Allow relative Python executable paths in Windows trampoline (#3717)
## Summary
This is a prerequisite for https://github.com/astral-sh/uv/issues/3669
## Test Plan
Download one of the standalone distributions on Windows then use its
Python to run the following script and then run the scripts it creates
(only pip):
```python
from __future__ import annotations
import sys
import sysconfig
from contextlib import closing
from importlib.metadata import entry_points
from io import BytesIO
from os.path import relpath
from pathlib import Path
from tempfile import TemporaryDirectory
from zipfile import ZIP_DEFLATED, ZipFile, ZipInfo
# Change this line to your real path
LAUNCHERS_DIR = Path('C:\\Users\\ofek\\Desktop\\code\\uv\\crates\\uv-trampoline\\target\\x86_64-pc-windows-msvc\\release')
SCRIPT_TEMPLATE = """\
#!{executable}
# -*- coding: utf-8 -*-
import re
import sys
from {module} import {import_name}
if __name__ == "__main__":
sys.argv[0] = re.sub(r"(-script\\.pyw|\\.exe)?$", "", sys.argv[0])
sys.exit({function}())
"""
def select_entry_points(ep, group):
return ep.select(group=group) if sys.version_info[:2] >= (3, 10) else ep.get(group, [])
def main():
interpreters_dir = Path(sys.executable).parent
scripts_dir = Path(sysconfig.get_path('scripts'))
ep = entry_points()
for group, interpreter_name, launcher_name in (
('console_scripts', 'python.exe', 'uv-trampoline-console.exe'),
('gui_scripts', 'pythonw.exe', 'uv-trampoline-gui.exe'),
):
interpreter = interpreters_dir / interpreter_name
relative_interpreter_path = relpath(interpreter, scripts_dir)
launcher_data = (LAUNCHERS_DIR / launcher_name).read_bytes()
for script in select_entry_points(ep, group):
# https://github.com/astral-sh/uv/tree/main/crates/uv-trampoline#how-do-you-use-it
with closing(BytesIO()) as buf:
# Launcher
buf.write(launcher_data)
# Zipped script
with TemporaryDirectory() as td:
zip_path = Path(td) / 'script.zip'
with ZipFile(zip_path, 'w') as zf:
# Ensure reproducibility
zip_info = ZipInfo('__main__.py', (2020, 2, 2, 0, 0, 0))
zip_info.external_attr = (0o644 & 0xFFFF) << 16
module, _, attrs = script.value.partition(':')
contents = SCRIPT_TEMPLATE.format(
executable=relative_interpreter_path,
module=module,
import_name=attrs.split('.')[0],
function=attrs
)
zf.writestr(zip_info, contents, compress_type=ZIP_DEFLATED)
buf.write(zip_path.read_bytes())
# Interpreter path
interpreter_path = relative_interpreter_path.encode('utf-8')
buf.write(interpreter_path)
# Interpreter path length
interpreter_path_length = len(interpreter_path).to_bytes(4, 'little')
buf.write(interpreter_path_length)
# Magic number
buf.write(b'UVUV')
script_data = buf.getvalue()
script_path = scripts_dir / f'{script.name}.exe'
script_path.write_bytes(script_data)
if __name__ == '__main__':
main()
```
