
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_random_Random_randbytes_impl(RandomObject *self, Py_ssize_t n);
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static PyObject *
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_random_Random_randbytes(RandomObject *self, PyObject *arg)
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{
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PyObject *return_value = NULL;
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Py_ssize_t n;
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if (PyFloat_Check(arg)) {
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PyErr_SetString(PyExc_TypeError,
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"integer argument expected, got float" );
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goto exit;
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}
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{
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Py_ssize_t ival = -1;
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PyObject *iobj = PyNumber_Index(arg);
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if (iobj != NULL) {
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ival = PyLong_AsSsize_t(iobj);
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Py_DECREF(iobj);
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}
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if (ival == -1 && PyErr_Occurred()) {
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goto exit;
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}
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n = ival;
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}
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return_value = _random_Random_randbytes_impl(self, n);
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exit:
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return return_value;
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}
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/*[clinic end generated code: output=e515c651860c4001 input=a9049054013a1b77]*/
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3
setup.py
3
setup.py
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@ -808,7 +808,8 @@ class PyBuildExt(build_ext):
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self.add(Extension('_datetime', ['_datetimemodule.c'],
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libraries=['m']))
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# random number generator implemented in C
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self.add(Extension("_random", ["_randommodule.c"]))
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self.add(Extension("_random", ["_randommodule.c"],
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extra_compile_args=['-DPy_BUILD_CORE_MODULE']))
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# bisect
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self.add(Extension("_bisect", ["_bisectmodule.c"]))
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# heapq
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