sage-bootstrap-python

#!/bin/sh

# Run the system python.
#
# This is only for use by the build toolchain.
#
# (It has nothing to do with the python3 that configure --with-system-python3
# is looking for in build/pkgs/python3/spkg-configure.m4.)

if [ -z "$SAGE_ORIG_PATH" ]; then
    # If not we're running from within sage-env just set the existing path
    SAGE_ORIG_PATH="$PATH"
fi
IFS=':'
NEW_PATH=""
for path in $SAGE_ORIG_PATH
do
    case "$path" in
        */.pyenv/shims*);;
        *) NEW_PATH="$NEW_PATH$path:";;
    esac
done
unset IFS
SAGE_ORIG_PATH=${NEW_PATH%%':'}
# In particular, it is invoked by "bootstrap -d" for sage-download-file,
# i.e., before a configure run, and by "sage-spkg", also for sage-download-file.
# So it needs to find a python that has the urllib module.
# For example, on Debian buster, the python3-minimal package does NOT provide it.
#
# Also, Issue #20023 removed the vendored argparse library from sage_bootstrap,
# so we test that python is new enough (>= 2.7) to run it.
#
# See https://github.com/sagemath/sage/issues/29090

# Issue #29890: Our first choice is "python", not "python3". This is to avoid
# a defect of sage_bootstrap on macOS regarding SSL URLs.

# Issue #30177: Also check for hashlib.sha1 to guard against broken python2
# from old homebrew installations.  Also check whether the current directory
# is accessible by this python; this is to guard on WSL against Pythons
# installed somewhere else in Windows.

# Issue #29285: Do not accept pythons that manipulate PATH, such as
# the shims provided by pyenv.

# Issue #30008: Make it work even if the environment tries to sabotage UTF-8
# operation in Python 3.0.x-3.6.x by setting LC_ALL=C or similar.

if [ "$LC_ALL" = "C" -o "$LANG" = "C" -o "$LC_CTYPE" = "C" ]; then
    LC_ALL=$(locale -a | grep -E -i '^(c|en_us)[-.]utf-?8$' | head -n 1)
    LANG=$LC_ALL
    export LC_ALL
    export LANG
fi

PYTHONS="python python3 python3.12 python3.11 python3.10 python3.9 python3.8 python3.7 python2.7 python3.6 python2"
# Issue #32405: Prefer a Python that provides ssl with SNI, which allows developers
# to download from upstream URLs (configure --enable-download-from-upstream-url),
# in particular from PyPI, which requires SNI.
for PY in $PYTHONS; do
    PYTHON="$(PATH="$SAGE_ORIG_PATH" command -v $PY)"
    if [ -n "$PYTHON" ]; then
        if CHECK_PATH="$PATH" "$PYTHON" -c "import argparse; import urllib; from hashlib import sha1; from ssl import HAS_SNI; assert HAS_SNI; from os import listdir, environ; listdir(\"$(pwd)\"); assert environ[\"PATH\"] == environ[\"CHECK_PATH\"];" 2>/dev/null; then
            exec "$PYTHON" "$@"
        fi
    fi
done
# Second round, no ssl/SNI test.
for PY in $PYTHONS; do
    PYTHON="$(PATH="$SAGE_ORIG_PATH" command -v $PY)"
    if [ -n "$PYTHON" ]; then
        if CHECK_PATH="$PATH" "$PYTHON" -c "import argparse; import urllib; from hashlib import sha1; from os import listdir, environ; listdir(\"$(pwd)\"); assert environ[\"PATH\"] == environ[\"CHECK_PATH\"];" 2>/dev/null; then
            exec "$PYTHON" "$@"
        fi
    fi
done
echo >&2 "$0: error: none of $PYTHONS is a suitable Python"
exit 1