"""

Get bytes from the given url or local cache.

Parameters

----------

url : str

The url to download.

sha : str

The sha256 of the file.

Returns

-------

BytesIO

The file loaded into memory.

"""

cache_dir = _get_xdg_cache_dir()

if cache_dir is not None: # Try to read from cache.

try:

data = (cache_dir / version).read_bytes()

except OSError:

pass

else:

return BytesIO(data)

with urllib.request.urlopen(

urllib.request.Request(url, headers={"User-Agent": ""})

) as req:

data = req.read()

if cache_dir is not None: # Try to cache the downloaded file.

try:

cache_dir.mkdir(parents=True, exist_ok=True)

with open(cache_dir / version, "xb") as fout:

fout.write(data)

except OSError:

pass

"""

Return the XDG cache directory.

See

https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html

"""

cache_dir = os.environ.get("XDG_CACHE_HOME")

if not cache_dir:

cache_dir = os.path.expanduser("~/.cache")

if cache_dir.startswith("~/"): # Expansion failed.

return None