1 files changed, 77 insertions, 0 deletions
diff --git a/gitlint-core/gitlint/shell.py b/gitlint-core/gitlint/shell.py
new file mode 100644
index 0000000..365c65d
--- /dev/null
+++ b/gitlint-core/gitlint/shell.py
@@ -0,0 +1,77 @@
+
+"""
+This module implements a shim for the 'sh' library, mainly for use on Windows (sh is not supported on Windows).
+We might consider removing the 'sh' dependency altogether in the future, but 'sh' does provide a few
+capabilities wrt dealing with more edge-case environments on *nix systems that are useful.
+"""
+
+import subprocess
+from gitlint.utils import USE_SH_LIB, DEFAULT_ENCODING
+
+
+def shell(cmd):
+    """ Convenience function that opens a given command in a shell. Does not use 'sh' library. """
+    with subprocess.Popen(cmd, shell=True) as p:
+        p.communicate()
+
+
+if USE_SH_LIB:
+    from sh import git  # pylint: disable=unused-import,import-error
+    # import exceptions separately, this makes it a little easier to mock them out in the unit tests
+    from sh import CommandNotFound, ErrorReturnCode  # pylint: disable=import-error
+else:
+
+    class CommandNotFound(Exception):
+        """ Exception indicating a command was not found during execution """
+        pass
+
+    class ShResult:
+        """ Result wrapper class. We use this to more easily migrate from using https://amoffat.github.io/sh/ to using
+        the builtin subprocess module """
+
+        def __init__(self, full_cmd, stdout, stderr='', exitcode=0):
+            self.full_cmd = full_cmd
+            self.stdout = stdout
+            self.stderr = stderr
+            self.exit_code = exitcode
+
+        def __str__(self):
+            return self.stdout
+
+    class ErrorReturnCode(ShResult, Exception):
+        """ ShResult subclass for unexpected results (acts as an exception). """
+        pass
+
+    def git(*command_parts, **kwargs):
+        """ Git shell wrapper.
+        Implemented as separate function here, so we can do a 'sh' style imports:
+        `from shell import git`
+        """
+        args = ['git'] + list(command_parts)
+        return _exec(*args, **kwargs)
+
+    def _exec(*args, **kwargs):
+        pipe = subprocess.PIPE
+        popen_kwargs = {'stdout': pipe, 'stderr': pipe, 'shell': kwargs.get('_tty_out', False)}
+        if '_cwd' in kwargs:
+            popen_kwargs['cwd'] = kwargs['_cwd']
+
+        try:
+            with subprocess.Popen(args, **popen_kwargs) as p:
+                result = p.communicate()
+        except FileNotFoundError as e:
+            raise CommandNotFound from e
+
+        exit_code = p.returncode
+        stdout = result[0].decode(DEFAULT_ENCODING)
+        stderr = result[1]  # 'sh' does not decode the stderr bytes to unicode
+        full_cmd = '' if args is None else ' '.join(args)
+
+        # If not _ok_code is specified, then only a 0 exit code is allowed
+        ok_exit_codes = kwargs.get('_ok_code', [0])
+
+        if exit_code in ok_exit_codes:
+            return ShResult(full_cmd, stdout, stderr, exit_code)
+
+        # Unexpected error code => raise ErrorReturnCode
+        raise ErrorReturnCode(full_cmd, stdout, stderr, p.returncode)