Build executable from Python

October 28, 2020

We often use executables from Python with data transfer via:

stdin/stdout (small transfers, less than a megabyte)
temporary files (arbitrarily large data)

This provides a language-agnostic interface that we can use from other scripted languages like Matlab or Julia, future-proofing our efforts at the price of some runtime efficiency due to the out-of-core data transfer.

Here is a snipping we use to compile a single C code executable from Python (from GeoRINEX program):

"""
save this in say src/mypkg/build.py
then from the code that needs the output executable, say "myprog.bin":

from .build import build
exe = "myprog.bin"
...
if not exe.is_file():
    build("src/myprog.c")
# code that passes data via stdin/stdout and/or files using subprocess.run()

"""
import subprocess
import shutil
from pathlib import Path


def build(src: Path, cc: str = None) -> int:
    """

    Parameters
    ----------

    src: pathlib.Path
        path to single C source file.
    cc: str, optional
        desired compiler path or name

    Returns
    -------

    ret: int
        return code from compiler (0 is success)
    """
    if cc:
        return do_compile(cc, src)

    compilers = ["cc", "gcc", "clang", "icx", "clang-cl"]
    ret = 1
    for cc in compilers:
        if shutil.which(cc):
            ret = do_compile(cc, src)
            if ret == 0:
                break

    return ret


def do_compile(cc: str, src: Path) -> int:
    if not src.is_file():
        raise FileNotFoundError(src)

    if cc.endswith("cl"):  # msvc-like
        cmd = [cc, str(src), f"/Fe:{src.parent}"]
    else:
        cmd = [cc, str(src), "-O2", f"-o{src.with_suffix('.bin')}"]

    ret = subprocess.run(cmd).returncode

    return ret