1# Test utilities for fetching & caching assets
2#
3# Copyright 2024 Red Hat, Inc.
4#
5# This work is licensed under the terms of the GNU GPL, version 2 or
6# later.  See the COPYING file in the top-level directory.
7
8import hashlib
9import logging
10import os
11import subprocess
12import sys
13import unittest
14import urllib.request
15from time import sleep
16from pathlib import Path
17from shutil import copyfileobj
18
19
20# Instances of this class must be declared as class level variables
21# starting with a name "ASSET_". This enables the pre-caching logic
22# to easily find all referenced assets and download them prior to
23# execution of the tests.
24class Asset:
25
26    def __init__(self, url, hashsum):
27        self.url = url
28        self.hash = hashsum
29        cache_dir_env = os.getenv('QEMU_TEST_CACHE_DIR')
30        if cache_dir_env:
31            self.cache_dir = Path(cache_dir_env, "download")
32        else:
33            self.cache_dir = Path(Path("~").expanduser(),
34                                  ".cache", "qemu", "download")
35        self.cache_file = Path(self.cache_dir, hashsum)
36        self.log = logging.getLogger('qemu-test')
37
38    def __repr__(self):
39        return "Asset: url=%s hash=%s cache=%s" % (
40            self.url, self.hash, self.cache_file)
41
42    def _check(self, cache_file):
43        if self.hash is None:
44            return True
45        if len(self.hash) == 64:
46            sum_prog = 'sha256sum'
47        elif len(self.hash) == 128:
48            sum_prog = 'sha512sum'
49        else:
50            raise Exception("unknown hash type")
51
52        checksum = subprocess.check_output(
53            [sum_prog, str(cache_file)]).split()[0]
54        return self.hash == checksum.decode("utf-8")
55
56    def valid(self):
57        return self.cache_file.exists() and self._check(self.cache_file)
58
59    def _wait_for_other_download(self, tmp_cache_file):
60        # Another thread already seems to download the asset, so wait until
61        # it is done, while also checking the size to see whether it is stuck
62        try:
63            current_size = tmp_cache_file.stat().st_size
64            new_size = current_size
65        except:
66            if os.path.exists(self.cache_file):
67                return True
68            raise
69        waittime = lastchange = 600
70        while waittime > 0:
71            sleep(1)
72            waittime -= 1
73            try:
74                new_size = tmp_cache_file.stat().st_size
75            except:
76                if os.path.exists(self.cache_file):
77                    return True
78                raise
79            if new_size != current_size:
80                lastchange = waittime
81                current_size = new_size
82            elif lastchange - waittime > 90:
83                return False
84
85        self.log.debug("Time out while waiting for %s!", tmp_cache_file)
86        raise
87
88    def fetch(self):
89        if not self.cache_dir.exists():
90            self.cache_dir.mkdir(parents=True, exist_ok=True)
91
92        if self.valid():
93            self.log.debug("Using cached asset %s for %s",
94                           self.cache_file, self.url)
95            return str(self.cache_file)
96
97        if os.environ.get("QEMU_TEST_NO_DOWNLOAD", False):
98            raise Exception("Asset cache is invalid and downloads disabled")
99
100        self.log.info("Downloading %s to %s...", self.url, self.cache_file)
101        tmp_cache_file = self.cache_file.with_suffix(".download")
102
103        for retries in range(3):
104            try:
105                with tmp_cache_file.open("xb") as dst:
106                    with urllib.request.urlopen(self.url) as resp:
107                        copyfileobj(resp, dst)
108                break
109            except FileExistsError:
110                self.log.debug("%s already exists, "
111                               "waiting for other thread to finish...",
112                               tmp_cache_file)
113                if self._wait_for_other_download(tmp_cache_file):
114                    return str(self.cache_file)
115                self.log.debug("%s seems to be stale, "
116                               "deleting and retrying download...",
117                               tmp_cache_file)
118                tmp_cache_file.unlink()
119                continue
120            except Exception as e:
121                self.log.error("Unable to download %s: %s", self.url, e)
122                tmp_cache_file.unlink()
123                raise
124
125        try:
126            # Set these just for informational purposes
127            os.setxattr(str(tmp_cache_file), "user.qemu-asset-url",
128                        self.url.encode('utf8'))
129            os.setxattr(str(tmp_cache_file), "user.qemu-asset-hash",
130                        self.hash.encode('utf8'))
131        except Exception as e:
132            self.log.debug("Unable to set xattr on %s: %s", tmp_cache_file, e)
133            pass
134
135        if not self._check(tmp_cache_file):
136            tmp_cache_file.unlink()
137            raise Exception("Hash of %s does not match %s" %
138                            (self.url, self.hash))
139        tmp_cache_file.replace(self.cache_file)
140
141        self.log.info("Cached %s at %s" % (self.url, self.cache_file))
142        return str(self.cache_file)
143
144    def precache_test(test):
145        log = logging.getLogger('qemu-test')
146        log.setLevel(logging.DEBUG)
147        handler = logging.StreamHandler(sys.stdout)
148        handler.setLevel(logging.DEBUG)
149        formatter = logging.Formatter(
150            '%(asctime)s - %(name)s - %(levelname)s - %(message)s')
151        handler.setFormatter(formatter)
152        log.addHandler(handler)
153        for name, asset in vars(test.__class__).items():
154            if name.startswith("ASSET_") and type(asset) == Asset:
155                log.info("Attempting to cache '%s'" % asset)
156                asset.fetch()
157        log.removeHandler(handler)
158
159    def precache_suite(suite):
160        for test in suite:
161            if isinstance(test, unittest.TestSuite):
162                Asset.precache_suite(test)
163            elif isinstance(test, unittest.TestCase):
164                Asset.precache_test(test)
165
166    def precache_suites(path, cacheTstamp):
167        loader = unittest.loader.defaultTestLoader
168        tests = loader.loadTestsFromNames([path], None)
169
170        with open(cacheTstamp, "w") as fh:
171            Asset.precache_suite(tests)
172