4040log = logging .getLogger (__name__ )
4141
4242
43+ def _get_windows_ansi_encoding ():
44+ """Get the encoding specified by the Windows system-wide ANSI active code page."""
45+ # locale.getencoding may work but is only in Python 3.11+. Use the registry instead.
46+ import winreg
47+
48+ hklm_path = R"SYSTEM\CurrentControlSet\Control\Nls\CodePage"
49+ with winreg .OpenKey (winreg .HKEY_LOCAL_MACHINE , hklm_path ) as key :
50+ value , _ = winreg .QueryValueEx (key , "ACP" )
51+ return f"cp{ value }
52+
53+
4354@sumtype
4455class WinBashStatus :
4556 """Status of bash.exe for native Windows. Affects which commit hook tests can pass.
4657
47- Call :meth:`check` to check the status.
48-
49- The :class:`CheckError` and :class:`WinError` cases should not typically be used in
50- ``skip`` or ``xfail`` mark conditions, because they represent unexpected situations.
58+ Call check() to check the status. (CheckError and WinError should not typically be
59+ used to trigger skip or xfail, because they represent unexpected situations.)
5160 """
5261
5362 Inapplicable = constructor ()
5463 """This system is not native Windows: either not Windows at all, or Cygwin."""
5564
5665 Absent = constructor ()
57- """No command for `` bash.exe`` is found on the system."""
66+ """No command for bash.exe is found on the system."""
5867
5968 Native = constructor ()
60- """Running `` bash.exe`` operates outside any WSL distribution (as with Git Bash)."""
69+ """Running bash.exe operates outside any WSL distribution (as with Git Bash)."""
6170
6271 Wsl = constructor ()
63- """Running `` bash.exe`` calls `` bash`` in a WSL distribution."""
72+ """Running bash.exe calls bash in a WSL distribution."""
6473
6574 WslNoDistro = constructor ("process" , "message" )
66- """Running `` bash.exe` tries to run bash on a WSL distribution, but none exists."""
75+ """Running bash.exe tries to run bash on a WSL distribution, but none exists."""
6776
6877 CheckError = constructor ("process" , "message" )
69- """Running `` bash.exe`` fails in an unexpected error or gives unexpected output."""
78+ """Running bash.exe fails in an unexpected error or gives unexpected output."""
7079
7180 WinError = constructor ("exception" )
72- """`` bash.exe`` may exist but can't run. `` CreateProcessW`` fails unexpectedly."""
81+ """bash.exe may exist but can't run. CreateProcessW fails unexpectedly."""
7382
7483 @classmethod
7584 def check (cls ):
76- """Check the status of the ``bash.exe`` :func:`index.fun.run_commit_hook` uses.
77-
78- This uses EAFP, attempting to run a command via ``bash.exe``. Which ``bash.exe``
79- is used can't be reliably discovered by :func:`shutil.which`, which approximates
80- how a shell is expected to search for an executable. On Windows, there are major
81- differences between how executables are found by a shell and otherwise. (This is
82- the cmd.exe Windows shell, and shouldn't be confused with bash.exe itself. That
83- the command being looked up also happens to be an interpreter is not relevant.)
84-
85- :func:`index.fun.run_commit_hook` uses :class:`subprocess.Popen`, including when
86- it runs ``bash.exe`` on Windows. It doesn't pass ``shell=True`` (and shouldn't).
87- On Windows, `Popen` calls ``CreateProcessW``, which checks some locations before
88- using the ``PATH`` environment variable. It is expected to try the ``System32``
89- directory, even if another directory containing the executable precedes it in
90- ``PATH``. (The other differences are less relevant here.) When WSL is present,
91- even with no distributions, ``bash.exe`` usually exists in ``System32``, and
92- `Popen` finds it even if another ``bash.exe`` precedes it in ``PATH``, as on CI.
93- If WSL is absent, ``System32`` may still have ``bash.exe``, as Windows users and
94- administrators occasionally put executables there in lieu of extending ``PATH``.
85+ """Check the status of the bash.exe that run_commit_hook will try to use.
86+
87+ This runs a command with bash.exe and checks the result. On Windows, shell and
88+ non-shell executable search differ; shutil.which often finds the wrong bash.exe.
