Skip to content

bpo-31482: Missing bytes support for random.seed() version 1 #3614

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
rhettinger merged 3 commits into from
Sep 17, 2017
Merged

bpo-31482: Missing bytes support for random.seed() version 1 #3614

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
36c028c
Issue 31482: Missing bytes support for random.seed() version 1
rhettinger Sep 16, 2017
c71a239
Add comment to test. Add test for higher byte values.
rhettinger Sep 16, 2017
00b1a1c
Minor speed improvement by using map()
rhettinger Sep 16, 2017
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 3 additions & 2 deletions Lib/random.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -110,9 +110,10 @@ def seed(self, a=None, version=2):
"""

if version == 1 and isinstance(a, (str, bytes)):
a = a.decode('latin-1') if isinstance(a, bytes) else a

@serhiy-storchaka serhiy-storchaka Sep 16, 2017

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Maybe instead convert a string to a list of integers and remove ord() in the following code?

if isinstance(a, str):
    a = list(map(ord, a))

This would make the following code clearer and maybe slightly faster.

@rhettinger rhettinger Sep 16, 2017

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I prefer to leave the current code alone and just add a conversion for the bytes which is so uncommon that no one ever noticed the lack of bytes support.

x = ord(a[0]) << 7 if a else 0
for c in a:
x = ((1000003 * x) ^ ord(c)) & 0xFFFFFFFFFFFFFFFF
for c in map(ord, a):
x = ((1000003 * x) ^ c) & 0xFFFFFFFFFFFFFFFF
x ^= len(a)
a = -2 if x == -1 else x

Expand Down
27 changes: 27 additions & 0 deletions Lib/test/test_random.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -430,6 +430,33 @@ def test_bug_27706(self):
['0x1.b0580f98a7dbep-1', '0x1.84129978f9c1ap-1',
'0x1.aeaa51052e978p-2', '0x1.092178fb945a6p-2'])

def test_bug_31482(self):
# Verify that version 1 seeds are unaffected by hash randomization
# when the seeds are expressed as bytes rather than strings.
# The hash(b) values listed are the Python2.7 hash() values
# which were used for seeding.

self.gen.seed(b'nofar', version=1) # hash('nofar') == 5990528763808513177
self.assertEqual([self.gen.random().hex() for i in range(4)],
['0x1.8645314505ad7p-1', '0x1.afb1f82e40a40p-5',
'0x1.2a59d2285e971p-1', '0x1.56977142a7880p-6'])

self.gen.seed(b'rachel', version=1) # hash('rachel') == -9091735575445484789
self.assertEqual([self.gen.random().hex() for i in range(4)],
['0x1.0b294cc856fcdp-1', '0x1.2ad22d79e77b8p-3',
'0x1.3052b9c072678p-2', '0x1.578f332106574p-3'])

self.gen.seed(b'', version=1) # hash('') == 0
self.assertEqual([self.gen.random().hex() for i in range(4)],
['0x1.b0580f98a7dbep-1', '0x1.84129978f9c1ap-1',
'0x1.aeaa51052e978p-2', '0x1.092178fb945a6p-2'])

b = b'\x00\x20\x40\x60\x80\xA0\xC0\xE0\xF0'
self.gen.seed(b, version=1) # hash(b) == 5015594239749365497
self.assertEqual([self.gen.random().hex() for i in range(4)],
['0x1.52c2fde444d23p-1', '0x1.875174f0daea4p-2',
'0x1.9e9b2c50e5cd2p-1', '0x1.fa57768bd321cp-2'])

def test_setstate_first_arg(self):
self.assertRaises(ValueError, self.gen.setstate, (1, None, None))

Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2017-09-16-01-53-11.bpo-31482.39s5dS.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
``random.seed()`` now works with bytes in version=1