gh-145980: Add support for alternative alphabets in the binascii module by serhiy-storchaka · Pull Request #145981 · python/cpython

serhiy-storchaka · 2026-03-15T14:43:04Z

Add the alphabet parameter in functions b2a_base64(), a2b_base64(), b2a_base85() and a2b_base85().
And a number of "*_ALPHABET" constants.
Remove b2a_z85() and a2b_z85().

Issue: Support alternative alphabets in BaseXX encodings #145980

📚 Documentation preview 📚: https://cpython-previews--145981.org.readthedocs.build/

…i module * Add the alphabet parameter in functions b2a_base64(), a2b_base64(), b2a_base85() and a2b_base85(). * And a number of "*_ALPHABET" constants. * Remove b2a_z85() and a2b_z85().

Doc/library/binascii.rst

Lib/base64.py

Lib/test/test_binascii.py

picnixz · 2026-03-15T17:47:37Z

Modules/binascii.c

+static PyObject *
+get_reverse_table(binascii_state *state, PyObject *alphabet, int size, int padchar)
+{
+    PyObject *reverse_table;


I'd suggest having a goto error for cleanup in case this function grows.

I think this is preliminary.

serhiy-storchaka · 2026-03-17T13:57:59Z

Damn, what is now? I spent more time fighting the CI than fixing genuine bugs.

serhiy-storchaka · 2026-03-20T09:03:21Z

Are there other suggestions or notes? I am going to merge this PR, because it is a dependence for #146192 and other changes.

picnixz · 2026-03-20T09:27:28Z

Not from side!

serhiy-storchaka · 2026-03-20T11:07:24Z

Thank you for your review @picnixz.

bedevere-bot · 2026-03-20T12:42:23Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 MacOS M1 Refleaks NoGIL 3.x (tier-2) has failed when building commit 4507d49.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1368/builds/4852) and take a look at the build logs.
Check if the failure is related to this commit (4507d49) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1368/builds/4852

Failed tests:

test_capi
test.test_concurrent_futures.test_interpreter_pool
test_import

Test leaking resources:

test_interpreter_pool: references
test_capi: references
test_interpreter_pool: memory blocks
test_import: references
test_capi: memory blocks
test_import: memory blocks

Summary of the results of the build (if available):

==

Click to see traceback logs

TracebackTests.test_nonexistent_module_nested) ... ok


TracebackTests.test_broken_parent) ... ok


TracebackTests.test_unencodable_filename) ... skipped 'need TESTFN_UNENCODABLE'


TracebackTests.test_exec_failure_nested) ... ok


Traceback (most recent call last):
  File "<string>", line 10, in <module>
  File "<frozen importlib._bootstrap>", line 786, in module_from_spec
  File "<frozen importlib._bootstrap_external>", line 1025, in create_module
  File "<frozen importlib._bootstrap>", line 491, in _call_with_frames_removed
ImportError: module _test_module_state_shared does not support loading in subinterpreters
xpected failure


TracebackTests.test_import_bug) ... ok


TracebackTests.test_syntax_error) ... ok


TracebackTests.test_nonexistent_module) ... ok


TracebackTests.test_broken_from) ... ok


TracebackTests.test_broken_submodule) ... ok


TracebackTests.test_exec_failure) ... ok


TracebackTests.test_broken_parent_from) ... ok

bedevere-bot · 2026-03-20T13:12:17Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x Fedora Stable Refleaks 3.x (tier-3) has failed when building commit 4507d49.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1641/builds/1849) and take a look at the build logs.
Check if the failure is related to this commit (4507d49) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1641/builds/1849

Failed tests:

test_capi
test.test_concurrent_futures.test_interpreter_pool
test_import

Test leaking resources:

test_interpreter_pool: references
test_capi: references
test_interpreter_pool: memory blocks
test_import: references
test_capi: memory blocks
test_import: memory blocks

Summary of the results of the build (if available):

==

Click to see traceback logs

TracebackTests.test_nonexistent_module_nested) ... ok


TracebackTests.test_broken_parent) ... ok


TracebackTests.test_exec_failure_nested) ... ok


TracebackTests.test_import_bug) ... ok


TracebackTests.test_syntax_error) ... ok


TracebackTests.test_nonexistent_module) ... ok


TracebackTests.test_unencodable_filename) ... ok


TracebackTests.test_broken_from) ... ok


TracebackTests.test_broken_submodule) ... ok


TracebackTests.test_exec_failure) ... ok


TracebackTests.test_broken_parent_from) ... ok

bedevere-bot · 2026-03-20T14:47:09Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot PPC64LE Fedora Stable Refleaks 3.x (tier-2) has failed when building commit 4507d49.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/280/builds/2905) and take a look at the build logs.
Check if the failure is related to this commit (4507d49) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/280/builds/2905

Failed tests:

test_capi
test.test_concurrent_futures.test_interpreter_pool
test_import

Test leaking resources:

test_interpreter_pool: references
test_capi: references
test_interpreter_pool: memory blocks
test_import: references
test_capi: memory blocks
test_import: memory blocks

Summary of the results of the build (if available):

