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import os.path

from typing import Mapping

from typing import Optional

from typing import Tuple

from typing import TYPE_CHECKING

from identify.identify import parse_shebang_from_file

if TYPE_CHECKING:

from typing import NoReturn

class ExecutableNotFoundError(OSError):

def to_output(self) -> Tuple[int, bytes, None]:

return (1, self.args[0].encode(), None)

def parse_filename(filename: str) -> Tuple[str, ...]:

if not os.path.exists(filename):

return ()

else:

return parse_shebang_from_file(filename)

def find_executable(

exe: str, _environ: Optional[Mapping[str, str]] = None,

) -> Optional[str]:

exe = os.path.normpath(exe)

if os.sep in exe:

return exe

environ = _environ if _environ is not None else os.environ

if 'PATHEXT' in environ:

exts = environ['PATHEXT'].split(os.pathsep)

possible_exe_names = tuple(f'{exe}{ext}' for ext in exts) + (exe,)

else:

possible_exe_names = (exe,)

for path in environ.get('PATH', '').split(os.pathsep):

for possible_exe_name in possible_exe_names:

joined = os.path.join(path, possible_exe_name)

if os.path.isfile(joined) and os.access(joined, os.X_OK):

return joined

else:

return None

def normexe(orig: str) -> str:

def _error(msg: str) -> 'NoReturn':

raise ExecutableNotFoundError(f'Executable `{orig}` {msg}')

if os.sep not in orig and (not os.altsep or os.altsep not in orig):

exe = find_executable(orig)

if exe is None:

_error('not found')

return exe

elif os.path.isdir(orig):

_error('is a directory')

elif not os.path.isfile(orig):

_error('not found')

elif not os.access(orig, os.X_OK): # pragma: win32 no cover

_error('is not executable')

else:

return orig

def normalize_cmd(cmd: Tuple[str, ...]) -> Tuple[str, ...]:

"""Fixes for the following issues on windows

- https://bugs.python.org/issue8557

- windows does not parse shebangs

This function also makes deep-path shebangs work just fine

"""

# Use PATH to determine the executable

exe = normexe(cmd[0])

# 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:]

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