bpo-39068: Fix race condition in base64 (GH-17627)
There was a race condition in base64 in lazy initialization of multiple globals.
diff --git a/Lib/base64.py b/Lib/base64.py
index 539ad16..e1256ad 100755
--- a/Lib/base64.py
+++ b/Lib/base64.py
@@ -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)
diff --git a/Misc/ACKS b/Misc/ACKS
index 80e51f9..211455b 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1659,6 +1659,7 @@
Frank Stajano
Joel Stanley
Kyle Stanley
+Brandon Stansbury
Anthony Starks
David Steele
Oliver Steele
diff --git a/Misc/NEWS.d/next/Library/2019-12-16-17-55-31.bpo-39068.Ti3f9P.rst b/Misc/NEWS.d/next/Library/2019-12-16-17-55-31.bpo-39068.Ti3f9P.rst
new file mode 100644
index 0000000..fe6503f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-12-16-17-55-31.bpo-39068.Ti3f9P.rst
@@ -0,0 +1,2 @@
+Fix initialization race condition in :func:`a85encode` and :func:`b85encode`
+in :mod:`base64`. Patch by Brandon Stansbury.