bpo-39068: Fix race condition in base64 (GH-17627)

There was a race condition in base64 in lazy initialization of multiple globals.
This commit is contained in:
Brandon Stansbury 2020-12-31 01:44:46 -08:00 committed by GitHub
parent f421bfce80
commit 9655434cca
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 5 additions and 2 deletions

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@ -344,7 +344,7 @@ def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False):
global _a85chars, _a85chars2
# Delay the initialization of tables to not waste memory
# if the function is never called
if _a85chars is None:
if _a85chars2 is None:
_a85chars = [bytes((i,)) for i in range(33, 118)]
_a85chars2 = [(a + b) for a in _a85chars for b in _a85chars]
@ -452,7 +452,7 @@ def b85encode(b, pad=False):
global _b85chars, _b85chars2
# Delay the initialization of tables to not waste memory
# if the function is never called
if _b85chars is None:
if _b85chars2 is None:
_b85chars = [bytes((i,)) for i in _b85alphabet]
_b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
return _85encode(b, _b85chars, _b85chars2, pad)

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@ -1659,6 +1659,7 @@ Quentin Stafford-Fraser
Frank Stajano
Joel Stanley
Kyle Stanley
Brandon Stansbury
Anthony Starks
David Steele
Oliver Steele

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@ -0,0 +1,2 @@
Fix initialization race condition in :func:`a85encode` and :func:`b85encode`
in :mod:`base64`. Patch by Brandon Stansbury.