Fix SystemError buffer overflow on Python 3.14+ and add Python 3.14 support

.github/workflows/ci.yml

@@ -86,7 +86,7 @@ jobs:
       fail-fast: false
       matrix:
         os: ["ubuntu-latest", "ubuntu-24.04-arm", "macos-latest", "windows-latest"]
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "pypy3.9", "pypy3.10"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14", "pypy3.9", "pypy3.10"]
         exclude:
           - os: "macos-latest"
             python-version: "pypy3.10"
@@ -118,7 +118,7 @@ jobs:
         run: nox -vs integration -p ${{ matrix.python-version }} -- -m "not require_secrets"
       - name: Run integration tests (with secrets)
         # Limit CI workload by running integration tests with secrets only on edge Python versions.
-        if: ${{ env.B2_TEST_APPLICATION_KEY != '' && env.B2_TEST_APPLICATION_KEY_ID != '' && contains(fromJSON('["3.8", "pypy3.10", "3.13"]'), matrix.python-version) }}
+        if: ${{ env.B2_TEST_APPLICATION_KEY != '' && env.B2_TEST_APPLICATION_KEY_ID != '' && contains(fromJSON('["3.8", "pypy3.10", "3.14"]'), matrix.python-version) }}
         run: nox -vs integration -p ${{ matrix.python-version }} -- -m "require_secrets" --cleanup
   test-docker:
     timeout-minutes: 90

b2/_internal/arg_parser.py

@@ -130,7 +130,14 @@ def _encode_description(self, value: str):
             return textwrap.dedent(value)
         else:
             encoding = self._get_encoding()
-            return rst2ansi(value.encode(encoding), output_encoding=encoding)
+            try:
+                return rst2ansi(value.encode(encoding), output_encoding=encoding)
+            except SystemError:
+                # FALLBACK(PARSER): rst2ansi can raise SystemError on Python 3.14+ due to
+                # buffer overflow bug in get_terminal_size ioctl call.
+                # See: https://github.com/Backblaze/B2_Command_Line_Tool/issues/1119
+                # TODO-REMOVE-BY: When rst2ansi is updated or replaced
+                return textwrap.dedent(value)
 
     def _make_short_description(self, usage: str, raw_description: str) -> str:
         if usage:

changelog.d/+python-3.14-support.infrastructure.md

@@ -0,0 +1 @@
+Added Python 3.14 support to CI/CD pipeline and test matrix.

changelog.d/1119.fixed.md

@@ -0,0 +1 @@
+Fixed SystemError buffer overflow crash on Python 3.14+ caused by rst2ansi's terminal size detection bug. The CLI now gracefully handles this error and continues to function normally.

noxfile.py

@@ -42,6 +42,7 @@
         '3.11',
         '3.12',
         '3.13',
+        '3.14',
     ]
     if NOX_PYTHONS is None
     else NOX_PYTHONS.split(',')

pyproject.toml

@@ -21,6 +21,7 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
 ]
 dependencies = [
     "argcomplete>=3.5.2,<4",

test/helpers.py

@@ -8,7 +8,9 @@
 #
 ######################################################################
 import platform
+import sys
 
+import pexpect
 import pytest
 
 _MISSING = object()
@@ -21,6 +23,40 @@ def skip_on_windows(*args, reason='Not supported on Windows', **kwargs):
     )(*args, **kwargs)
 
 
+def patched_spawn(*args, **kwargs):
+    """
+    Wrapper around pexpect.spawn with improved error messages.
+
+    pexpect's errors are confusing to interpret when things go wrong,
+    because it doesn't output the actual stdout by default. This wrapper
+    addresses that inconvenience.
+    """
+    instance = pexpect.spawn(*args, **kwargs)
+
+    def _patch_expect(func):
+        def _wrapper(pattern_list, **kwargs):
+            try:
+                return func(pattern_list, **kwargs)
+            except pexpect.exceptions.TIMEOUT as exc:
+                raise pexpect.exceptions.TIMEOUT(
+                    f'Timeout reached waiting for `{pattern_list}`'
+                ) from exc
+            except pexpect.exceptions.EOF as exc:
+                raise pexpect.exceptions.EOF(f'Received EOF waiting for `{pattern_list}`') from exc
+            except Exception as exc:
+                raise RuntimeError(f'Unexpected error waiting for `{pattern_list}`') from exc
+
+        return _wrapper
+
+    instance.expect = _patch_expect(instance.expect)
+    instance.expect_exact = _patch_expect(instance.expect_exact)
+
+    # capture child shell's output for debugging
+    instance.logfile = sys.stdout.buffer
+
+    return instance
+
+
 def b2_uri_args_v3(bucket_name, path=_MISSING):
     if path is _MISSING:
         return [bucket_name]

