qemu/tests/functional/qemu_test/asset.py

# Test utilities for fetching & caching assets
#
# Copyright 2024 Red Hat, Inc.
#
# This work is licensed under the terms of the GNU GPL, version 2 or
# later.  See the COPYING file in the top-level directory.

import hashlib
import logging
import os
import subprocess
import urllib.request
from pathlib import Path
from shutil import copyfileobj


# Instances of this class must be declared as class level variables
# starting with a name "ASSET_". This enables the pre-caching logic
# to easily find all referenced assets and download them prior to
# execution of the tests.
class Asset:

    def __init__(self, url, hashsum):
        self.url = url
        self.hash = hashsum
        cache_dir_env = os.getenv('QEMU_TEST_CACHE_DIR')
        if cache_dir_env:
            self.cache_dir = Path(cache_dir_env, "download")
        else:
            self.cache_dir = Path(Path("~").expanduser(),
                                  ".cache", "qemu", "download")
        self.cache_file = Path(self.cache_dir, hashsum)
        self.log = logging.getLogger('qemu-test')

    def __repr__(self):
        return "Asset: url=%s hash=%s cache=%s" % (
            self.url, self.hash, self.cache_file)

    def _check(self, cache_file):
        if self.hash is None:
            return True
        if len(self.hash) == 64:
            sum_prog = 'sha256sum'
        elif len(self.hash) == 128:
            sum_prog = 'sha512sum'
        else:
            raise Exception("unknown hash type")

        checksum = subprocess.check_output(
            [sum_prog, str(cache_file)]).split()[0]
        return self.hash == checksum.decode("utf-8")

    def valid(self):
        return self.cache_file.exists() and self._check(self.cache_file)

    def fetch(self):
        if not self.cache_dir.exists():
            self.cache_dir.mkdir(parents=True, exist_ok=True)

        if self.valid():
            self.log.debug("Using cached asset %s for %s",
                           self.cache_file, self.url)
            return str(self.cache_file)

        self.log.info("Downloading %s to %s...", self.url, self.cache_file)
        tmp_cache_file = self.cache_file.with_suffix(".download")

        try:
            resp = urllib.request.urlopen(self.url)
        except Exception as e:
            self.log.error("Unable to download %s: %s", self.url, e)
            raise

        try:
            with tmp_cache_file.open("wb+") as dst:
                copyfileobj(resp, dst)
        except:
            tmp_cache_file.unlink()
            raise
        try:
            # Set these just for informational purposes
            os.setxattr(str(tmp_cache_file), "user.qemu-asset-url",
                        self.url.encode('utf8'))
            os.setxattr(str(tmp_cache_file), "user.qemu-asset-hash",
                        self.hash.encode('utf8'))
        except Exception as e:
            self.log.debug("Unable to set xattr on %s: %s", tmp_cache_file, e)
            pass

        if not self._check(tmp_cache_file):
            tmp_cache_file.unlink()
            raise Exception("Hash of %s does not match %s" %
                            (self.url, self.hash))
        tmp_cache_file.replace(self.cache_file)

        self.log.info("Cached %s at %s" % (self.url, self.cache_file))
        return str(self.cache_file)