set-fuzzy-libmath.py

#!/usr/bin/env python3

# TODO rewrite this script in bash to avoid the python3 dependency

import argparse
import os
import textwrap

ld_preload_file = "/etc/ld.so.preload"
fuzzy_libmath_root = "/opt/mca-libmath"

versions = ["no-fuzzy", "fast", "standard", "quad", "mpfr"]

libmath_so = "libmath.so"


def switch_version(version):
    try:
        with open(ld_preload_file, encoding="utf-8") as fi:
            current_so = fi.readline().strip().split()
    except FileNotFoundError:
        current_so = []

    new_so = [so for so in current_so if not so.startswith(fuzzy_libmath_root)]

    if version != "no-fuzzy":
        new_version = os.path.join(fuzzy_libmath_root, version, libmath_so)
        new_so.append(new_version)

    to_write = " ".join(new_so)

    with open(ld_preload_file, "w", encoding="utf-8") as fo:
        fo.write(to_write)


def parse_args():
    help_msg = """\
    Fuzzy libmath version to use:
        - no-fuzzy: Disable fuzzy libmath
        - fast:     Use the standard libmath available on the system.
                    Not possible to modify the virtual precision!
                    Fastest instrumentation but possibly not accurate
        - standard: Use the standard libmath available on the system.
                    Fast instrumentation but possibly not accurate
        - quad:     Use the libquadmath for intermediate results.
                    Slower than the standard version but more accurate.
        - mpfr:     Use the mpfr library for intermediate results.
                    Slowest version but gives the correct rounding.
    """

    parser = argparse.ArgumentParser(
        "set-fuzzy-libmath",
        formatter_class=argparse.RawTextHelpFormatter,
        epilog=textwrap.dedent(help_msg),
    )
    parser.add_argument("--version", required=True, choices=versions, action="store")
    args = parser.parse_args()
    return args


def main():
    args = parse_args()
    switch_version(args.version)


if "__main__" == __name__:
    main()