89+
90+ run_commit_hook uses Popen, including to run bash.exe on Windows. It doesn't
91+ pass shell=True (and shouldn't). On Windows, Popen calls CreateProcessW, which
92+ checks some locations before using the PATH environment variable. It is expected
93+ to try System32, even if another directory with the executable precedes it in
94+ PATH. When WSL is present, even with no distributions, bash.exe usually exists
95+ in System32; Popen finds it even if a shell would run another one, as on CI.
96+ (Without WSL, System32 may still have bash.exe; users sometimes put it there.)
9597 """
9698 if os .name != "nt" :
9799 return cls .Inapplicable ()
@@ -124,39 +126,35 @@ def check(cls):
124126
125127 @staticmethod
126128 def _decode (stdout ):
127- """Decode `` bash.exe`` output as best we can. (This is used only on Windows.) """
129+ """Decode bash.exe output as best we can."""
128130 # When bash.exe is the WSL wrapper but the output is from WSL itself rather than
129131 # code running in a distribution, the output is often in UTF-16LE, which Windows
130132 # uses internally. The UTF-16LE representation of a Windows-style line ending is
131133 # rarely seen otherwise, so use it to detect this situation.
132134 if b"\r \0 \n \0 " in stdout :
133135 return stdout .decode ("utf-16le" )
134136
135- import winreg
136-
137- # At this point, the output is probably either empty or not UTF-16LE. It's often
138- # UTF-8 from inside a WSL distro or a non-WSL bash shell. But our test command
139- # only uses the ASCII subset, so it's safe to guess wrong for that command's
140- # output. Errors from inside a WSL distro or non-WSL bash.exe are arbitrary, but
141- # unlike WSL's own messages, go to stderr, not stdout. So we can try the system
142- # active code page first. (Although console programs usually use the OEM code
143- # page, the ACP seems more accurate here. For example, on en-US Windows set to
144- # fr-FR, the message, if not UTF-16LE, is windows-1252, same as the ACP, while
145- # the OEM code page on such a system defaults to 437, which can't decode it.)
146- hklm_path = R"SYSTEM\CurrentControlSet\Control\Nls\CodePage"
147- with winreg .OpenKey (winreg .HKEY_LOCAL_MACHINE , hklm_path ) as key :
148- value , _ = winreg .QueryValueEx (key , "ACP" )
137+ # At this point, the output is either blank or probably not UTF-16LE. It's often
138+ # UTF-8 from inside a WSL distro or non-WSL bash shell. Our test command only
139+ # uses the ASCII subset, so we can safely guess a wrong code page for it. Errors
140+ # from such an environment can contain any text, but unlike WSL's own messages,
141+ # they go to stderr, not stdout. So we can try the system ANSI code page first.
142+ # (Console programs often use the OEM code page, but the ACP seems more accurate
143+ # here. For example, on en-US Windows with the original system code page but the
144+ # display language set to fr-FR, the message, if not UTF-16LE, is windows-1252,
145+ # same as the ACP, while the OEMCP is 437, which can't decode its accents.)
146+ acp = _get_windows_ansi_encoding ()
149147 try :
150- return stdout .decode (f"cp { value } "
148+ return stdout .decode (acp )
151149 except UnicodeDecodeError :
152150 pass
153151 except LookupError as error :
154152 log .warning ("%s" , str (error )) # Message already says "Unknown encoding:".
155153
156- # Assume UTF-8. If we don't have valid UTF-8 , substitute Unicode replacement
157- # characters. (For example, on zh-CN Windows set to fr-FR, error messages from
158- # WSL itself, if not UTF-16LE, are in windows-1252, even though the ACP and OEM
159- # code pages are 936; decoding as code page 936 or as UTF-8 both have errors.)
154+ # Assume UTF-8. If invalid , substitute Unicode replacement characters. (For
155+ # example, on zh-CN Windows set to display fr-FR, errors from WSL itself, if not
156+ # UTF-16LE, are in windows-1252, even though the ANSI and OEM code pages both
157+ # default to 936, and decoding as code page 936 or as UTF-8 both have errors.)
160158 return stdout .decode ("utf-8" , errors = "replace" )
161159
162160
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