test/integration/helpers.py

@@ -368,7 +368,15 @@ def print_json_indented(value):
 
 
 def remove_warnings(text):
-    return linesep.join(line for line in text.split(linesep) if 'DeprecationWarning' not in line)
+    """Filter out Python warnings from command output."""
+    return linesep.join(
+        line
+        for line in text.split(linesep)
+        if 'DeprecationWarning' not in line
+        and 'resource_tracker' not in line  # Python 3.14+ multiprocessing warnings
+        and 'UserWarning' not in line  # Python 3.14+ shows more warning details
+        and 'warnings.warn(' not in line  # Python 3.14+ shows source line in warnings
+    )
 
 
 class StringReader:

test/integration/test_autocomplete.py

@@ -13,7 +13,7 @@
 import pexpect
 import pytest
 
-from test.helpers import skip_on_windows
+from test.helpers import patched_spawn, skip_on_windows
 
 TIMEOUT = 120  # CI can be slow at times when parallelization is extreme
 
@@ -27,41 +27,6 @@
 """
 
 
-def patched_spawn(*args, **kwargs):
-    """
-    Patch pexpect.spawn to improve error messages
-    """
-
-    instance = pexpect.spawn(*args, **kwargs)
-
-    def _patch_expect(func):
-        def _wrapper(pattern_list, **kwargs):
-            try:
-                return func(pattern_list, **kwargs)
-            except pexpect.exceptions.TIMEOUT as exc:
-                raise pexpect.exceptions.TIMEOUT(
-                    f'Timeout reached waiting for `{pattern_list}` to be autocompleted'
-                ) from exc
-            except pexpect.exceptions.EOF as exc:
-                raise pexpect.exceptions.EOF(
-                    f'Received EOF waiting for `{pattern_list}` to be autocompleted'
-                ) from exc
-            except Exception as exc:
-                raise RuntimeError(
-                    f'Unexpected error waiting for `{pattern_list}` to be autocompleted'
-                ) from exc
-
-        return _wrapper
-
-    instance.expect = _patch_expect(instance.expect)
-    instance.expect_exact = _patch_expect(instance.expect_exact)
-
-    # capture child shell's output for debugging
-    instance.logfile = sys.stdout.buffer
-
-    return instance
-
-
 @pytest.fixture(scope='session')
 def bashrc(homedir):
     bashrc_path = homedir / '.bashrc'

test/integration/test_help.py

@@ -7,10 +7,16 @@
 # License https://www.backblaze.com/using_b2_code.html
 #
 ######################################################################
+import os
 import platform
 import re
 import subprocess
 
+import pexpect
+import pytest
+
+from test.helpers import patched_spawn
+
 
 def test_help(cli_version):
     p = subprocess.run(
@@ -26,3 +32,54 @@ def test_help(cli_version):
         expected_name += '.exe'
     assert re.match(r'^_?b2(v\d+)?(\.exe)?$', expected_name)  # test sanity check
     assert f'{expected_name} <command> --help' in p.stdout
+
+
+@pytest.mark.skipif(
+    platform.system() == 'Windows',
+    reason='PTY tests require Unix-like system',
+)
+def test_help_with_tty(cli_version):
+    """
+    Test that B2 CLI --help works correctly with a real PTY.
+
+    Verifies fix for rst2ansi buffer overflow on Python 3.14+.
+    See: https://github.com/Backblaze/B2_Command_Line_Tool/issues/1119
+
+    NOTE: Works in CI with pytest-xdist, but may not trigger the bug locally.
+    """
+    # Set up environment - remove LINES/COLUMNS to ensure ioctl is called
+    env = os.environ.copy()
+    env.pop('LINES', None)
+    env.pop('COLUMNS', None)
+
+    # Spawn b2 --help with pexpect to create a real PTY
+    # This is where the bug would trigger on Python 3.14 without our fix
+    child = patched_spawn(
+        cli_version,
+        ['--help'],
+        env=env,
+        timeout=10,
+    )
+
+    # Wait for process to complete
+    child.expect(pexpect.EOF)
+
+    # Get the output
+    output = child.before.decode('utf-8', errors='replace')
+
+    # Check exit status
+    child.close()
+    exit_code = child.exitstatus
+
+    # Verify the command succeeded and produced help output
+    assert exit_code == 0, (
+        f'b2 --help failed with exit code {exit_code}.\n'
+        f'This may indicate the buffer overflow bug is not properly handled.\n'
+        f'Output: {output}\n'
+        f'See: https://github.com/Backblaze/B2_Command_Line_Tool/issues/1119'
+    )
+
+    # Verify help output contains expected content
+    assert (
+        'b2 <command>' in output or cli_version in output
+    ), f'Help output does not contain expected content.\nOutput: {output}'