==

Click to see traceback logs

TracebackTests.test_nonexistent_module_nested) ... ok


TracebackTests.test_broken_parent) ... ok


TracebackTests.test_exec_failure_nested) ... ok


TracebackTests.test_import_bug) ... ok


TracebackTests.test_syntax_error) ... ok


TracebackTests.test_nonexistent_module) ... ok


TracebackTests.test_unencodable_filename) ... ok


TracebackTests.test_broken_from) ... ok


TracebackTests.test_broken_submodule) ... ok


TracebackTests.test_exec_failure) ... ok


TracebackTests.test_broken_parent_from) ... ok

…i module (pythonGH-145981) * Add the alphabet parameter in functions b2a_base64(), a2b_base64(), b2a_base85(), and a2b_base85(). * And a number of "*_ALPHABET" constants. * Remove b2a_z85() and a2b_z85().

- Use the new `alphabet` parameter in `binascii` - Remove `binascii.a2b_base32hex()` and `binascii.b2a_base32hex()` - Change value for `.. versionadded::` ReST directive in docs for new `binascii` functions to "next" instead of "3.15"

vstinner · 2026-03-20T17:44:26Z

This change introduced reference leaks in 3 tests:

test_capi: test.test_capi.test_misc.SubinterpreterTest.test_mutate_exception test
test_concurrent_futures.test_interpreter_pool
test_import

I wrote #146230 to fix the leak.

* upstream/main: (1475 commits) Docs: replace all `datetime` imports with `import datetime as dt` (python#145640) pythongh-146153: Use `frozendict` in pure python fallback for `curses.has_key` (python#146154) pythongh-138234: clarify returncode behavior for subprocesses created with `shell=True` (python#138536) pythongh-140947: fix contextvars handling for server tasks in asyncio (python#141158) pythonGH-100108: Add async generators best practices section (python#141885) pythonGH-145667: Merge `GET_ITER` and `GET_YIELD_FROM_ITER` (pythonGH-146120) pythongh-146228: Better fork support in cached FastPath (python#146231) pythongh-146227: Fix wrong type in _Py_atomic_load_uint16 in pyatomic_std.h (pythongh-146229) pythongh-145980: Fix copy/paste mistake in binascii.c (python#146230) pythongh-146092: Raise MemoryError on allocation failure in _zoneinfo (python#146165) pythongh-91279: Note `SOURCE_DATE_EPOCH` support in `ZipFile.writestr()` doc (python#139396) pythongh-146196: Fix Undefined Behavior in _PyUnicodeWriter_WriteASCIIString() (python#146201) pythongh-143930: Reject leading dashes in webbrowser URLs pythongh-145916: Soft-deprecate ctypes.util.find_library (pythonGH-145919) pythongh-146205: Check the errno with != 0 in close impls in select module (python#146206) pythongh-146171: Fix nested AttributeError suggestions (python#146188) pythongh-146099: Optimize _GUARD_CODE_VERSION+IP via function version symbols (pythonGH-146101) pythongh-145980: Add support for alternative alphabets in the binascii module (pythonGH-145981) pythongh-145754: Update signature retrieval in unittest.mock to use forwardref annotation format (python#145756) pythongh-145177: Add emscripten run --test, uses test args from config.toml (python#146160) ...

pythongh-145980: Add support for alternative alphabets in the binasci…

f47f4bd

…i module * Add the alphabet parameter in functions b2a_base64(), a2b_base64(), b2a_base85() and a2b_base85(). * And a number of "*_ALPHABET" constants. * Remove b2a_z85() and a2b_z85().

serhiy-storchaka requested a review from AA-Turner as a code owner March 15, 2026 14:43

bedevere-app bot mentioned this pull request Mar 15, 2026

Support alternative alphabets in BaseXX encodings #145980

Closed

bedevere-app bot added the awaiting core review label Mar 15, 2026

serhiy-storchaka mentioned this pull request Mar 15, 2026

gh-145968: fix base64.b64decode altchars translation in specific cases #145969

Merged

picnixz reviewed Mar 15, 2026

View reviewed changes

serhiy-storchaka added 10 commits March 15, 2026 20:38

Update documentation.

ce5bcd2

Update tests.

f59fffe

Refactoring: inline static functions for Base85.

33437a5

Merge branch 'main' into binascii-alphabet

044fa5a

Regen global strings.

3caf10d

Fix Sphinx warnings.

c27319a

Merge branch 'main' into binascii-alphabet

1abf3dd

Remove old tests.

4444158

Remove less common alphabets.

133505d

Merge branch 'main' into binascii-alphabet

f0f5960

Merge branch 'main' into binascii-alphabet

c609bbb

This was referenced Mar 19, 2026

gh-101178: Add Ascii85, Base85, and Z85 support to binascii #102753

Merged

gh-146192: Add base32 support to binascii #146193

Open

serhiy-storchaka merged commit 4507d49 into python:main Mar 20, 2026
50 checks passed

serhiy-storchaka deleted the binascii-alphabet branch March 20, 2026 11:07

bedevere-app bot removed the awaiting core review label Mar 20, 2026

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