POC or MVP: Succeeds checking shfmt on Windows which uses bash. Requires that bash is meaningful (WSL, MSys64) on the command prompt, and shfmt is installed in the bash environment.

.pre-commit-config.yaml

@@ -40,3 +40,11 @@ repos:
     hooks:
     -   id: check-hooks-apply
     -   id: check-useless-excludes
+    # Requires to be run under `bash`.
+    # Requires installation of additional tools. Tools are available on Windows.
+    # shfmt: https://github.com/mvdan/sh/releases
+-   repo: https://github.com/syntaqx/git-hooks
+    rev: v0.0.16
+    hooks:
+    -   id: shfmt
+        args: [-i 4, -w, -s]

bash_script.sh

@@ -0,0 +1,2 @@
+#!/bin/bash
+set -Eeuo pipefail

pre_commit/ShelPathConv.py

@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+"""."""
+import glob
+import os
+import pathlib
+import re
+import subprocess
+import sys
+
+GLOB_PATTERN = re.compile(r'([^:/\\])(?=[/\\]|$)')
+
+
+def GetRealCasePath(path):
+    """Convert a case preserving path to a case sensitive compatible path."""
+    drive, tail = os.path.splitdrive(path)
+    return next(
+        iter(glob.glob(''.join((drive, re.sub(GLOB_PATTERN, r'[\1]', tail))))),
+        path,
+    )
+
+
+def ConvertPath(path, prefix, drive_letter_case):
+    """Convert a Windows path to a POSIX path."""
+    if os.path.exists(path):
+        path = GetRealCasePath(path)
+        drive, tail = os.path.splitdrive(path)
+        if drive and not os.path.isabs(path):
+            drive, tail = os.path.splitdrive(os.path.abspath(path))
+        if drive and drive[1:2] == r':':
+            path = (
+                prefix /
+                drive_letter_case(drive[0]) /
+                pathlib.PureWindowsPath(tail[1:]).as_posix()
+            ).as_posix()
+        else:
+            path = pathlib.PureWindowsPath(path).as_posix()
+    return path
+
+
+def ConvertArgsWin32(*args):
+    """Convert all path like arguments from Windows to POSIX."""
+    path = os.path.abspath(os.environ.get('SystemRoot'))
+    if not path or path[1:2] != r':':
+        return args
+
+    try:
+        nix_path = subprocess.run(
+            [args[0], '-c', 'pwd'],
+            check=True,
+            cwd=path,
+            stdout=subprocess.PIPE,
+            universal_newlines=True,
+        ).stdout.strip()
+    except Exception:
+        return args
+
+    path = pathlib.PureWindowsPath(
+        os.path.splitdrive(GetRealCasePath(path))[1],
+    ).as_posix()
+    prefix, nix_path, tail = (
+        pathlib.PurePosixPath(nix_path).as_posix().partition(path)
+    )
+    if not prefix or nix_path != path or tail:
+        return args
+
+    drive_letter_case = (
+        (lambda s: s.upper())
+        if prefix[-1:].isupper()
+        else (lambda s: s.lower())
+        if prefix[-1:].islower()
+        else (lambda s: s)
+    )
+    prefix = pathlib.PurePosixPath(prefix[0:-1])
+
+    return [args[0]] + [
+        ConvertPath(arg, prefix, drive_letter_case) for arg in args[1:]
+    ]
+
+
+ConvertArgs = (
+    ConvertArgsWin32 if sys.platform == 'win32' else (lambda *args: args)
+)
+
+if __name__ == '__main__':
+    print(*ConvertArgs(*sys.argv[1:]))

pre_commit/parse_shebang.py

@@ -4,6 +4,9 @@ from __future__ import unicode_literals
 import os.path
 
 from identify.identify import parse_shebang_from_file
+from identify.identify import tags_from_path
+
+from pre_commit import ShelPathConv
 
 
 class ExecutableNotFoundError(OSError):
@@ -71,10 +74,12 @@ def normalize_cmd(cmd):
     # Use PATH to determine the executable
     exe = normexe(cmd[0])
 
+    convert = 'shell' in tags_from_path(exe)
+
     # Figure out the shebang from the resulting command
     cmd = parse_filename(exe) + (exe,) + cmd[1:]
 
     # This could have given us back another bare executable
     exe = normexe(cmd[0])
-
-    return (exe,) + cmd[1:]
+    cmd = (exe,) + cmd[1:]
+    return ShelPathConv.ConvertArgs(*cmd) if convert else cmd